Venous axis: Methods of obtaining peripheral venous access in difficult situations
Authors: Bradley A. Wallace, MD; Todd Taylor, MD, Emory University School of Medicine, Department of Emergency Medicine
Editor: Matthew Tews, DO, MS; Medical College of Wisconsin
Both vascular access and bedside ultrasound are vitally important aspects of Emergency Medicine and can often be used in conjunction with one another. Whenever there is difficulty in obtaining peripheral intravenous access by traditional means (i.e., sight or palpation), bedside ultrasound can be a useful adjunct to the procedure and can often succeed when other methods fail. Additionally, using ultrasound at the bedside when obtaining central venous access has become commonplace within Emergency Medicine and throughout the medical field. As vascular access as a whole has been described elsewhere on this site (https://cdemcurriculum.com/vascular-access/), this chapter will focus almost exclusively on using bedside ultrasound as an adjunct when obtaining vascular access.
Ultrasound-Guided Peripheral Intravenous Access
A vast majority of patients in the emergency department will ultimately require peripheral venous access. While venipuncture can be performed on many patients with ease, there are times when obtaining peripheral venous access on patients by traditional means can prove difficult. In situations such as these, the ultrasound machine is a very useful tool with a high success rate.1 Additionally, studies have shown that, when compared to traditional blind venipuncture techniques, ultrasound guided peripheral IV access is frequently more successful on first attempt, requires less time, reduces the number of needle punctures, and improves patient satisfaction.2
Patients on which to consider ultrasound-guided IV access
- Self-proclaimed “hard sticks”
- Patients with end-stage renal disease
- Patients with a history of IV drug abuse
- Obese patients
- Patients with significant edema
- Patients with sickle cell anemia or other blood dyscrasias
- Severely dehydrated patients with poor landmarks
Selecting a Vessel
Location: Sites that are specifically good for ultrasound guided access include:
- Antecubital fossa
- Basilic vein of the medial upper arm
- External jugular vein
Identifying the Vessel
After placing a tourniquet on the patient’s upper arm, use the linear ultrasound probe to evaluate for an appropriate vein making sure to differentiate between vein and artery. The characteristic differentiation between veins and arteries on ultrasound is collapsibility. When applying direct downward pressure with the ultrasound probe, veins should collapse easily while arteries will keep their cross-sectional circular shape.
Clip 1. When gentle downward pressure is applied with the ultrasound probe, veins will easily collapse while arteries will remain patent and often exhibit pulsatility.
Additionally, arteries will have thicker, hyperechoic walls as well as pulsatility when compared to veins.
Image 1. An artery (A) will have thicker, hyperechoic walls (arrows) when compared to veins (V).
If you have identified a vessel that you believe to be a vein but are still uncertain, it can be useful to turn on the ultrasound machine’s color flow. When color flow is turned on, a vein will have a low flow continuous color (or may sometimes be anechoic) while an artery will exhibit a higher velocity pulsatile flow.
Clip 2. The vessel at the center of the clip exhibits pulsatile color flow, indicating that it is an artery. The other vessels in the clip remain anechoic when color flow is turned on, indicating that they are veins.
Once you have identified a vein, it is important to evaluate its depth and size.
According to a 2010 study by Witting et al., ultrasound-guided IV access is more likely to be successful when the vein is:
- Less than 1.5 cm below the skin
- Greater than 0.4 cm in diameter3
When attempting to locate an appropriately sized vein, it can be useful to adjust the depth on the ultrasound machine to 2.0 cm or less. The advantages of this are twofold: it decreases attempts at IV placement on veins that are too deep as well as making superficial veins appear larger on the screen and therefore easier to successfully puncture.
In addition to evaluating the vessel’s depth and size it is a good idea to scan along the vessel lengthwise to determine its degree of tortuosity. If the vein is exceedingly tortuous it can be difficult to thread the IV catheter. Be sure to scan proximally and distally to your proposed puncture site to evaluate the trajectory of the vein.
Once you have identified an appropriate vessel as above, there are two views that can be used on the ultrasound machine for peripheral IV placement: short axis (cross-sectional) or long axis (longitudinal). Each method has its individual advantages and disadvantages, which will be discussed shortly. The supplies needed are the same for either method.
- High frequency linear ultrasound probe
- Sterile gel/lubricant
- Adhesive dressing (e.g., Tegaderm®)
- IV catheter (ideally longer than 1.16 inches)
- Antiseptic solution
Image 2. Supplies needed for an ultrasound guided IV insertion.
Short Axis (Cross-Sectional) Approach
- Apply tourniquet to upper arm
- Cleanse the skin with antiseptic solution
- Place adhesive dressing over ultrasound probe
- Apply sterile gel/lubricant to ultrasound probe over adhesive dressing
- Place ultrasound probe on skin perpendicular to the previously identified vein making sure to keep the cross-section of the vein at the center of the screen
- Ensure that the ultrasound probe indicator is pointing to the patient’s right—i.e., the ultrasound operator’s left—so that the left side of the ultrasound screen corresponds to the ultrasound indicator
Image 3. Orientation of ultrasound probe for short-axis approach. Note the probe indicator pointing to the patient’s right (the operator’s left).
6. Pierce the skin at a 45O angle with the catheter at the center of the probe
7. Identify the hyperechoic needle tip on the screen
- It may be useful to push the catheter up-and-down or fan the probe back-and-forth to help identify the needle tip on the screen
Clip 3. The hyperechoic needle tip is visualized proximal/superficial to the blood vessel. Note that when the needle is gently moved back-and-forth it can be more easily identified.
8. Pierce the vein looking for the “target sign” or “bull’s eye sign” (the hyperechoic needle tip in the center of the anechoic vessel)— you should see a corresponding flash of blood in the catheter once the needle tip has pierced the vessel
Image 4. Hyperechoic needle tip localized in blood vessel in short axis. This is called the “target sign” or “bull’s eye sign.”
9. Once the target sign is visualized, thread the catheter in the usual manner and secure the catheter to the skin with an adhesive dressing
10. The IV should now flush easily and painlessly if placed correctly
Long Axis (Longitudinal) Approach
- Use the same technique as described in steps 1-4 of the short axis approach above
- Place the ultrasound probe on the skin parallel to the axis of the previously identified vein with the probe indicator facing towards the patient’s head
Image 5. Orientation of ultrasound probe for long-axis approach. Note that the probe indicator is pointing towards the patient’s head.
3. Pierce the skin at a 45O angle just distal to the ultrasound probe with the needle at the center of the probe
4. Identify the hyperechoic needle tip on the right side of the screen
5. Advance the needle tip until you visualize it piercing the wall of the vessel on the screen— you will see a corresponding flash of blood in the catheter once the needle has pierced the vessel
Image 6. Hyperechoic needle tip localized in blood vessel in long axis.
6. Thread the catheter in the usual fashion and secure the catheter to the skin with adhesive
7. The IV should now flush easily and painlessly if placed correctly
Comparison of Methods
Both the short axis and long axis approaches have advantages and disadvantages. The main advantage of the short axis method is better lateral resolution (i.e., after piercing the skin, one is able to tell if the needle tip is lateral to the vein). The main drawback to the short axis technique is the requirement of moving the ultrasound probe dynamically to keep the needle tip on the screen.
Image 7. In a short axis view, the location of the ultrasound probe can result in the needle appearing to be in multiple different positions. Though the needle in the image above has gone entirely through the vessel, the needle appears to be proximal to the vessel using position 1, within the vessel using position 2, or through the back wall of the vessel using position 3.
Compared to the short axis method, the long axis technique allows the operator to visualize the entirety of the needle and see in real time as it enters the vein in profile, as illustrated in Image 6 above.
While the short axis method has good lateral resolution, the long axis method can be more technically challenging due to its poor lateral resolution (i.e., the needle can appear to be in the same plane as the vessel despite being just lateral to the vessel). Furthermore, with the long axis approach it can be easy to lose sight of the vein and accidentally re-focus the probe onto an adjacent artery with very small moves of the ultrasound probe.
If one is learning the technique for ultrasound-guided IV access for the first time, the short axis approach has been shown to be easier to learn than the long-axis approach for novice operators.4 Furthermore, a 2011 study demonstrated that the short axis method both resulted in a higher success rate and took less time than the long axis approach.5
The Videos in Clinical Medicine series by The New England Journal of Medicine provides a review of ultrasound-guided IV placement: http://www.nejm.org/doi/full/10.1056/NEJMvcm1005951
Ultrasound-Guided Central Venous Catheter Placement
While many patients in the emergency department can be successfully resuscitated with only peripheral access, some patients will require central venous access. Though central venous catheters have been associated with certain complications (e.g., pneumothorax, arterial puncture, bleeding, and infection), there have been multiple prospective, randomized controlled trials and several meta-analyses that have shown that the use of real-time ultrasound guidance during catheter placement has reduced the number of complications as well as reducing the number of cannulation attempts when compared to using landmarks alone.6-9
Note: Central venous access is discussed in depth elsewhere on this site; as such, this chapter will focus on using ultrasound to locate and cannulate central veins. For further information on central venous catheter placement, including indications, contraindications, and the individual steps required for the entirety of the procedure, please refer to the Vascular Access chapter (https://cdemcurriculum.com/vascular-access/).
The three traditional locations for central venous line placement are the internal jugular vein, the femoral vein, and the subclavian vein. The technique for ultrasound-guided central line placement into the internal jugular vein and femoral vein is nearly identical; as such, the discussion here will focus mainly on placement into the internal jugular vein as it tends to be the favored location for central line placement. While the use of ultrasound for subclavian central line placement is becoming more popular, this is a more advanced technique and will not be discussed in this chapter.
Image 8. Anatomy of major neck vasculature. Both the internal jugular vein and common carotid artery are located in an anatomic triangle formed by the two heads of the sternocleidomastoid muscle and the clavicle. (Image courtesy of Sierra Beck, MD.)
As discussed in the ultrasound-guided peripheral IV access section above, the ultrasound machine can be used to visualize blood vessels in both short axis and long axis. The materials needed are the same for both, though the technique varies slightly. The short axis approach will be discussed first.
- Central line kit (including drape)
- Sterile gown/gloves/cap
- Probe cover kit (with sterile gel)
- Ultrasound machine with linear probe
Image 9. Supplies needed for ultrasound guided central line insertion.
Short Axis Approach—Internal Jugular Vein
- Standing at the head of the bed, place the ultrasound machine to patient’s right or left depending on which internal jugular vein you plan to cannulate. Some operators prefer the machine on the ipsilateral side to the internal jugular vein that is being accessed while others prefer the ultrasound machine on the contralateral side— this is largely a matter of personal preference
- Place patient in Trendelenberg position
- Have patient turn head contralaterally to the desired puncture site
- Apply gel to linear ultrasound probe
- Place probe on patient’s neck just above the clavicle, making sure to have the indicator pointing to the patient’s (and the operator’s) left side so that the left side of the probe corresponds to the left side of the ultrasound machine
- Walk probe proximally and distally in an attempt to find a site where the internal jugular vein is largest and relatively remote from the carotid artery. Keep in mind that movements of the patient’s head may alter vascular anatomy greatly
- Remember that arteries are typically thick-walled, pulsatile, and non-collapsible when applying pressure with the ultrasound probe while veins are thin-walled, non-pulsatile, and collapse easily when applying pressure with the probe (see Clip 1 and Clip 2 above for how to better differentiate arteries and veins).After locating an appropriate puncture site, remove gel from patient’s neck and apply appropriate sterilizing solution (e.g., Chlorhexadine, betadine, etc.)
- Open central line kit, don sterile gown, hat, mask and gloves, and open ultrasound probe cover
- While you hold the ultrasound probe cover, have an assistant apply ultrasound gel to ultrasound probe and drop probe into cover making sure to keep probe cover sterile
Image 10. Sterile gloved hand holding sterile probe cover open while an assistant places the ultrasound probe into the probe cover.
10. Place sterile ultrasound gel on outside of probe cover
11. Anesthetize skin overlying the puncture site
12. Place ultrasound on patient’s neck perpendicular to orientation of vasculature
13. Pierce skin at 45o angle at the center of the ultrasound probe (keeping the vessel in the middle of the screen) making sure to continuously aspirate immediately after piercing skin
Image 11. Ultrasound operator in foreground with sterile gloves piercing skin at 45o angle to the skin at center of the ultrasound probe. Note that the operator is continuously aspirating given that the needle tip has pierced the patient’s skin. In the background of the image, note that the ultrasound image is centered on the hypoechoic internal jugular vein in short axis as the operator is advancing the needle towards the vessel.
14. Identify the hyperechoic needle tip in relation to the internal jugular vein. It may be useful to fan the probe back-and-forth or gently bounce the needle up-and-down in the soft tissue when attempting to locate the needle tip. Be sure to keep the needle tip on the screen by advancing the ultrasound probe along the skin as you advance the needle—this will ensure the you do not inadvertently cannulate the wrong vessel (viz., the artery)
15. Once you note the bull’s eye or target sign (see Image 4 above) you should have aspiration of blood into the syringe
16. When aspiration of blood is confirmed, place the ultrasound probe on the sterile drape, remove the syringe from the needle, and advance the guidewire
17. Remove the needle from the skin
18. Grab the ultrasound probe and place it on the patient’s neck to obtain a longitudinal view of the internal jugular vein. If the wire is appropriately positioned, you will be able to visualize a hyperechoic structure (the wire) in long axis on the ultrasound machine
Image 12. Hyperechoic guidewire localized in internal jugular vein.
19. Complete placement of the central venous catheter using the Seldinger technique and secure the catheter to the skin
20. Obtain chest X-ray to confirm appropriate positioning of central venous catheter
Long Axis Approach—Internal Jugular Vein
- Carry out the same steps as above (steps 1-13)
- Place ultrasound probe on skin parallel to venous structures when surveying vascular anatomy. Ensure that the probe indicator is oriented towards the patient’s head, corresponding to the left side of the ultrasound screen
- When piercing the skin at 45o angle, be sure that the entire vessel is visualized on the screen
- With the probe indicator oriented towards the patient’s head, you should see the needle tip enter the left side of the screen after piercing the skin
- Once you visualize the needle tip enter the vessel (see Image 6 above), you should note aspiration of blood into the syringe
- Place probe onto sterile drape, remove syringe, and thread guidewire
- Place ultrasound probe back onto skin in long axis, attempting to visualize the guidewire within the vessel in long axis— it is critical to verify the location of the guidewire prior to dilation (see Image 12 above)
- Complete placement of the central venous catheter using the Seldinger technique and secure the catheter to the skin
- Obtain chest X-ray to confirm appropriate positioning of central venous catheter and ensure that there is no iatrogenic pneumothorax
Note: The femoral vein can be accessed using the same steps as above. When surveying femoral anatomy, keep in mind that the femoral vein is located medially to the femoral artery.
While both peripheral venous access and central venous access were traditionally performed using palpation or anatomic landmarks, the use of ultrasound for both procedures has become more prevalent in Emergency Medicine. Using ultrasound guidance while performing peripheral IV placement has been shown to be a robust alternative to traditional approaches on patients whom venipuncture has proven difficult while also helping to improve patient satisfaction. Similarly, ultrasound guided central line placement has been shown to decrease both number of attempts at cannulation and complications of the procedure. As such, the ultrasound machine should be a consideration whenever contemplating venous access strategies in the emergency department.
- Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D. Ultrasound-guided brachial and basilic vein cannulation in emergency department patients with difficult intravenous access. Ann Emerg Med. 1999 Dec. 34(6):711-4.
- Costantino TG, Parikh AK, Satz WA, Fojtik JP. Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med. 2005 Nov. 46(5):456-61.
- Witting MD, Schenkel SM, Lawner BJ, Euerle BD. Effects of vein width and depth on ultrasound-guided peripheral intravenous success rates. J Emerg Med. 2010 Jul. 39(1):70-5.
- Blaivas M, Brannam L, Fernandez E. Short-axis versus long-axis approaches for teaching ultrasound-guided vascular access on a new inanimate model. Acad Emerg Med. 2003 Dec. 10(12):1307-11.
- Mahler SA, Wang H, Lester C, Skinner J, Arnold TC, Conrad SA. Short- vs long-axis approach to ultrasound-guided peripheral intravenous access: a prospective randomized study. Am J Emerg Med. 2011 Nov. 29(9):1194-7.
- Leung J, Duffy M, Finckh A. Real-time ultrasonographically guided internal jugular vein catheterization in the emergency department increases success rates and reduces complications:a randomized, prospective study. Ann Emerg Med. 2006;48:540-547.
- Karakitsos D, Labropoulos N, De Groot E, et al. Real-time ultrasound guided catheterization of the internal jugular vein: A prospective comparison to the landmark technique in critical care patients. Crit Care. 2006;10:R162.
- Randolph AG, Cook DJ, Gonzales CA, Pribble CG. Ultrasound guidance for placement of central venous catheters: A meta-analysis of the literature. Crit Care Med. 1996;24:2053-2058.
- Hind D, Calvert N, McWilliams R, Davidson A, Paisley S, Beverley C, Thomas S. Ultrasonic locating devices for central venous cannulation: Meta-analysis. BMJ. 2003;327:361.
Methods of obtaining peripheral venous access in difficult situations
The placement of peripheral intravenous lines forms a significant part of the workload of junior medical1
2and, increasingly, nursing staff3-6 in a hospital environment. However, peripheral venous line placement can be difficult, especially at the extremes of age or if the patient is obese, dark skinned, an intravenous drug abuser, is hypotensive or has multiple injuries limiting the number of limbs available for use.
Central venous line placement is not to be undertaken lightly as a substitute for difficult peripheral venous access. The procedures involved usually require a high level of operator skill, as well as conferring a risk of morbidity and mortality.7-9 Central venous lines can, in any case, be inserted via peripheral veins if required.10
We therefore decided to review methods of obtaining peripheral venous access, with emphasis on difficult situations. We believe that proper selection of site and optimal technique will minimise the need for repeated attempts at venous access. We have devised an algorithmic approach to help in this situation.
We carried out a Medline search for the years from 1980 to 1998 using the keywords ‘peripheral venous access’ and ‘venous cannulation’. We chose 35 articles for the purposes of the review. This includes a 1975 reference obtained by cross-referencing the articles initially generated. We also manually searched current textbooks on anaesthetics, intensive care, emergency medicine, phlebotomy and acute paediatrics. All the articles chosen were in the English language.
Methods of improving venous prominence and/or locating peripheral veins
In general, the upper limb is the preferred site for placing an intravenous cannula. This is because of the increased incidence of thrombophlebitis and thrombosis with lower limb infusions,12
13 as well as the need to often immobilise the patient if a drip is sited in the lower limb. The non-dominant upper limb is preferred as an initial option.
An attempt should initially be made to locate visible veins with the limb dependent, that is, below the level of the heart. A visible vein should also be easily compressible in order to qualify for use. The vein should be palpated by the operator’s index finger to determine the relative size of the vessel and the direction in which it runs. A firm to hard non-compressible vein is indicative of thrombosis and not suitable for further efforts at venous access.
If the peripheral veins are not prominent and need to be made more prominent, gentle slapping of the skin overlying the vein may make it more prominent. The mechanism by which this occurs is unclear. This slapping must not be too firm as pain may cause reflex vasoconstriction. Milking the vein from proximal to distal may also increase venous prominence. Venous prominence is further augmented by the use of a proximal venous tourniquet. This can be either a purpose-made tourniquet or the tourniquet effect can be achieved by manual proximal circumferential compression of the limb by an assistant. The tourniquet should be applied 5–10 cm proximal to the selected site. This compression must be sufficient to permit arterial inflow whilst restricting venous outflow. In order to get accurate control of outflow occlusion, a sphygmomanometer cuff may be used. There are various views on what inflation pressure is best for this purpose but consensus opinion appears to indicate a choice of at or just below diastolic pressure.14-16 Manual limb compression by an assistant is difficult to control and, in our experience, a purpose-made tourniquet is preferable. Prolonged application of a venous tourniquet, for more than 5 minutes, increases venous tortuosity and fragility and should thus be avoided.
If venous prominence is not improved by these measures, asking the patient to grip and relax their hands repeatedly, and application of a warm compress (pads soaked in lukewarm water) for at least 2–3 minutes will improve venous visibility. This is achieved by increased local blood flow which increases venous distension. Immersing the limb in warm water may achieve the same effect. The use of betadine swabs is reportedly helpful in dark skinned patients.17 Gently wiping the skin with an alcohol swab may help visualisation of the vein as the reflection of the light off the skin changes.18
Transillumination may help at this stage. The lights in the treatment room need to be turned off and a torch can be placed under the limb to visualise the veins. Venous visualisation may also be possible, even with haematoma formation and with previously punctured veins. The Landry light is a portable battery-operated device which uses a halogen light source delivered through dual fibre-optic arms which rotate 360°. Veins can be identified between the fibre-optic arms as dark lines in the pinker subcutaneous tissue. Surface veins appear darker and more defined than the diffuse lines of deep veins. It does, however, require experience in interpreting visual cues, which is not difficult to acquire.19-21 Topical venodilatation may be achieved by the application of 4% nitroglycerine ointment, smeared onto the skin and left for 2–3 minutes.22-24
A venous distension device has been evaluated in adults in whom non-emergent intravenous cannulation was found to be difficult. This essentially relies on the production of a vacuum around the limb distal to a tourniquet.25
26 The device is a plastic film-covered cardboard mailing tube that can be placed over the forearm. A rubber sleeve attached to the distal end forms a seal after a blood pressure cuff is wrapped around the sleeve and the upper arm. A rubber squeeze bulb is attached to the distal end of the device and is used to generate a vacuum within the device. The cuff is used as a tourniquet. Although initial results were promising, the method does not seem to have gained widespread acceptance.
Infusion of small veins beyond a proximal tourniquet with a bolus of warm crystalloid may help in improving visualisation of larger veins, when large bore access is required.27
Ultrasound-guided venepuncture has been described for placement of central venous lines via peripheral veins.29-33 This is operator dependent, with a long learning curve, but with increasing availability of ultrasound facilities in accident and emergency departments and perhaps on general wards and in clinics, may become an option for the near future. The use of a transversely oriented 7.5 MHz linear transducer is helpful to locate superficial veins (see figure 1) which can be identified even in the presence of oedema. In one study, a hand-held Doppler was felt to accurately identify forearm veins larger than 2 mm in diameter in patients with invisible and impalpable veins, in the presence of a venous tourniquet.34
Transverse scan of right antecubital region, without tourniquet, using 10 MHz linear array probe. A = artery; V = vein; NS = shadow of needle/cannula assembly
Peripheral venous cut-down is suggested as an option for securing venous access in an emergency situation, especially in multiple trauma victims.35 A skin incision can be made directly over either the long saphenous vein in the ankle or the median basilic vein in the elbow. The vein is exposed by blunt dissection and cannulated under direct vision after making a small incision in the wall and ligating the distal end. The cannula is secured with another ligature to the proximal end. Even if the operator is not familiar with this procedure, a catheter over needle assembly can be introduced into the vein under direct vision.
There are a variety of methods described to improve peripheral venous access. The use of a sequential algorithmic approach (see figures 2 and3) and the employment of adjunctive measures should make venepuncture less of an ordeal than it can be. A view has been expressed that structured venepuncture training is essential and we would concur with this view.36
Algorithm for peripheral venous access in adults
Algorithm for peripheral venous access in children
Safe Central Venous Access in an Overburdened Health System | Critical Care Medicine | JAMA
A previously healthy man, intubated in the intensive care unit (ICU) for respiratory failure due to coronavirus disease 2019 (COVID-19), required central venous access for vasopressor infusion. The intensivists were occupied managing other critically ill patients, so an available intern attempted to place a triple-lumen catheter in the right internal jugular vein using only anatomic landmarks for guidance. When the access needle was inserted, pulsatile return of blood was noted.
What Should Be Done Next?
Remove the needle and hold pressure.
Place a small single-lumen catheter to prevent bleeding.
Use a percutaneous closure device to close the puncture site.
Surgically expose the artery to remove the needle and repair the artery.
With immediate recognition of the arterial puncture and only the access needle in place, the needle can safely be removed and prolonged pressure held over the site for 10 to 30 minutes.1 The risk of hematoma or pseudoaneurysm formation is low and can be further reduced by using a small 22-gauge or 25-gauge micropuncture needle for the access.1 The tract should not be dilated by placement of a single-lumen catheter. Percutaneous arterial closure devices have been effectively used off label for repair of iatrogenic carotid artery injuries associated with central venous access when a large-bore catheter has been placed.2 However, given that the artery was not dilated and the catheter was not yet placed, neither percutaneous closure nor surgical repair is indicated. In the unlikely event that despite prolonged pressure a hematoma or pseudoaneurysm results, surgical repair may be required.
This iatrogenic arterial injury associated with a central venous access procedure may have resulted from several factors, including failure to use ultrasound guidance, which is the contemporary standard practice, and central line placement attempt by an inexperienced and likely inadequately trained operator.3
Placement of central venous access, a routine occurrence in critical care units and emergency departments, poses a unique challenge during health care crises when experienced clinicians are overburdened with acutely ill patients. To better utilize the specialized skills of the available workforce and maximize patient safety during the COVID-19 pandemic, central venous access line teams have been developed to address the venous access needs of hospitalized patients.4,5 The teams typically include vascular surgeons, general surgeons, interventional radiologists, and anesthesiologists, all specialists with training and experience in central venous access. During the height of the COVID-19 pandemic and other health care emergencies, elective operations and procedures were deferred, freeing up personnel and resources that could serve on line insertion teams. These specialists also have experience identifying and managing the complications associated with these procedures. Some line insertion teams also placed arterial lines, orogastric and nasogastric tubes, and Foley catheters to further assist other overburdened clinicians.5
To evaluate the implementation and outcomes of these central venous access line teams, a cross-sectional, self-reported multi-institutional study was performed.5 Sixty hospitals in 13 countries and 37 US states contributed data regarding their experiences of creating and implementing line insertion teams. They also reported on technical aspects of the central venous access procedures in the pandemic setting and the management of associated iatrogenic complications. Of the 60 hospitals, 58 had designated teams of clinicians available for central line placement. Most of these hospitals did not have line insertion teams prior to the pandemic. Line insertion team protocols were rapidly developed to address urgent and unique venous access requirements during the pandemic. Most of the participating hospitals were urban, academic, university-affiliated hospitals with more than 400 beds. Data were collected between April 22 and May 4, 2020. Most line insertion teams provided services for ICU patients with positive or pending COVID-19 test results. Some teams also placed lines in COVID-19–negative patients to assist the overburdened ICU teams, and some also placed lines for patients in the medical/surgical units or in the emergency department. All centers continued to adhere to standard practice and use ultrasound guidance for central venous access procedures whenever possible, including confirming wire position in the long-axis ultrasound view.
There were 2657 lines placed in patients with positive, pending, and negative COVID-19 test results in the 20 participating sites that were able to report the total number of lines placed. Of these, 11 (0.41%) line placements were associated with iatrogenic complications, less than the expected complication rate of 4% to 9%.6-9 There were 2 inadvertent arterial catheter placements, 7 puncture-site bleeding episodes (hematoma or active bleeding), 1 pneumothorax, and 1 air embolism. The air embolism was in a patient with COVID-19 who was not intubated, and the patient died shortly thereafter. This was the only death reported from these sites that was directly related to an iatrogenic venous access complication. The lower-than-expected complication rate might have been attributable to the greater level of experience and expertise of the vascular access teams.
Line insertion teams managed a total of 48 iatrogenic complications in COVID-19–positive patients at 23 of the 60 participating sites. Most (39/48) complications were associated with line placement procedures performed by clinicians who were not part of the line insertion team. In 20 of the 48 complications, the participating site reported that the complications were attributable to insufficient operator experience and inadequate use of ultrasound or wire control during the procedures. Every line insertion team reported using ultrasound guidance for all procedures, but this was not the case for lines placed by clinicians who were not associated with the line insertion teams.
When initiating a central venous access line team, an appropriate schedule for the team’s activation should be established based on available resources and institutional needs. Ideally, the team should be available at all times and be able to provide service throughout the hospital; any limitations of hours or sites served should be communicated clearly to all relevant hospital personnel. The activation and conclusion of line insertion team services should be tailored to the needs of the institution and the requirement of the line insertion team members’ expertise in other clinical areas. Understanding variations in individual institutional resource allocation and having open communication between relevant stakeholders is key to providing appropriate, high-quality service to all hospitalized patients at the optimal time and place. In preparation for future surges of the COVID-19 pandemic and other health care emergencies, protocols should be developed that include central venous access line teams composed of physicians with percutaneous vascular access expertise, development of standardized protocols, and a method to track procedural outcomes.
An adequately stocked line cart increases the efficiency of line placements. This cart should have all the supplies and personal protective equipment (PPE) necessary to safely perform the procedures. An appropriately stocked cart minimizes potential clinician exposure to infectious agents and allows for a more streamlined performance. Further increases in the efficiency of clinician utilization can be realized by limiting the number of clinicians in the room performing the procedure to 2, with a runner outside the room to retrieve additional supplies as needed. This likewise can preserve PPE and minimize personnel exposed to infectious agents.
The internal jugular vein was the preferred anatomic location for central venous access used in this study of 60 hospitals during the COVID-19 pandemic due to ease of accessibility by ultrasound. Subclavian lines were discouraged, given the known increased incidence of pneumothorax compared with internal jugular lines. Due to the frequent use of prone positioning in patients with COVID-19, study participants reported successfully placing a triple-lumen catheter in the popliteal vein under ultrasound guidance with techniques commonly used in the lysis of iliofemoral deep vein thrombosis (Video).10 This demonstrates the ability of clinicians with appropriate specialized technical expertise to adapt to unusual challenges that may be imposed by a health care crisis. A caveat of placing central lines in the popliteal vein is a potential increase in the risk of deep vein thrombosis. Thus, each case should be carefully considered and executed with caution.
The needle was removed and pressure was held for 20 minutes. The patient did not develop any clinical signs of a hematoma or pseudoaneurysm during the hospitalization, which was confirmed by ultrasound.
Box Section Ref ID
Even during a health care emergency, standard practices including use of ultrasound guidance for central venous access and prioritization of standard anatomic locations should be maintained to minimize procedural complications.
Dedicated central venous access line teams composed of physicians trained in percutaneous central venous access can ease a stressed health care system during a health care crisis.
Appropriately staffed dedicated central venous access line teams can perform high volumes of procedures with low procedural complication rates.
Planning for future health care emergencies should include protocols for central venous access line teams that describe staffing, a dedicated line cart, recommendations on the optimal anatomic site and technique, and a method to evaluate outcomes.
Corresponding Author: Karen Woo, MD, MS, Division of Vascular Surgery, Department of Surgery, University of California, Los Angeles, 200 UCLA Medical Plaza, Ste 526, Los Angeles, CA 90095 ([email protected]).
Conflict of Interest Disclosures: None reported.
et al. Recommendations on the use of ultrasound guidance for central and peripheral vascular access in adults. J Hosp Med. 2019;14:E1-E22. doi:10.12788/jhm.3287PubMedGoogle ScholarCrossref
Approach to Difficult Vascular Access
Intravenous (IV) access is a basic and invaluable skill for emergency physicians. For patients requiring rapid fluid resuscitation, airway management, or medication administration, the placement of one or more IV lines is absolutely essential. Most patients do well with a simple, landmark-based, blind placement of a superficial peripheral IV. However, we often encounter situations where this may be difficult or impossible to achieve, and so we all should have a repertoire of other sites and techniques to employ.
[su_tabs vertical=”yes”][su_tab title=”US-Guided Deep Peripheral IVs”]
Ultrasound (US)-guided IV placement has been shown to be safe, quick, and patient-friendly in adults and children [1, 2]. In at least 10% of patients, we encounter in the ED, blind insertion of a peripheral IV may be complicated by obesity, edema, IV drug use, surgical scars, dialysis, burns, etc. Obtaining peripheral IV access rapidly can avoid the time and risk associated with central venous catheterization or the discomfort of intraosseous access.
Deep veins of the upper arm are generally larger and are the best targets, especially the basilic and cephalic veins.
Ideal in these situations: Peripheral IV candidates complicated by obesity, IV drug use, or inability to lie flat for procedures
Not ideal in these situations: Central access needed, cardiac arrest
Optimal positioning: Ideally, position patient with shoulder slightly abducted, elbow completely extended, forearm completely supinated. The ultrasound machine should be placed next to the patient’s head or on the opposite side of the bed, so that you turn your neck as little as possible.
- Use a long (1.8 or 2.5 inch) catheter because it typically needs to traverse through more tissue to a deep vein.
- Clean the ultrasound transducer should be cleaned and apply sterile lubricant.
- Apply a tourniquet proximal to the site.
- Use universal precautions.
- Clean the skin just distal to the probe with an antiseptic swab.
- Use the linear ultrasound transducer and adjust the position/depth so that the vessel is in the center of the image.Veins will be thin-walled and easily compressible, compared with arteries that will be thick-walled and non-compressible.
- Insert the needle at a 30-45 degree angle, just distal to the ultrasound probe.
- Slowly sweep the probe proximally as the needle tip moves proximally.
- Once a flash is seen in the IV chamber, the rest of the procedure proceeds similar to the blind technique.
- Drop the angle of the needle about 15 degrees and advance it another 1-2 mm to ensure that both the tip of the catheter and the needle are in the vein.
- Hold the needle in place as the catheter is completely advanced.
Complications: Paresthesias, brachial artery puncture, hematoma formation, IV decannulation
- The best target will be the vein that is the largest and most superficial.
- For deep veins, angle your catheter at a steeper angle than you would for a superficial vein (35-45 degrees).
- You can use the ultrasound to confirm catheter placement afterwards by visualizing tiny bubbles within the vessel during saline flush. Anechoic fluid in the soft tissue suggests extraluminal placement.
[/su_tab] [su_tab title=”External Jugular Vein (EJ)”]
The EJ vein is a great site for rapid IV access. It can often be accessed without ultrasound guidance and is a large vein that can often be used for medication/fluid administration and phlebotomy. Vasoactive medications and radiographic contrast should not be administered due to potential complications such as extravasation and airway compromise. The EJ vein courses over the sternocleidomastoid (SCM) before joining the subclavian vein under the clavicular head of the SCM.
Ideal in these situations: Ultrasound not readily available, EJ vein easily seen on exam
Not ideal in these situations: Unable to visualize landmarks on neck, patient unable to tolerate laying flat
Optimal positioning: Position the patient in Trendelenburg about 10-15 degrees. Turn head slightly away from side of EJ cannulation.
- With the patient positioned properly, cleanse the site and use a finger to provide slight traction next to the vein to anchor it.
- Approach the vein at a 5-10 degrees angle, about midway between the angle of the jaw and the clavicle.
- After a blood flash return in the IV catheter, advance the catheter until the hub is secure against the skin.
Complications: Hematoma, laceration of the deeper internal jugular vein, air embolism, infection, airway compromise
Start at the 1-minute mark for the actual procedure.
[/su_tab] [su_tab title=”Intraosseous (IO) Line”]
Intraosseus (IO) Line
An intraosseus line is used for emergent vascular access when one is unable to obtain peripheral venous access. It allows you to draw almost any lab, including blood cultures and lactate, as well as administer large volumes of fluid, blood, inotropes, and vasopressors. While historically used in pediatric cardiac arrest, IO access is also used in adult resuscitation for rapid vascular access. The most common site for IO access in the anteromedial tibia, 1-2 cm distal to the tibial tuberosity. Alternative sites include the humeral head and the distal femur in the anterior midline above the external epicondyles, 1-3 cm proximal to the femoral plateau.
Ideal in these situations: Cardiac arrest or profound cardiogenic shock, when peripheral or central access have failed or are difficult
Not ideal in these situations: Previous IO attempts in the same bone, osteogenesis imperfecta, osteoporosis, proximal fractures, overlying infection or skin damage
Method: This assumes use of a powered device, such as the EZ-IO.
- Sterilize the insertion site with povidone-iodine, chlorhexidine, or alcohol.
- Use your nondominant hand to stabilize the arm or leg.
- Insert the IO needle perpendicular to the bone. The resistance suddenly decreases once the marrow cavity is entered.
- Remove the trocar.
- Use a 5- to 10-mL syringe to aspirate blood for confirmation.
- Slowly instill lidocaine into the intraosseous space to anesthetize the visceral pain fibers.
- Observe the area for signs of extravasation.
- Secure the needle and immobilize the extremity.
- For humeral IO insertion, be sure the patient’s shoulder is internally rotated (patient’s hand on his/her abdomen).
- Monitor the extremity continuously for compartment syndrome.
- IOs should be removed within 24 hours.
- For removal, connect a Luer lock syringe to the hub of the catheter, and twist clockwise while pulling the needle straight out. Do not rock back and forth which could cause bone cracks.
- Infusion is still going to be painful despite lidocaine.
- EZ-IO drills are not to be used for the sternum like they do in the military. They use a different apparatus.
Central Venous Access
Central venous access is indicated for infusions that require larger, less fragile veins, such as vasopressors, hyperosmolar solutions, and hyperalimentation (Note: vasopressors can be infused peripherally in certain circumstances per EMCrit.) Central access could also be considered when peripheral IV access is very difficult, such as with extensive burns to the body, or if multiple medications need to be infused, or blood draws need to happen frequently. A 2012 Critical Care Medicine systematic review suggests that there is no difference in catheter-related bloodstream infections between the three typical sites: internal jugular, subclavian, and femoral veins. The best site to place a central line can depend on several factors detailed below. Ultimately, line selection is a complex clinical judgment rather than a ‘one size fits all’ strategy. It is driven by setting (level of hemodynamic instability, risks for abrupt crash), patient factors (anxiety, cooperativeness, sedation levels or safety for sedation, airway sustainability/adequacy/patency), operator experience and flexibility, and probable need for multiple drug infusions and therapies.
[su_tabs vertical=”yes”][su_tab title=”Internal Jugular (IJ) Vein”]
The IJ vein is often the ideal site to place a central line. An IJ central line will allow placement of a pulmonary artery catheter or a transvenous pacing wire, as well as for measurement of CVP. The IJ vein typically lies anterolaterally to the carotid artery at the apex of the triangle formed by the clavicle and the two heads of the sternocleidomastoid muscle.
Ideal in these situations: Most central venous access needs
Not ideal in these situations: Patients who cannot lay flat or have respiratory distress, distorted anatomy or trauma at site, suspected cervical spine fracture
Optimal positioning: Place patient in 15 degree Trendelenburg position and rotate patient’s head opposite the site of cannulation.
Method: The standard basic technique on the placement of a central line will not be reviewed here. Please consult your preferred textbook, or watch the videos below to review the procedure.
Complications: Airway compromise from hematoma, pneumothorax, carotid artery puncture, thrombosis, infection
[/su_tab] [su_tab title=”Femoral Vein”]
The femoral vein is a useful site for code/crash situations, where the neck is inaccessible due to active airway management and/or the chest is occupied with ongoing CPR. It it often the easiest site to perform blind central vein cannulation based on landmarks alone, and thus quickest if very rapid central access must be achieved, e.g. in patients in extremis. It is also the site to use if patients cannot lay flat for a subclavian or IJ central line. The femoral vein is classically located medial to the femoral artery, best remembered by the mnemonic NAVEL (from lateral to medial- Nerve, Artery, Vein, Empty space, Lymphatics).
Ideal in these situations: Patients in extremis, code situations, coagulopathic patients, patients who cannot lay flat
Not ideal in these situations: Distorted anatomy or trauma to region, suspected proximal vascular injury (e.g. the IVC)
Optimal positioning: Patient can be sitting about 45 degrees to supine. Externally rotate leg and bend the knee to expose the groin.
Method: Basic technique on the placement of a central line will not be reviewed here. Please consult your preferred textbook, or watch the videos below to review the procedure.
- During chest compressions, pulses may be felt in either the artery or vein. Some would argue that it is safer to always choose intraosseus access in cardiac arrest.
- If you inadvertently start too inferiorly, your needle may be cannulating the greater saphenous vein, in which it is difficult to introduce the guidewire due to its valves and smaller diameter.
Complications: Retroperitoneal hematoma, thrombosis, infection
Placing a femoral central line in a pulseless patient:
NEJM video on femoral central line placement
[/su_tab] [su_tab title=”Subclavian Vein”]
The subclavian vein is another common site, especially when an ultrasound is not available. The subclavian vein is classically located just over the 1st rib. It lies immediately posterior to the medial 1/3 of the clavicle. It is separated from the deeper subclavian artery by the anterior scalene muscle, and is 1-2 cm in diameter.
Ideal in these situations: For any central venous access needs, ultrasound not readily available
Not ideal in these situations: Coagulopathic patients, distorted anatomy or trauma, pneumothorax on opposite site of cannulation, fracture of the clavicle or proximal ribs
Optimal positioning: Place the patient in Trendelenburg position. The vein is kept patent by surrounding costoclavicular ligaments but Trendelenburg position will help prevent air embolism. Place a small towel between the scapulae to reduce deltoid muscle bulge. Abduct arm slightly.
Method: Basic technique on the placement of a central line will not be reviewed here. Please consult your preferred textbook, or watch the videos below to review the procedure.
- Most patients with a malpositioned catheter were into the IJ. Apply external pressure over the base of the IJ vein using a sterile finger during guidewire insertion to prevent the guidewire from going into the IJ. [Ambesh et al 2002]
- Patients with ear pain or a tickling throat sensation during guidewire insertion typically means that the guidewire is in the IJ. [Ambesh et al 2002]
- Avoid placing a subclavian line opposite to a known or suspected pneumothorax, due to the risk of creating bilateral pneumothoraces.
- Try using ultrasound to guide your placement if anatomy is difficult or with patients who have high risk of pneumothorax.
Complications: Pneumothorax, thrombosis, infection
- Costantino TG, Parikh AK, Satz WA, Fojtik JP. Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med. 2005 Nov;46(5):456-61. PMID 16271677
- Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D. Ultrasound-guided brachial and basilic vein cannulation in emergency department patients with difficult intravenous access. Ann Emerg Med. 1999 Dec;34(6):711-4. PMID 10577399
- Shah, Kaushal, and Chilembwe Mason, eds. Essential emergency procedures. Lippincott Williams & Wilkins, 2007.
Additional Reading: Lin, M. (2012). Difficult Vascular Access: Alternative Approaches & Troubleshooting Tips [Powerpoint slides]. Retrieved from UCSF CME Department.
Ultrasound-guided central venous access – The British Journal of Cardiology
Ultrasound guidance is a useful technique to aid central venous access. Alignment of the ultrasound probe and visualisation of the needle is a skill that takes some practice. This article describes how to perform ultrasound guidance to gain central venous access via the internal jugular, femoral and axillary/subclavian veins.
For UK healthcare professionals only
Central venous catheterisation is ubiquitous in hospital practice. Complications may occur in 10% of cases using surface landmark techniques.1,2 When used to locate vessels and give real-time guidance, ultrasound limits these complications.3 The UK National Institute for Health and Clinical Excellence (NICE) suggests ultrasound guidance is used for elective cannulation of the internal jugular vein. However, similar advantages are seen for cannulation of veins and arteries at other sites in elective and acute situations.
Monitor the patient with pulse oximetry, electrocardiography and non-invasive blood pressure measurement. Establish peripheral intravenous access and offer conscious sedation. Place the patient 15o head down with arms supported by their sides. Ensure the field is aseptic, image the vein at the chosen site with the ultrasound and infiltrate the skin and subcutaneous tissues with local anaesthetic.
Ultrasound probes of 7–10 MHz are suitable. Arteries are identifiable as they pulsate and are difficult to compress. Veins are non-pulsatile, easily compressible, have respiratory variation, and distend when the patient is tilted or performs the Valsalva manoeuvre.4,5 Real-time images are easier to interpret because of these dynamic findings. Doppler verification may also be used.
Position the ultrasound display at eye level on the opposite side of the patient to the operator. Place the probe lightly on the skin (the vein will collapse easily). Choose a site where the vein lies side-by- side with the artery (rather than anterior to it) as the vein will often need to be transfixed to puncture its anterior wall. If the vein is transfixed, successful aspiration then occurs on gentle withdrawal of the needle.
Transducer and display set-up
Touch one side of the probe and observe the image to allow orientation. A palpable marker is often present on the side of the transducer corresponding to the marker on the display. Adjust the depth to ensure structures are visualised in the centre of the screen. Alter the gain to create a dark image that allows discrimination of the white dot generated by the needle. Use sterile ultrasound gel inside and outside the protective sterile sheath.
Needles can be guided through tissues directly and indirectly.6
Indirect ultrasound guidance
This involves the identification of a patent non-diseased vessel prior to puncture. Mark the skin and estimate the angle and depth of the needle course. Collateral structures may still be hit if the approach of the needle is not correct.
Direct ultrasound guidance
Table 1. Factors influencing needle visualisation
This involves the use of ultrasound to visualise the needle in real time. There are two techniques – the use of needle guides and freehand puncture. An appreciation of appearances of needles crossing the ultrasound beam in transverse (short axis) and longitudinal (long axis) is required. Other factors affecting needle visualisation are summarised in table 1.
Needle guides direct the needle in a pre-determined direction to various depths from the transducer surface, depending on the selected angle of the guide.7 Guides vary and may be fixed or detachable from the transducer. Guidance lines generated on the display show the projected path of the needle. Adjust the probe so the target vessel lies within the guidance lines and assess the depth. With the probe held still, clamp the needle in the guide and pass it through the tissues either to a pre-determined depth or until the needle tip is positioned in the vessel.
For freehand puncture, hold the needle with one hand and the transducer with the other. This approach provides greater flexibility without having to use secondary instruments and allows for subtle compensatory adjustments.
Short- and long-axis approaches
Insert the needle at a shallow angle until the tip (a white dot) enters the ultrasound beam. Withdraw slightly, realign more steeply and advance until seen again in a deeper position. Repeat, correcting the insertion direction to approach and puncture the vessel centrally. Because this approach gives poorer visualisation of the needle (the needle tip may be mistaken for the needle shaft), the position of the needle tip may need to be re-established by either rocking the transducer or realigning the needle in a more vertical plane. A needle passing through the ultrasound beam in short axis produces an acoustic shadow, seen as a black line passing to the base of the image.
Though this allows better needle visualisation, practice is required to keep the needle precisely within the image plane and the target vessel within the beam. Novices may find this method more difficult.8
Verification of needle-tip placement
Irrespective of the technique used, verify the needle-tip placement by either aspirating blood or noting the vein to re-open following collapse due to the pressure of the advancing needle. The vein wall may occlude the needle tip, which appears to lie within the vessel lumen.
Internal jugular vein cannulation
Figure 2. Cross-sectional images of the right axillary vein (AV), with the cephalic vein (CV) lying anteriorly. The axillary artery (AA) is seen deeper and more cranial. The pleura (P) and chest wall are easily visualised. The ultrasound probe is placed just lateral to medial clavicle with the image orientated to be as seen from patient’s right sideFigure 1. Cross-sectional images of the right internal jugular vein (IJV), partially overlying the right carotid artery (CA) next to the thyroid gland (TG). The centre of the IJV is only 1.5 cm deep to the skin. The images are orientated as seen from the patient’s head
The vein lies surprisingly superficial (1–2 cm) and is close to the carotid artery (figure 1). The thyroid is easily visible with a characteristic grey appearance. Lymph nodes may be mistaken for vessels but are non-compressible and moving the probe up and down shows their outline.
Axillary/subclavian vein cannulation
The conventional flat approach to the subclavian vein is not possible with ultrasound as the clavicle obscures visualisation. Instead, move laterally over the deltopectoral triangle to visualise the axillary artery and vein and branches, in particular the cephalic vein (figure 2). The axillary vein is the continuation of the basilic vein and extends from the outer border of teres major to the outer border of the first rib. On moving laterally to the axillary vein, the artery and vein are further apart, and the rib cage and pleura fall away (a misplaced needle transfixing the vein does not hit vital structures). The brachial plexus is just cephalad to the artery.
Femoral vein cannulation
Figure 4. Cross-sectional images of the right common femoral vessels just below the inguinal ligament, showing the ‘Mickey Mouse sign’. The femoral artery (FA) is depicted on the left and the femoral vein (FV) on the right. The sapheno-femoral junction (SFJ) comprises the long saphenous vein (LSV) and the FVFigure 3. Cross-sectional images of the right femoral vessels approximately 3 cm below the inguinal ligament, orientated to be as seen from patient’s feet. The superficial femoral artery (SFA) partially overlaps the femoral vein (FV). The profunda femoris artery (PFA) is deeper
The side-by-side orientation of the femoral vein, artery and nerve as depicted in anatomy texts is an oversimplification, and only true at the level of the inguinal ligament, which is difficult to palpate in most subjects. Below this level lies the saphenofemoral vein junction, and the arterial bifurcation into deep and superficial femoral branches. The superficial artery overlies the femoral vein, making access difficult. The use of ultrasound allows differentiation of these structures and accurate first pass puncture of the common femoral vein immediately below the inguinal ligament (figures 3 and 4). For arterial access, ultrasound guidance allows the choice of the most appropriate site for puncture in the common femoral artery with avoidance of heavily diseased areas.
Ultrasound guidance is a useful technique to aid central venous access. It is effective in difficult cases,9 allows easy cannulation of the veins10,11 and reduces complications. Similar advantages should apply for arterial access. Though alignment of the ultrasound probe and visualisation of the needle is a skill that takes some practice, the time spent understanding and practising the technique will be repaid many times over when performing invasive procedures.
Conflict of interest
Andrew Bodenham has recieved honoraria from Sonosite for teaching in this area of practice.
- Routine use of ultrasound guidance significantly reduces the risk of procedural complications during central venous access. Practice is required to use it to best effect
- The National Institute for Health and Clinical Excellence (NICE) has recommended its use in central venous access and is auditing compliance in this area
- It can potentially be used at all sites of vascular access including the axillary/subclavian vein and peripheral arteries
- It is particularly useful in the more difficult case
- Mansfield PF, Hohn DC, Fornage BD, Gregurich MA, Ota DM. Complications and failures of subclavian-vein catheterization. N Engl J Med 1994;331:1735–8.
- Sznajder JI, Zveibil FR, Bitterman H, Weiner P, Bursztein S. Central vein catheterization. Failure and complication rates by three percutaneous approaches. Arch Intern Med 1986;146:259–61.
- Randolph AG, Cook DJ, Gonzales CA, Pribble CG. Ultrasound guidance for placement of central venous catheters: a meta-analysis of the literature. Crit Care Med 1996;24:2053–8.
- Armstrong PJ, Sutherland R, Scott DH. The effect of position and different manoeuvres on internal jugular vein diameter size. Acta Anaesthesiol Scand 1994;38:229–31.
- Troianos CA, Jobes DR, Ellison N. Ultrasound-guided cannulation of the internal jugular vein. A prospective, randomized study. Anesth Analg 1991;72:823–6.
- Chapman GA, Johnson D, Bodenham AR. Visualisation of needle position using ultrasonography. Anaesthesia 2006;61:148–58.
- Reid MH. Real-time sonographic needle biopsy guide. Am J Roentgenol 1983;140:162–3.
- Blaivas M, Brannam L, Fernandez E. Short-axis versus long-axis approaches for teaching ultrasound-guided vascular access on a new inanimate model. Acad Emerg Med 2003;10:1307–11.
- Hatfield A, Bodenham A. Portable ultrasound for difficult central venous access. Br J Anaesth 1999;82:822–6.
- Galloway S, Bodenham A. Ultrasound imaging of the axillary vein–anatomical basis for central venous access. Br J Anaesth 2003;90:589–95.
- Sharma A, Bodenham AR, Mallick A. Ultrasound-guided infraclavicular axillary vein cannulation for central venous access. Br J Anaesth 2004;93:188–92.
Integrating Long-Axis and Short-Axis Views with a Twist for Ultrasound-Guided Vascular Access, Part I: Femoral Approach
Jonathan Salcedo, MD, FACC, FHRS
Cardiac Electrophysiology; Palo Alto Medical Foundation – Sutter Health; Silicon Valley Cardiology; Sequoia Hospital, Redwood City, California
Ultrasound-guided vascular access has emerged as a ubiquitous tool used by a variety of specialties, including cardiologists, vascular surgeons, emergency room physicians, and critical care specialists. Studies have shown that femoral artery access guided by ultrasound results in safer outcomes.1 In addition, femoral ultrasound guidance for common electrophysiology procedures has proven to be superior than landmark-guided access to reduce adverse events.2,3 The most common approach to ultrasound-guided access involves using short-axis (ie, transverse axis) views to guide the needle puncture. This article will describe a hybrid approach using both short-axis and long-axis (ie, longitudinal axis) techniques to enhance visualization of the needle tip into the femoral vessel with a twisting motion to further reduce the chance of inadvertent posterior wall puncture.4
A standard linear array probe (5-15 MHz) made by most ultrasound equipment companies (Sonosite, Philips, etc.) provides the best resolution and depth for femoral vessel access. To enhance visualization, an 18-gauge echo-visible needle should be used with every access attempt. A 21-gauge needle can also be used, and there are echo-visible versions available as well. In my experience, an 18-gauge echo-visible needle has a modest advantage over a 21-gauge needle due to enhanced visualization (and thus, confidence of needle tip position), one less step for wire/sheath introduction, and a better bevel-cutting function with a twisting motion. Ideally, the lab staff should prepare the access needle, J-wires, sheaths, and ultrasound probe in a sterile sleeve near the groin site to minimize the amount that the operator has to move or reach while obtaining access (Figure 1).
The first step involves a short-axis survey of the femoral artery and vein anatomy, including the bifurcations of each into the superficial femoral and deep branches, the location of posterior bony structures (femoral head and ischial tuberosity), and identification of any superficial crossing vessels to avoid on the path down to the target vessel (Figure 2). The goal is to puncture the femoral vein or artery in the common femoral portion above the bifurcation of the branches and below the inguinal ligament to avoid the inferior epigastric branch of the artery or vein. Given the 3- to 4-centimeter distance of travel from the surface of the skin to the surface of the vessel, it is best to start just superior or at the bifurcation of the intended femoral vessel. Frequently, the femoral vein branches inferiorly to the femoral artery. If the vein is the target, starting at this level (ie, the arterial bifurcation and not the venous bifurcation) is usually necessary, since the superficial femoral artery branch will frequently travel anterior to the vein as the vessels are scanned down inferiorly.
Next, with the target vessel in the middle of the field of view, an echo-visible needle is also inserted into the middle of the field of view. In Figure 3, Video 1 and Video 2, the right common femoral vein is the target for three separate puncture attempts. Fanning of the ultrasound view in an inferior-to-superior motion as the needle is inserted facilitates visualization of the tip of the needle at all times. The short-axis view is not as optimal for visualizing the needle tip versus the long-axis view; however, given the importance of landing the needle in the center of the target vessel to avoid a glancing injury to any neighboring structures, the short-axis view is preferred for the initial approach of the needle toward the vessel. Using a fine jiggling motion and slow insertion of the needle, the needle tip can be approximated visually as the ultrasound view is fanned superiorly.
When the needle is at the anterior surface of the vessel, the ultrasound probe is then rotated clockwise 90 degrees to visualize the vessel and needle in long-axis view. Here, maximal tenting is obtained by further slow advancement of the needle. Fine adjustments of the probe and/or tilt of the needle will aid in finding the optimal visualization. After maximal tenting is confirmed, a rapid twisting motion of the needle with consistent forward pressure allows the sharp beveled edge of the needle to cut through the anterior wall of the vessel. This technique avoids the frequently taught jabbing motion, which could inadvertently puncture too far and cause a “through-and-through” injury to the vessel. Once blood flow is confirmed, then the introducer guidewire is inserted under ultrasound guidance by holding the probe in place with the left hand and using the right hand to remove the syringe (slip-tip preferably if one is used), let go of the needle, and insert the wire (Figure 3, Videos 1 and 2). Alternatively, since visualizing the wire enter on ultrasound is not completely necessary for safety, the operator can choose to set down the ultrasound probe and hold the needle in place with the left hand while removing the syringe and inserting the guidewire with the right hand.
If multiple venous access sites are needed — such as the protocol in our lab, which uses three puncture sites into the right femoral vein for all atrial fibrillation and supraventricular tachycardia ablations — the subsequent entry site is attempted about 2-3 millimeters below (inferior to) the prior puncture site (Figure 4). The prior wire is seen on ultrasound but does not usually interfere with seeing the second or third puncture needle tip, especially once switching to the long-axis view. After all punctures have been achieved, a quick ultrasound surveillance in long-axis view can show all three wires cleanly entering the target vessel.
For femoral artery punctures, the same approach applies with identifying the bifurcation, using short axis for the initial needle approach, and then utilizing the long-axis view to see the maximal tenting while twisting the needle to pop through the anterior wall of the artery (Figure 5). However, it is even more crucial to stay as centered as possible on the artery. With its muscular (and thus, more rigid) vessel wall and higher intravascular pressures, any off-center attempts may result in the needle glancing off the side of the vessel or the tip of the needle only inserting obliquely through the muscular wall and not into or partially into the lumen of the vessel. Trying to insert a wire in this situation could result in dissection of the arterial wall. Therefore, slow advancement, jiggling of the needle, and meticulous fanning of the probe during the approach of the needle will pay dividends in a perfectly centered needle tent before rotating over to long axis. After that, the twisting motion of the needle and continued forward pressure will easily result in quick cannulation into the lumen and brisk pulsatile bright red blood flow back.
There is a learning curve of approximately 5-10 cases with rotating the probe and finding the best angle to view the anterior wall of the target vessel and the needle tip in long axis. This takes some coordination between both hands, with fine adjustments of both until the needle tip and ultrasound plane are in phase with each other. Therefore, it is best to begin learning with femoral vessel puncture (versus axillary vein or artery puncture), given the wider field to move the probe and the lower serious risk of posterior structure injury (such as pneumothorax). Also, roughly 5-10% of ultrasound-guided femoral access will not have perfect visualization of the anterior vessel wall due to a variety of factors, including body habitus (and thus, deeper vessels, although not necessarily a perfect correlation), presence of renal disease, scar tissue from prior procedures, or poor tissue visualization quality (unclear contributing factors in otherwise normal habitus individuals). Once an operator has performed an adequate number of “normal” attempts (25-50) using this hybrid technique, then safe and successful puncture is still possible due to prior experience, despite suboptimal visualization of the vessel wall and needle tip. Another function that is not used on every case but is valuable to keep in mind is the color Doppler function, which aids in keeping the needle centered and knowing the approximate depth to the vessel when adequate visualization of the vessel is not possible due to superficial tissue characteristics of the patient.
With the availability of ultrasound technology in nearly every procedure lab, ultrasound-guided vascular access should be the first-choice approach for all proceduralists needing to gain femoral artery or vein access. Combining short-axis and long-axis views during needle advancement and using a twisting, cutting motion during maximal tent further optimizes the safety of this approach, and can be easily adopted by all operators at no or minimal additional cost. Future enhancements will involve the integration of a biplane view in all vascular probes to avoid needing to manually rotate the probe.
Acknowledgments: I would like to thank John Crowell (Abbott EP territory manager) for his superb video and photography skills using my Apple iPhone 11 Pro.
Disclosure: Dr. Salcedo has no conflicts of interest to report regarding the content herein.
Contact the author on Twitter: @50wattdoc
Exclusive Online Content:
Watch Dr. Salcedo discuss the article in a video overview:
Bonus quiz also available: Test your knowledge on this topic here!
Central Venous Access via Posterior Approach to Internal Jugular Vein: Background, Indications, Contraindications
Bradford L Walters, MD, FACEP Assistant Residency Director, Emergency Medicine Residency Program, Department of Emergency Medicine, Lead Physician of Keystone Sepsis Project, William Beaumont Hospital; Assistant Clinical Professor, Department of Emergency Medicine, Wayne State University School of Medicine, Detroit Receiving Hospital
Bradford L Walters, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, Michigan College of Emergency Physicians
Disclosure: Nothing to disclose.
E Jedd Roe, lll, MD, MBA, FACEP, FAAEM, MSF, CPE Professor, Department of Emergency Medicine, University of Florida at Jacksonville College of Medicine
E Jedd Roe, lll, MD, MBA, FACEP, FAAEM, MSF, CPE is a member of the following medical societies: American Academy of Emergency Medicine, American Association for Physician Leadership, American College of Emergency Physicians, American Medical Association, Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Specialty Editor Board
Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Nothing to disclose.
Vincent Lopez Rowe, MD Professor of Surgery, Program Director, Integrated Vascular Surgery Residency and Fellowship, Department of Surgery, Division of Vascular Surgery and Endovascular Therapy, Keck School of Medicine of the University of Southern California
Vincent Lopez Rowe, MD is a member of the following medical societies: American College of Surgeons, American Surgical Association, Pacific Coast Surgical Association, Society for Clinical Vascular Surgery, Society for Vascular Surgery, Western Vascular Society
Disclosure: Nothing to disclose.
Gil Z Shlamovitz, MD, FACEP Associate Professor of Clinical Emergency Medicine, Keck School of Medicine of the University of Southern California; Chief Medical Information Officer, Keck Medicine of USC
Gil Z Shlamovitz, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association
Disclosure: Nothing to disclose.
90,000 Specific features of the structure of the venous system of the anterior part of the body in domestic hens. Text of a scientific article in the specialty “Veterinary Sciences”
SPECIFIC FEATURES OF THE STRUCTURE OF THE VENOUS SYSTEM OF THE FRONT TRUNK OF A CHICKEN
Candidate of Veterinary Sciences, Associate Professor G.A. KHONIN,
Doctor of Veterinary Science, Professor, ICM of Omsk State Agrarian University, Omsk
Keywords: domestic chicken, venous system, blood circulation, trunk, chest.
The rib cage of terrestrial vertebrates, including birds, serves as a vivid example for revealing the influence of the organizing action of external factors on the development and formation of all its structural elements.The muscles of the shoulder girdle and chest wall, formed in terrestrial vertebrates, in connection with the development of active organs of locomotion in birds, with their adaptation to flight, led to significant and characteristic transformations not only in the bone and muscle base, but also in the vascular system.
Despite significant advances in the study of the morphology of birds, still unresolved questions about the structure of the venous system and especially intraorgan relationships with arteries and nerves in the muscles of the shoulder girdle and chest wall.Studying the domestic literature, we were able to get acquainted with the results of fragmentary studies devoted to the study of only individual venous vessels of the body of birds (Selyansky V.M., 1980; Vrakin V.F., Sidorova M.V., 1984). In foreign literature on the anatomy of birds, veins are described schematically and only some information is given about the branching of the main major vessels of the neck, head and extremities (Kolda J., Komarek V., 1958; Nickel R., Schummer A, Seiferle E., 1977). Of special works, attention is paid to the study of the veins of the trunk in humans and some animals (Luzha D., 1973; Van-kov V.N., 1974; Tkachenko B.I., 1984; Krylova N.V., Volosok N.I., 2006).
Elucidation of the specific features of the structure of the venous system in birds is of great importance for establishing their species norm, which is a harmonious set of structural and functional data of the body, adequate to its environment and providing the body with optimal vital activity. That is why the information available in the literature on the morphology of birds, which is often given in a generalized form and is often far from being understood.
muds do not allow us to judge the changes that occur in specific bird species in the structure of individual organs or systems under the influence of both the conditions of existence and various purposeful influences of the human factor.
Purpose and research methodology
Given the presence of not only a wide network of poultry farms, but also personal subsidiary farms in various regions of our country, there is an urgent need to constantly improve the professional level of poultry specialists in the field of bird biology – to develop scientifically based techniques and methods of working with birds. All of the above was the reason for conducting a comprehensive comparative anatomical study in order to obtain factual material that allows one to have a holistic idea of the functional structure of the venous system of the anterior part of the body in birds.In addition, this knowledge is necessary primarily to substantiate the anatomical and physiological changes occurring in the body of birds not only under the influence of endogenous, but also exogenous factors. The establishment of morphological patterns in the structure and development of individual organs and systems of poultry, in comparison with wild relatives, will make it possible to more fully identify their potentialities on the path of further evolutionary transformations, which is not only of great theoretical, but also practical importance.
The method of fine dissection (according to V.P. Vorobiev) under a falling drop of water using an MBS-2 microscope was used to study five corpses of domestic chicken.
As a result of our studies, we found that in birds, unlike mammals, two cranial vena cava are distinguished, which are formed by the fusion of the jugular, vertebral and subclavian veins on each side. They collect venous blood into the right atrium from
three sources: veins of the head and neck, veins of both upper extremities, veins of the thoracic section of the front part of the body and flow into the right atrium.Throughout the cranial vena cava lie in front of the mediastinum. Their front part is covered with connective tissue, and the back lies in the pericardial sac. At the very beginning, the cranial vena cava forms a gentle bend towards the heart, projecting onto the lateral surface of the chest wall at the level from the first to the third thoracic vertebrae, passing at an acute angle to the third sternal rib. Inside between the cranial vena cava is the initial section of the aortic arch and the ascending part of the aorta. In front, in their lower part, they are covered with the pericardium, the right and left ears of the heart, and in the dorsal part with the connective tissue of the mediastinum.The cranial vena cava at the level of the second rib pierce the pericardium and at the level of the third rib flow into the right atrium. The length of the right cranial vena cava is longer, which is obviously due to the fact that birds have a developed right aortic arch, which is located at the level of 3-4 thoracic vertebrae. In addition, several small veins from the mediastinum and pericardium flow into the initial part of the cranial vena cava.
The paired jugular veins run on the sides of the trachea, are accompanied by a small superficial cervical artery and the vagus nerve, are covered from the outside by the thin saphenous cervical muscle and skin.The right jugular vein is formed from the veins of the brain, its membranes and veins of the head, it is somewhat larger than the left, collecting blood from the head and neck. A small vein departs from the ventromedial surface of the jugular vein, giving the ascending and descending branches to the esophagus. At the base of the neck, the ascending branch with the same branch of the opposite side forms a venous arch, along which blood from the left branch is redistributed to the right and vice versa. In the jugular veins on both sides at the level of the penultimate cervical vertebra, inflows in the form of 4-5 branches from the thyroid and parathyroid glands flow.
At the level of the first thoracic vertebra in the chicken, a superficial cervical artery passes along the neck, which
The hen house, venous system, blood circulation, a trunk, a thorax.
paradise lies between the jugular vein and the vagus nerve. The superficial cervical artery and the jugular vein in their course exchange branches with each other, simultaneously feeding the vagus nerve, enclosed with them in the common connective tissue vagina.These branches enter its wall by the shortest path in a direction parallel to the axis of the nerve to the side facing the main sources of blood supply. The superficial cervical vein flows at an acute angle into the vertebral trunk. At the level of the last cervical vertebra, a branch is poured into the middle of the vertebral cervical vein at an acute angle, collecting blood according to the main type from the medial surface of the brachial plexus and from the scalene muscle, in which it also branches according to the main type.
Three venous collectors are involved in the outflow of venous blood from the cervical and initial thoracic spine in the chicken.They represent dense venous plexuses located symmetrically on both sides of the neck at the level of the last three cervical and first thoracic segments. These veins lie not only outside, but also inside the spinal canal, forming the external and internal vertebral venous plexuses.
The external venous plexus is formed by the vertebral cervical and thoracic veins. The vertebral cervical vein passes in the transverse canal of the cervical vertebrae and between the head and the tubercle of the first rib, collects venous blood from the dorsal and ventral muscles of the neck, the periosteum of the bodies of the cervical and first thoracic vertebrae and the scalene muscle through numerous tributaries.On the border between the last cervical and first thoracic vertebrae in the chicken, the vertebral cervical vein flows into the common vertebral trunk. The vertebral thoracic vein collects the inflows of venous blood from the first three intercostal spaces: from the external and internal intercostal muscles, rib lifters, periosteum of the bodies of the thoracic vertebrae, dorsal muscles of the back, long ventral flexor of the neck. It is directed cranially between the heads and necks of the ribs and then flows into the common vertebral trunk.
The internal venous plexus of the spinal canal is located in the epidural space of the cervical and thoracic vertebrae and consists of two horizontal collector veins running parallel to both sides of the neck and 3-4 transverse ones connecting the veins of the opposite side to each other.The internal venous plexus receives venous blood from the spinal cord and its membranes, partly from the spongy substance of the vertebrae. All three veins on each side are infused with two trunks – cranial –
at the level of the penultimate cervical vertebra and caudal at the level of the first thoracic vertebra, enter the common vertebral trunk, which then flows into the jugular vein. In the noted venous plexuses, it is obvious that opposite directions of blood flow are possible with an increase in hydraulic pressure and a change in the direction of blood flow during a sharp takeoff or landing of birds.In addition, the venous plexus may interfere with the formation of hydrostatic pressure in the veins of the spinal canal, thereby extinguishing the hydrodynamic shocks of the blood that occur during sharp longitudinal accelerations of the body.
Segments with complete or partial fixation of internal epidural veins to the paravasal structures and the periosteum of the spinal canal were found along the cervicothoracic spine. They pass to the external vertebral venous plexus in the form of small veins and bundles of connective tissue fibers.The latter should be considered as a fixator of the venous trunk, and the arteries passing nearby, due to their pulsation, act as a component that activates blood flow.
On the sides of the trachea are tracheal veins, which lie next to the arteries of the same name. Throughout the trachea of the right and left sides, they form numerous annular anastomoses in its serous membrane.
Chicken goiter is an enlargement of the esophagus, lies in the lower third of the neck to the right of the trachea.In the area of the goiter, small veins pass under the adventitia or between the muscle layers, forming numerous anastomoses with each other in the form of small-looped polygonal networks, which then flow into the collecting veins, uniting with each other, and enter the common trunk from the dorsal surface into the jugular vein of the right or left side. The intraorgan veins of the goiter branch according to the main type, represent a multilayer arrangement and have a tortuous course. From the surface of the goiter, venous blood flows from three sides: through the right, left and ventral thymus veins.Venous blood from the right side of the esophagus and goiter is collected through 7-8 collecting veins, which are spaced from each other every 0.3-0.4 mm and flow at an acute angle into the right thymus vein passing between the jugular vein and the esophagus. From the ventral surface of the goiter, venous blood flows out of the main type along the ventral thymus vein and, merging with the right thymus vein, flows into the right jugular vein at a distance of 1.8 mm before it flows into the right subclavian vein. Left goiter vein collects
venous tributaries in the amount of 9-10 pieces from the goiter and esophagus and flows from the dorsal surface in the same way as the left thymus vein into the jugular vein of its side.The marked multi-storey level in the microvascularization of the muscular membrane is obviously associated with the degree of filling and emptying of the goiter in its various functional states.
Subclavian veins – large branches of the cranial vena cava lie in the chest below the subclavian arteries behind the sternoclavicular joint of the corresponding side. In the tributaries of the veins entering the subclavian veins, symmetry is noted. The right subclavian vein, 1.5 cm long, runs almost vertically behind the sternoclavicular joint, the left – 2.6 cm, crosses the front of the large branches of the aortic arch and the left vagus nerve.A jugular vein flows into each subclavian vein, which is located on the neck and represents a large trunk that carries blood from the head. The sternoclavicular vein is formed by the fusion of the thoracic and clavicular veins, which collect venous blood from the sternocoracoid muscle.
The subclavian vein flows from the caudal side: the internal thoracic vein, collecting venous blood from the anterior part of the medial surface of the chest wall,
The external thoracic vein runs along the caudal edge of the scapula, receiving venous blood from the pectoralis major, cranial dentate, and latissimus dorsi.
The axillary vein is a continuation of the brachial vein and collects blood from the side of the wing and the outer surface of the chest. It lies at the level of the lower edge of the pectoralis major muscle and the outer edge of the first rib, where it flows into the subclavian vein, located in front of the artery of the same name. A cutaneous vein, which has a wide branching zone from the skin of the anterior third of the abdominal wall, flows into the axillary vein from the caudal side.
The skin of chickens in the area of the abdominal wall has good vascularization.It has four main sources of venous blood flow from large venous trunks: in the cranial region – in the area of the skin of the base of the neck, covering the goiter from the caudal muscular cervical vein; in the anterior section – into the saphenous thoracic vein, which flows into the cutaneous branch of the axillary vein, which flows from the caudal edge of the axillary vein. In the middle section, branches branch off from the external thoracic cranial artery. In the posterior section – the thoracic branch of the internal pelvic artery, which is a branch of the femoral artery.
From the ventral surface of the skin
in the region of the base of the neck covering the goiter, blood is collected along small branches, forming fine-meshed networks, which flow by tributaries into the larger veins, and in a dichotomous manner, connecting with each other, flow into the caudal muscular jugular vein.
From the upper middle third of the skin of the chest wall, many small branches begin with fine-mesh venous networks located in thin ribbon-like subcutaneous muscles and subcutaneous tissue.They are collected in the main type in larger branches, pass in the cranioventral direction in the skin in the intermuscular fascial septa. The tributaries of the veins flow into the middle cutaneous vein, and then into the external thoracic vein, which then flows into the subclavian vein.
From the lower ventral region of the skin of the abdominal wall, venous tributaries follow from its ventral surface at the level of the keel in the form of two branches, which collect blood according to the main type along the cranial and caudal veins, which pierces the pectoralis major muscle and then flows into the posterior pectoral vein.These veins, before reaching the skin, immediately combine into thicker branches that connect to each other, again collect branches, which connect between themselves and with the branches of neighboring veins, ultimately forming many anastomoses on the border of the subcutaneous tissue. A characteristic feature of small veins in the skin area is the branching of vessels in the main or loose types. Veins are located next to the arteries mostly from their cranial side in the form of a single trunk thicker in diameter.The venous networks of this area of the skin are rich in intersystem anastomoses that form large-looped networks, the arteries surrounding them are thin, even or slightly twisted.
Arteries and veins lie next to each other. The direction of the arteries and veins in the skin corresponds mainly to its connective tissue fibers. Long loops are located between the vessels and around them, which give off thin branches, forming –
nous numerous anastomoses in all areas of the skin, at the same time crumbling into a ribbon-like shape of the subcutaneous muscles.These vessels, as soon as they reach the subcutaneous tissue, immediately disintegrate into thinner branches, anastomosed with each other and with the branches of neighboring arteries and veins, ultimately forming a rich subcutaneous arterial and venous network with rounded loops on the border with the subcutaneous tissue and skin. and polygonal shapes. Most of these loops lie in the same plane, parallel to the surface of the skin.
Thus, in the skin of the abdominal region of birds, it is possible to distinguish parallel connected venous circles, functionally specialized sections that provide closed organ blood flow.The loops of the skin network almost always go along the body line, coinciding with the skin tension lines. Consequently, the forces that determine the guides of the connective tissue bundles act in a form-generating manner on the cutaneous arteries and their capillary networks. The structure of the arterial and venous skin network depends on the degree of mobility of different areas of the skin and on the direction of skin tension forces acting in different directions. The direction of the arteries and veins in the skin corresponds mainly to its connective tissue fibers.So, in the skin there are arteriolar-venular anastomoses, which are involved in the regulation of heat exchange. Such specialized pathways of blood flow are practically devoid of their own tone and are located among the subcutaneous muscle fibers that act as constrictors that can change the functional state of the vessels from maximum dilatation to complete closure of the lumen. Consequently, the temperature of the skin in chickens depends not so much on the width of the lumen of the capillaries and the density of capillary networks, but more on the state of the tone of the arterioles and the blood flow velocity.At the same time, they form a network, the structure of which is determined by the functional load on the skin. It is important to note that some of the loops are oriented perpendicular to the plane of the vascular network and
enters feather follicles.
Noteworthy is the exceptionally dense subcutaneous venous network in the adjacent muscle fibers and the surrounding subcutaneous tissue, where the venous vessels are prominently expressed in multicellular networks.The presence in the skin of wide capillaries and well-developed capillary networks serves in birds as a device for maintaining body temperature or as a source of additional heat transfer during intensive work of the wings during flight, as noted by V.D. Ilyichev et al. (1982). In addition, the presence of rich skin capillary networks can be explained by the high level of oxidative processes in the body of birds.
As a result of our studies, we found that the structure of the main and extraorganic veins, as well as intraorganic venous vessels of the anterior part of the body in birds, reflects the species, ontogenetic and phylogenetic patterns of the development of these higher vertebrates, depending on the conditions of their habitation and adaptation to flight.
In birds, the right and left cranial hollow veins, in the tributaries of the venous vessels of which symmetry is observed, take blood into the right atrium from three main sources: veins of the head and neck, veins of both upper extremities, veins of the chest wall.
The subcutaneous venous line in birds is significantly developed in the area of the skin of the abdominal wall, where parallel connected venous circles can be distinguished.
From the outer membrane of the veins there are fibers that we consider as a fixator of the venous vessel, and the arteries, due to their pulsation, as a component that activates their blood flow. These formations should be considered not only as a hemodynamic system, but also as a form that provides the design features of the paravasal sheath, not only as an adaptation of the venous sinuses to complex relationships with arteries, but also as components that play a significant role in the biomechanics of the venous wall.
1. Bankov V.N. The structure of the veins. – M .: Medicine, 1974. – 205 p.
2. Vrakin V.F., Sidorova M.V. Anatomy and histology of poultry. – M .: Kolos, 1984. – S. 255-269.
3. Ilyichev V.D., Kartashev N.N., Shilov I.A. General ornithology. – M .: Higher school, 1982.- S. 185-192.
4. Krylova N.V., Volosok N.I. Anatomy of the venous system. – M .: MIA, 2006 .– 109 p.
5. Puddle D. X-ray anatomy of the vascular system. – Budapest, 1973. -S. 35-44, 50-89.
6. Selyansky V.M. Anatomy and physiology of poultry. – M .: Kolos, 1980 .– S. 116-117.
7.Tkachenko B.I. Physiology of blood circulation. Physiology of the vascular system. – L .: Nauka, 1984 .– 652 p.
8. Baumel J.J. et.al. Handbook of Avian Anatomy: Nomina Apatina Aucht, Second Edition, Cambridge, Massachusetts, 1993. -P. 440-471.
9. Kolda J., Komarek V. 1958 Anatomie Domacich Ptaku. – Praga, 1958 .– p. 232-237.
10. Nickel R., Schummer A, Seiferle E., Lehrbuch der Anatomie der Haustiere, Bd. Y, Yerlag Paul Parey, 1997. – R. 444-453.
Varicose veins of the lower extremities
List of abbreviations
GSV – great saphenous vein
VBVNK – varicose veins of the lower extremities
MPV – small saphenous vein
PDPV – anterior accessory great saphenous vein
RCT – randomized controlled trial
RF – femoral anastomosis
USAS – ultrasound angioscanning
USDAS – ultrasound duplex angioscanning
CVD – chronic venous diseases
EVLO – endovasal laser obliteration
Prevalence of varicose veins
Varicose veins of the lower extremities is a common surgical disease of blood vessels in humans.According to Bergan, J J. (2007), its prevalence in Western Europe ranges from 2–56% in men and 1–60% in women. The incidence of complications (venous trophic ulcers) is 0.1% of the adult population. An epidemiological study carried out in 2004 in Moscow showed that 67% of women and 50% of men have chronic diseases of the veins of the lower extremities. Increasingly, there are reports of the detection of this pathology in schoolchildren. The annual increase in morbidity in industrialized countries reaches 2.6% in women and 1.9% in men.In Russia, more than 35 million people with chronic diseases of the venous system of the lower extremities need phlebological care. Of these, 1.5–2 million suffer from severe trophic disorders and have a disability (Saveliev V.S., 2001). Even in our time, medicine does not yet have the means of radical prevention of chronic venous diseases. Failure to diagnose and start treatment at the wrong time lead to an increase in the number of advanced forms of the disease. The apparent simplicity of diagnosis and treatment of this pathology often becomes the reason for the failure of conservative therapy and the occurrence of relapses of the disease after surgical treatment.
Brief anatomical and physiological data
Embryogenesis of veins of the lower extremities
In the embryogenesis of the venous system of the lower extremities of a person, three key phases can be conventionally distinguished:
– the formation of the primary venous network, which is a superficial system of veins;
– formation of the deep vein system;
– Creation of numerous anastomoses leading to the formation of the finalized pathways of venous outflow.
The superficial venous system appears in the limb bud already in a 6-week-old embryo.It is represented by three collectors that drain blood from the limb bud into the posterior cardinal veins. The latter are the main venous vessels located on the sides of the notochord and draining the posterior part of the embryo (the inferior vena cava does not yet exist at this stage). These three collectors run along the nerves directing them to growth:
1. Ventral-preaxial or femoral nerve. It gives off a sensitive branch called nervus saphenus . The venous plexus that forms around this nerve is called the preaxial plexus.Subsequently, it is divided into the great saphenous vein (GSV) and the femoral vein (BV).
2. The sciatic or axial nerve runs along the axis of the limb. The venous plexus that runs along this nerve is called axial (axial) or sciatic.
3. The dorsal – postaxial venous plexus follows the lesser sciatic nerve, which in an adult is represented by the posterior cutaneous nerve of the thigh. It goes down along the posterior axis of the lower limb, the resulting venous plexus follows along it.
It is known for certain that the so-called primary capillary plexus is formed first. The precursors of endothelial cells, scattered along the mesenchyme, form aggregates, which then take the form of primitive tubes, consisting of a single layer of endothelial cells. This primitive capillary network gradually becomes functionally deficient, causing the capillaries to condense. The most distally located venous capillaries merge and form the so-called marginal (marginal) venous sinus.With the formation of blood vessels, the primary drainage of blood from the kidney of the lower extremity is carried out through the postaxial venous plexus. This occurs approximately 38–39 days after fertilization, when the embryo is only about 8–9 mm long. At the base of the limb kidney, the postaxial vein drains into the sciatic and further into the pelvis. There, the blood enters, at first, into the umbilical vein and partially into the posterior cardinal vein. Then, the blood flow is completely redirected to the posterior cardinal vein system.
The postaxial venous plexus, otherwise called the embryonic lateral marginal vein, is the prototype of the small saphenous vein. At this stage (approximately from 37 to 50 days after fertilization), it is she who becomes the main main venous collector of the formed lower limb. The next vein that appears is the great saphenous vein. This happens approximately 44–45 days after fertilization. It arises directly from the posterior cardinal vein. At the same time, another draining vessel arises from the posterior cardinal vein – the prototype of BV.On the 50th day, pelvic rotation (by 90 °) and significant lengthening of the limb occur, the drainage system finally moves forward from the postaxial system to the preaxial iliac vein system. At this moment, the main outflow of blood is carried out through the GSV. Gradually, with further growth of the limb, the main outflow of blood begins to shift in depth, from the GSV to the BV. This is due to the fact that the deep venous axis of the limb becomes functionally the shortest path to the venous collector of the base of the growing limb.An axial-preaxial anastomosis is formed between the sciatic and femoral veins. BV finally becomes the main drainage vessel of the lower extremity. From this point on, the sciatic vein finally loses its significance and gradually atrophies (in an adult state, it remains only in the form of small arcades along the sciatic nerve and the lower gluteal vein). The axial-preaxial anastomosis, located ventrally from the axis of the limb, eventually turns into a deep vein of the thigh.
Finally, the venous system takes on a form close to an adult by the 13th week of intrauterine development.In the same period, valves appear in the BPV.
Clinical investigation Central venous catheterization: Modified Seldinger technique, Experienced group, Seldinger technique, Experienced group, Modified Seldinger technique, Inexperienced group, Seldinger technique, Inexperienced group, Longitudinal axis technique, Short axis technique – Clinical trial register
Modified Seldinger technique, Experienced group
This is a technique for central venous catheterization.We will use needle that is covered with guiding sheath. After desired vessel puncture, guiding sheath is instantly slid over the needle into the vessel. The needle is withdrawn, guidewire is advanced through the guiding sheath, central catheter is placed into the vessel. The procedure will be performed by experienced practitioners who are board-certified anesthesiologist staffs and have experience of more than 50 central venous catheterizations in both techniques.
Arm Group label:
Modified Seldinger technique, Experienced group
Seldinger Technique, Experienced Group
This is a method of central venous catheterization.The desired vessel is pierced with a sharp hollow needle, the syringe is detached, the guidewire is advanced through the lumen of the needle, and then the needle is removed. The central catheter is then inserted through the guidewire into the vessel. The procedure will be performed by experienced medical practitioners who are board certified anesthesiologists with experience in over 50 central venous catheterizations using both methods.
Arm Group label:
Seldinger Technique, Experienced Group
Modified Seldinger Technique, Inexperienced Group
This is a method of central venous catheterization.We will use a needle covered with a guide sheath. After the desired puncture of the vessel, the guide sheath instantly slides over the needle into the vessel. The needle is removed, the guidewire is advanced through the guide sheath, and the central catheter is inserted into the vessel. This method will be performed by inexperienced practitioners who are junior residents and have experience with fewer than 50 central venous catheterizations with both methods.
Arm Group label:
Modified Seldinger Technique, Inexperienced Group
Seldinger Technique, Inexperienced Group
This is a method of central venous catheterization.The desired vessel is pierced with a sharp hollow needle, the syringe is detached, the guidewire is advanced through the lumen of the needle, and then the needle is removed. The central catheter is then inserted through the guidewire into the vessel. This method will be performed by inexperienced practitioners who are junior residents and have experience with fewer than 50 central venous catheterizations with both methods.
Arm Group label:
Seldinger Technique, Inexperienced Group
Longitudinal axis technique
The ultrasonic probe is placed parallel to the paths of the vessel, and the needle is advanced in a plane.
Short axis technique
The ultrasound probe is positioned vertically with respect to the vessel paths and the needle is advanced out of plane.
90,000 Stiffness in the legs
As they age, people find that there is stiffness in their legs after a hard day’s work or long walks. At first, there are no external manifestations – just the lower limbs become heavy and immobile.
Gradually, even minimal physical activity in the form of swimming or jogging increases the symptoms, which indicates the development of pathological processes.
The blood circulation in the body is a complex process involving the heart, arteries, valves, etc. The blood passes through the force of gravity, in which it is assisted by valves. If there are failures in the system, then it can no longer return at an optimal speed. This leads to stagnation, which causes stiffness in the legs.Visual symptoms in the form of puffiness, dilated veins and changes in the color of the epidermis gradually appear.
What causes the decrease in mobility?
- Excess weight.
- Lack or excess load on the legs.
- Diseases of the cardiovascular system.
- Joint problems.
- Diabetes mellitus.
- Taking strong drugs.
- Hormonal changes.
- Increased blood clotting.
The main cause is diseases of the veins of the lower extremities. Stiffness in the legs appears due to thrombosis, chronic venous insufficiency, or varicose veins. At the same time, at the initial stage, it is impossible to see external manifestations in the form of blue discoloration or pallor of the skin, puffiness, a decrease in temperature, dilated veins or spider veins.
High physical activity
Physical education has not hurt anyone yet. Even intense cycling or swimming in the pool cannot negatively affect your health.On the contrary, adequate physical activity accelerates blood and improves circulation, which is very beneficial for health.
Lack of stress leads to stagnation of blood. Moreover, some people cannot avoid the negative impact, because it is associated with professional activities. Drivers, programmers, hairdressers, salespeople, security guards or surgeons are susceptible to varicose veins. Stiffness in the legs appears under static and dynamic loads (all day at the computer or standing at the cash register).
Heavy sports can affect the health of your veins and valves. This includes weightlifting and powerlifting. Athletes work with huge weights, so it is imperative for them to periodically visit a phlebologist. More about phlebologist consultation
Pregnancy and contraceptives
According to statistics, stiffness in the legs is much more common in women. This is not always due to genetics and is related to lifestyle.
Problems arise from wearing uncomfortable high-heeled shoes.But the main reason is the shift in hormonal balance. This happens both during the menstrual cycle and during pregnancy. Changes in hormonal balance can be affected by the use of contraception. If you are at risk, then periodically get tested, conduct an ultrasound scan and visit a phlebologist.
Adaptation to the environment
Stiffness in the legs may appear while vacationing in southern countries. Many people like to travel to Egypt or Thailand during severe frosts and take a vacation in January or February.A sharp change in climate shocks the body, therefore, metabolism changes and the retention or burning of fluid is accelerated. All this leads to temporary pathological processes in the veins of the lower extremities.
This affects not only travel lovers, but all people. The body rebuilds in the summer. This can be seen in the absence of hunger and increased thirst (lack of water). Circulatory disorders are reversible and taking blood-thinning drugs is inappropriate (just consult a phlebologist).
Being overweight increases the load on the legs, but this is not the main factor. Stiffness in the legs appears due to an increase in interstitial fluid and blood volume in general. In addition, the movement of blood becomes difficult due to the layer of fat, which creates an extra load on the veins. The solution to the problem is elementary – you need to get rid of bad habits, balance the diet and play sports.
To exclude cardiovascular and venous diseases, you need to undergo a comprehensive medical examination.Otherwise, you will be fighting the symptoms, not the root of the problem.
Cardiomyopathy can lead to swelling and decreased mobility. There is restrictive, dilated, and hypertrophic cardiomyopathy. Each type of disease has its own symptoms:
- Hypertrophic leads to fainting, shortness of breath pain and rapid heartbeat. Over time, causes stiffness in the legs.
- Restrictive causes shortness of breath and severe edema of the lower extremities.In the initial stages, it proceeds without pronounced symptoms.
- Dilation leads to increased fatigue, swelling, blue discoloration and blanching of the epidermis.
Chronic heart failure can also lead to decreased mobility. It has a range of symptoms:
- Rapid fatigue.
- Discoloration of the skin.
- Hair loss and nail reshaping.
- Shortness of breath.
- Dry cough.
- Stiffness in the legs.
Diseases of veins and arteries
Bad habits and unhealthy diets lead to high bad cholesterol and the formation of plaque inside the arteries. Due to the increase in the hardness and thickness of the vascular walls, a person begins to feel pain in the calves. They appear even with minimal physical activity (while walking). The main symptom is a decrease in the temperature of the extremities for no apparent reason (even in summer).
Endarteritis can cause stiffness in the legs, which leads to inflammatory processes in the tissues.The person feels constraint and pain. The main symptom of the disease is instability. A person can walk 50 meters, but after that there is itching, pain, restraint, etc. After resting, he can walk a similar distance again, but the symptoms return again.
The most common venous disease is varicose veins , which women most often experience. The enlarged veins are not immediately visible with the naked eye, but a person begins to feel:
- Swelling, pain and stiffness in the legs.
- Night cramps.
- Decreased physical activity (weakness in the lower limbs).
It is possible to accurately identify the stage of varicose veins only on duplex scanning or ultrasound. The disease may not manifest itself in any way for many years. Its development can be accelerated by genetic predisposition, excess weight, hormonal changes, lack or excess of physical activity and other factors.
Stiffness in the legs is a danger sign
To protect your health and find out the cause of the problem, see a specialist.Phlebology Center “First Phlebological Center” performs a comprehensive medical examination. The condition of the veins, vessels and valves is checked. We will select the optimal treatment regimen for you, which is guaranteed to give a positive result. Make an appointment by phone right now.
In the eyeball, two poles are distinguished: anterior and posterior. The distance between the anterior and posterior poles of the eyeball is its largest size and is equal to 24 mm on average.The line connecting both poles is called the outer axis of the eyeball, or the geometric axis of the eye, or the sagittal axis of the eye. The largest transverse horizontal size of the eyeball is 23.6 mm on average, and the vertical size is 23.3 mm. The line connecting the points of the largest circumference of the eyeball is called the equator and runs approximately 10-12 mm from the anterior pole.
The bulk of the eyeball is formed by the inner core – a transparent content surrounded by three membranes, which includes the vitreous body, lens, and aqueous humor.The nucleus of the eyeball is surrounded on all sides by three membranes: outer, or fibrous; middle, or choroid; inner, or mesh, shell.
Fibrous membrane of the eyeball.
The outer shell, the fibrous shell of the (eye) globe, is the strongest of all three shells. Thanks to her, the eyeball retains its shape.
Cornea, cornea – anterior, smaller, section of the outer shell of the eyeball (1/6 of the entire shell).The cornea is the most convex part of the eyeball and has the appearance of a somewhat elongated concave-convex lens facing backward with its concave surface. The corneal thickness is approximately 0.5 mm. The horizontal diameter of the cornea is 11-12 mm, the vertical diameter is 10.5-11 mm. The cornea consists of a transparent connective tissue stroma and corneal corpuscles, which form the cornea’s own substance. The anterior and posterior boundary plates adjoin the stroma from the anterior and posterior surfaces.The first is a modified basic corneal substance, the second is a derivative of the endothelium, which covers the posterior surface of the cornea and lines the entire anterior chamber of the eye. The anterior surface of the cornea is covered with a stratified epithelium, which, without sharp boundaries, passes into the epithelium of the connective membrane of the eye. Due to the homogeneity of the tissue and the absence of blood and lymphatic vessels, the cornea is completely transparent.
– albuminous membrane; the posterior, larger, section of the outer shell of the eyeball (5/6 of the entire shell).The sclera is a direct continuation of the cornea; unlike the latter, it is formed by fibers of dense connective tissue with an admixture of elastic fibers and is opaque. The transition from the sclera to the cornea occurs gradually. On the border between them there is a translucent rim called the edge of the cornea. The outer surface of the sclera in the anterior section is covered with a connective tissue sheath, or conjunctiva, and in the posterior – only endothelium. The inner surface of the sclera, facing the choroid, is also covered with endothelium.The sclera does not have the same thickness throughout. The thinnest area is the place where the sclera is penetrated by the fibers of the optic nerve leaving the eyeball. Here the ethmoid plate of the sclera is formed. The sclera has the greatest thickness in the circumference of the optic nerve – from 1 to 1.5 mm; further, the thickness of the sclera decreases, reaching 0.4-0.5 mm at the equator; corresponding to the area of muscle attachment, it thickens again to 0.6 mm. In addition to the fibers of the optic nerve, arterial and venous vessels and nerves pass through the sclera in many places, forming a series of holes in it, called the graduates of the sclera.In the thickness of the anterior part of the sclera, near the edge of the cornea, the circular venous sinus of the sclera lies along its entire length.
Choroid of the eyeball.
The middle shell – the choroid of the eyeball – is divided into three unequal parts: 1) the back, large, lining 2/3 of the inner surface of the sclera, called the choroid itself; 2) the middle part, located on the border between the sclera and the cornea, – the ciliary body; 3) the anterior, smaller part that shines through the cornea – the iris or iris.
(eye )ball, in the anterior sections, without sharp boundaries, passes into the ciliary body. The jagged edge of the retina can serve as the border between them. The choroid itself, almost along its entire length, only adjoins the sclera, with the exception of the spot area (macla), and the area corresponding to the optic nerve head. In the area of the optic nerve head, the choroid has an optic opening of the choroid itself, through which the fibers of the optic nerve go outside the ethmoid plate of the sclera.For the rest of the length, the outer surface of the choroid itself is covered with endothelial and pigment cells and, together with the inner surface of the sclera, limits the capillary perivascular space. The remaining layers of the choroid itself consist of a layer of large vessels – the vascular plate, mainly veins, as well as arteries, between which elastic connective tissue fibers (mainly elastic) and pigment cells are located; deeper than this layer lies a layer of middle vessels, less pigmented, to which a dense network of small vessels and capillaries, forming a vascular-capillary plate, is adjacent.The capillary network is especially well developed in the macular region. The deepest part of the choroid itself is a fibrous, structureless layer called the base plate; the choroid in the anterior section thickens somewhat and passes into the ciliary body without sharp boundaries.
Ciliary body , from the side of the inner surface, is covered with a main plate, which is a continuation of the same sheet of the choroid itself.The bulk of the ciliary body is formed by the ciliary muscle and the stroma of the ciliary body, consisting of loose connective tissue rich in pigment cells and a large number of vessels. In the ciliary body, there are: ciliary muscle, ciliary corolla, ciliary circle. The ciliary muscle occupies the outer part of the ciliary body and is directly adjacent to the sclera. The ciliary muscle is formed by smooth muscle fibers, among which meridional and circular fibers are distinguished. The meridional fibers are highly developed and form a muscle that stretches the choroid itself; its fibers start from the corner of the anterior chamber of the eye and from the sclera and, heading posteriorly, are lost in the choroid.Contraction of this muscle pulls forward the anterior part of the choroid itself and the posterior part of the ciliary body, thereby reducing the tension of the ciliary girdle. Circular fibers take part in the formation of the circular muscle, the contraction of which reduces the lumen of the ring formed by the ciliary body, and thereby brings the place of fixation of the ciliary band closer to the equator of the lens. The latter causes relaxation of the specified girdle and an increase in the curvature of the lens, due to which the circular part of the ciliary muscle is called the muscle that compresses the lens.The ciliary circle, represents the posterior inner part of the ciliary body; it has an arcuate shape, an uneven surface and without sharp boundaries continues posteriorly into the choroid itself. The ciliary corolla occupies the antero-inner part of the ciliary body. It distinguishes between radially running small ciliary folds, which anteriorly pass into the ciliary processes. The latter, in an amount of about 70, freely hang down into the cavity of the posterior chamber of the eyeball. The place of transition of the surface of the ciliary circle into the ciliary corolla forms a rounded edge, which is the place of attachment of the ciliary band that fixes the lens.
Iris , or iris , represents the most anterior part of the choroid, unlike the other parts, it does not directly adjoin the fibrous membrane of the (eye) apple, but, being a continuation of the anterior part of the ciliary body, is located in the frontal plane on some distance from the cornea. In the center of the iris there is a round opening – the pupil. The pupil is limited by the free, or pupillary, edge of the iris.The opposite edge of the iris, which runs along its entire circumference, is called the ciliary edge. It is fixed at the fibrous membrane by means of the ridge ligament of the iris-corneal angle, in the thickness of which is the slit-like space of the iris-corneal angle. The thickness of the iris consists of loose connective tissue, blood vessels, smooth muscles, and a large number of nerve fibers. The cells in the back of the iris contain pigment that determines the “color.” The smooth muscles of the iris are located in two directions: circular and radial.The circular layer lies in the circumference of the pupil and forms a muscle that constricts the pupil; radially located muscle fibers form a muscle that dilates the pupil. The anterior surface of the iris is somewhat convex anteriorly, the posterior surface is correspondingly concave. On the front surface of the iris, in the circumference of the pupil, an inner small ring of the iris is distinguished, as the pupillary part (or the pupillary belt). The width of this part of the iris reaches 1 mm. The small ring of the iris is bounded on the outside by a circularly running irregular jagged line called the small circle of the iris.The rest of the anterior surface of the iris is 3-4 mm wide and belongs to the outer large ring of the iris or ciliary part. On the surface of this part of the iris there are inconsistent depressions – crypts of the iris, a number of radial folds and along the periphery a small number of circular folds of the iris.
Inner shell of the eyeball.
The inner lining of the eye is called the retina, or retina; it has a complex structure.With its outer surface, it adjoins the choroid throughout its entire length, and the inner surface – to the vitreous body. In the mesh, two unequal parts are distinguished. The posterior, large, perceiving light stimuli – the visual part of the retina – extends to the ciliary body and ends in the dentate edge of the retina. The other, the front part of the retina, does not contain light-sensitive elements and is called the blind part of the retina; it is divided according to the parts of the choroid, it is divided into the ciliary part and the iris part of the retina.The visual part of the retina consists of layers that are only microscopically distinguishable: the pigment layer of the retina, rich in pigment; adjoins the inner surface of the choroid and the medulla, or nerve layer. The neural layer is adjacent to the vitreous body and consists, in turn, of the following layers: the neuroepithelial layer containing rods and cones, light and color perceiving elements of the retina; outer boundary plate of glia; the outer granular layer formed by those parts of the cones and rods in which the nuclei lie; outer plexus of the visible layer; inner granular layer; inner plexus of the visible layer; multipolar nerve (nodal) cells; optic nerve fiber layer; inner boundary plate of glia.The outermost layer of the visual part of the retina is the pigment layer, anatomically more closely associated with the choroid and loosely with the rest of the retina. On the posterior surface of the visual part of the retina, a well-pronounced oval-shaped elevation is noticeable – the optic nerve head. Here axons of multipolar nerve nodal cells of the retina are collected, which, penetrating the sclera, form the optic nerve trunk. Further, these fibers pass as part of the optic nerve, optic chiasm and further to the cortical end of the optic analyzer.In the center of the optic nerve head, there is a depression of the disc, which is the entry and exit site of the vessels supplying the retina with blood. In the area of the disc, there is an area of the retina devoid of light-sensitive elements (the so-called blind spot). 3-4 mm from the optic nerve in the retina there is a spot, macla, which is the place of the best vision (previously it was called a “yellow spot”). It has a round or oval shape with a small depression in the center, a central fossa. cones.The posterior parts of the visual part of the retina contain a large number of cones and rods; anteriorly, the number of rods decreases and they are absent at the dentate edge of the retina.
The part of the retina that lines the inner surface of the ciliary body and the posterior surface of the iris consists of two layers: the outer, pigment, which is a continuation of the pigment layer, and the inner, consisting of epithelial cells containing pigment in the iris.These layers of the retina are connected here more firmly than it is in the region of the visual part of the retina.
Vitreous chamber of the eyeball. The vitreous chamber of the eyeball includes the vitreous body and the lens.
Covered on the outside with a thin transparent vitreous membrane and occupies most of the cavity (eye) ball. The vitreous body consists of a completely transparent gelatinous mass, devoid of blood vessels and nerves.It consists of a delicate intertwining filaments and a liquid rich in proteins – vitreous moisture. The anterior surface of the vitreous body faces the posterior surface of the lens, bears, according to its shape, a cup-shaped vitreous fossa. The rest of the vitreous body adjoins the inner surface of the retina and approaches a spherical shape.
has the shape of a biconvex lens. The posterior surface of the lens, more convex, is adjacent to the vitreous body; the front is facing the iris.Distinguish between the anterior and posterior poles of the lens – the central points of its anterior and posterior surfaces. The line connecting the anterior and posterior poles of the lens is called the axis of the lens and is 3.6 mm on average. The lens substance is completely transparent and, like the vitreous body, does not contain blood vessels and nerves. The bulk of the lens consists of lens fibers, which are elongated six-sided epithelial cells. The peripheral parts of the lens are covered from the side of its anterior and posterior surfaces with a lens capsule.The latter is a homogeneous transparent membrane, thicker on the anterior surface of the lens, where a layer of epithelial cells is located under it. The substance of the lens has an unequal density: in the center it is denser and is called the nucleus of the lens, and on the periphery it is less dense – the cortex of the lens. The lens, located between the vitreous body and the iris, is fixed by its peripheral, rounded edge, called the equator of the lens, to the ciliary body by means of stretched thin belt fibers.The latter are interwoven with the inner end into the lens capsule, and with the outer end, they start from the ciliary body. The combination of these fibers forms a ligament around the lens – the ciliary band. Between the fibers of the ciliary ligament are the lymph girdle spaces. Watery moisture, a clear, colorless liquid, fills the anterior and posterior chambers of the eyeball. They are slit-like cavities in front of and behind the iris.
The posterior chamber of the eyeball is bounded behind by the front surface of the lens, the ciliary girdle and the ciliary body; in front – the posterior surface of the iris.The ciliary processes hang freely into the cavity of the posterior chamber. The posterior chamber communicates with the girdle spaces. The anterior chamber of the eyeball is bounded in front by the posterior, concave surface of the cornea, and behind by the front surface of the iris. The anterior and posterior chambers of the eyeball communicate with each other through the pupil. Watery moisture is produced by the vessels of the ciliary body and the iris. The outflow of aqueous humor is carried out in the following ways: from the posterior chamber, aqueous humor enters the anterior one, from where it flows into the system of convoluted vortex veins.
Perinatal lesion of the central nervous system
Children’s diagnoses are becoming more and more widespread: hyperactivity, ZRR, ZPRR . These diseases are associated with birth trauma: Atlas subluxation (I m.p.), when the vertebral artery is compressed and the brain does not receive sufficient nutrition.
Consequences: Decrease in self-control, not the ability to concentrate, and therefore make informed decisions.
If the spine is not corrected, the brain simply gets used to working at a low level.
Having switched to the American option of treatment, neurologists in this case are obliged to give drugs that limit hyperactivity.
Based on this tactic, the cause is not cured, the spine is not straightened, the blood supply to the brain is not normalized, but the behavioral structures are only slightly eliminated.
Will a person be healthy or suffer unnecessarily? Does it depend on Atlanta?
Seven cervical vertebrae support the skull.Atlant is located first. It is he, like the Titan, who holds the skull on himself.
Atlas (Atlas) rests on the 2nd cervical vertebra – Axis (Greek axis). The 2nd cervical vertebra gives the axis of rotation for Atlanta and the head.
The skull and the 1st cervical vertebra have articular surfaces. They form the first movable joint in which the head can nod.
The second movable joint in the spine is located between the 1st and 2nd cervical spines. Here the skull can make turns and, together with 1 cervical spine, slides relative to Axis.
The neck is motionless, but the head can make turns. At this point, the neck is resting and has a supporting function.
When the Atlas is located in its natural place, a person can enjoy a long and harmonious life in complete mental and physical health.
However, practice shows that 1 cervical spine is displaced in all and this position has been going on since time immemorial.
The displaced Atlas rotates and takes a tilt position. So Atlas partially blocks the exit from the skull (large zat.otv).
In this case, the medulla oblongata suffers, which provides the vital functions of the body. The vertebral arteries, which pass in the lateral processes of the 1st cervical vertebra, suffer, while the blood supply to the brain decreases, and the outflow of fluid worsens.
The child has severe headaches, the baby becomes restless, loud, there is a disturbance in appetite or sleep. Apparatus research methods (HSS) can state a deterioration in blood flow through the Galen’s vein and / or a violation of venous outflow.
Unfortunately, Atlas himself cannot get out of this situation. It is fixed by small muscles of the cervico-occipital junction (short extepsors), which came into reflex spasm.
And one moment, according to the laws of Biomechanics, long exteproses and short flexors weaken, and as a result, a spasm of long flexors (sternocleidomastoid muscle) occurs.
Moreover, on the one hand (opposite to the dislocation of Atlanta), the baby also gets torticollis for all diagnoses, and it is already useless to treat it with only massages.
The displaced Atlas also exerts increased pressure on the spinal column and cranial nerves. In infancy, the most interesting thing for us is the vagus nerve, which, among other things, innervates the stomach.
Due to insufficiency or / and distortion of the nerve signal, the child’s stomach cannot adequately respond to food intake and the baby has profuse (or not so much) regurgitation.
In addition, the displaced Atlas has a pathological effect on the carotid arteries and lymphatic vessels.
There is no need to describe the consequences of this trauma, any sane mother imagines it.
Atlas not only wears a skull, he also participates in maintaining balance and shaping the posture and movement of the human body. And for the kid who moves, he will have a primary role. and if the position of the 1st cervical vertebra is not corrected, then the collective diagnosis of a primary lesion of the central nervous system, which implies dysfunctions of the brain or the structure of the brain itself, will grow into not ephemeral at all:
- delays in mental, motor or speech development;
- Minimal cerebral dysfunction and ADHD;
- neurotic reactions;
- cerebrasthenic syndrome;
- vigetative-visceral dysfunction syndrome;
- Cerebral Palsy.
12.4. Venous system
adrenal gland; hepatic veins (3 – 4) – from the liver. It should be noted that blood enters the liver through the hepatic artery (arterial) and through the portal vein (contains substances absorbed in the gastrointestinal tract). Due to the special vascular structure of the liver, these two streams unite. The outflow of blood that has passed through the organ is carried out through the hepatic veins into the inferior cavity.
Internal iliac vein, v. iliaca interna, collects blood from the walls and internal organs of the small pelvis.The obturator veins (accompanying the artery of the same name), the superior and inferior gluteal veins, which do not draw blood from the gluteal muscles, flow into the internal iliac vein from the walls of the pelvis into the internal iliac vein. Veins collecting blood from the pelvic organs form numerous anastomoses called venous plexuses. Venous plexuses are well expressed in the area of the internal genital organs, bladder, rectum. In men, these plexuses are located near the prostate, seminal vesicles, and in women, near the uterus, vagina and external genital organs.
External iliac vein, v. iliaca externa, continuation
femoral vein and carries blood from
and also partially from the anterior abdominal wall.
limbs divided into
(c o y)
and L e b o c e.All deep veins of the inferior course
STI accompany the arteries of the same name. In most cases, the artery is surrounded by two veins, but the femoral vein, popliteal vein, and deep vein of the thigh are unpaired vessels. The largest of the deep veins is the femoral vein, which passes through the vascular lacuna and continues into the external iliac vein.
Superficial veins start from the dorsal venous arch of the foot. LARGE LOOKING VENANO GI, v.saphena magna, starts from the inner surface of the foot, goes along the inner surface of the lower leg and thigh, and flows into the femoral vein. Small saphenous vein of the leg, v. saphena parva, begins on the outer edge of the foot and near the outer ankle passes to the back of the leg, flowing into the popliteal vein. There are numerous anastomoses between the superficial and deep veins.
Knowledge of the architectonics of the veins of the lower extremity helps surgeons carry out operations for one of the most common diseases – varicose veins.
Portal vein system. Portal vein, v. portae, collects blood from unpaired abdominal organs: from the stomach, pancreas, gallbladder, small and large intestines, spleen (Fig.