How can urethral trauma be prevented during catheterisation. What are the key parameters for urethral rupture. How effective is a novel safety device in preventing urethral injury. What are the implications for clinical practice.

Understanding Urethral Catheterisation and Associated Risks

Urethral catheterisation is a common medical procedure performed on approximately 25% of hospitalized patients. However, this routine task carries potential risks, particularly for male patients. One of the most significant complications is urethral injury, which typically occurs when the catheter’s anchoring balloon is inadvertently inflated inside the urethra instead of the bladder.

The consequences of such an error can be severe, ranging from immediate complications like pain, bleeding, and acute urinary retention to long-term issues such as urethral stricture disease. In severe cases, patients may even require urethral reconstruction.

Why is urethral injury during catheterisation a concern?

• It can cause immediate pain and discomfort for the patient
• It may lead to bleeding and acute urinary retention
• Long-term complications can include urethral stricture disease
• Severe cases might necessitate complex urethral reconstruction procedures

Investigating Urethral Strain Thresholds for Rupture

Prior to this study, there was a lack of research demonstrating the specific urethral strain thresholds for rupture during traumatic urethral catheterisation. To address this gap in knowledge, researchers set out to investigate two key parameters:

1. Internal urethral diametric strain
2. Threshold maximum inflation pressure

These parameters were examined to determine at what point urethral rupture occurs during inadvertent inflation of a catheter anchoring balloon in the urethra.

How was the study conducted?

The research team used 21 ex vivo porcine models to simulate urethral catheterisation. They inflated 16 Fr catheters in the bulbar urethra of these models and used retrograde urethrography to characterize and grade urethral trauma. The researchers then correlated urethral rupture with internal urethral diametric strain (measured as a percentage) and maximal urethral pressure threshold values (measured in kilopascals).

Key Findings: Urethral Rupture Thresholds

The study yielded crucial insights into the conditions under which urethral rupture occurs during catheterisation. The researchers found that porcine urethral rupture consistently occurred under the following conditions:

• Internal urethral diametric strain exceeding 40%
• Maximum inflation pressure greater than 150 kPa

These findings provide valuable benchmarks for understanding the physical limits of the urethra during catheterisation and offer a foundation for developing safer catheterisation techniques and devices.

What do these thresholds mean for catheterisation procedures?

The identified thresholds serve as critical safety parameters. Any catheterisation procedure or device that exceeds these limits significantly increases the risk of urethral rupture. This knowledge can inform the development of safer catheterisation protocols and equipment designed to operate well below these dangerous thresholds.

Designing a Novel Safety Device for Catheterisation

Armed with the knowledge of urethral rupture thresholds, the research team took a proactive approach to patient safety. They designed and evaluated a novel safety device specifically engineered to prevent urethral trauma, even in cases of inadvertent balloon inflation in the urethra.

How does the safety device work?

The prototype safety syringe incorporates a pressure-sensitive valve mechanism. When the plunger is depressed, the device allows for normal inflation up to a certain point. However, once the pressure reaches the predetermined safety threshold, the valve activates, allowing the sterile water in the syringe to decant through the valve instead of continuing to inflate the balloon.

This clever design ensures that even if a healthcare provider mistakenly attempts to inflate the catheter balloon while it’s still in the urethra, the device will prevent the pressure from reaching dangerous levels that could cause urethral rupture.

Comparing Standard and Safety Syringes in Human Cadaver Studies

To validate the effectiveness of their novel safety device, the researchers conducted a comparative study using human cadavers. They inflated urethral catheters in the bulbar urethras of seven fresh male cadavers using both a standard syringe and their prototype safety syringe.

What were the results of the cadaver studies?

The findings from the cadaver studies were striking:

• The mean maximum human urethral threshold inflation pressure required to activate the safety prototype syringe pressure valve was 153±3 kPa.
• In contrast, the mean maximum inflation pressure using the standard syringe was significantly higher at 452±188 kPa (p<0.001).

These results demonstrate that the safety syringe consistently activated at a pressure very close to the identified safe threshold of 150 kPa, while standard syringes allowed pressures to reach potentially dangerous levels far exceeding this limit.

Implications for Clinical Practice

The research findings have significant implications for improving patient safety during urethral catheterisation procedures. By identifying specific parameters for urethral rupture and developing a device that operates within safe limits, the study paves the way for safer catheterisation practices.

How can these findings be applied in healthcare settings?

Healthcare providers can use this information to:

1. Develop more comprehensive training programs for catheterisation procedures
2. Implement new safety protocols based on the identified pressure and strain thresholds
3. Consider adopting safety devices similar to the prototype tested in this study
4. Increase awareness among medical staff about the specific risks of urethral trauma during catheterisation

The researchers have already taken steps to translate their findings into clinical practice. They have implemented their safety device at Tallaght Hospital in Dublin, Ireland, for patients requiring urethral catheterisation. This real-world application represents a significant step forward in preventing catheterisation-related urethral injuries.

Validation and Recognition of the Research

The importance of this research has not gone unnoticed in the medical community. The study findings were presented at the European Association of Urology (EAU) congress in London, UK, in March 2017, where they received commendation.

Why is this research significant in the field of urology?

This study is noteworthy for several reasons:

• It addresses a common but potentially serious complication of a routine medical procedure
• It provides quantifiable data on urethral rupture thresholds, which were previously not well-established
• It demonstrates a successful transition from bench research to bedside application
• It offers a practical solution to prevent urethral trauma during catheterisation

The recognition at the EAU congress underscores the potential impact of this research on urological practice and patient care.

Future Directions and Ongoing Research

While the current study has made significant strides in understanding and preventing urethral trauma during catheterisation, there is still room for further research and development in this area.

What are the next steps in this line of research?

Potential avenues for future investigation include:

1. Conducting larger-scale clinical trials to further validate the safety and efficacy of the prototype device
2. Exploring the application of similar safety principles to other types of medical catheters and devices
3. Investigating the long-term outcomes of patients catheterized using the safety device compared to standard methods
4. Developing additional training tools and simulations based on the identified urethral rupture thresholds
5. Collaborating with medical device manufacturers to integrate safety features into commercially available catheterisation equipment

As research in this area continues, it holds the promise of further improving patient safety and reducing the incidence of catheterisation-related complications across healthcare settings.

Conclusion and Key Takeaways

The research on preventing urethral trauma during catheterisation represents a significant advancement in urological care. By identifying specific thresholds for urethral rupture and developing a practical safety device, the study offers a clear path forward for reducing the risk of this common complication.

What are the main points to remember from this research?

• Urethral rupture occurs at internal diametric strains exceeding 40% and pressures above 150 kPa
• A novel safety syringe can prevent dangerous pressure levels during catheter balloon inflation
• The safety device has been successfully implemented in clinical practice
• This research demonstrates the importance of translating laboratory findings into practical medical applications

As healthcare providers continue to adopt safer catheterisation practices and equipment, patients can look forward to reduced risk of urethral trauma and improved outcomes from this common medical procedure. The successful transition of this safety device from bench to bedside serves as an inspiring example of how targeted research can lead to tangible improvements in patient care.

Preventing Urethral Trauma During Catheterisation

Authors:

^*Niall F. Davis,^1,2
Rory O’C. Mooney,²
Conor V. Cunnane,²
Eoghan M. Cunnane,²
John A. Thornhill,¹
Michael T. Walsh²

1. Department of Urology, Tallaght Hospital, Dublin, Ireland
2. Centre for Applied Biomedical Engineering Research, Materials and Surface Science Institute, University of Limerick, Castletroy, Ireland
*Correspondence to: [email protected]

Citation:

EMJ Urol. 2017;5[1]:60-61. Abstract Review No. AR19.

Keywords:

Urethral trauma,
urethral catheterisation,
urethral rupture,
urethral injury,
urethral catheter,
safety device,
safety syringe

Each article is made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.

Urethral catheterisation is a routine task that is frequently performed within a healthcare setting. Almost 25% of hospitalised patients are catheterised during their inpatient stay.¹ Urethral injury typically occurs in men when the catheter’s anchoring balloon is inadvertently inflated inside the urethra.² Short-term complications include pain, bleeding, and acute urinary retention.² Urethral rupture can lead to the long-term complication of urethral stricture disease and may require urethral reconstruction in severe cases.²

There are currently no studies that demonstrate urethral strain thresholds for rupture during traumatic urethral catheterisation. Our aim was to investigate internal urethral diametric strain and threshold maximum inflation pressure as parameters for urethral rupture during inadvertent inflation of a catheter anchoring balloon in the urethra. In addition, we also designed and evaluated a novel safety device with the inability to cause urethral trauma, despite inadvertent balloon inflation in the urethra based on these parameters.

Inflation of a urethral catheter anchoring balloon was performed in the bulbar urethra of 21 ex vivo porcine models using 16 Fr catheters. Urethral trauma was characterised and graded with retrograde urethrography. Urethral rupture was correlated with internal urethral diametric strain (%) and maximal urethral pressure threshold values in kilopascals (kPa). Internal urethral diametric strain was calculated by averaging urethra luminal diameter proximal and distal to the traumatised site, and maximum luminal diameter at the traumatised site. Urethral catheters were then inflated in the bulbar urethras of seven fresh male cadavers using a standard syringe and a prototype safety-syringe prototype safety-syringe (Figure 1). The plunger of the standard syringe was depressed until opposing resistance pressure generated by the urethra prevented further inflation of the anchoring balloon. The plunger of the prototype safety-syringe was depressed until sterile water in the syringe decanted through an activated safety threshold pressure valve (Figure 1).

Figure 1: The prototype syringe used to determine urethral resistance pressure. The safety valve (arrow) is activated at threshold resistance pressure, allowing fluid to vent out of the activated valve.

Retrograde urethrography demonstrated that porcine urethral rupture consistently occurred at an internal urethral diametric strain >40% and a maximum inflation pressure >150 kPa (Figure 2). The mean±standard deviation maximum human urethral threshold inflation pressure required to activate the safety prototype syringe pressure valve was 153±3 kPa. In comparison, the mean maximum inflation pressure was significantly greater using the standard syringe than the activated prototype syringe (452±188 kPa, [p<0.001]).

Figure 2: Maximum catheter balloon/urethral pressure and internal diametric strain recorded for each of the 21 urethral samples tested.
This figure clearly demonstrates a safety cut-off of >40% internal urethral diametric strain and/or maximum balloon pressure cut-off of 150 kPa before urethral rupture (red dashed lines). Open circles indicate ruptured urethral samples. Filled circles indicate unruptured samples.

Internal urethral diametric strain and threshold maximum inflation pressures are important parameters for designing a safer urethral catheter system with lower intrinsic threshold inflation pressures. We have validated our porcine and cadaver findings in human male-to-female transgender urethral models and have recently implemented our safety device into clinical practice in Tallaght Hospital, Dublin, Ireland for patients requiring urethral catheterisation. This transition of a safety device from bench to bedside was commended during my presentation during March 2017, held at the European Association of Urology (EAU) congress, hosted in London, UK.

References

Chenoweth C, Saint S. Preventing catheter-associated urinary tract infections in the intensive care unit. Crit Care Clin. 2013;29(1):19-32.
Davis NF et al. Incidence, Cost, Complications and Clinical Outcomes of Iatrogenic Urethral Catheterization Injuries: A Prospective Multi-Institutional Study. J Urol. 2016;196(5):1473-7.

Misplaced Catheter Causes Significant Urological Damage

This case involves a misplaced catheter resulting in serious, long-term urological damage.

On the date of the incident in question, the patient was admitted to the hospital undergo a hip replacement. Pre-surgery, the patient was anaesthetized, and the nurse attempted to place a Foley catheter. However, the Foley catheter balloon was inflated in the patient’s urethra instead of his bladder. The balloon remained in the urethra for hours, despite not producing a good return of urine, and the patient did not recieve a urology consultation. This misplacement necessitated a surgical procedure to implant a temporary suprapubic tube and additional surgery of the urethra. Due to this misplacement, the patient ultimately spent multiple days in intensive care and suffered permanent disability and disfigurement.

Question(s) For Expert Witness

1. Are you able to address standard of care/ongoing complications as it relates to using a Foley catheter improperly?

Expert Witness Response E-014220

I am very familiar with current standard of care for Foley catheter placement and management (especially for inpatients) and catheter related complications, such as trauma related complications and catheter associated UTIs (CAUTIs). I’m familiar with risk factors associated with catheter related complications (i.e. traumatic catherizations) which include but not limited to prior lower urinary tract surgery/procedure (ex. TURP, RRP/RALP etc), presence of urinary tract device, such as sphincter or sling, and prior lower urinary tract trauma or infections. In 2012 I was a member of a multidisciplinary committee at my institution addressing catheter associated complications, such as UTIs and traumatic injury due to placement of Foley catheter. Our committee’s findings led to significant changes in urethral catheter management in inpatients. Protocols were created for placement and subsequent management of Foley catheters for all inpatients. This included, specific to minimizing risk of traumatic catheterization, that the catheter balloon should not be inflated until the catheter is completely in and there is return of urine. Also, if the patient has risk factors for catheter related complications (as described above), developed blood per urethra upon initial attempts to catheterize, or requires a Coude cath (specialized catheter) Urology should be consulted. These are typically patients on trauma service, ICU/CCU, and surgical services. This often involves urgent or semi-urgent placement of a Foley catheter by a nurse or intern/junior resident in the ER, trauma unit, resuscitation bay, ICU or operating room. The malposition is not recognized for hours or days (and sometimes week(s)) later. The subsequent history usually involves blood/urine bypassing around the catheter and poor drainage/urine output via catheter. Significant number of these patients has encountered long term sequelae from the injury due to the inflation of the balloon within the urethra. This injury inevitably leads to a urethra stricture which typically requires treatment either endodcopically, i.e. urethral dilation and/or DVIU (incising the stricture) or surgical repair/reconstruction, what is known as urethroplasty.

Placement, replacement and care of the Foley catheter.

Structure of the bladder

Placement of a Foley catheter.

Hygiene procedures must be carried out before insertion of the catheter.

The clinician should wash the patient’s hands and perineum with soap and water, disinfect with an antiseptic, and wear sterile gloves. Prepare the catheter (take with sterile tweezers, treat with a lubricant if necessary).

Female catheter insertion procedure:

Lying on your back, bend and spread your legs.

After parting the labia and finding the opening of the urethra, carefully insert the catheter. As soon as urine has gone through the catheter, you should stop.

After that, through one of the passages at the outer end of the catheter, inject sterile water with a syringe in a volume sufficient to inflate the balloon. Then attach the urine collection bag to the outer end. It is necessary to ensure that the bag is always below the level of the belt in order to avoid backflow of urine through the catheter.

Catheter insertion procedure for men:

Catheter insertion is more difficult for men. Since the urinary canal is longer and has physiological constrictions. The patient needs to lie on his back and slightly bend his knees, relax, the catheter is inserted into the urethra slowly and smoothly, with rotational movements, clamping the catheter with 5 and 4 fingers of the right hand, and first the genital organ must be held vertically, and then tilted down. Carefully advance the catheter. The presence of urine indicates that the catheter is placed correctly.

For children:

When placing a catheter, it is necessary to ensure the psychological comfort of the child.

Disinfect the genital area twice and wrap it with a sterile drape. Lubricate the end of the catheter, such as Vaseline.

Do not force the catheter if an obstruction is felt – this can damage the urethra.

The procedure for inserting the catheter is similar to that for adults, but the insertion depth is less because the urethra is shorter.

Urinary catheter care:

Wash the area around the catheter with soap and water several times a day to avoid irritating the infection. Do this after every bowel movement. Women are washed from front to back.

Drain the bag in time, keeping it below the level of the bladder to avoid urine flowing back into the catheter.

Change of catheter:

In case of normal urine outflow, the catheter is changed according to the recommendation of the doctor and instructions for use of the catheter.

Silicone has a shelf life of up to 30 days, latex up to 7 days, silicone with silver up to 90 days.

Never pull on the catheter. Disconnect the catheter only for rinsing or replacing it, as well as emptying the urinal.

Cases when you need to see a doctor:

– There are pains in the abdomen, flakes and blood in the urine.

— Urine is leaking from under the catheter.

– Urine outflow stopped.

Reasons for leaking urine:

catheter too thin, balloon not inflated enough, catheter or urinal tube kinked, catheter blocked.

Reasons for not passing urine:

a kink in the catheter or tube of the urinal,

insufficient fluid intake in the body (increase the amount of fluid consumed),

urinal is fixed too high (lower it below the level of the bladder),

blockade of the catheter,

impaired renal function (anuria) when the patient’s condition worsens.

Urinary catheters are flushed as directed by a physician:

Warm saline is used for flushing. If sediment or flakes appear in the urine, the catheter is washed with a solution of furacilin, as well as miramistin or chlorhexidine solution. For washing, Jeanne’s syringe is used.

Foley catheter

FAQ

When and why is intermittent catheterization recommended?

Intermittent catheterization is an effective and safe urinary diversion method that offers patients independence and significantly improves quality of life. In recent years, intermittent catheterization has become the preferred method for managing patients with neurogenic bladder dysfunction, paraplegia, diseases such as spina bifida or multiple sclerosis.

The choice of method of intermittent catheterization is carried out only after this method is recommended by the doctor in each case. Catheterization is carried out by emptying the bladder at regular intervals with disposable catheters.

How is intermittent catheterization performed in children?

Children with neurogenic bladder dysfunction may be catheterized by a parent or healthcare professional, always using asepsis. Parents should ask their doctor or medical professional who will explain and demonstrate the correct catheterization procedure. Only by carefully preparing you can be sure that you are performing the catheterization procedure correctly.

For infants and small children, the following sizes are generally used: 2.0-2.7 mm (Ch06-Ch08).

How many times a day should the bladder be catheterized?

Normal bladder emptying frequency is approximately 56 times a day. The frequency of catheterizations depends on the individual and factors such as how much you drink, medication, etc. Your healthcare provider can recommend how often you need to catheterize your bladder. You can determine for yourself when and how it will be best for you to carry out catheterization.

How much liquid should I drink every day?

This may vary depending on how active you are. You should aim to drink about 1.5-2 liters of fluid per day. Try to avoid drinks that contain caffeine, such as tea or coffee.

What should I do if I have difficulty inserting a catheter?

Sit in a comfortable position, try to relax and wait a while before performing the catheterization procedure. If you are unable to insert the catheter on your own, contact your healthcare provider.

What if I have difficulty removing the catheter?

Try not to worry and wait a while before trying again.