Commentary: Pressure Bandaging for North American Snake Bite? No!

J Med Toxicol. 2011 Dec; 7(4): 324–326.

Published online 2011 Nov 8. doi: 10.1007/s13181-011-0188-9

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This issue of The Journal of Medical Toxicology includes a position statement regarding the use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation. This commentary discusses the background behind the creation of the position statement and explores the issues involved in applying science to real-world public health recommendations and practice.

Keywords: Pressure immobilization, Crotalinae, Envenomation

This issue of The Journal of Medical Toxicology includes a position statement regarding the use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation [1]. It has been jointly endorsed by the American College of Medical Toxicology, the American Academy of Clinical Toxicology, the American Association of Poison Control Centers, the International Society on Toxinology, the European Association of Poison Centres and Clinical Toxicologists, and the Asia Pacific Association of Medical Toxicology, and concludes that pressure bandage with immobilization (PBI) cannot be recommended as pre-hospital care in areas such as North America, where non-neurotoxic snakebite is the norm.

This position statement was formulated because of concern about recently published first aid guidelines of the American Heart Association (AHA) and American Red Cross (ARC) [2]. Those guidelines, designed to be applied by bystanders or the victim, included the following:

“Applying [PBI] with a pressure between 40 and 70 mm Hg in the upper extremity and between 55 and 70 mm Hg in the lower extremity around the entire length of the bitten extremity is an effective and safe way to slow the dissemination of venom by slowing lymph flow (Class IIa, LOE C). For practical purposes pressure is sufficient if the bandage is comfortably tight and snug but allows a finger to be slipped under it. Initially it was theorized that slowing lymphatic flow by external pressure would only benefit victims bitten by snakes producing neurotoxic venom, but the effectiveness of pressure immobilization has also been demonstrated for bites by non-neurotoxic American snakes….”

Even though the AHA/ARC recommendation is weak (Class II: “conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment.” Class IIa: “weight of evidence/opinion is in favor of usefulness/efficacy”; level of evidence C: “recommendation based on expert opinion, case studies, or standards of care.”) [3] and meant to apply to snakebites worldwide, we are concerned that the recommendations will be applied to North American Crotalinae envenomations. We are also concerned that this guideline was graded above the level of current evidence and that the subtleties of the recommendation grading system are very likely to be underappreciated by most.

The pre-hospital use of PBI in North American snakebite would be a major change in how such cases are managed. The history of snakebite first aid and emergency care is full of concepts that, despite initial theoretical appeal and/or anecdotal evidence, ultimately proved to be harmful. Once-common practices, such as tourniquets, cryotherapy, incision, suction, electrotherapy, and fasciotomy, have been eliminated as their effectiveness was refuted, and more importantly, evidence of harm emerged [4–9]. With this perspective, the introduction of a new practice must be based on the scientific demonstration of efficacy and safety.

The application of science to real-world scenarios can be complex. The aim of PBI is to sequester venom in the limb, delaying its arrival into the central circulation and thereby delaying or even preventing the onset of the potential systemic consequences of envenomation [10]. Apart from directly measuring the clinical efficacy of PBI for various endpoints, together with risks of harm of properly applied PBI, it is important to consider context-specific considerations. Key questions are: (1) the certainty regarding the kind of snake involved, (2) the expected time to arrival at a place where definitive therapy can be provided, (3) whether lay individuals are able to distinguish between scenarios with different management considerations, and (4) the likelihood that PBI will be applied correctly or incorrectly and that immobilization can be realistically maintained.

In addition to these concerns, the larger questions include when, how, and on what basis should a new recommendation in the management of snakebite be put forward? Moreover, when universal benefit may not result, should first aid training be guided by utilitarian endpoints in which many patients might benefit by an intervention that harms some, or even worse, harms many patients and benefits few?

When evaluating the application of PBI to Crotalinae envenomations, the science is incomplete. Randomized, prospective, controlled, studies of PBI in human Crotalinae envenomations have not been performed. Our current state of knowledge comes primarily from animal models and a few studies in neurotoxic snakebite, where local tissue injury is not the major concern. This is an entirely different clinical problem to that posed by Crotalinae envenomations, where local tissue injury predominates. Furthermore, extrapolating from animal models to humans can be problematic, especially when animal studies have used fatality from systemic effects—rather than tissue injury—as a primary end-point. The data on tissue injury in animal studies is limited, but a porcine study demonstrated that tissue pressures in a range that would, in other contexts, result in the consideration of fasciotomy, and which might result in ischemic injury, can occur from PBI [11]. Recent studies in humans have demonstrated that both trained and lay individuals applied PBI that resulted in either ineffective or tissue pressures in the same range [12–14]. Finally, the porcine study of Crotalinae envenomation used in support of the AHA/ARC guidelines [2] actually drew the opposite conclusion, stating: “On the basis of our findings, we cannot recommend pressure immobilization widely for viper envenomation…” [11].

Thus the existing science points away from adoption of PBI in Crotalinae envenomation rather than towards it. Given that 98% of North American venomous snakebites are by Crotalinae, that fewer than 0.2% of those victims die, and that virtually all have soft-tissue injury, the key question is whether deploying pressure immobilization as a first aid strategy in this context will lead to a large number of people with increased and/or permanent limb injury while saving virtually no lives [15, 16]. Clearly, more work needs to be done. But our interpretation of the current state of knowledge is that the potential for harm of PBI in the vast majority of Crotalinae envenomations outweighs the potential benefits.

In the context of limited evidence, it is understandable that learned and well-intentioned individuals may disagree. This makes the consensus of toxicologists and envenomation specialists worldwide in opposition to the use of PBI in the prehospital setting all the more striking. The six organizations that endorse the position statement represent the mainstream medical opinion among experts on four continents. There is currently strong consensus that this technique should not be promulgated or taught in areas where non-neurotoxic snakebite predominates. Thus, in North American Crotalinae snakebite, the evidence for PBI would be more properly graded as Class III: “conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmful [3].”

In response to criticisms from members of the clinical toxicology community, the AHA and the ARC have acknowledged that their guideline regarding snakebite does not define the snake groups, geographic locations, and individual circumstances in which PBI might be applicable and also that the data regarding PBI in Crotalinae envenomation are limited and insufficient to deem PBI safe and effective. They are planning to clarify the guideline. For future guidelines, content experts from the position-statement-sponsoring organizations will be invited to assist in the writing (Rose Marie Robertson, personal communication 2011). We applaud the AHA and ARC for their evidence-based approach and their ongoing process of review and clarification.

We agree with the conclusions of the position statement: “The use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation is not recommended [1].”

In the absence of definitive data on much of the pre-hospital management of Crotalinae snakebite, the following recommendations are based on the best available evidence, as well as expert consensus [17, 18]:

1. Get a safe distance away from the snake.

2. Remove jewelry and loosen tight-fitting clothing.

3. Loosely splint or otherwise immobilize the extremity in a functional position.

4. As a default action, maintain the bitten extremity in a neutral position with regard to the heart. Other potential actions should be guided by an experienced clinician.

5. Get to a hospital, preferably transported by an EMS provider. In general, supine positioning will prepare providers in managing possible effects such as hypotension and/or vomiting.

6. Avoid useless and/or potentially harmful interventions, such as tourniquets, incision, suction, cryotherapy, or electric shock.

Steven A. Seifert, Email: ude.mnu.dulas@trefiess.

Julian White, Email: [email protected].

Bart J. Currie, Email: ua.ude.seiznem@trab.

1. American College of Medical Toxicology, American Academy of Clinical Toxicology, American Association of Poison Control Centers, European Association of Poison Control Centres, International Society of Toxinology, Asian Pacific Association of Medical Toxicology (2011) Pressure immobilization after North American Crotalinae snake envenomation. J Med Toxicol. doi:10.1007/s13181-011-0174-2 [PMC free article] [PubMed]

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Pressure Immobilisation First Aid : School of Biomedical Sciences

Bites to the lower limb

1. Move the victim away from the snake. Calm and reassure them. Jewelry such as toe rings and ankle bracelets should be removed before the bandage is applied.

Regardless of where on the limb the bite has occurred, commence bandaging from just above the toes (leave these uncovered so that blood flow to the nail beds can be monitored).

Crepe bandages are ideal, but any flexible material may be used. Clothing, towels etc may be torn into strips.  Panty hose have been successfully used.

Do not take off clothing, as the movement of doing so will promote the movement of venom into the blood stream. Keep the bitten limb, and the patient, still.

Bandage upwards from the lower portion of the bitten limb. Even though a little venom may be squeezed upwards, the bandage will be more comfortable, and therefore can be left in place for longer if required.

2. The bandage should be as tight as you would apply to a sprained ankle.

3. Extend the bandage as high as possible up the limb.

4. Apply a splint to the leg. Any rigid object may be used as a splint.  e.g. spade, piece of wood or tree branch, rolled up newspapers etc.

5. Bind it firmly to as much of the leg as possible.

Keep the patient still. Lie the patient down to prevent walking or moving around.

Bites to the hand or forearm

Bandage as much of the arm as possible, starting at the fingers.

Use a splint to the elbow.

Keep the patient still. Lie the patient down to prevent walking or moving around.

Note: We do not recommend that the arm be bent at the elbow and placed in a sling as this can create a tourniquet effect at the elbow.

Bites to the trunk

If possible apply firm pressure over the bitten area. Do no restrict chest movement. Keep the patient still.

Bites to the head or neck

No first aid for bitten area. Keep the patient still.

Summary

1. Research stresses the importance of keeping the patient still. This includes all the limbs. Bring transport to the patient if possible.
2. DO NOT cut or incise the bitten area.
3. DO NOT apply an arterial tourniquet. (Arterial tourniquets, which cut off the circulation to the limb, are potentially dangerous, and are no longer recommended for any type of bite or sting in Australia.)
4. DO NOT wash the bitten area or suck the bite. The type of snake involved may be identified by the detection of venom on the skin. No attempt should be made to catch or kill the snake.
5. Note: Even if the bitten or stung person is ill when first seen, the application of pressure-immobilisation first aid may prevent further absorption of venom from the bite or sting site during transport to hospital.
6. If the bandages and splint have been applied correctly, they will be comfortable and may be left on for several hours. They should not be taken off until the patient has reached medical care.
7. The treating doctor will decide when to remove the bandages. If a significant amount of venom has been injected, it may move into the blood stream very quickly when the bandages are removed. They should be left in position until appropriate antivenom and resuscitation equipment have been assembled.
8. Bandages may be quickly reapplied if clinical deterioration occurs, and left on until antivenom therapy has been effective.
9. Hospital Staff 
   Please note that first aid measures are usually removed soon after the patient is admitted. Do not leave on for hours.

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Imposition of a plaster bandage from 2,000 rubles in Rostov-on-Don

A medical bandage can be an effective treatment tool in the hands of an experienced qualified doctor. The duration of the recovery period after a surgical operation or injury directly depends on the correct application of the bandage. Specialists of the Rostov medical center “Best-Clinic” are fluent in the techniques of applying dressings of all types and apply their experience in helping our patients.

Why dressings are applied

Dressings are necessary to achieve the following goals:

• protection of the wound surface from external factors and infection
• pressurizing internal organs to stop internal bleeding
• retention of drugs on the surface of the wound
• immobilization of the site of dislocation or fracture

The purposes pursued when applying dressings can be very different, so there are many varieties of medical dressings that differ from each other in the application technique and dressing materials used. Also, dressing is carried out not only for injuries of the limbs, but also after surgical procedures, for example, during operations on the face.

Types of dressings

Different types of dressings are used in modern medicine:

• Pressure

A medical pressure bandage is commonly called a tourniquet and is applied when venous or capillary bleeding occurs. It is also effective when used to stop bleeding from large arteries. It is important to know that a pressure bandage should not be left on the body for a long period of time (in the cold season, the tourniquet must be removed after two hours from the moment of application, and in the warm season – after one hour).

• Occlusal (preventing air and moisture exposure to the wound)

This type of bandage has a powerful therapeutic effect, as it accelerates the formation of epithelium on the surface of the wound, protects the wound from external factors and improves the granulation process. Occlusive dressings are applied during the treatment of dermatological diseases, and are also often used in military field surgery.

• Medicinal (ensuring the supply of medicinal substances to the wound)

When such dressings are applied, the material used is impregnated with the drug. Thus, a long-term access of the drug to the wound surface is achieved. Naturally, the drug bandage can be on the body for a strictly defined time, after which it is necessary to perform a dressing.

• Retainers

Retaining bandages are widely used in sports medicine. Medical dressings of this variety are applied to athletes to ensure the fixation of the joints in case of instability resulting from sports injuries. Retaining dressings are made of modern elastic materials, making their use as comfortable as possible for patients.

• Compression

Bandages of this variety are very effective in the treatment of diseases of the veins of the legs. After applying the bandage, the patient should experience the feeling of a tight-fitting boot, while the toes should not go numb. Compression bandages are applied using special elastic bandages.

• Immobilization (immobilization)

Immobilization dressings are also called transport dressings because they are applied to patients to ensure immobility at the time of transport of the patient. They are applied for joint injuries, fractures, suppurative processes of the limbs and soft tissue injuries, characterized by a large area.

• Aseptic

The main function of an aseptic medical dressing is to prevent infection from entering the wound surface. To apply a dressing of this type, a sterile gauze napkin is used, used in several layers, and cotton wool. Also, an aseptic dressing helps to dry the wound.

• Corrective (providing correction of deformities)

These dressings are applied with an elastic or mesh-tubular bandage, wadding and cotton fabric. Corrective dressings allow you to eliminate congenital or acquired body deformities.

Dressings can be applied using different types of materials. They are thus divided into three categories:

• Splints (hard bandages)

When applying a splint, it is necessary to lay the areas of bony protrusions with a soft material so that abrasions and bedsores do not form under the dressing.

• Soft
• Hardening (starch and gypsum)

Plaster casts are most often used in the treatment of fractures and are an effective means of immobilization. They are very durable and allow the patient to perform an X-ray examination without removing the dressing.

The comfort of the patient and the therapeutic effect of dressings directly depends on the quality of the consumables used in the application.

What is an application kit

This term refers to a collection of medical consumables needed to make various types of dressings that are applied for first aid purposes.