• 
• 

Three Part Question

In [persons who have been bitten by a venomous snake] does [a compression bandage combined with immobilisation] reduce [the effect of envenomation]?

Clinical Scenario

A 30 year old woman has been bitten by a venomous snake. In anticipation of emergency medical care, a bystander tied a compression bandage and a splint. You wonder if a compression bandage combined with immobilisation is a safe and effective first aid measure to reduce the effect of envenomation.

Search Strategy

Medline 1966-1 August 2010 using the Pubmed interface:
("Snake Bites"[Mesh] OR "Snake venoms"[Mesh]) AND ("Immobilization"[Mesh] OR "Pressure"[Mesh] OR "Bandages"[Mesh] OR "First Aid"[Mesh])
Embase and Medline 1947-1 February 2010 via the Embase.com interface:
('snakebite'/exp OR 'snake venom'/exp) AND ('bandage'/exp OR 'compression bandage'/exp OR 'pressure'/exp OR 'immobilization'/exp OR 'first aid'/exp)

The Cochrane Library using the Wiley interface:
MeSH descriptor explode all trees for (“Snake Bites" OR "Snake venoms") AND ("Immobilization" OR "Pressure" OR "Bandages" OR "First Aid")

We only included randomised and nonrandomised controlled studies with humans.

Search Outcome

Pubmed: 272 hits
Embase: 226 hits
Cochrane Central Register of Controlled Trials (CENTRAL): 4 hits

430 papers were found after removal of 73 duplicates. 424 papers were either irrelevant, animal studies, or had no intervention study design. The remaining 6 papers are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Anker et al 1983 Australia	12 healthy volunteers who received a subcutaneous injection in lower leg with mock venom (radioactively labeled insulin)	Nonrandomised controlled trial with comparison groups: a) firm pad and bandage (80-100 mmHg); b) air splint (50 to 65 mmHg); c)elastic bandage and splint (55 mmHg); d) no treatment	% of maximum radioactivity in blood after 60 minutes	After 60 minutes: 1.5 to 8% with firm pad and bandage; 32 to 36% with air splint; 36 to 45% with elastic bandage and splint; 37 to 65% without treatment	small sample size, indirectness through use of a mock venom, risk of performance bias through different treatment times, no statistical tests
			% of maximum radioactivity in blood at release of treatment	At release of treatment: 2 to 16% with firm pad and bandage (release after 64 to 116 minutes); 64 to 69% with air splint (release after 120 to 130 minutes); 41 to 67% with elastic bandage and splint (release after 60 to 99 minutes)
Anker et al. 1982 Australia	12 healthy volunteers who received a subcutaneous injection in lower leg with mock venom (radioactive sodium iodide	Nonrandomised controlled trial with comparison groups: a) firm pad and bandage (70-120 mmHg); b) air splint (55 mmHg); c) elastic bandage and splint (55 mmHg); d) no treatment	Time to 80 % of maximum radioactivity in blood	70 to 77 minutes with firm pad and bandage (treatment was discontinued after 58 to 67 minutes); 20 to 35 minutes with air splint; 12 to 45 minutes with elastic bandage and splint; 22 to 29 minutes without treatment	small sample size, indirectness through use of a mock venom, no statistical tests
Howarth et al. 1994 USA	15 healthy volunteers who received a subcutaneous injection in wrists and ankles with mock venom (99m technetium antimony sulfur colloid) (9 additional volunteers received an intradermal injection with mock venom, but did not receive first aid treatments)	Within subjects study design with comparison groups: a) bandage and splint for one lower limb; b) bandage and splint for one upper limb; c) bandage and splint for either both lower/upper limbs (no results reported) d)local pressure over injection site. Target bandage pressure was 50 to 70 mmHg, the applied bandage pressure ranged from 20 to 110 mmHg; the unbandaged limbs acted as control.	Prevention of mock venom transit from periphery to systemic circulation while in rest	In rest: No transit in lower limbs of 9 out of 13 volunteers; No transit in upper limbs of 6 out of 13 volunteers; No transit with local pressure in 1 out of 4 volunteers	small sample size, indirectness through use of a mock venom, no statistical tests
			Prevention of mock venom transit from periphery to systemic circulation while walking with bandage and splints in place	While walking: subjects without transit in rest, all showed transit in upper and lower limbs after walking.
Tun-Pe et al. 1994 Myanmar	22 healthy volunteers who received a subcutaneous injection in lower leg with mock venom (radioactive natrium iodide)	Nonrandomised controlled trial with comparison groups: a) firm pad and bandage and splint (mean 60 ± 10 mmHg); b) no treatment	Prevention of mock venom transit	No transit in 12 out of 14 volunteers with pad and bandage and splint	small sample size, indirectness through use of a mock venom, bandage pressures and mock venom dosages varied in the intervention group, no statistical tests
			Time to 80 % of maximum radioactivity in blood	50 to 87 minutes with firm pad and bandage and splint (treatment was discontinued after 45 to 79 minutes); 40 to 54 minutes without treatment
Canale et al. 2009 Australia	96 volunteers ( 78 healthcare workers and 18 laypersons)	RCT with comparison groups: a)crepe bandage; b)elastic bandage	Median (IQR) bandage pressure	Without information about the requirements of the technique: 28 mmHg (IQR 17–42 mmHg) with crepe bandage; 47 mmHg (IQR 26–83 mmHg) with elastic bandage. Following training: 65 mmHg (IQR 56–71 mmHg) with elastic bandage; there was no comparison group	Indirectness through use of healthcare workers and absence of stress of a situation with a real snakebite
Simpson et al. 2008 India	40 volunteers (laypersons)	RCT with comparison groups: a)written instructions on application of compression bandage and splint; b)focused training on application of compression bandage and splint	Pressure bandage application within range of 55 to 70 mmHg	0 out of 20 with written instructions; 12 out of 20 with focused training measured 1 hour after training, 7 measured 1 day after training, 5 measured 3 days after training, 3 (upper limb) measured 3 months after training, 5 (lower limb) measured 3 months after training. No significant differences for bandage materials used (crepe bandage versus turban cloth)

Comment(s)

A compression bandage should be applied tightly, but applying it not tightly enough or too tightly is ineffective and sometimes harmful. Three studies indicate that applying a compression bandage over a firm cloth pad is effective, but this technique increases the risk of creating an arterial tourniquet. Two studies indicate that motivated persons have difficulty to apply a compression bandage at the correct pressure, even after intense training. One study indicates that walking increases the transit of venom.

Clinical Bottom Line

Based on the above findings, the first aid treatment appears to be stopping the bitten person from moving, calming the person, and immobilising the bitten limb.

Level of Evidence

Level 3 - Small numbers of small studies or great heterogeneity or very different population.

References

1. Anker RL, Straffon WG, Loiselle DS, Anker KM. Snakebite. Comparison of three methods designed to delay uptake of 'mock venom'. Aust Fam Physician 1983;12(5):365-8
2. Anker RL, Straffon WG, Loiselle DS, Anker KM. Retarding the uptake of 'mock venom' in humans. Comparison of three first-aid treatments. Med J Aust 1982;1(5):212-4.
3. Howarth DM, Southee AE, Whyte IM. Lymphatic flow rates and first-aid in simulated peripheral snake or spider envenomation. Med J Aust 1994;161(11-12):695-700
4. Tun-Pe, Muang-Muang-Thwin, Myint-Myint-Than, Aye-Aye-Myint, Kyaw-Myint, Thein Than. The efficacy of compression immobilization technique in retarding spread of radio-labeled Russell's viper venom in rhesus monkeys and 'mock venom' NaI131 in human volunteers. Southeast Asian J Trop Med Public Health 1994;25(2):349-53
5. Canale E, Isbister GK, Currie BJ. Investigating pressure bandaging for snakebite in a simulated setting: bandage type, training and the effect of transport. Emerg Med Australas 2009;21(3):184-90.
6. Simpson ID, Tanwar PD, Andrade C, Kochar DK, Norris RL. The Ebbinghaus retention curve: training does not increase the ability to apply pressure immobilisation in simulated snake bite-implications for snake bite first aid in the developing world. Trans R Soc Trop Med Hyg 2008;102(5):451-9.