Snakebite (bite)
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A snakebite is, of course, the bite of a snake, often a venomous one.
Most snake species are not venomous. Some venomous snakes are capable of biting without injecting poison into the victim, and such snakes will often deliver such a 'dry bite' rather than waste their venom on a creature too large for them to eat. However, all bites from any snake, whether or not it is known to be venomous, and especially if it is an unknown species, should be treated seriously.
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Prevention
Snakes will generally attempt to avoid confrontation with humans, and are most likely to bite when startled, cornered, or provoked; attempting to kill a snake is a particularly risky activity. According to Steven Curry, Associate Medical Director at Samaritan Regional Poison Control Center in Phoenix, Arizona - "The majority [of snakebite victims in the United States] are inebriated men, frequently unemployed, and almost universally tattooed." - Mr Curry estimates that around 80% of snakebite victims have been 'messing around' with snakes.
When travelling in snake country, wear sturdy boots if possible and be wary of reaching into potential hiding places (hollow branches etc) without checking first.
Snakes are most likely to approach residential areas when attracted by prey species (e.g. rats) and long grass or thick undergrowth. Removing these attractions around the home reduces the risk of confrontation between snake and man.
First-Aid
Snakebite first-aid recommendations vary, in part because different snakes have different sorts of venom. Some have little local effect, but life-threatening systemic effects, in which case containing the venom in the region of the bite (e.g. by pressure immobilization) is highly desirable. Other venoms cause localized tissue damage around the bitten area, and immobilization may increase the severity of the damage in this area, but also reduces the total area effected; whether this trade-off is desirable remains a point of controversy.
Because snakes vary from one country to another, first-aid methods also vary; treatment methods suited for rattlesnake bite in the USA might well be fatal if applied to a tiger snake bite in Australia. Readers are strongly advised to obtain guidelines from a reputable first-aid organization in their own region, and to beware of home-grown or anecdotal remedies.
However, most first-aid guidelines agree on the following:
1. Protect the patient (and others, including yourself) from further bites. While identifying the species is desirable, do not risk further bites or delay other first-aid in trying to capture or kill the snake. If the snake has not already fled, remove the patient from the area of the snake.
2. Keep the patient calm and call for help to arrange for transport to the nearest hospital emergency room. Antivenom for snakes common to the area will often be available there.
3. Do not give the patient anything to eat or drink.
4. Remove items that may constrict if the bitten limb swells (rings, watches, footwear, etc.)
5. Keep the patient as still as possible.
Pressure Immobilization
Caution: Pressure immobilization may not be appropriate for all bites; see above.
The object of pressure immobilization is to contain venom within a bitten limb by preventing it from moving through the lymphatic system.
This is preferably done by use of an elastic bandage. Bandaging begins above the bite site (i.e. between the bite and the heart), winding around in overlapping turns and moving up towards the heart, then back down over the bite and past it towards the hand or foot. The bandage should be about as tight as when strapping a sprained ankle; it should not cut off blood flow. If possible, the limb should be further immobilized by splinting and the location of the bite should be clearly marked on the bandages.
Once a pressure bandage has been applied, it should not be removed until the patient has reached a medical professional. A pressure bandage can contain venom so effectively that no symptoms are visible for more than twenty-four hours, giving the impression of a dry bite; removing the bandage releases that venom into the patient's system with possibly fatal results.
Outmoded Treatments
The following treatments have all been recommended at one time or another, but are now considered to be ineffective or outright dangerous, and should not be used. Many cases in which such treatments appear to work are in fact the result of dry bites.
- Application of a tourniquet to the bitten limb.
- Cutting open the bite area.
- Application of potassium permanganate ('Condy's Crystals').
- Electroshock. Although still advocated by some, animal testing has shown this treatment to be useless and potentially dangerous (cf Postgrad Med 1987 Oct;82(5):32; Postgrad Med 1987 Aug;82(2):42; Ann Emerg Med 1988 Mar;17(3):254-256; Toxicon 1987;25(12):1347-1349; Ann Emerg Med 1991 Jun;20(6):659-661).
- Suctioning out venom, either by mouth or with a pump. Suctioning by pump removes a clinically insignificant quantity of venom ('Suction for Venomous Snakebite: A Study of "Mock Venom" Extraction in a Human Model', February 2004 Annals of Emergency Medicine, p. 181). Suctioning by mouth presents a risk of further poisoning through the mouth's mucous tissues (Riggs et al: Rattlesnake evenomation with massive oropharyngeal edema following incision and suction (Abstract) AACT/AAPCC/ABMT/CAPCC Annual Scientific Meeting, 1987).
- Application of ice. The process of chilling the wound area or the affected limb should certainly be avoided. These procedures would have the effect of slowing the blood flow to the area, thus preventing the natural dissipation of the venom and likely increasing its damaging effects. There have been emergency room cases in which patients were brought into the hospital for treatment where well-meaning friends or family members might have used a combination of these outmoded treatments (e.g., attempts at cutting and suction, following by a tourniquet, and, finally, the placing of the limb on ice). In extreme cases, in cases where the patient was in a remote area, these misguided attempts at treatment have resulted in the amputation of a limb in a cases where the proper treatment would have resulted in a full recovery of an otherwise mild to moderate snakebite.