FIRST AID FOR SNAKE BITES:-
1. Do NOT wash the area of the bite! It is extremely important to retain traces of venom for use with venom identification kits!
2. Stop lymphatic spread - bandage firmly, splint and immobilise!
The "pressure-immobilisation" technique is currently recommended by the Australian Resuscitation Council, the Royal Australasian College of Surgeons and the Australian and New Zealand College of Anaesthetists.
The lymphatic system is responsible for systemic spread of most venoms. This can be reduced by the application of a firm bandage (as firm as you would put on a sprained ankle) over a folded pad placed over the bitten area. While firm, it should not be so tight that it stops blood flow to the limb or to congests the veins. Start bandaging directly over the bitten area, ensuing that the pressure over the bite is firm and even. If you have enough bandage you can extend towards more central parts of the body, to delay spread of any venom that has already started to move centrally. A pressure dressing should be applied even if the bite is on the victims trunk or torso.
Immobility is best attained by application of a splint or sling, using a bandage or whatever to hand to absolutely minimise all limb movement, reassurance and immobilisation (eg, putting the patient on a stretcher). Where possible, bring transportation to the patient (rather then vice versa). Don't allow the victim to walk or move a limb. Walking should be prevented.
The pressure-immobilisation approach is simple, safe and will not cause iatrogenic tissue damage (ie, from incision, injection, freezing or arterial torniquets - all of which are ineffective).
See the AVRU site for more details of bandaging techniques.
Bites to the head, neck, and back are a special problem - firm pressure should be applied locally if possible.
Removal of the bandage will be associated with rapid systemic spread. Hence ALWAYS wait until the patient is in a fully-equipped medical treatment area before bandage removal is attempted.
Do NOT cut or excise the area or apply an arterial torniquet! Both these measures are ineffective and may make the situation worse.
Joris Wijnker's Snakebite Productions has more information on envenomation and he can supply a suitable first aid kit and booklet.
Medical Management of Snake Bites
Only 1 in 20 snake bites require active emergency treatment or the administration of antivenom. Medical management depends on the degree of systemic envenomation and the type of venom.
See also the AVRU site for more info on clincial assessment and management.
Critically ill patients
Maintain immobilisation, splint and bandage until the situation is under control!
Support airway, breathing and circulation.
Intubate and ventilate with 100% Oxygen if airway or respiration fail.
Give antivenom immediately (See below for details). Intravenous adrenaline should be given only for lifethreatening hypotension or anaphylaxis - its use has been associated with cerebral haemorrhage.
Volume expansion may be necessary.
Severe coagulation disturbances, electrolyte abnormalities, and muscle damage leading to acute renal failure are likely.
Repeat antivenom as clinically indicated.
General management as for less seriously ill patients as well (see below).
Less seriously ill patients - no signs of systemic spread
Admit to ICU for non-invasive monitoring, strict bedrest and full head injury observations (wake hourly).
Leave bandages in place.
Obtain appropriate antivenoms and venom detection kit.
Obtain intravenous access.
Take blood for group and X-match, coagulation screen (including fibrinogen levels, and tests for DIC), full blood count, electrolytes and calcium, creatinine kinase and arterial blood gases. Perform ECG. Repeat at appropriate intervals.
Collect urine for microscopy to detect haematuria and for free protein, haemoglobin and myoglobin measurement. Record urine output. Freeze the first sample for venom detection.
Draw up adrenaline, antihistamine, and steroids in case of anaphylaxis to antivenom.
When ready, cut a hole over the wound site, inspect and take swabs for use with the venom detection kit.
Once the results of the venom detection kit are known, slowly and progressively remove the bandages. Don't rush!
If systemic symptoms ensue:
Re-apply bandages and give antivenom as clinically indicated.
Ensure the patient is well hydrated (to reduce the risk of acute renal failure due to rhabdomyolysis).
Repeat blood tests, ECG, etc at clinically relevant intervals.
Correct abnormal coagulation; look out for disseminated intravascular coagulation (heparin probably contra-indicated in DIC from snake bite).
Analgesia and sedation - be cautious.
Correct hypotension, if present, with volume expansion and vasopressors (exclude occult bleeding).
Watch for development of renal failure - monitor urine output and composition.
Tetanus prohylaxis is recommended.
Usually, if there are no signs of envenomation four hours after removal of the bandages, and if repeat blood tests taken at that time are normal, then it is probable that significant envenomation has not occurred. If laboratory tests are not available, 12 to 24 hours is a reasonable period of observation.
Recovery is usually complete, though the patient usually develops a sensitivity to equine immunoglobulin.
If the patient develops serum sickness (see below), the severity is reduced by steroid administration (eg. prednisolone 1mg/kg every 8 hours) until resolution occurs. A course of steroids is recommended in all patients who receive polyvalent antivenoms.