WHO SNAKE-BITE MANAGEMENT - Antivenom (AV) therapy and supportive care
(adapted to: Warrell DA, WHO guidelines for physicians 2010)
AV should be given only to patients in whom its benefits are considered likely to
exceed its risks.
Indications for AV therapy
AV is indicated:
1) Systemic envenoming (one or several of the following):
2) Local envenoming (one or several of the following):
When indicated, AV should be given as early as possible, and in case of coagulopathy, as long as coagulopathy exists.
Adverse reactions of patients to AV, and treatment
Adverse reactions to AV typically in >10% of patients
Treatment for both: adrenalin (0.1% solution, 1:1000, 1 mg/ml), 0.5 mg for adults, 0.01 mg/kg for children; intramuscularly into upper lateral thigh; repeat dose every 5-10 min if patient’s condition deteriorates. In addition: antihistamines (chlorphenamine maleate, adults: 10 mg, children: 0.2 mg/kg i.v.; hydrocortisone, adults: 100 mg, children: 2 mg/kg i.v. In pyrogenic reactions: paracetamol per os to reduce fever. In all cases: i.v. fluids to correct hypovolemia.
Treatment: Oral anithistamines: chlorphenamine, adults: 2 mg hourly, children: 0.25 mg/kg/day in 5-7 doses; or: prednisolone, adults: 5 mg six-hourly, children: 0.7 mg/kg/day in 5-7 doses.
Administration of AV
Have adrenalin ready before AV administration
AV must be given until symptoms resolve; if necessary at 1-2 hour intervals, for coagulopathy at 6 hour intervals. Bleeding stops within 15-30 minutes; coagulopathy within 3-9 hours; blood pressure
back to normal within 60 minutes; neurotoxicity resolves within 30 min to several hours, haemolysis and rhabdomyolysis within a few hours.
All patients have to be monitored for at least 48 hours.
Treatment when no AV is available, and medical support of AV therapy
1) Neurotoxic envenoming:
2) Hypotension and shock:
3) Oliguria and acute kidney injury (urine output <20 ml/hour):
If no clinical improvement is achieved: dialysis
Dialysis is also indicated in case of: clinical uraemia, fluid overload, creatinine >4 mg/dl (500 micromol/litre), urea >130 mg/dl (27 mmol/litre), potassium >7mmol/litre and symptomatic acidosis
4) Haemostatic disturbances:
DO NOT use heparin or antifibrinolytic agents
In patients with coagulopathy, placement of venipuncture (if necessary) should be chosen where haemostasis by external pressure is most likely to be effective (e.g., antecubital fossa)
Treatment of bitten part: aspirate bullae only when rupture seems likely. Control secondary infection by single dose of amoxycillin and tetanus prophylaxis
Compartment syndrome: intracompartmental pressure of >40 mm Hg (less in children): if possible, fasciotomy should be delayed until haemostatic disturbances have been corrected.