– NO ASV TEST DOSE MUST BE ADMINISTERED.
– SKIN/CONJUNCTIVAL HYPERSENSITIVITY TESTING DOES NOT RELIABLY PREDICT
EARLY OR LATE ANTISNAKE VENOM REACTIONS AND IS NOT RECOMMENDED.
– Rarely patients may develop severe life-threatening anaphylaxis characterized byhypotension, bronchospasm, and angioedema. However, 20%-60% patients treated with ASV develop either early or late mild reactions.
– Early anaphylactic reactions occurs within 10–180 min of start of therapy and is characterized by itching, urticaria, dry cough, nausea and vomiting, abdominal colic, diarrhoea, tachycardia, and fever.
– Pyrogenic reactions usually develop 1–2 h after treatment. Symptoms include chills and rigors, fever, and hypotension. These reactions are caused by contamination of the ASV with pyrogens during the manufacturing process.
– Any new sign or symptom after starting the ASV in drip should be suspected as a reaction to ASV.
– Late (serum sickness–type) reactions develop 1–12 (mean 7) days after treatment. Clinical features include fever, nausea, vomiting, diarrhoea, itching, recurrent urticaria, arthralgia, myalgia, lymphadenopathy, immune complex nephritis and, rarely, encephalopathy.
Treatment of Early ASV reaction
– Stop ASV temporarily.
– Start fresh IV normal saline infusion with a new IV set
– Administer Epinephrine (adrenaline) (1 in 1,000 solution, 0.5 mg (i e 0.5 ml) in adults intramuscular over deltoid or over thigh; In children 0.01 mg/kg body weight) for early anaphylactic and pyrogenic ASV reactions.
– Administer Chlorpheniramine maleate (adult dose 10 mg, in children 0.2 mg/kg) intravenously.
– Role of Hydrocortisone in managing ASV reaction is not proved.
– Once the patient has recovered, re-start ASV slowly for 10-15 minutes keeping the patient under close observation. Then resume normal drip rate.
– For high risk patients
In patients with history of hypersensitivity or exposure to animal serum such as equine ASV, tetanus-immune globulin or rabies-immune globulin in past, severe atopic conditions:
• Give ASV only if they have signs of systemic envenoming.
• Give Inj. Hydrocortisone 200 mg and Chlorpheniramine maleate 22.75 mg prior to the administration of ASV.
– Epinephrine premedication is not given as routine as it can cause hypertension and in patients with bleeding tendency can lead to intracranial bleeding (Expert
Consensus). However, epinephrine should be kept handy for adults. No trials have been done in children and old people. Inj. Adrenaline 0.25 ml of 1:1000 (as available in one ampoule of 1 ml) subcutaneously just before adding ASV to the running IV fluid.
Treatment of Late (serum sickness–type) reactions
– Inj. Chlorpheniramine 2 mg in adults (In children 0.25 mg/kg/day) 6 hourly for 5 days.
– In patients who fail to respond within 24–48 h give a 5-day course of Prednisolone (5 mg 6 hourly in adults and 0.7 mg/kg/day in divided doses in children.