Antivenom use, premedication and early adverse reactions in the management of snake bites in rural Papua New Guinea

To examine antivenom use, premedication, early adverse reactions and patient outcomes after snake bite in rural Papua New Guinea. Retrospective chart analysis of all admissions for snake bite with documented antivenom use at 11 rural health facilities from January 1994 to June 2004. No formal protocol was followed and there was no attempt at randomisation or blinding of prophylaxis. Antivenom use was documented in 136/1881 (7.2%) snake bite admissions and most (121/136: 88.9%) received a single vial. CSL Polyvalent antivenom was administered to 112/136 (82.4%). One hundred and eleven patients (81.6%) happened to have been given premedication with adrenaline and/or promethazine and/or hydrocortisone. Early adverse reactions were reported in 25 patients (18.4%) including 23 treated with polyvalent antivenom. Intravenous test doses of antivenom were given to 32 patients, none of whom had a positive test result. Subsequent adverse reactions occurred in 9 of these 32 (28.1%) patients. One death may have been attributable to anaphylaxis after polyvalent antivenom. Reaction rates were significantly (p⩽0.005) lower in adrenaline premedicated patients (7.7%) compared to patients premedicated without adrenaline (28.3%) and unpremedicated patients (28.0%). Adrenaline premedication caused no detectable changes in vital signs. The case fatality rate was 9.6% (13/136 patients). Polyvalent antivenom is the main treatment for envenomation in rural health centres, and early adverse reactions are common. Adrenaline premedication appears to significantly reduce acute adverse reaction rates. Premedication with promethazine and/or hydrocortisone without adrenaline did not reduce early adverse reactions.