Low dose subcutaneous adrenaline to prevent acute adverse reactions to antivenom serum in snake bite patients

Abstract

OBJECTIVE: To test efficacy and safety of low dose adrenaline as pretreatment for prevention of such reactions to AVS in patients with snake bite envenoming. METHODS: A prospective, randomized, double-blind, placebo .controlled trial was conducted at Base Hospital, Polonnaruwa. Patients with snake bite envenoming, who were recruited for the study, received 0.25ml of 1:1000 adrenaline (cases) or placebo (controls) subcutaneously as the only pretreatment immediately prior to full dose (10 vials) AVS infusion. Results: Of 196 patients admitted to hospital with snake bite envenoming who required AVS, 105 were recruited for the study. The other 91 had one or more exclusion criteria: treatment started in peripheral hosp'ital-72; age <12 or >70years-G; history of atopy-2, wheezing-3, hypertension -3, IHD-2; too ill to get consent-3.56 cases received adrenaline and 49 controls received placebo. The two groups were similar for age, gender, species of offending snake, degree of envenomation, proportion receiving first aid, and delay in hospital admission. Six (10.7%) cases and 21 (42.8%) controls developed acute adverse reactions to AVS, RR 0.25, Cl 0.11 - 0-57, p=0.0002. Significant reductions in acute adverse reactions to AVS were also found after grading them as mild, moderate and severe. There were no adverse effects attributable to adrenaline. CONCLUSIONS: 0.25ml of 1:1000 adrenaline injected subcutaneojjsly immediately prior to AVS infusions in patients with envenomation following snake bite significantly reduces the rate of acute adverse reactions to antivenom. The use of adrenaline in this manner is safe.