Blister and Bulla Following Snake Bite in Nigeria: A Prospective Cohort Study

Abstract

Introduction: Snakebites are a major health problem in several rural areas of tropical countries worldwide. Timely administration of appropriate antivenoms (AV) has been shown to significantly improve outcome. It has been hypothesized that presence of blisters may lead to poor outcome because of potential sequestration of snake venom with gradual systemic absorption. We explore the impact of blisters on outcome of snake bite envenomation. Methods: The study was a prospective cohort, enrolling all snake bite victim reporting to hospital in Febuary-April 2013. Data on demography, type of snake, circumstances of bite, presence or absent of blisters, systemic bleeding, 20min Whole Blood Clotting Time (WBCT), amount of anti-venom needed to restore clotting, and outcomes were recorded. Analyses explored relationship between blister and poor outcome (PO) defined as deaths, gangrene, prolonged Length of Hospital Stay (LOS), amputation, altered consciousness or requiring more than 10mls or 30mls of Echitab or Echitab plus respectively to restore clotting. Results: A total of 128 cases were studied, 101 were males. The mean age of the victims was 25.19 years ±17.51. Carpet viper was the most common responsible snake 89/106(84.0%). Local 84/128(65.6%), systemic bleeding 33/128(25.8%) and non-clotting 20WBCT 100/128(78.1%) were common while amputations 3/128(2.3%), gangrene 5/128(3.9%), altered consciousness 2/128(1.6%) and deaths 4/128(3.1%) were fewer. Blister was present in 42/128(32.8%) which had no relationship with gender (P=.39). Patients with blisters compared to those without blisters had more gangrene 4/42(9.5%) vs 1/86(1.2%) (P=.04), non-clotting 20WBCT 40/42(95.2%) vs 60/86(69.8%) (P<.001) and required more amount of antivenom to restore clotting >10mls (Echitab) or 30mls (Echitab plus) in 8/32(25%) vs 3/57(5.3%) (P=.03). Using Wilcoxon Rank-Sum test patients with blisters had a median LOS of 6.0±2.3 days compared to those without blisters 5.0±3.5 days (P=.02). In a logistic regression adjusting for LOS and systemic bleeding, blister predicted PO with P=.043 (95%CI: 0.110- 0.963). Conclusion: Presence of blister predicts PO (LOS, gangrene and large amount of antivenom needed to restore clotting). Deblistering of blister in snake bite patients may improve outcome. A randomised control trial is recommended to look at the effect of deblistering on outcome among patients with snake bite envenomation.