Mortality predictors of snake bite envenomation in southern India--a ten-year retrospective audit of 533 patients.

Snake bite incidence is highest in Asia and sub-Saharan Africa. This retrospective audit of 533 adult patients, who had presented to the Emergency Department, collates clinical features, effect of pharmacologic interventions and the risk factors that influence morbidity and mortality. Dual toxicity, neurological and haematological, was observed in 30.4% of patients. Laboratory evidence of haematotoxicity was demonstrated in 314 (58.9%) and 40% demonstrated clinical evidence of bleeding. However, 7.3% of these patients did not have laboratory evidence of bleeding disorder (p < 0.001). Conversely, 60% did not have clinical evidence of bleeding, but demonstrated laboratory evidence of abnormal parameters. Acute kidney injury (AKI) was evident in 28% of patients and 15.3% required haemodialysis. About 25% with no haematotoxicity showed evidence of AKI. The majority received 6-12 vials of poly-valent anti-snake venom. Hypersensitivity reaction rate was 8% and predominantly anaphylactoid in nature. The length of hospital stay ranged from 2 to 28 days and 20% required mechanical ventilation. Overall mortality rate was 7.5% with significant association to AKI, haematotoxicity and assisted ventilation. The mortality rate was 18% in patients with pre-hospital delay more than 24 h, as against 5% when admitted within the above specified period (p = <0.001). The strength of this study is the accrued information of over a period of 10 years of snake-bite management through the Emergency Department of a university hospital setting. The limitations are the retrospective study design and the rejection percentage of 15.5% due to insufficient information from the total chart pool.