South American rattlesnake bite in a Brazilian teaching hospital. Clinical and epidemiological study of 87 cases, with analysis of factors predictive of renal failure.

Records of 87 victims of rattlesnake bite who were admitted to a teaching in south-eastern Brazil from 1984 to 1990 were retrospectively examined. The patients came from 27 municipalities in 3 states. Most of the bites (47%) occurred between 10.00 h and 18.00 h and in April (13%). Identification of the snake was possible in only 17% of the cases, diagnosis being made on clinical grounds in the others. The lower limbs were the most common site of bite (85%). The median time interval between bite and receiving medical help was 3 h. Fang marks were observed in 47% of the cases, neurotoxic facies in 61%, and myalgia in 29%. Dark urine was reported in 40% of the cases. Clotting time was above 15 min in 53% of the tested cases. Use of a tourniquet before admission to hospital was reported 11 times. The mean dose of specific antivenom was 190 +/- 95.69 mg. The case fatality rate was 1%; 13 cases (18%) developed renal failure, 10 of whom needed dialysis. The chi 2 test for trend showed that both increased age and increased time interval between bite and medical help significantly increased the risk of renal failure (P < 0.02). Myalgia and neurotoxic facies were predictive of renal failure in patients older than 40 years (Fisher's exact test, P < 0.002 and P < 0.02, respectively). There was no significant association between dark urine or prolonged clotting time and renal failure.