Prognostic significance of clinical grading of patients envenomed by Bothrops lanceolatus in Martinique. Members of the Research Group on Snake Bite in Martinique.

The correlation between clinical grading of patients bitten by Bothrops lanceolatus and the subsequent development of their envenoming was examined. Severity of envenoming was graded using a 1-4 scale (minor to major). Patients were classified into 2 groups according to the time elapsed between bite and treatment with a specific purified equine F(ab')2 antivenom. The late/no treatment group (n = 33) was characterized by a systemic thrombotic complication rate of 14/33 (42.4%) leading to 4 deaths, which increased with the maximum severity assessed on the first day following the bite (P = 0.003). However, infarctions could develop in patients who presented initially with signs of moderate envenoming, normal blood clotting and low serum levels of venom antigens. No such complication of fatality occurred in the early (0.5-6 h) treatment group (n = 70). Multiple regression analysis showed that duration of stay in hospital in this group increased with the length of the snake (P = 0.017), venom antigenaemia (P = 0.016), initial grading (P < 0.001), and with the need for surgical debridement (n = 10/70, P < 0.001). Outcome was correlated with initial severity of envenoming. However, the only factor with a positive prognostic significance for the individual envenomed patient was the early infusion of specific antivenom, which led to 100% recovery in our series.

Clinical indicators of envenoming and serum levels of venom antigens in patients bitten by Bothrops lanceolatus in Martinique. Research Group on Snake Bites in Martinique.

An enzyme-linked immunosorbent assay was developed to measure venom antigen levels in the serum of 40 patients bitten by Bothrops lanceolatus. The grading system used for the severity of envenomation (grades 1 to 4, minor to major) was predominantly based on the presence of local signs. Serum venom levels increased with the grade of severity (P < 0.001, by Spearman's rank correlation test); they were 6 +/- 6 ng/mL (mean +/- SD) in clinically non-envenomed patients (grade 1, n = 3), 7.6 +/- 11.7 (n = 17), 44.3 +/- 41.8 (n = 17), and 80.3 +/- 34.1 ng/mL (n = 3) in patients diagnosed as grade 2, 3 and 4 respectively. However, venom antigens could not be detected in the serum of 54% of patients who showed clinical signs of envenomation. Most patients diagnosed as grade 2, 3 or 4 were given 20, 40 and 60 mL of a monospecific F(ab')2 antivenom, respectively. Venom concentrations > or = 15 ng/mL were observed in all patients with progressive aggravation of swelling despite the use of early antivenom therapy. No venom was detectable in blood samples taken after completion of serotherapy. All patients recovered. These results confirm the efficacy of both the clinical severity scoring system used and the therapeutic regimen.

Prevention of thromboses in human patients with Bothrops lanceolatus envenoming in Martinique: failure of anticoagulants and efficacy of a monospecific antivenom. Research Group on Snake Bites in Martinique.

Envenomation by the Bothrops lanceolatus, a snake found only in Martinique, leads to swelling and pain, and occasionally to systemic signs and/or coagulopathy. Severe thromboses at some distance from the site of the bite may appear within 48 hr. Uncertainties as to the actual development of thrombotic complications in patients appearing to be suffering from moderate poisoning and as to the availability and the toxicity of a monospecific antivenom (AVS) initially led us to reserve antivenom for the most severe cases, and to use anticoagulants to prevent thromboses in all patients. This approach was modified after we observed serious thromboses in patients with moderate poisoning. Of 50 adult snake bite cases hospitalized between June 1991 and August 1994, 11 developed serious thrombotic complications at 36 /+- 27 hr (mean +/- SD) (range 12-96) following envenomation, despite early preventive anticoagulant therapy. Those included pulmonary embolism (two cases), cerebral infarction (six cases), myocardial infarction (one case), and cerebral and myocardial infarctions (two cases). Sixteen patients were not treated with AVS: 10 of these recovered without complications and six developed systemic thrombosis causing permanent disability in three cases. Thirty were treated with an intravenous infusion of 2-6 vials of AVS given 2-48 hr after the bite. Of these, three died of cerebral infarction that developed before the initiation of serotherapy. All others recovered. Among patients treated with AVS, three presented with mild anaphylactic reactions, while one developed serum sickness that responded to steroids. These data indicate that preventive anticoagulant therapy is of limited efficacy in Martinique.(ABSTRACT TRUNCATED AT 250 WORDS)