Medically significant late bleeding after treated crotaline envenomation: a systematic review.

STUDY OBJECTIVE: We estimate the proportion of patients with crotaline snake envenomation who are treated with Crotalidae polyvalent immune Fab (ovine) antivenom and who develop medically significant late bleeding. METHODS: We performed a systematic review of all published cohort studies of North American crotaline snake envenomation patients treated with Fab antivenom. We searched PubMed, Ovid MEDLINE, and EMBASE from January 1, 1997, to April 30, 2012. Data were extracted by 2 trained researchers. Late bleeding was defined as bleeding that began or recurred after initial control of the envenomation syndrome. Medically significant late bleeding was defined a priori as late bleeding treated with RBC transfusion, vasoactive drug infusion, surgery, or rehospitalization or associated with a hemoglobin decrease of greater than or equal to 3 g/dL, hematocrit decrease of greater than or equal to 8%, disability, or death. Summary incidence and 95% confidence intervals (CIs) were calculated with a random-effects Poisson regression model. RESULTS: Nineteen unique cohort studies were identified. Four studies collected data prospectively, and in 9 studies, patients were followed actively after hospital discharge. A total of 1,017 subjects were enrolled in these cohort studies. Late bleeding was reported in 9 subjects (0.9%; 95% CI 0.4% to 2.2%), of whom 5 subjects (0.5%; 95% CI 0.1% to 1.7%) had medically significant late bleeding. Three patients received RBC transfusion; no deaths or permanent sequelae were reported. Estimates of risk may be affected by underreporting. CONCLUSION: Medically significant late bleeding appears to be uncommon in snakebite victims treated with Fab antivenom.

QTc interval screening in an opioid treatment program.

Methadone is highly effective for opioid dependency, but it is associated with Torsade de pointes. Although electrocardiography (ECG) has been proposed, its utility is uncertain, because an ECG-based intervention has not been described. An ECG-based cardiac safety program in methadone maintenance patients was evaluated in a single opioid treatment program from September 1, 2009, to August 31, 2011, in the United States. Time from pretreatment to repeat ECG in new entrants was assessed. The proportion with marked rate-corrected QT (QTc) interval prolongation (>500 ms) and the effect of the intervention on the QTc interval in this group were evaluated. Multivariate predictors of QTc interval change were assessed using a mixed-effects model. Of 531 new entrants, 436 (82%) underwent ≥1 electrocardiographic assessment, and 186 (35%) underwent pretreatment ECG. Median time to follow-up ECG was 43 days but decreased over time (p <0.0001). In 21 patients with QTc intervals >500 ms, the mean QTc interval from peak to final ECG decreased significantly (-55.5 ms, 95% confidence interval -77.0 to -33.9, p = 0.001), and 12 of 21 (57.1%) decreased to lower than the 500-ms threshold. In new entrants with serial ECG, only methadone dose (p = 0.009) and pretreatment QTc interval (p <0.0001) were associated with the magnitude of QTc interval change. In conclusion, this study suggests that the implementation of an ECG-based intervention in methadone maintenance can decrease the QTc interval in high-risk patients; clinical characteristics alone were inadequate to identify patients in need of electrocardiographic screening.