Jude McNally

Continuous Intravenous Midazolam Infusion for Centruroides exilicauda Scorpion Envenomation

STUDY OBJECTIVE We sought to describe the effects of continuous intravenous midazolam infusion as therapy for severe bark scorpion (Centruroides exilicauda) envenomation. METHODS A retrospective chart review from July 1, 1993, through January 1, 1998, identified all patients treated at a university hospital with International Classification of Diseases, Ninth Revision, codes 989.5 (toxic effect of venom) or E905.2 (scorpion sting causing poisoning). By using standardized collection forms, data were extracted from the medical record of every patient who had a grade III or IV envenomation and was treated with a continuous intravenous midazolam infusion. RESULTS Our search identified 104 patients; 34 had grade III or IV envenomation. Of these, 33 were treated in the ICU with continuous intravenous midazolam infusion. Median patient age was 4 years (range, 1 to 68 years). Midazolam dosage was adjusted to induce a light sleep state to control agitation and involuntary motor activity. The median amount of midazolam resulting in the first recorded decrease in agitation and involuntary motor activity was 0.30 mg/kg (range, 0.03 to 1.76 mg/kg). This first evidence of clinical improvement was recorded as 1.00 hour (median), with a range of 0.00 to 3.75 hours. The initial midazolam infusion rate was 0.10 mg x kg(-1) x h(-1) (median), with a range of 0.01 to 0.31 mg x kg(-1) x h(-1). The maximal midazolam infusion rate was 0.30 mg x kg(-1) x h(-1) (median), with a range of 0.06 to 1.29 mg x kg(-1) x h(-1). The median time until the maximal midazolam infusion rate was 2.5 hours (range, 0.00 to 8.50 hours). The median duration of infusion was 9. 50 hours (range, 4.25 to 20.50 hours). The median length of stay in the ICU was 15.17 hours (range, 6.0 to 28.0 hours), and 85% of patients were discharged directly home. All patients had resolution of abnormal motor activity and agitation during their midazolam infusion. Transient hypoxemia without evidence of end-organ dysfunction was documented in 4 patients during midazolam therapy. CONCLUSION A continuous intravenous midazolam infusion can be a safe, effective, and readily available treatment option for patients with grade III or IV C exilicauda envenomation.

Epidemiology of severe and fatal rattlesnake bites published in the American Association of Poison Control Centers’ Annual Reports

Introduction. No study has focused on the nationwide epidemiology of severe and fatal rattlesnake bites during the last 25 years. We examined rates and temporal trends of severe and fatal rattlesnake bites across the United States. Our hypothesis was that nationwide annual rates of both severe and fatal outcomes from rattlesnake bites have remained unchanged over time. Methods. This study retrospectively analyzed all human rattlesnake bites published in the Annual Reports of the American Association of Poison Control Centers from 1983 through 2007. Annual rates of severe (major) and fatal rattlesnake bites were calculated using the annual number of major outcomes and fatalities as respective numerators and the total annual number of single rattlesnake bites (exposures) as denominators. Negative binomial and Poisson regressions were used to examine trends of severe and fatal rattlesnake bites over time. Results. Annually, from 1985 to 2007, the incidence rate of major outcomes decreased by 2% per year (incidence rate ratio = 0.980; CI = 0.967–0.993), corresponding to an absolute annual rate decrease of two major outcomes per 1,000 bites per year. Annual rates of fatalities showed no statistically significant change from 1983 through 2007. Conclusion. This is the first study to examine rates and trends of published severe and fatal rattlesnake bites across the United States over the past 25 years. Annual rates of severe rattlesnake bites, derived from the published Annual Reports of the American Association of Poison Control Centers, have significantly decreased over time, whereas rates of fatal rattlesnake bites have remained unchanged.

Serum levels and urine detection of Centruroides sculpturatus venom in significantly envenomated patients.

Introduction. Envenomation by Centruroides sculpturatus can cause systemic signs and symptoms requiring treatment. The toxicokinetics of C. sculpturatus venom has not been described. Methods. Venom components were separated for cross-reactivity testing. Serum and urine collected from three patients envenomated by C. sculpturatus had venom levels determined by sandwich enzyme-linked immunosorbent assay (ELISA). Results. Western blot analysis indicated recognition of C. sculpturatus venom by Alacramyn®, an equine F(ab′)2 antivenom developed against Centruroides scorpion venoms, including C. sculpturatus. Serum venom levels in ng/mL with post-envenomation times in minutes (min) were as follows: 85-year-old woman = 8.2 (∼150), 2.8 (515), 1.6 (1,200); 14-month-old girl = 29.7 (∼50), 5.0 (729); 3-year-old girl = 11.1 (∼313), urine venom level of 9.0 (∼490). Conclusion. There is sufficient venom cross-antigenicity among different Centruroides species to allow this ELISA technique with Alacramyn® to determine serum and urine C. sculpturatus venom concentrations in envenomated patients.

Epidemiology of the Reported Severity of Copperhead (Agkistrodon contortrix) Snakebite

Objective The goal of this study was to analyze trends in the annual rates of reported medical outcomes of US copperhead (Agkistrodon contortrix) snakebites published in the annual reports of the American Association of Poison Control Centers in the course of 26 years. Methods This was a retrospective analysis of medical outcomes for copperhead snakebite victims who developed fatal, major, moderate, minor, or no effects. The annual rates for these medical outcomes were calculated by dividing the annual number of patients in each outcome category by the total annual number of people reported as being bitten by copperheads. Poisson and negative binomial regression were used to examine trends in annual rates. Results From 1983 through 2008, the incidence rate of copperhead snakebites causing no effect significantly decreased by 12.1%/year (incidence rate ratio [IRR] 0.879; 95% confidence interval [CI] 0.848–0.911]. From 1985 through 2008, the incidence rate of minor outcomes significantly decreased by 2.3%/year (IRR 0.977; 95% CI 0.972–0.981), whereas the rate of moderate outcomes significantly increased by 2.8%/year (IRR 1.028; 95% CI 1.024–1.033). The rate of major outcomes did not significantly change. One fatality was reported in 2001. Conclusions Annual rates of copperhead snakebites producing no effects and minor outcomes significantly decreased, those producing moderate outcomes significantly increased, and those producing major outcomes did not significantly change in a 26-year period.

Toxicologic information resources for reptile envenomations.

The United States is the largest importer of reptiles in the world, with an estimated 1.5 to 2.0 million households keeping one or more reptiles. Snakes account for about 11% of these imports and it has been estimated that as many as 9% of these reptiles are venomous. Envenomations by nonindigenous venomous species are a rare but often serious medical emergency. Bites may occur during the care and handling of legitimate collections found in universities, zoos, or museums. The other predominant source of exotic envenomation is from amateur collectors participating in importation, propagation, and trade of non-native species. This article provides toxicologic information resources for snake envenomations.

Epidemiology of the reported severity of cottonmouth (Agkistrodon piscivorus) snakebite.

Objective The goal of this study was to analyze trends in the annual rates of reported medical outcomes of cottonmouth (Agkistrodon piscivorus) snakebites in the United States, published in the annual reports of the American Association of Poison Control Centers in the course of 29 years. Methods This was a retrospective analysis of medical outcomes for cottonmouth snakebite victims who developed fatal, major, moderate, minor, or no effects. The annual rates for these medical outcomes were calculated by dividing the annual number of patients in each outcome category by the total annual number of people reported as being bitten by cottonmouths. Negative binomial regression was used to examine trends in annual rates. Results From 1985 through 2011, after controlling for the availability of CroFab, the annual incidence rate of cottonmouth snakebites causing no effect decreased significantly by 7.3%/year (incidence rate ratio [IRR] 0.927, 95% confidence interval [CI] 0.885–0.970), the incidence rate of minor outcomes did not change significantly (IRR 0.989, CI 0.974–1.006), the incidence rate of moderate outcomes increased significantly by 2.3%/year (IRR 1.023, CI 1.004–1.042), and the incidence rate of major outcomes did not change significantly (IRR 0.987, CI 0.935–1.041). One fatality was reported in 2011. Conclusions Annual rates of cottonmouth snakebites producing no effects decreased significantly, those producing minor outcomes did not change significantly, those producing moderate outcomes increased significantly, and those producing major outcomes did not change significantly, from 1985 through 2011.

Exotic snakebite: envenomation by an African puff adder (Bitis arietans)

We report an envenomation by the African puff adder (Bitis arietans), an exotic snake in the United States. The patient developed swelling and ecchymoses in the affected extremity, and cutaneous necrosis of the envenomated fingertip. There was no significant coagulopathy. He received 20 vials of specific antivenin (Schlangengift-Immunserum Behring Zentralafrika, Behringwerke, Marburg, Germany) and debridement of devitalized finger tissue. The only permanent sequelae were cutaneous scarring and permanent loss of the fingernail on the envenomated finger. Exotic snakebite is a rare presenting problem in emergency departments. The initial approach to a patient envenomated by an exotic venomous snake is discussed. Use of antivenin and supportive care are emphasized.

ACMT Position Statement: Institutions housing venomous animals.

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