Emergency department management of North American snake envenomations.

There are approximately 10,000 emergency department visits in the United States for snakebites every year, and one-third of those involve venomous species. Venomous North American indigenous snakes include species from the Crotalinae (pit vipers) and Elapidae (coral snakes) subfamilies. Treatment relies on supportive care, plus antivenom for select cases. While certain principles of management are widely accepted, controversies exist with regard to prehospital use of pressure immobilization, antivenom use, coagulation testing after copperhead envenomation, and fasciotomy. An evidence-based approach to management of North American venomous snakebites will be discussed, along with a review of the current controversies.

Harmful Algal Bloom Exposures Self-reported to Poison Centers in the United States, May-October 2019.

The National Poison Data System (NPDS) comprises self-reported information from people who call US poison center hotlines. NPDS data have proven to be important in identifying emerging public health threats. We used NPDS to examine records of people who had self-reported exposure to harmful algal blooms (HABs). Participating poison centers then contacted people who had called their centers from May through October 2019 about their HAB exposure to ask about exposure route, symptoms, health care follow-up, and awareness of possible risks of exposure. Of 55 callers who agreed to participate, 47 (85%) reported exposure to HABs while swimming or bathing in HAB-contaminated water. Nine callers reported health symptoms from being near waters contaminated with HABs, suggesting potential exposure via aerosolized toxins. Symptoms varied by the reported routes of exposure; the most commonly reported symptoms were gastrointestinal and respiratory. More public and health care provider education and outreach are needed to improve the understanding of HAB-related risks, to address ways to prevent HAB-related illnesses, and to describe appropriate support when exposures occur.

Comparison of F(ab')2 versus Fab antivenom for pit viper envenomation: a prospective, blinded, multicenter, randomized clinical trial.

BACKGROUND: Crotalidae Polyvalent Immune Fab (Ovine) has been the only antivenom commercially available in the US since 2007 for treatment of Crotalinae envenomation. Late coagulopathy can occur or recur after clearance of Fab antivenom, often after hospital discharge, lasting in some cases more than 2 weeks. There have been serious, even fatal, bleeding complications associated with recurrence phenomena. Frequent follow-up is required, and additional intervention or hospitalization is often necessary. F(ab')2 immunoglobulin derivatives have longer plasma half life than do Fab. We hypothesized that F(ab')2 antivenom would be superior to Fab in the prevention of late coagulopathy following treatment of patients with Crotalinae envenomation. METHODS: We conducted a prospective, double-blind, randomized clinical trial, comparing late coagulopathy in snakebitten patients treated with F(ab')2 with maintenance doses [F(ab')2/F(ab')2], or F(ab')2 with placebo maintenance doses [F(ab')2/placebo], versus Fab with maintenance doses [Fab/Fab]. The primary efficacy endpoint was coagulopathy (platelet count < 150 K/mm(3), fibrinogen level < 150 mg/dL) between end of maintenance dosing and day 8. RESULTS: 121 patients were randomized at 18 clinical sites and received at least one dose of study drug. 114 completed the study. Of these, 11/37 (29.7%) in the Fab/Fab cohort experienced late coagulopathy versus 4/39 (10.3%, p < 0.05) in the F(ab')2/F(ab')2 cohort and 2/38 (5.3%, p < 0.05) in the F(ab')2/placebo cohort. The lowest heterologous protein exposure was with F(ab')2/placebo. No serious adverse events were related to study drug. In each study arm, one patient experienced an acute serum reaction and one experienced serum sickness. CONCLUSIONS: In this study, management of coagulopathic Crotalinae envenomation with longer-half-life F(ab')2 antivenom, with or without maintenance dosing, reduced the risk of subacute coagulopathy and bleeding following treatment of envenomation.

Validation of a pre-existing formula to calculate the contribution of ethanol to the osmolar gap.

PURPOSE: The aim of this study was to validate the formula derived by Purssell et al. that relates blood ethanol concentration to the osmolar gap and determine the best coefficient for use in the formula. The osmolar gap is often used to help diagnose toxic alcohol poisoning when direct measurements are not available. METHODOLOGY: Part I of the study consisted of a retrospective review of 603 emergency department patients who had a concurrent ethanol, basic metabolic panel and a serum osmolality results available. Estimated osmolarity (excluding ethanol) was calculated using a standard formula. The osmolar gap was determined by subtracting estimated osmolarity from the actual osmolality measured by freezing point depression. The relationship between the osmolar gap and the measured ethanol concentration was assessed by linear regression analysis. In Part II of this study, predetermined amounts of ethanol were added to aliquots of plasma and the estimated and calculated osmolarities were subjected to linear regression analysis. RESULTS: In the cases of 603 patients included in Part I of the study, the median ethanol concentration in these patients was 166 mg/dL (Q1: 90, Q3: 254) and the range ethanol concentrations was 10-644 mg/dL. The mean serum osmolality was 338 mOsm/kg (SD: 30) and a range of 244-450 mOsm/kg. The mean osmolar gap was 47 (SD: 29) and a range of - 15 to 55. There was a significant proportional relationship between ethanol concentration and osmolar gap (r(2) = 0.9882). The slope of the linear regression line was 0.2498 (95% CI: 0.2472-0.2524). The slope of the linear regression line derived from the data in Part II of the study was 0.2445 (95% CI: 0.2410-0.2480). CONCLUSIONS: The results of our study are in fairly close agreement with previous studies that used smaller samples and suggest that an accurate conversion factor for estimating the contribution of ethanol to the osmolar gap is [Ethanol (mg/dL)]/4.0.

Acute ethanol poisoning in a 6-year-old girl following ingestion of alcohol-based hand sanitizer at school.

BACKGROUND: Alcohol-based hand sanitizers (ABHSs) have been widely used in homes, workplaces and schools to prevent the spread of infectious diseases. We report a young child unintentionally ingested ABHS at a school, resulting in intoxication. METHODS: The child was a 6-year-old girl who had been brought to the emergency department (ED) for hypothermia, altered mental status (AMS), periods of hypoventilation, hypothermia and vomiting. Computed tomography of her head revealed nothing abnormal in intracranial pathology. Urine drug screening was negative. Alcohol level was 205 mg/dL on admission. Other abnormal values included potassium of 2.8 mEq/L, osmolality of 340 mOsm/kg and no hypoglycemia. Further investigation revealed that the patient had gone frequently to the class restroom for ingestion of unknown quantities of ABHSs during the day. The patient was admitted for one day for intravenous fluid hydration and close observation of her mental status. RESULTS: The patient was discharged from the hospital the next day without any complications. CONCLUSION: Despite the large safety margin of ABHSs, emergency physicians need to be aware of the potential risk of ingestion of a large amount of such products in children and consider it in the assessment and management of school-age children with acute AMS.

Diphenhydramine dose-response: a novel approach to determine triage thresholds.

CONTEXT: It is unclear how much diphenhydramine (DPH) is toxic in humans. Previous dose-response studies have had conflicting results. Objective. We sought to evaluate DPH dose-response using a unique method that utilizes acetaminophen (APAP) serum concentrations to estimate DPH doses in patients ingesting APAP/DPH in a fixed-combination product. METHODS: We retrospectively analyzed APAP/DPH-only exposures in patients 2-80 years of age using case data from 15 U.S. poison centers. DPH dose was extrapolated from measured serum APAP concentrations. A clinically significant response (CSR) was predefined in terms of eight specific manifestations (e.g., coma) that would warrant emergency department intervention. Nominal logistic regression was used to model the probability of each recorded manifestation across DPH dose ranges examining fits for mg, mg/kg, log10 mg, and log10 mg/kg DPH doses. The threshold value where patients reliably became symptomatic was determined by further examining receiver operating characteristic curves. RESULTS: There were 509 cases that met inclusion criteria. Forty-five patients (9%) developed CSRs. A higher percentage of patients developed CSR at ≥ 7.5 mg/kg DPH and ≥1 g total DPH cutoff points (p < 0.05, Fisher's exact test). The best model for predicting the probability of CSR was a logistic fit of log(10) mg/kg dose (p < 0.05). By this model, for every 1 log(10) unit increase of mg/kg DPH dose, the odds of developing a CSR increased 47-fold (95% CI 17, 154). Receiver operating characteristic analyses showed a dose-related progression of symptoms. The cut-point with greatest sensitivity (98%) versus 1-specificity (57%) corresponded to an extrapolated mg/kg DPH dose of 8.2 mg/kg (95% CI 5.6, 10.5). CONCLUSION: Our findings support the current American Association of Poison Control Centers' guideline recommendation to refer patients to the hospital for evaluation if they have ingested greater than or equal to 7.5 mg/kg of DPH.