How Should Native Crotalid Envenomation Be Managed in the Emergency Department?

Transient Hematotoxicity After Emerald Horned Pitviper (Ophryacus smaragdinus) Envenomation: A Case Report

BACKGROUND

A minority of snake envenomations in the United States involve non-native snakes. In this report, we describe what we believe is the first documented human envenoming from an emerald horned pitviper, Ophryacus smaragdinus.

CASE REPORT

A previously healthy 36-year-old woman was bitten on her left index finger by a captive emerald horned pitviper she was medicating at work. Swelling to the entire hand was present on emergency department arrival. She had no systemic symptoms and her initial laboratory studies were unremarkable. The affected limb was elevated. We administered five vials of Antivipmyn TRIⓇ (Bioclon), which specifically lists Ophryacus among the envenomations for which it is indicated. She developed pruritus and was treated with IV diphenhydramine and famotidine. Her swelling improved, but her repeat laboratory studies were notable for a platelet count of 102 K/µL and a fibrinogen level of 116 mg/dL. She declined additional antivenom because of the previous allergic reaction. She was admitted for further monitoring and pain control. Subsequent laboratory tests were better, but a small hemorrhagic bleb developed at the bite site. She was discharged the next day and followed up as an outpatient. Her swelling had resolved, her bleb had healed, and her laboratory studies continued to improve. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians may be required to treat bites from non-native snakes. Many of these bites will warrant treatment with non-U.S. Food and Drug Administration-approved antivenoms. Consultation with a regional poison center or medical toxicologist may be necessary to procure the proper antivenom.

Upper Extremity Crotalid Envenomation: A Review of Incidence and Recent Trends in Management of Snakebites

PURPOSE

The goal of this study was to evaluate the recent trends in the management of upper extremity Crotalid envenomation in the state of Georgia, United States.

METHODS

A retrospective review of the Georgia Poison Center database looking at the reported snakebites to the upper extremity between 2015 and 2020 was performed. Patient demographics, timing and location of injury, severity of envenomation, treatment, including use of antivenin and surgical intervention, and reported complications related to the use of antivenin was extracted.

RESULTS

A retrospective review of snakebites between 2015 and 2020 showed 2408 snakebite cases with a mean patient age of 37.4 years. Males incurred 62.8% of all bites. The highest incidence was in summer 52.5%, and between the hours of 5 PM to midnight 57.2%. Overall, 1010 (41.9%) of all bites were categorized as venomous snakebites (55.6% copperhead, 20% rattlesnake, 2.4% cottonmouth, and 22% miscellaneous [including 3 Elapid envenomations] or unidentified. The total number of venomous bites to the upper extremity was 575 (56.9%) and 567 patients received antivenin. Envenomation severity was mild in 29%, moderate in 45%, severe in 10%, and undetermined in 16% of cases. Crotalidae polyvalent immune Fab (Ovine) was the main antivenin used, with overall mean initial therapy dose of 6.2 vials and 59% of patients receiving maintenance therapy. Three patients (0.5%) had a severe anaphylactic reaction to antivenin requiring cessation of therapy. Seven patients had acute compartment syndrome of the upper extremity requiring fasciotomy (3 copperhead, 2 rattlesnake, and 2 unidentified). There was no reported mortality during this period.

CONCLUSIONS

Hand surgeons should be familiar with the management of upper extremity Crotalid envenomation. Antivenin remains the main treatment for symptomatic patients. Crotalid snakebites rarely require operative intervention.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Medically important snakes and snakebite envenoming in Iran

Snakebite is a common health condition in Iran with a diverse snake fauna, especially in tropical southern and mountainous western areas of the country with plethora of snake species. The list of medically important snakes, circumstances and effects of their bite, and necessary medical care require critical appraisal and should be updated regularly. This study aims to review and map the distributions of medically important snake species of Iran, re-evaluate their taxonomy, review their venomics, describe the clinical effects of envenoming, and discuss medical management and treatment, including the use of antivenom. Nearly 350 published articles and 26 textbooks with information on venomous and mildly venomous snake species and snakebites of Iran, were reviewed, many in Persian (Farsi) language, making them relatively inaccessible to an international readership. This has resulted in a revised updated list of Iran's medically important snake species, with taxonomic revisions of some, compilation of their morphological features, remapping of their geographical distributions, and description of species-specific clinical effects of envenoming. Moreover, the antivenom manufactured in Iran is discussed, together with treatment protocols that have been developed for the hospital management of envenomed patients.

Clinical aspects of snakebite envenoming and its treatment in low-resource settings

There is increasing recognition of the public health importance of snakebite envenoming. Worldwide annual incidence is likely to be 5 million bites, with mortality exceeding 150 000 deaths, and the resulting physical and psychological morbidity leads to substantial social and economic repercussions. Prevention through community education by trained health workers is the most effective and economically viable strategy for reducing risk of bites and envenoming. Clinical challenges to effective treatment are most substantial in rural areas of low-resource settings, where snakebites are most common. Classic skills of history taking, physical examination, and use of affordable point-of-care tests should be followed by monitoring of evolving local and systemic envenoming. Despite the profusion of new ideas for interventions, hyperimmune equine or ovine plasma-derived antivenoms remain the only specific treatment for snakebite envenoming. The enormous interspecies and intraspecies complexity and diversity of snake venoms, revealed by modern venomics, demands a radical redesign of many current antivenoms.

Neurotoxic respiratory failure absent following Arizona rattlesnake bites

Warnings of neurotoxic respiratory paralysis following envenomation by rattlesnakes (Crotalus sp.) have been included in numerous scholarly publications over the past 60 years, resulting in fear and anxiety in the public and among clinicians. We examine the validity of the widespread belief that rattlesnakes in the arid southwestern United States, and particularly the Mohave Rattlesnake (Crotalus scutulatus), pose a significant risk of medically relevant respiratory weakness and paralysis in humans. A retrospective review of 3440 suspected rattlesnake bites reported to the Arizona Poison and Drug Information Center between 1999 and 2020 produced no evidence of respiratory weakness in a region with three species known to express significant amounts of neurotoxin in their venoms: Crotalus concolor, C. tigris, and the more widely distributed C. scutulatus. A literature review produced numerous warnings regarding respiratory paralysis following envenomation by rattlesnakes in our region that either lacked references or cited sources that did not contain strong supportive data. We found no case reports of neurotoxic respiratory weakness following Arizona rattlesnake bites in the literature and such reports in surrounding states were scant. We conclude that neurotoxic respiratory failure in this region following rattlesnake envenomation is extraordinarily rare. All rattlesnake bites should receive the same consideration and critical care, and warnings about significant risk of respiratory failure are unwarranted, regardless of species involved.