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.

Lipid emulsion therapy during management of the critically-ill poisoned patient: a prospective cohort study.

BACKGROUND: Despite conflicting data, intravenous lipid emulsion has emerged as a potential antidote. The "lipid sink" theory suggests that following intravenous administration of lipid, lipophilic drugs are sequestered in the vascular compartment, thereby reducing their tissue concentrations. This study sought to determine if survival is associated with the intoxicant's degree of lipophilicity. METHODS: We reviewed all cases in the Toxicology Investigators Consortium's lipid sub-registry between May 2012 through December 2018. Information collected included demographics, exposure circumstances, clinical course, management, disposition, and outcome. The primary outcome was survival after lipid emulsion therapy. Survival was stratified by the log of the intoxicant's octanol-water partition coefficient. We also assessed the association between intoxicant lipophilicity and an increase in systolic blood pressure after lipid emulsion administration. RESULTS: We identified 134 patients, including 81 (60.4%) females. The median age was 40 years (interquartile range 21-75). One hundred and eight (80.6%) patients survived, including 45 (33.6%) with cardiac arrest during their intoxication. Eighty-two (61.2%) were hypotensive, and 98 (73.1%) received mechanical ventilation. There was no relationship between survival and the log of the partition coefficient of the intoxicant on linear analysis (P = 0.89) or polynomial model (P = 0.10). Systolic blood pressure increased in both groups. The median (interquartile range) systolic blood pressure before lipid administration was 68 (60-78) mmHg for those intoxicants with a log partition coefficient < 3.6 compared with 89 (76-104) mmHg after lipid administration. Among those drugs with a log partition coefficient > 3.6, the median (interquartile range) was 69 (60-84) mmHg before lipid and 89 (80-96) mmHg after lipid administration. CONCLUSION: Most patients in this cohort survived. Lipophilicity was not correlated with survival or the observed changes in blood pressure. The study did not address the efficacy of lipid emulsion.

Captive Black Mamba (Dendroaspis Polylepis) Bite Leading to Respiratory Failure.

BACKGROUND: Of the 8000-10,000 snake envenomations evaluated in U.S. emergency departments (ED) annually, approximately 1% are due to non-native snakes. We describe a 26-year-old man who was bitten by his captive black mamba (Dendroaspis polylepis) as he was packing it up for transport to another snake collector. CASE REPORT: The patient presented to the ED 1 h after being bitten on the forearm, complaining of left arm pain, oral paresthesias, and dyspnea. His vital signs: heart rate 96 beats/min, blood pressure 167/101 mm Hg, temperature 36.7°C (97.9°F), respiratory rate 20 breaths/min, and room air oxygen saturation 100%. Two mildly tender puncture wounds without swelling or ecchymosis were found on the posterior aspect of the forearm. Over the ensuing 30 min his dyspnea worsened, and he developed objective weakness. He was intubated and placed on mechanical ventilation. He was treated with atropine 2 mg for bronchorrhea. Five vials of South African Vaccine Producers (Johannesburg, South Africa) polyvalent antivenom were administered 2.5 h post-bite and the patient was admitted to the intensive care unit. He was extubated 18 h post-envenomation and discharged the following day. He has remained asymptomatic since leaving the hospital. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The primary manifestations of D. polylepis envenomings are neurological. Initial signs may include paresthesias, dysarthria, dysphagia, and ptosis. Progressive descending paralysis leading to respiratory failure develops within 60 min. Muscarinic features are frequently observed. Cardiotoxicity and hematologic laboratory abnormalities may be present. Although pain is common, significant local tissue injury does not occur. In addition to supportive care, several non-native antivenoms are indicated for D. polylepis envenomations. Black mamba envenomings differ from the native snakebites with which U.S. physicians are familiar. Rapid, progressive neurological toxicity and muscarinic features are most common. Treatment consists of supportive care and appropriate antivenom administration.

Anticonvulsant fatalities reported to the American Association of Poison Control Centers 2000 - 2019.

BACKGROUND: Anticonvulsants are frequently prescribed, and exposures are commonly reported to American Association of Poison Control Centers sites. The purpose of this study was to describe the epidemiology of fatalities associated with oral anticonvulsant use, including patient demographics, specific medications, and the circumstances surrounding the deaths. METHODS: This was a retrospective analysis of cases coded with oral anticonvulsants as a single substance and associated with a fatal outcome reported to the AAPCC National Poison Data System from 2000 to 2019. Polydrug ingestions and parenteral exposures were excluded. Patient characteristics, circumstances of the ingestion, specific medication, and chronicity of use were described. RESULTS: We identified 126 cases that were classified as fatalities associated with single anticonvulsant use. The five most implicated anticonvulsants were carbamazepine, gabapentin, lamotrigine, phenytoin, and valproic acid. The majority (68.3%) of fatal cases were suicides. Phenytoin was implicated in eight (89%) adverse reactions and seven (70%) therapeutic errors. Valproic acid caused one (11.1%) adverse reaction and was associated with one (10%) therapeutic error. Three (75%) unintentional fatalities were caused by carbamazepine. The plurality (42.1%) of fatal ingestions occurred in acute-on-chronic use. An additional 40 (31.7%) were acute. Chronic use accounted for 15 (11.9%) of fatal exposures, including 5/10 of fatalities attributed to therapeutic error. The chronicity of medication use was unknown in 18 (14.3%) of fatal ingestions. Narrative summaries were available in 14 cases. Four of the patients presented to the emergency department with minimal symptoms. The other 10 had varying degrees of central nervous system (CNS) depression. Seizures were observed in six cases. Hyperammonemia was reported in seven of nine valproic acid ingestions. CONCLUSIONS: Fatalities associated with isolated anticonvulsant use are uncommon and typically occur following intentional overdoses. Fatal adverse reactions and therapeutic errors are most associated with phenytoin use and disproportionately affect elderly patients.

Clinical Presentations, Treatments, and Outcomes of Non-native Snake Envenomations in the United States Reported in the North American Snakebite Registry.

BACKGROUND: Non-native snake envenomations in the United States are uncommon with much unknown about a patient's presenting signs and symptoms. Antivenoms for non-native snake envenomations are not typically available in hospital pharmacies which may limit their administration. What are the clinical presentations, treatments, and outcomes of non-native snake envenomation cases reported to the North American Snakebite Registry (NASBR) of the Toxicology Investigators Consortium (ToxIC)? METHODS: This is a descriptive review of all non-native envenomations reported to the NASBR from 2013 to March 2022. Data abstracted included snake species, patient history, clinical signs, diagnostics, treatment (including antivenom usage), follow-up, and final outcome. RESULTS: We identified 19 non-native snake envenomations resulting from encounters with eleven different species, eight of which belonged to the Viperidae family. The most common presenting symptoms were edema (18 patients), ecchymosis (seven patients), and necrosis (six patients). Systemic effects and hematologic abnormalities were less common. The most common treatments were extremity elevation and analgesia, with two patients receiving mechanical ventilation. Ten patients received antivenom. No patients died. Three patients had loss of mobility in a digit at the last follow-up visit. One patient had permanent tissue loss of a small area on a finger. CONCLUSIONS: The results of this study suggest that non-native snake envenomations in the United States frequently cause local soft tissue effects and less frequently cause systemic or hematologic effects. Most patients received antivenom, although several patients envenomated by snakes for which a specific antivenom exists did not receive any. Sequelae at the last follow-up of such encounters consisted of local mobility deficits.

Antivenom Does Not Cause Snakebite Complications, Withholding It Does.

We read with interest the retrospective chart review "Crotalidae Polyvalent Immune Fab and Cost-Effective Management of Hospital Admission for Snakebites" by Bowden, et al. The efficacy of US snake antivenoms has been well established for decades. A randomized double-blind placebo-controlled clinical trial (RCT) has demonstrated Fab antivenom efficacy using patient-centered outcomes such as return of functionality and other patient-reported outcomes. These benefits occurred in a predominantly mildly envenomated patient population in a time-dependent manner. The cost-effectiveness of snake antivenom has been demonstrated globally, but no US cost-effectiveness studies have been published. Based on the evidence hierarchy of evidence-based medicine, the discordance between this study and the RCT merits discussion.

Predictors of severe outcome following opioid intoxication in children.

INTRODUCTION: While the opioid crisis has claimed the lives of nearly 500,000 in the U.S. over the past two decades, and pediatric cases of opioid intoxications are increasing, only sparse data exist regarding risk factors for severe outcome in children following an opioid intoxication. We explore predictors of severe outcome (i.e., intensive care unit [ICU] admission or in-hospital death) in children who presented to the Emergency Department with an opioid intoxication. METHODS: In this prospective cohort study we collected data on all children (0-18 years) who presented with an opioid intoxication to the 50 medical centers in the US and two international centers affiliated with the Toxicology Investigators Consortium (ToxIC) of the American College of Medical Toxicology, from August 2017 through June 2020, and who received a bedside consultation by a medical toxicologist. We collected relevant demographic, clinical, management, disposition, and outcome data, and we conducted a multivariable logistic regression analysis to explore predictors of severe outcome. The primary outcome was a composite severe outcome endpoint, defined as ICU admission or in-hospital death. Covariates included sociodemographic, exposure and clinical characteristics. RESULTS: Of the 165 (87 females, 52.7%) children with an opioid intoxication, 89 (53.9%) were admitted to ICU or died during hospitalization, and 76 did not meet these criteria. Seventy-four (44.8%) children were exposed to opioids prescribed to family members. Fentanyl exposure (adjusted OR [aOR] = 3.6, 95% CI: 1.0-11.6; p = 0.03) and age ≥10 years (aOR = 2.5, 95% CI: 1.2-4.8; p = 0.01) were independent predictors of severe outcome. CONCLUSIONS: Children with an opioid toxicity that have been exposed to fentanyl and those aged ≥10 years had 3.6 and 2.5 higher odds of ICU admission or death, respectively, than those without these characteristics. Prevention efforts should target these risk factors to mitigate poor outcomes in children with an opioid intoxication.

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

BACKGROUND: Pit vipers, also known as crotalids, are a group of snakes including rattlesnakes, copperheads, and cottonmouths (water moccasins). Crotalids have a broad geographic distribution across the United States, and bites from these snakes can carry significant morbidity. Their envenomations are characterized by local tissue effects, hematologic effects, and systemic effects. Envenomations are generally treated with 1 of 2 antivenoms available in the United States. OBJECTIVE: We developed a series of clinical questions to assist and guide the emergency physician in the acute management of a patient envenomated by a crotalid. METHODS: We conducted a PubMed literature review from January 1970 to May 2020 in English for articles with the keywords "bite" and "crotalidae." RESULTS: Our literature search resulted in 177 articles. A total of 33 articles met criteria for rigorous review and citation in the development of these consensus guidelines. CONCLUSIONS: Patients should be initially evaluated, stabilized, and assessed for local effects, hematologic effects, and systemic toxicity suggestive of envenomation. Antivenom should be given if toxic effects are present. Surgical intervention including debridement and fasciotomy should be avoided. Prophylactic antibiotics are not necessary.

Epidemiology, Clinical Features, and Management of Texas Coral Snake (Micrurus tener) Envenomations Reported to the North American Snakebite Registry.

INTRODUCTION: Few of the 5000-8000 snakebites reported to poison control centers annually in the USA are attributed to coral snakes. This study describes Texas coral snake envenomations reported to the North American Snakebite Registry. METHODS: All Texas coral snake envenomation cases reported to the registry were identified for the period from January 1, 2015, through December 31, 2019. Data reviewed for this study included details regarding the snake encounter, patient demographics, signs and symptoms, treatment, and outcomes. Descriptive statistics were used to report results. RESULTS: Ten men and four nonpregnant women reported coral snake bites. The median patient age was 15.5 (range 5-72 years). There were 12 upper extremity bites and two bites to the lower extremity. The most common symptoms reported were paresthesias and pain. All subjects had paresthesias, often described as an "electric" sensation. Seven patients described them as painful. The most common clinical findings were erythema and swelling. No patient developed tissue damage, hematotoxicity, rhabdomyolysis, hypotension, weakness, or respiratory symptoms. Thirteen subjects were treated with opioids. Six patients were treated with antiemetics: three prophylactically and two for opioid-induced nausea. One patient developed nausea and non-bloody, nonbilious emesis within 1 hour of the bite, prior to receiving opioids. No patients were treated with antivenom. Antibiotics were not administered to any patient, and no infections were reported. CONCLUSIONS: Envenomations from M. tener in Southeast Texas are characterized by painful paresthesias. Mild swelling and erythema are common. Neurotoxicity necessitating antivenom or mechanical ventilation did not occur.

Monocled Cobra (Naja kaouthia) Envenomations Requiring Mechanical Ventilation.

BACKGROUND: Bites from nonnative snakes are uncommon, accounting for 1.1% of envenomations reported to poison centers between 2015 and 2018. Here we discuss two monocled cobra (Naja kaouthia) envenomations resulting in respiratory failure. CASE REPORTS: A 30-year-old man and a 40-year-old man were bitten by their captive monocled cobras. At the first hospital, the first patient was mildly hypotensive, transiently bradycardic, and confused. He was intubated for respiratory distress. He was hypertensive to 211/119 mm Hg upon arrival to the second hospital. In the Emergency Department, cobra antivenom was administered. He was admitted to the medical intensive care unit (MICU) and had an additional bradycardic episode that corrected with atropine. He was extubated after 35 h. He was observed for an additional 9 h prior to going home, where he recovered without incident. The second patient developed abdominal pain, blurry vision, and dyspnea within 90 min of the bite. He was intubated at the first hospital. At the second hospital he received cobra antivenom and was admitted to the MICU. He was extubated after 9 h and discharged the following day with no further symptoms. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Envenomations after N. kaouthia bites are characterized by local tissue injury and various neurotoxic effects. Nonspecific signs and symptoms are common. Hematologic toxicity and cardiovascular manifestations are uncommon. Antivenom is the specific treatment for snake envenomation, but only certain antivenoms are indicated for N. kaouthia. Cholinesterase inhibitors may reduce toxicity from postsynaptic alpha toxins by increasing acetylcholine concentrations.

Epidemiology of fatal snakebites in the United States 1989-2018.

BACKGROUND: There are 5000-10,000 snake envenomations annually in the United States. Fortunately, few are fatal. In this study we review the epidemiology of fatal snakebites. METHODS: Native snakebite cases from the American Association of Poison Control Centers (AAPCC) National Poison Data System from 1989 to 2018 were reviewed. Additional cases that were not reported to the AAPCC were identified by reviewing Wikipedia and by searching PubMed and online news outlets using various combinations of relevant keywords. RESULTS: We identified 101 fatal bites from native snakes. Rattlesnakes accounted for 74 (90.2%) of the 82 deaths for which the species was known or which occurred where rattlesnakes are the only native crotalids. There were five fatalities attributed to copperheads, two due to cottonmouths, and one caused by an eastern coral snake. Males were disproportionately affected. The median age for victims was 40 years old. In cases for which data were available, many of the snake interactions were intentional, e.g. religious services, animal husbandry, and attempting to kill the snake. CONCLUSIONS: Death following envenomation from a native U.S. snake is unlikely, particularly if medical attention is sought promptly. Rattlesnake envenomations are more likely to be fatal than bites from other species. Intentionally engaging with a venomous snake raises the risk of incurring a fatal bite, as does concurrent alcohol or drug use. Age less than 12 years old does not appear to be a risk factor for a fatal outcome, while elderly patients may have a slightly increased risk of death.

Recovery from Copperhead Snake Envenomation: Role of Age, Sex, Bite Location, Severity, and Treatment.

INTRODUCTION: Few data exist to understand the recovery phase of pit viper envenomation. A recently published placebo-controlled clinical trial affords this opportunity. The purpose of this study is to examine the time course of recovery from copperhead snake (Agkistrodon contortrix) envenomation patients managed with and without the use of antivenom, stratified by age, sex, anatomic site of envenomation, initial severity of envenomation, and geographic region. METHODS: This is a post-hoc subgroup analysis of data from a multi-center double-blinded clinical trial of Fab antivenom (FabAV) vs. placebo. Outcomes were the Patient-Specific Functional Scale (PSFS) score at 3, 7, 10, and 14 days after envenomation. Least-squares mean PSFS score curves were calculated for each subgroup, and repeated measures ANOVA was used to estimate between-group comparisons. RESULTS: Seventy-two subjects were included, of whom 44 received FabAV. Males demonstrated better overall recovery than females (model predicted PSFS score 6.18 vs 4.99; difference 1.19; 95% CI 0.12 to 2.25; p = 0.029). No sex difference was found in response to FabAV. Overall recovery and effect of FabAV were similar in adult vs adolescent patients, patients with upper vs lower extremity envenomation, and patients with initially mild vs moderate envenomation signs. Analysis by geographic location was not successful due to ANOVA mode instability. CONCLUSIONS: Male victims of copperhead snake envenomation demonstrate slightly better recovery than females, but response to Fab antivenom overall is similar across all subgroups studied.

Puss Caterpillar Envenomation: Erucism Mimicking Appendicitis in a Young Child.

A 4-year-old female presented to the emergency department with 2 days of abdominal pain, nausea, and vomiting. She was tachycardic and had abdominal tenderness. Laboratory studies revealed a leukocytosis, hypokalemia, and metabolic acidosis. Her Pediatric Appendicitis Score (MDCalc) was calculated as 6, indicating that appendicitis could not be excluded. She was transferred to our pediatric hospital for further evaluation. Her ultrasound at our facility was normal. Upon reexamination, the patient was noted to have a red mark on her left index finger, and the family reported that the patient may have been stung by a puss caterpillar before the onset of her symptoms. The patient was treated with ondansetron, morphine, and intravenous fluids, and her symptoms resolved. Erucism frequently develops after stings from the puss caterpillar, which can be found through the southern United States. The most consistent clinical feature is pain. Numbness, muscle cramping, paresthesias, nausea, vomiting, and chest pain have also been described. Severe abdominal pain is reported rarely and may be mistaken for peritonitis. Analgesia is the mainstay of treatment. Topical icepacks have demonstrated inconsistent benefit in relieving pain. Oral medications, including acetaminophen, nonsteroidal anti-inflammatory drugs, and, rarely, opioids, typically suffice. Severe envenomations may require parenteral narcotics.

Validity and reliability of telephone administration of the patient-specific functional scale for the assessment of recovery from snakebite envenomation.

OBJECTIVES: Although more than 1.8 million people survive snakebite envenomation each year, their recovery is understudied. Obtaining long-term follow-up is challenging in both high- and low-resource settings. The Patient-Specific Functional Scale (PSFS) is an easily administered, well-accepted patient-reported outcome that is validated for assessing limb recovery from snakebite envenomation. We studied whether the PSFS is valid and reliable when administered by telephone. METHODS: This is a secondary analysis of data from a randomized clinical trial. We analyzed the results of PSFS collected in-person on days 3, 7, 14, 21, and 28 and by telephone on days 10, 17, and 24. We assessed the following scale psychometric properties: (a) content validity (ceiling and floor effects), (b) internal structure and consistency (Cronbach's alpha), and (c) temporal and external validity using Intraclass Correlation Coefficient (ICC). Temporal stability was assessed using Spearman's correlation coefficient and agreement between adjacent in-person and telephonic assessments with Cohen's kappa. Bland Altman analysis was used to assess differential bias in low and high score results. RESULTS: Data from 74 patients were available for analysis. Floor effects were seen in the early post-injury time points (median: 3 (IQR: 0, 5) at 3 days post-enrollment) and ceiling effects in the late time points (median: 9 (IQR: 8, 10). Internal consistency was good to excellent with both in-person (Cronbach α: 0.91 (95%CI 0.88, 0.95)) and telephone administration (0.81 (0.73, 0.89). Temporal stability was also good (ICC: 0.83 (0.72, 0.89) in-person, 0.80 (0.68, 0.88) telephone). A strong linear correlation was found between in-person and telephone administration (Spearman's ρ: 0.83 (CI: 0.78, 0.84), consistency was assessed as excellent (Cohen's κ 0.81 (CI: 0.78, 0.84), and Bland Altman analysis showed no systematic bias. CONCLUSIONS: Telephone administration of the PSFS provides valid, reliable, and consistent data for the assessment of recovery from snakebite envenomation.

The validity, reliability and minimal clinically important difference of the patient specific functional scale in snake envenomation.

OBJECTIVE: Valid, reliable, and clinically relevant outcome measures are necessary in clinical studies of snake envenomation. The aim of this study was to evaluate the psychometric (validity and reliability) and clinimetric (minimal clinically important difference [MCID]) properties of the Patient-Specific Functional Scale (PSFS) in snakebite envenomation. METHODS: We performed a secondary analysis of two existing snakebite trials that measured clinical outcomes using the PSFS as well as other quality of life and functional assessments. Data were collected at 3, 7, 10, and 17 days. Reliability was determined using Cronbach's alpha for internal consistency and the intraclass correlation coefficient (ICC) for temporal stability at 10 and 17 days. Validity was assessed using concurrent validity correlating with the other assessments. The MCID was evaluated using the following criteria: (1) the distribution of stable patients according to both standard error of measurement (SEM) and responsiveness techniques, and (2) anchor-based methods to compare between individuals and to detect discriminant ability of a positive change with a receiver operator characteristic (ROC) curve and optimal cutoff point. RESULTS: A total of 86 patients were evaluated in this study. The average PSFS scores were 5.37 (SD 3.23), 7.95 (SD 2.22), and 9.12 (SD 1.37) at 3, 7, and 10 days, respectively. Negligible floor effect was observed (maximum of 8% at 3 days); however, a ceiling effect was observed at 17 days (25%). The PSFS showed good reliability with an internal consistency of 0.91 (Cronbach's alpha) (95% CI 0.88, 0.95) and a temporal stability of 0.83 (ICC) (95% CI 0.72, 0.89). The PSFS showed a strong positive correlation with quality of life and functional assessments. The MCID was approximately 1.0 for all methods. CONCLUSIONS: With an MCID of approximately 1 point, the PSFS is a valid and reliable tool to assess quality of life and functionality in patients with snake envenomation.

Early administration of Fab antivenom resulted in faster limb recovery in copperhead snake envenomation patients.

BACKGROUND: No previous research has studied whether early snake antivenom administration leads to better clinical outcomes than late antivenom administration in North American pit viper envenomation. METHODS: A secondary analysis of data from a clinical trial of Fab antivenom (FabAV) versus placebo for copperhead snake envenomation was conducted. Patients treated before the median time to FabAV administration were classified as receiving early treatment and those treated after the median time were defined as the late treatment group. A Cox proportional hazards model was used to compare time to full recovery on the Patient-Specific Functional Scale (PSFS) instrument between groups. Secondary analyses compared estimated mean PSFS scores using a generalized linear model and the estimated proportion of patients with full recovery at each time point using logistic regression. To evaluate for confounding, the main analysis was repeated using data from placebo-treated subjects. RESULTS: Forty-five subjects were treated with FabAV at a median of 5.47 h after envenomation. Patients in the early treatment group had a significantly shorter time to full recovery than those treated late (median time: 17 versus 28 days, p = .025). Model-estimated PSFS scores were numerically higher at each time point in the early group. No difference was found between patients treated early versus late with placebo. CONCLUSIONS: In this secondary analysis of trial data, recovery of limb function was faster when Fab antivenom was administered soon after envenomation, as opposed to late administration.