Angela Padilla-Jones

The Epidemiology, Clinical Course, and Management of Snakebites in the North American Snakebite Registry

The American College of Medical Toxicology established the North American Snakebite Registry (NASBR), a national database of detailed, prospectively collected information regarding snake envenomation in the United States, in 2013. This report describes the epidemiology, clinical course, and management of snakebites in the NASBR. All cases entered into the NASBR between January 1, 2013 and December 31, 2015 were identified. Descriptive statistics are used to report results. Fourteen sites in 10 states entered 450 snakebites. Native species comprised 99% of cases, almost all of which were pit viper bites. 56.3% were identified as rattlesnakes and 29.4% as copperheads. 69.3% were male and 28.2% were children age 12 and under. Fifty-four percent of bites were on the lower extremity. Twenty-seven percent of patients with lower extremity bites were not wearing shoes. Common tissue findings associated with envenomation were swelling, ecchymosis, and erythema. Systemic effects and hematologic toxicity were more common in rattlesnake than copperhead or cottonmouth envenomations. Crotalidae Polyvalent Immune Fab antivenom was given to 84% of patients. Twelve patients (4.3%) were re-admitted to the hospital after completion of treatment. Eight were re-treated with antivenom. The NASBR gathers detailed data on venomous snakebites across the US. In its initial years, useful information has already been gained. Data regarding footwear will inform public health interventions and education, and information regarding the clinical presentation may help physicians better anticipate effects and manage snakebite. As the number of cases in the NASBR grows, associations between patient-related factors and outcomes may be studied.

Bleeding Following Rattlesnake Envenomation in Patients With Preenvenomation Use of Antiplatelet or Anticoagulant Medications

OBJECTIVES Rattlesnake envenomations commonly produce coagulopathy and thrombocytopenia, yet clinically significant bleeding is uncommon. It is unknown if patients who use antiplatelet or anticoagulant medications prior to envenomation are at increased risk for bleeding after envenomation. METHODS This was a retrospective cohort study of patients age 14 years and older who were admitted to a single academic medical center for rattlesnake envenomation. Patients who reported use of antiplatelet or anticoagulant medications prior to envenomation were compared to patients not on those medications. Severity and timing of bleeding was compared between groups, as was a composite endpoint of major bleeding at any time, shock, readmission, or death. RESULTS A total of 319 patients met inclusion criteria; 31 (9.7%) were documented to be taking antiplatelet or anticoagulant medications including aspirin, clopidogrel, and/or warfarin. Seventeen of the 319 patients developed bleeding associated with envenomation (major = 9; minor = 4; trivial = 4), with major bleeding occurring in five patients on antiplatelet or anticoagulant medications versus four patients not on antiplatelet or anticoagulant medications (p < 0.001). Seven of the 17 presented with early bleeding. This early bleeding occurred in three of 31 (9.7%) patients on antiplatelet or anticoagulant medications and four of 288 (1.4%) patients not on antiplatelet or anticoagulant medications (relative risk [RR] = 6.9; 95% confidence interval [CI] = 1.6 to 29.4; p = 0.022). Clinical outcome data were available for 300 of the 319 (94%) subjects following discharge. Late bleeding (bleeding after discharge from the index hospitalization) occurred in nine subjects, one of whom also had early bleeding (major = 2, minor = 3, trivial = 4). Three of these nine subjects with late bleeding were on antiplatelet or anticoagulant medications, compared with six not on antiplatelet or anticoagulant medications (p = 0.042). Both cases of late major bleeding occurred in patients on antiplatelet or anticoagulant medications. Therefore, among patients with follow-up data available, the overall rate of bleeding (early and late) was seven of 28 (25%) in patients taking antiplatelet or anticoagulant medications and 10 of 273 (3.7%) in patients not taking antiplatelet or anticoagulant medications (p < 0.001). The use of antiplatelet or anticoagulant medications was also associated with an increased risk of reaching the composite endpoint of major bleeding, shock, readmission, or death (6 of 31, or 19.4% vs. 14 of 288, or 4.9%; RR = 3.98; 95% CI = 1.65 to 9.62; p = 0.008). CONCLUSIONS The risk of developing bleeding following rattlesnake envenomation is increased in patients who use antiplatelet or anticoagulant medications. This risk is greatest early after envenomation during the index hospitalization. However, risk of late, major bleeding appears also to be greatest in patients on antiplatelet or anticoagulant medications. Extra vigilance should be taken in patients on antiplatelet or anticoagulant medications and a careful risk/benefit analysis should be undertaken before continuing these medications in the weeks following the envenomation.

Epidemiology and clinical outcomes of snakebite in the elderly: a ToxIC database study*

Abstract Introduction: Epidemiologic studies of snakebites in the United States report typical victims to be young men. Little is known regarding other demographics including children and the elderly. The objective of this study was to describe the epidemiology and clinical manifestations of snake bite in elderly patients reported to the ToxIC (Toxicology Investigators Consortium) North American Snakebite Registry (NASBR) Methods: This was a multicenter analysis of a prospectively collected cohort of patients with snakebite reported to the ToxIC NASBR between 1 January 2013 and 31 December 2015. Inclusion criterion was age >65. Variables collected included patient demographics, medical comorbidities, medications, date the case was reported to the registry, location of exposure, bite location, snake species, clinical manifestations, outcomes, and management. Results: Of the 450 cases reported, 30 (6.7%) occurred in elderly patients, with an average age of 74 years. Rattlesnake envenomations were common (93.3%). The majority of patients were men (66.7%) and reported at least one medical comorbidity (83.3%). Most patients were on cardiac medications (60%) and use of antiplatelet or anticoagulant medications was common (33%). Hemotoxicity occurred in 30% of patients on initial presentation and 11.5% of patients on initial follow-up. No clinically significant early or late bleeding was observed. Conclusions: Elderly patients with North American snake envenomation are likely to have co-morbidities and to take medications that may increase their risk for hemotoxicity, however risk of bleeding or other complications was not increased in this group.

Severe bark scorpion envenomation in adults

Abstract Introduction: The preponderance of medical literature regarding severe bark scorpion envenomation describes pediatric patients; however, the majority (>66%) of annual poison center calls pertain to adults. This retrospective review sought to evaluate the clinical manifestations of adults with severe Centruroides sculpturatus envenomation and determine if significant morbidity occurred. Methods: This is a retrospective review of adults presenting to a single tertiary referral center with Grade-III or Grade-IV scorpion envenomation from 1 January 2007 to 3 March 2013. The primary objective is to describe clinical findings, treatment strategies, complications and short-term outcomes. Results: Thirty-three patients were included; 61% were female (20/33), average age was 40.7 (19–81) years. The average time to healthcare facility was 142 (14–720) minutes. The most common signs and symptoms of envenomation were: pain/paresthesias 94%, opsoclonus 82%, excessive motor activity 76%, visual disturbance 76%. Benzodiazepines 85% (29/33) and opioids 83% (28/33) were the most frequently used agents to control envenomation. Cardiac evaluation was performed in 24% of patients, 6% were pregnant and underwent fetal monitoring, 6% were intubated and 3% developed rhabdomyolysis. Average length of stay (LOS) was 28.3 (1.5–307) hours; 58% (19/33) required hospital admission. Four patients had LOS >48 h, with pre-existing cardiac disease, substance misuse disorder, acute ethanol withdrawal and medical errors identified as factors contributing to prolonged LOS. Conclusions: Bark scorpion envenomation in adults may be severe, necessitating medical intervention and hospital admission. Comorbid conditions and complications arising from treatment may contribute to prolonged LOS.

Clinical predictors of tissue necrosis following rattlesnake envenomation

Abstract Background: Rattlesnake envenomation (RSE) causes edema, hemotoxicity and tissue necrosis. Necrosis may result in permanent disability. Objective: To study patient-related factors associated with tissue necrosis after Crotalus envenomation. Methods: Prospective cohort study of patients admitted to the Medical Toxicology service with diagnosis of RSE between April 2011 and November 2014. Inclusion criteria were age ≥18 years and upper extremity (UE) envenomation site. Primary outcome was tissue necrosis, including dermonecrosis, manifesting as bullae. Secondary outcome was amputation. Results: 77 subjects, age 18 to 88 years, met inclusion criteria. Rattlesnake species was unknown in most cases. All received Fab antivenom. 62 (82%) had a digital envenomation. 31 (40.3%) had necrosis. Necrotic area ranged from 0.1 cm2 to 14 cm2. Procedural interventions, (superficial debridement, dermotomy, surgical exploration, and operative debridement of devitalized tissue) occurred in 25 (32.5%). Five (6.5%) underwent dermotomy and 6 (7.8%) operative debridement. No amputations were performed. Patients with cyanosis on presentation had increased risk of developing necrosis (11/12; RR 2.98 95% CI 1.99–4.46). Ecchymosis on presentation was also associated with increased risk of necrosis (24/32; RR 4.04 95% CI 2.08–7.86). Patients with social or regular ethanol use were more likely to develop necrosis than those without (28/53; RR 4.23 95% CI 1.42–12.6). Regular cocaine use was associated with increased risk of operative debridement (4/6; RR 9.13 95% CI 2.33–35.8). A nonsignificant risk of operative debridement occurred with tobacco use (RR 1.14 95%CI 0.99–1.31 p = 0.09). Time to antivenom did not correlate with risk of necrosis. Conclusion: UE RSE patients who presented with cyanosis, ecchymosis or history of ethanol use were at increased risk of developing necrosis. Cocaine use was associated with increased risk of operative debridement.