The Efficacy of Crotalidae Polyvalent Immune Fab (Ovine) Antivenom Versus Placebo Plus Optional Rescue Therapy on Recovery From Copperhead Snake Envenomation: A Randomized, Double-Blind, Placebo-Controlled, Clinical Trial.

STUDY OBJECTIVE: Copperhead snake (Agkistrodon contortrix) envenomation causes limb injury resulting in pain and disability. It is not known whether antivenom administration improves limb function. We determine whether administration of antivenom improves recovery from limb injury in patients envenomated by copperhead snakes. METHODS: From August 2013 through November 2015, we performed a multicenter, randomized, double-blind, placebo-controlled, clinical trial to evaluate the effect of ovine Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) antivenom therapy on recovery of limb function in patients with copperhead snake envenomation at 14 days postenvenomation. The study setting was 18 emergency departments in regions of the United States where copperhead snakes are endemic. Consecutive patients aged 12 years or older with mild- to moderate-severity envenomation received either FabAV or placebo. The primary outcome was limb function 14 days after envenomation, measured by the Patient-Specific Functional Scale. Additional outcomes included the Patient-Specific Functional Scale at other points; the Disorders of the Arm, Shoulder, and Hand, Lower Extremity Functional Scale, and Patient's Global Impression of Change instruments; grip strength; walking speed; quality of life (Patient-Reported Outcomes Measurement Information System Physical Fucntion-10); pain; and analgesic use. RESULTS: Seventy-four patients received study drug (45 FabAV, 29 placebo). Mean age was 43 years (range 12 to 86 years). Fifty-three percent were men, 62% had lower extremity envenomation, and 88% had mild initial severity. The primary outcome, the least square mean Patient-Specific Functional Scale score at 14 days postenvenomation, was 8.6 for FabAV-treated subjects and 7.4 for placebo recipients (difference 1.2; 95% confidence interval 0.1 to 2.3; P=.04). Additional outcome assessments generally favored FabAV. More FabAV-treated subjects experienced treatment-emergent adverse events (56% versus 28%), but few were serious (1 in each group). CONCLUSION: Treatment with FabAV reduces limb disability measured by the Patient-Specific Functional Scale 14 days after copperhead envenomation.

Prospective study of recovery from copperhead snake envenomation: an observational study.

BACKGROUND: Although much is known about signs, symptoms, and management in the acute phase of crotaline snake envenomation, little is known about signs, symptoms, function, and quality of life during the recovery phase. The purpose of this observational pilot investigation is to evaluate the utility of several clinical outcome instruments in the setting of copperhead snakebite, and to characterize the clinical course of recovery. METHODS: This is a multi-center prospective, open-label, observational study of patients envenomated by copperhead snakes. We administered the Disabilities of the Arm, Shoulder, and Hand (DASH), Lower Extremity Functional Scale (LEFS), Patient-Specific Functional Scale (PSFS), Work Productivity and Ability Impairment: Special Health Problem (WPAI: SHP), Patients' Global Impression of Change (PGIC), Patient's Global Assessment of Recovery (PGAR), and SF-36 instruments, obtained numeric pain rating scales, and measured grip strength, walking speed, and swelling prior to hospital discharge and 3, 7, 14, 21, and 28 days after envenomation. RESULTS: 20 subjects were enrolled; none were lost to follow-up. Most (80%) had moderate severity swelling, and most (75%) received antivenom. Across the broad range of measures, abnormalities of pain, swelling, impairments of physical and role function, and quality of life persisted for 7-14 days in most subjects. Validated self-reported outcome measures, such as the DASH, LEFS, PSFS, PGIC, SF-36, and the daily activities impairment portion of the WPAI: SHP were more responsive than measurements of swelling or walking speed. Data quality issues limited the utility of the work impairment portion of the WPAI: SHP. Residual signs, symptoms, and impairment in some subjects lasted through the 28-day study period. The study design precluded any assessment of the effectiveness of antivenom. CONCLUSIONS: Signs, symptoms, impaired function, and decreased quality of life typically last 7 - 14 days after copperhead envenomation. Several tools appear responsive and useful in studying recovery from pit viper envenomation. TRIAL REGISTRATION: ClinicalTrials.gov NCT01651299.

FabAV antivenin use after copperhead snakebite: clinically indicated or knee-jerk reaction?

Crotalidae Polyvalent Immune Fab (Ovine) (FabAV) antivenin is commonly recommended after pit viper snakebites. Because copperhead envenomations are usually self-limited, some physicians are reluctant to use this costly treatment routinely, while others follow a more liberal approach. We hypothesized that, in practice, only patients with evidence of significant (moderate or severe) copperhead envenomation [those with snakebite severity score (SSS) > 3] receive FabAV and examined a large cohort to determine the relationship between clinical findings and FabAV administration. Methods All data from patients evaluated for copperhead snakebite at a rural tertiary referral center from 5/2002 to 10/2013 were compiled. Demographics, transfer status, antivenin use, and clinical findings were collected; SSS was calculated. The relationships among FabAV use, clinical findings, and SSS were analyzed using t-test, chi-square, and Pearsons coefficient (p 0.05 was significant). Results During the study period, 318 patients were treated for copperhead snakebite; 44 (13.8 %) received antivenin. Median dose was four vials (range: 110; IQR: 4,6). There were no deaths. Most patients receiving FabAV (63.6 %) were admitted. With regard to demographics and symptoms, only the degree of swelling (moderate vs. none/mild; p 0.01) and bite location (hand/arm vs. leg: p 0.0001) were associated with FabAV use. A SSS > 3, indicating moderate or severe envenomation, was only very weakly correlated with antivenin use (r = 0.217;p 0.0001). The majority of patients with SSS > 3 (65.8 %) did not receive antivenin while most patients who did receive antivenin (70.5 %) had SSS 3 (indicating mild envenomation). Conclusions Considerable variation occurs in antivenin administration after copperhead snakebite. Use of FabAV appears poorly correlated with patients symptoms. This practice may expose patients to the risks of antivenin and increasing costs of medical care without improving outcomes. Guidelines used for treating other pit viper strikes, such as rattlesnake or cottonmouth snakebite may be too liberal for copperhead envenomations. Our data suggests that most patients with mild or moderate envenomation appear to do well independent of FabAV use. We suggest, for patients with copperhead snakebite, that consideration be given to withholding FabAV for those without clinical evidence of severe envenomation until prospective randomized data are available.

Envenenamento experimental por bothropoides jararaca e bothrops jararacussu em ovinos: aspectos clínico-patológicos e laboratoriais / Experimental poisoning by bothropoides jararaca and bothrops jararacussu in sheep: clinic-pathological and laboratory aspects

Esse estudo teve como objetivo determinar as alterações clínico-patológicas e laboratoriais em ovinos inoculados com a peçonha de Bothropoides jararaca e Bothrops jararacussu, no intuito de fornecer subsídios que possam facilitar o estabelecimento do diagnóstico e do diagnóstico diferencial dessa condição. Os venenos liofilizados foram diluídos em 1 ml de solução fisiológica e administrados a quatro ovinos por via subcutânea. Três ovinos foram a óbito e um que recebeu a dose de 0,5mg/kg (B. jararaca), recuperou-se. Os sinais clínicos tiveram início entre 7 minutos e 1 hora. O período de evolução variou de 7 horas 9 minutos a 21 horas 59 minutos. O quadro clínico, independentemente das doses, caracterizou-se por aumento de volume no local da inoculação, tempo de sangramento e de preenchimento capilar aumentados, taquicardia, dispnéia, mucosas hipocoradas e apatia. Os exames laboratoriais revelaram acentuada anemia normocítica normocrômica, trombocitopenia, acentuada redução de fibrinogênio e proteínas plasmáticas totais, hematócrito diminuído em dois animais, além de acentuado aumento de creatinaquinase e desidrogenase lática em todos os animais. À necropsia, os principais achados no local da inoculação e tecidos adjacentes eram extensas hemorragias no animal que recebeu o veneno de B. jararaca e edema e acentuado edema pulmonar agudo para os dois animais envenenados por B. jararacussu. Além de hemorragia e edema a principal alteração histopatológica verificada foi necrose das fibras musculares e de vasos, no local de inoculação e adjacências. A necrose tubular renal foi atribuída ao quadro de choque. Nos ovinos deste estudo, o aumento de volume observado no local de inoculação e adjacências era constituído predominantemente por sangue (B. jararaca) e por edema (B. jararacussu).

The purpose of this study was to establish the clinic-pathological and laboratory changes in sheep inoculated with Bothropoides jararaca and Bothrops jararacussu venom to provide subsidies for the differential diagnosis of snake bites. The liofilized venoms were diluted in 1 ml saline and administrated subcutaneously to four sheep. Three of the animals died, and the one that received 0.5mg/kg (B. jararaca venom) recovered. First symptoms were observed from 7 minutes to 1 hour after inoculation, and the clinical course varied from 7 hours and 9 minutes to 21 hours and 59 minutes. The symptoms, independent of the dosage, were swelling of the inoculation site, increased bleeding time and capillary filling, tachycardia, dyspnea, pale mucous membranes and diminished reaction to external stimuli. Laboratory tests revealed pronounced normocytic and normochromic anemia, trombocytopenia, slight reduction of fibrogen and total plasmatic protein, in two animals diminished hematocrit, besides pronounced increase of creatinaquinase and lactic dehydrogenase. At necropsy, the main findings at the inoculation site and adjacent tissues were extensive hemorrhages in the sheep inoculated with jararaca venom, and predominantly edema in the two animals inoculated with jararacussu venom. In two sheep which received jararacussu venom, acute pulmonary edema was observed. Hemorrhage and edema as the main histopathological changes, besides necrosis of muscle fibers and vessels at the inoculation site and adjacent tissue was observed. The renal tubular necrosis was attributed to shock. The volume increase at the inoculation site and surroundings was mainly due to hemorrhage (B. jararaca) or edema (B. jararacussu).

Effectiveness of delayed use of crotalidae polyvalent immune Fab (ovine) antivenom.

Traditionally, horse-serum-based antivenom has been used in the United States for North American crotaline snake evenomation. Crotalidae polyvalent immune Fab (ovine) was approved in 2000 for use in mild to moderate envenomations. The manufacture recommends use within 6 h of envenomation. Published postmarketing retrospective reports describe its use up to 9 h after envenomation. We describe a case of effective use of FabAV 52 h after envenomation with resultant correction of coagulopathy and mild improvement of local symptoms.

Snakebites in children in the densely populated city of Hong Kong: a 10-year survey.

AIM: To review the pattern and characteristics of snakebites in children in rural Hong Kong. METHODS: A retrospective chart review was conducted. RESULTS: Seven cases of snakebite in children were reported. Eighty-six percent of the victims were male, and the majority of bites (86%) occurred on the left extremities. Green pit vipers (Trimeresurus albolabris) accounted for most of the snakebites. Local symptomatology was common. Swelling, pain and fang marks were documented in all cases. A mildly deranged clotting profile was found in 70% of patients. There was no incidence of systemic symptoms, cardiopulmonary complications or compartment syndrome. Victims arrived at the hospital at a median (range) time of 40 (10-70) min since the snakebite. Only one child received antivenin owing to severe progressive local symptoms under intensive care monitoring. The median hospital stay of the patients was 4 d. The hands and feet of adolescent boys (n = 6) seem to be particularly prone to being bitten. CONCLUSION: Children should be discouraged to play in areas where snakes may hide, especially in the evening in summer to autumn. They should wear protective footwear.

Ofidiotoxicosis en Pediatría

El accidente por mordedura de serpientes venenosas es una emergencia que puede presentarse en las zonas tropicales de Colombia por la gran cantidad de especies existentes. Se hace una revisión de la clasificaión, actividad de sus venenos, fisiopatología y clínica de las serpientes venenosas conocidas en Colombia. Existen tres grande familias: Viperidae, Micruridae e Hidrophidae. En la primera familia hay tres géneros, Bothrops, Crotalus y Lachesis. El accidente más frecuente se produce por Bothrops. La familia Micruridae tiene 29 especies distribuídas por todo el territorio colonmbiabo, pero gracias a su poca agresividad no ocurren accidentes con frecuencia. Las serpientes marinas corresponden a la familia Hidrophidae y, solo se encuentran en aguas marinas del litoral pacífico. Se propone un protocolo de manejo orientado a la atención de niños afectados