Guideline sources The following summarized guidelines for the evaluation and management of pit viper envenomation are prepared by our editorial team based on guidelines from the Wilderness Medical Society (WMS 2015). 1 Guidelines 1. Classification and risk stratification Risk stratification: do not use prediction of the amount of envenomation from a snakebite or potential sequelae for risk stratification, because even a knowledgeable caregiver may not be able to predict it. D 2. Diagnostic investigations Physical examination in the field: Observe local tissue effects which are the most common physical manifestations of pitviper envenomations and occur in > 90% of patients with medically significant envenomations. B https://web.pathway.md/diseases/recNBfQkFlh47CxtP 1/4 6/29/23, 11:11 PM Pit viper envenomation Pathway Consider patients without local or systemic symptoms 8 hours after the bite as having a dry bite, if evacuation is difficult or prolonged. B Assessment in the emergency department: mark the leading edge of tenderness, erythema, and swelling and limb circumference above and below the envenomation measured for future comparison. Repeat it every 15 to 30 minutes until local tissue effects have stabilized. B Laboratory studies: obtain repeat laboratory studies within 4 hours of the initial set in patients with moderate-to-severe envenomations. B Abdominal imaging: consider abdominal ultrasound or CT to assess for possible intra- abdominal bleeding in patients with a potentially worrisome abdominal examination. B 3. Medical management Setting of care: hospitalize patients with moderate-to-severe envenomations. B Antibiotic prophylaxis: do not routinely administer antibiotic prophylaxis. Reserve antibiotic prophylaxis for patients with signs of infection, such as purulence (other signs of infection may be obscured by local tissue changes caused by venom). D Pain management: consider opioids as the preffered option for pain control. Avoid aspirin and NSAIDs as they are relatively contraindicated owing to risks of increased bleeding, platelet dysfunction, and potential for prerenal effects in patients with rhabdomyolysis. B Tetanus prophylaxis: administer tetanus immunization after reversing coagulopathy to minimize bleeding from injection sites. B Antivenom: consider administering antivenom in patients with moderate-to-severe envenomations. B Show 3 more Management of secondary infection: consider extensive debridement or antibiotic administration, or both, in patients with secondary infection. B 4. Nonpharmacologic interventions First aid: remove or cut jewelry or constrictive clothing near the bite to avoid constriction with subsequent swelling. B Show 3 more Evacuation: Immediately transport all patients with snakebite to a hospital for evaluation and monitoring for progression, especially those with local or systemic symptoms. B Contact the nearest healthcare facility ahead of time, and if antivenom is unavailable, consider sending from another facility or immediately transport the patient to a different facility. Consider directly contacting a poison control center to coordinate this process. B 5. Therapeutic procedures https://web.pathway.md/diseases/recNBfQkFlh47CxtP 2/4 6/29/23, 11:11 PM Pit viper envenomation Pathway Interventions to avoid: Avoid interventions that are harmful or without benefit: oral suction mechanical suction laceration or bleeding the bite site electrotherapy or electrical currents cryotherapy or cooling tourniquet placement pressure bandaging. D 6. Surgical interventions Fasciotomy: consider fasciotomy in rare patients who fail to respond. Perform fasciotomy according to the decision made by a surgeon within 6 hours of signs of neurovascular compromise and elevated intracompartmental pressure despite appropriate administration of antivenom. B Digital dermotomy: decide on performing digital dermotomy (rarely required) based on neurovascular examination with the aid of digital Doppler ultrasound. Make a longitudinal incision through the skin only from the web space to the mid distal phalanx under local anesthesia, if digital dermotomy is indicated. B Wound care: manage significant open wounds with moist dressings changed BID, and use negative pressure dressings for large debrided areas. Advise early active and passive physical therapy with ROM and occupational therapy, especially for hand and digit bites to avoid stiffness and long-term dysfunction. B 7. Specific circumstances Pregnant patients: administer antivenom in pregnant patients with snakebite, as indicated, and provide fetal assessment or monitoring as the fetus is at higher risk to coagulopathy- related complications, such as placental abruption. B Pediatric patients: Antivenom is safe to use in pediatric and infant patients. B Mix antivenom in a smaller volume to approximate a 20 mL/kg bolus for infant patients < 10 kg in whom fluid overload is a concern. A Critically ill patients: administer vasopressorsfor hemodynamic support if hypotension persists despite antivenom and fluid therapy. B Show 4 more Allergic reactions: pretreat patients with hypersensitivity to Crotalidae polyvalent immune fab or papain/papaya extracts (papain is used to cleave the whole antibody into Fab and Fc segments, and a small inactive amount may be left in the antivenom) for allergic reactions and monitor closely. B Show 2 more https://web.pathway.md/diseases/recNBfQkFlh47CxtP 3/4 6/29/23, 11:11 PM Pit viper envenomation Pathway 8. Follow-up and surveillance Clinical deterioration: administer repeat doses of antivenom and arrange timely toxinologist or poison control center consultation if the clinical condition deteriorates. B Monitoring before discharge: monitor dry bites showing no progression beyond the simple wound for a minimum of 8 hours and obtain repeated laboratory studies during observation to monitor for possible delayed onset of venom effects. B Show 2 more Discharge from hospital: Discharge patients if they have normal vital signs and not have abnormalities or concerning trends in laboratory studies. B Provide information about precautions on serum sickness and delayed coagulopathy upon discharge of patients who have admitted and received antivenom. Provide clear information to return immediately for any signs of envenomation progression. B Follow-up after discharge: obtain repeated laboratory studies (CBC, PT/INR, fibrinogen) in discharged patients as an outpatient 2-3 days and 5-7 days after their last antivenom dose to evaluate for delayed onset or recurrent coagulopathy. Advise avoidance of contact sports, dental extractions, tattoos/piercings, and elective surgery for as long as 2 weeks. B References 1. Nicholas C Kanaan, Jeremiah Ray, Matthew Stewart et al. Wilderness Medical Society Practice Guidelines for the Treatment of Pitviper Envenomations in the United States and Canada. Wilderness Environ Med. 2015 Dec;26 4 472 87. Open https://web.pathway.md/diseases/recNBfQkFlh47CxtP 4/4