Toxicology Case Files from the Utah Poison Control Center
Teaching Points
- Compartment syndrome after rattlesnake envenomation is exceedingly rare, and the mainstay of treatment is adequate dosing of antivenom.
- Muscle necrosis occurs because of direct venom effects, and animal models of fasciotomy do not show a decrease in necrosis with fasciotomy.
- Blood flow may actually be increased following envenomation and further improved with antivenom
- Rarely, digit dermotomy could be performed if there is a cold, pale, pulseless finger
- Always consult with a toxicologist before proceeding with fasciotomy or dermotomy
Case
A 27-year-old male presented to the emergency department shortly after a rattlesnake envenomation to the left index finger. The patient reported pain in the finger, and there was mild swelling, ecchymosis, and an oozing puncture wound. Swelling spread into the hand, and antivenom was administered.
The finger was initially described as pale, but with further clarification, this was likely early ecchymosis as there was good cap refill and no tense edema along the entire digit.
The patient was admitted to the hospital, received additional antivenom for ongoing soft tissue swelling in the hand/forearm, and there was no worsening of the finger swelling. He was discharged 24 hours after the last dose of antivenom and scheduled for outpatient labs to assess for ongoing coagulopathy. Fortunately, no specific intervention was required for the finger.
Surgical Intervention After Rattlesnake Envenomation
Historically, some providers routinely performed fasciotomy following rattlesnake envenomation due to suspected compartment syndrome.
However, current recommendations are to NOT perform fasciotomy as true compartment syndrome is very rare, and blood flow is often increased after rattlesnake envenomation. Additionally, modern antivenom is much better tolerated than the old whole IgG Wyeth antivenom that frequently caused anaphylaxis. If compartment syndrome is suspected, give additional doses of antivenom. If signs and symptoms of compartment syndrome persist or worsen, directly measure compartment pressures and give more antivenom. Consult with a toxicologist before consulting with a surgeon if there is true concern for compartment syndrome. See Hall 2001 and Cumpston 2011 for further information.
In contrast to limb muscle compartments, clinical signs of digital ischemia may occur with rattlesnake envenomation. While the fingers do not have muscle compartments like the leg or arm, there is limited space for a finger to swell. In case of clear clinical evidence of digit ischemia, a longitudinal dermotomy to release pressure may be indicated. Note that signs such as swelling, decreased sensation, and pain with passive stretch are common in rattlesnake envenomation and are not indicative of ischemia.
This procedure is performed at the bedside with a ring block and a single incision from the web space to the midportion of the distal phalanx (see figure from Watt 1985). Only one side of the finger is incised, and only subcutaneous tissue is opened to release swelling. This should be done only in consultation with a toxicologist and then a hand surgeon.
No studies have evaluated the role dermotomy in animal models, nor is there any comparative data in humans. Most studies report the authors’ decision to perform a surgical intervention without description of objective measures of ischemia.
Antivenom is the first-line treatment for rattlesnake envenomation, with surgical intervention reserved for only rare, convincing cases of compartment syndrome or digit ischemia.
References
- Kirk L. Cumpston (2011) Is there a role for fasciotomy in Crotalinae envenomations in North America?, Clinical Toxicology 2011, 49:5, 351-365, DOI: 10.3109/15563650.2011.597032
- Hall EL. Role of surgical intervention in the management of crotaline snake envenomation. Ann Emerg Med. 2001 Feb;37(2):175-80. doi: 10.1067/mem.2001.113373. PMID: 11174236.
- Watt CH Jr. Treatment of poisonous snakebite with emphasis on digit dermotomy. South Med J. 1985 Jun;78(6):694-9. doi: 10.1097/00007611-198506000-00020. PMID: 4002000.