353 Point-of-Care Ultrasound in the Evaluation of Rattlesnake Envenomation

Abstract

To our knowledge, no prior studies investigated the role of point-of-care ultrasound (POCUS) in the evaluation of rattlesnake envenomation. The objective of this study was to determine the utility of POCUS in the management of rattlesnake envenomation in the emergency department (ED). This was a retrospective review of patients presenting to an academic ED with rattlesnake bite and received a POCUS examination after initial clinical assessment. Proximal progression of symptoms and signs in the affected extremity was monitored clinically and repeat POCUS examinations of the extremity were performed. POCUS findings were collected from ED POCUS database. Medical records were then reviewed for history, physical examination findings, laboratory results, additional diagnostic testing, and disposition. The proportion of patients whose treatment plan was altered by the addition of POCUS findings was determined. A total of 21 patients (mean age 48 years ± 15 (SD); 14 males, 7 females) were included in this study. All patients presented with pain, swelling and tenderness at the site of bite (16-lower extremity, 5-upper extremity). On initial POCUS examination, all patients except one case were noted to have subcutaneous edema at the location of snake bite. Twelve patients were also noted to have cobblestoning on initial POCUS. Myokymia was visualized on initial POCUS in 2 patients. On repeat assessments, POCUS demonstrated subcutaneous edema and cobblestoning more proximally than what was determined and marked by treating emergency physicians in 16 patients. Four patients received additional doses of antivenom based on POCUS findings. The one patient who did not have any sonographic findings on initial POCUS was eventually determined to have dry bite by the toxicologist. Patients with myokymia had a complicated hospital course with thrombocytopenia and deterioration of hemodynamic status. Despite limited numbers, our study suggests that POCUS can be a useful adjunct in the evaluation of patients with rattlesnake bite. Ultrasound appears to be more sensitive than clinical assessment in detecting proximal progression of effects of venom and can potentially guide management. Our ongoing prospective study will further define the role of POCUS in the treatment of rattlesnake envenomation.