Fasciotomy worsens the amount of myonecrosis in a porcine model of crotaline envenomation.

STUDY OBJECTIVE: We evaluate the efficacy of fasciotomy or crotaline snake antivenom in reducing myonecrosis.

METHODS: We used a randomized, blinded, controlled acute animal preparation. Twenty anesthetized swine were injected intramuscularly in the anterior tibiales muscle of both hind limbs with 6 mg/kg of Crotalus atrox venom (total of 12 mg/kg of venom per animal). Immediately after venom injection, the right hind limb underwent fasciotomy. Muscle biopsies were obtained from the fasciotomized hind limb at 0, 4, and 8 hours and from the other hind limb at the conclusion of the study (8 hours). In addition, animals received either 8 vials of reconstituted Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) or an equal volume of normal saline solution intravenously 1 hour after venom injection. A pathologist blinded to the study determined the percentage of myonecrotic cells in each biopsy. Statistical analysis was performed using repeated measures analysis of variance for compartment pressure. Rank-order methods were used for comparison of myonecrosis between groups.

RESULTS: Biopsies from hind limbs undergoing fasciotomy revealed a progressive increase in the amount of myonecrosis over time (myonecrosis median at 0, 4, or 8 hours [or death]: 0%, 14%, or 14.5%, respectively; P<.001). Comparison of the amount of myonecrosis of biopsies at death or 8 hours revealed that limbs that underwent fasciotomy had significantly more myonecrosis than those that did not (myonecrosis median: 14.5% versus 2.5%, P=.048). No difference was detected in the amount of myonecrosis when FabAV was compared with normal saline solution on final biopsies from either fasciotomy or nonfasciotomy hind limb (myonecrosis median: 10.0% versus 10.0%, P=.64).

CONCLUSION: Fasciotomy significantly worsens the amount of myonecrosis in a porcine model of intramuscular crotaline venom injection. No change in the amount of myonecrosis was detected with the use of FabAV treatment at the dosages used in this animal model.