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


CONCLUSIONS
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.
Department of Emergency, Medicine Naval Medical Center, San Diego, CA 91234, USA. dtanen@yahoo.com
David A
DA
Tanen
David C
DC
Danish
Guerard A
GA
Grice
Robert H
RH
Riffenburgh
Richard F
RF
Clark
D000818:Animals; D000997:Antivenins / Q000627:therapeutic use*; D001706:Biopsy; D003161:Compartment Syndromes / Q000139:chemically induced / Q000188:drug therapy* / Q000601:surgery*; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors*; D004195:Disease Models, Animal; D000071938:Fasciotomy; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments / Q000627:therapeutic use*; D018482:Muscle, Skeletal / Q000473:pathology*; D009336:Necrosis / Q000188:drug therapy / Q000601:surgery; D011897:Random Allocation; D016037:Single-Blind Method; D013552:Swine
D000997:Antivenins; D003435:Crotalid Venoms; C431183:Crotalidae Polyvalent immune Fab; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments