Rattlesnake bites and surgical decompression: results using a laboratory model.

Studies were performed on the hind limbs of dogs and their anterolateral compartments to evaluate the effect of fasciotomy on tissue pressure and necrosis following pit viper envenomation. Venom from the southern Pacific rattlesnake, Crotalus viridis helleri, was injected into either the subcutaneous tissues, the intact anterolateral compartment or the anterolateral compartment following fasciectomy. Interstitial fluid pressure measurements, as well as limb girth and surface temperatures, were obtained over the first 48 hr following venom injection, after which time the compartment contents were examined microscopically. The results demonstrated intracompartment tissue pressure elevations only following intracompartment injections. Fasciectomy prior to injection did not prevent muscle necrosis, though it did reduce maximum compartment pressures. Clinically the limbs in each group could not be differentiated. Intracompartment pressure measurements were able to distinguish between muscle and subcutaneous envenomations by the differences in compartment pressures. These results demonstrate the value of tissue pressure measurements in the evaluation of patients envenomated by rattlesnakes. They also indicate the objectivity necessary to determine the need for surgical decompression.