Correlation of altitude and compartment pressures in porcine hind limbs.

Recent wartime contingencies have demanded frequent aeromedical evacuation of polytrauma patients, all with risk factors for the development of compartment syndrome. This study investigated the effect of altitude on the pressure in uninjured myofascial compartments of 10 pigs as part of a program with the ultimate goal of determining the behavior of an injured extremity in a changing altitude environment. The data showed a trend toward a small increase in pressure with increase in altitude--an average maximal delta of 2.7 mm Hg from the opening pressure. A small increase in compartment pressure, such as seen in this study, in a normal, uninjured compartment would likely go clinically unnoticed. However, aeromedical evacuation missions fly patients with fractures that can affect the physiology of compartments. Potentially, even a small change in pressure can lead to a compartment syndrome. Further study involving a fracture model will be required to further elucidate this clinical question.