Military antishock trousers prolong survival after otherwise fatal hemorrhage in pigs.

Military antishock trousers (MAST) have not received universal acceptance for use during hypovolemia because cardiac output results have been conflicting, lower extremity compartment syndromes have been reported, and a prospective clinical trial has not been performed. We completed survival studies in a fatal porcine hemorrhage model which simulates human exsanguination. Trousers were specifically made for the weight of the swine in this study and then were calibrated by observing transmitted pressure to the lower abdomen and upper hind limbs. When the trousers were inflated to 60 torr, 77% of the inflation pressure was transmitted to the proximal lower leg (46 +/- 8 torr) and 58% was monitored in the lower abdomen (35 +/- 4 torr). Compared to a noninflation control group, we found the survival time significantly prolonged after an otherwise fatal hemorrhage. The mechanism appears to be through increased tissue perfusion probably not related to a transient translocation of lower extremity blood volume.