Physiological Consequences of Abdominal Aortic and Junctional Tourniquet (AAJT) Application to Control Hemorrhage in a Swine Model.

Abstract

Specialized tourniquets such as Abdominal Aortic and Junctional Tourniquet (AAJT) have been deployed for control of junctional hemorrhage with limited information concerning their efficacy and safety. We examined physiological effects of a 2-h abdominal application of AAJT to control groin hemorrhage in a swine model. Anesthetized pigs were subjected to 25% controlled hemorrhage and a groin arterial injury. Resulting hemorrhage from the groin wound was controlled for 2 h by applying AAJT on each pig's abdomen. After AAJT removal, the artery was repaired and blood flow was fully restored for 1 h. CT angiography and blood analyses were done and tissues collected for histology. Experiments were conducted in three groups of pigs (n = 6/group): mechanically ventilated (MV); spontaneously breathing (SB); and spontaneously breathing during AAJT application but transitioned to mechanical ventilation (SB-MV) before AAJT release. AAJT application produced sharp increases in blood pressure and heart rate. SB animals experienced labored and rapid respiration, but their PaO2 and PaCO2 were unaffected. Their respiration suddenly stopped when the AAJT was released requiring manual respiratory assistance. However, three pigs in SB group eventually died from cardiac and respiratory arrests, which coincided with hyperkalemia and metabolic acidosis that occurred after reflow. These changes were less severe in other groups. Other measures including increased hematocrit, tissue injury biomarkers, and kidney function indicators were similar in all groups. Histological changes were mild and reversible. The ischemia-induced hyperkalemia and metabolic acidosis associated with AAJT application are life-threatening in spontaneously breathing subjects. Cardiopulmonary resuscitation appears necessary when AAJT is released to prevent life-threatening consequences.