J Trauma Acute Care Surg. 2018 Jul 5 Epub ahead of print

# Abdominal Aortic and Junctional Tourniquet release after 240 min is survivable and associated with small intestine and liver ischemia after porcine class II hemorrhage.

Brännström A, Rocksén D, Hartman J, Nyman N, BSc J, Arborelius U, Günther M

BACKGROUND: Uncontrolled hemorrhage is a leading cause of tactical trauma related deaths. Hemorrhage from the pelvis and junctional regions are particularly difficult to control due to the inability of focal compression. The Abdominal Aortic and Junctional Tourniquet (AAJT) occludes aortic blood flow by compression of the abdomen. The survivability of tourniquet release beyond 120 min is unknown and fluid requirements to maintain sufficient blood pressure during prolonged application are undetermined. We therefore compared 60 min and 240 min applications and release of the AAJT for 30 min, with crystalloid fluid therapy, after a class II hemorrhage.

METHODS: 60 kg anesthetized pigs were subjected to [SWUNG DASH]900 ml hemorrhage and AAJT application for 60 min (n=5), 240 min (n=5), fluid therapy only for 240 min (n=5) and reperfusion for 30 min.

RESULTS: AAJT application was hemodynamically and respiratory tolerable for 60 min and 240 min. Cumulative fluid requirements decreased by 64%, comparable to 3000 ml of crystalloids. Mechanical ventilation was impaired. AAJT increased the core temperature by 0.9°C compared to fluid therapy. Reperfusion consequences were reversible after 60 min but not after 240 min. 240 min application resulted in small intestine and liver ischemia, persisting hyperkalemia, metabolic acidosis and myoglobinemia, suggesting rhabdomyolysis.

CONCLUSIONS: AAJT application for 240 min with reperfusion was survivable in an intensive care setting and associated with abdominal organ damage. Long time consequences and spinal cord effects was not assessed. We propose an application time limit within 60-240 min, though further studies are needed to increase the temporal resolution. The AAJT may be considered a rescue option to maintain central blood pressure and core temperature in cases of hemorrhagic shock from extremity bleedings, if fluid therapy is unavailable or the supply limited.Therapeutic study, level II.