A new model of uncontrolled hemorrhage that allows correlation of blood pressure and hemorrhage

Abstract

Objective: To compare hemodynamics, mortality rates, and bleeding rates at 3 severities of hemorrhage in a new model of uncontrolled intra-abdominal bleeding that uses an injury of varying severity and geometry unfavorable to thrombosis. Methods: Ten swine were bled through a flow-monitored shunt placed between the femoral artery and the peritoneal cavity. The shunt was connected to catheters of varying diameters placed in the femoral artery to create 3 rates of hemorrhage. Blood flow through the shunt was measured with an in-line Doppler probe. Arterial pressures, cardiac output (CO), and ECGs were monitored. Survival and blood loss were calculated. Results: The model successfully produced 3 hemorrhage severities. At all 3 rates of bleeding, blood flow was linearly related to mean arterial pressure, with R2 > 0.72. Bleeding was continuous in all groups. The mean numbers of minutes until death were 53, 45, and 25, respectively, at the increasing shock severities. Blood pressure (BP) and CO decreased continuously in all groups, but did so more rapidly with increasing severity of hemorrhage. Conclusions: In this model of uncontrolled hemorrhage, bleeding was continuous and linearly related to BP. The hemodynamic response to uncontrolled bleeding in this model differs markedly from those in previous wire aortotomy models where wound geometry is favorable to thrombosis. Hence, when injury geometry is favorable to thrombosis (as in aortotomy), thrombosis formation affects hemorrhage rates and hemodynamic responses.