MYOCARDIAL O-2 BALANCE DURING FLUID RESUSCITATION IN UNCONTROLLED HEMORRHAGE - COMPUTER-MODEL

Objective: To study myocardial oxygen balance during fluid resuscitati on for uncontrolled hemorrhage. Design: A computer simulation, Materia ls and Methods: A mathematical model of the cardiovascular system was used to simulate uncontrolled hemorrhage with and without fluid replac ement, The parameters of initial bleeding rates, fluid replacement, an d time intervals were selected to approximate typical values encounter ed in an urban emergency medical services system, The model was used t o calculate myocardial oxygen supply and demand, and the time from inj ury to myocardial oxygen deficit was calculated for each fluid regimen , Main Results: The model predicts an exponential decline in bleeding rate when no fluids are administered, Optimal fluid infusion rate was predicted as a function of initial bleeding rate, The time to a negati ve myocardial oxygen balance was shorter when a fluid bolus (100 mL/mi n or more) was given compared with no fluid administration, Conclusion s: For uncontrolled hemorrhage at initial bleeding rates of 100 mi/min or more, the time interval from injury to cardiac oxygen deficit is i nversely related to the infusion rate, A detailed study of the myocard ial oxygen balance provides a pathophysiologic rationale for fluid res triction in the initial management of uncontrolled hemorrhage.