A computer model of hemorrhagic shock in domestic swine.

We used a modified version of the computer model of the circulation developed by C.V. Greenway (Pharmacol Rev 33:213-251, 1982) to study the volume-pressure relationship of the systemic venous circulation during and immediately after massive blood loss. Our theoretical predictions were based on experimental measurements performed in conscious, chronically instrumented swine subjected to massive and rapid loss of a predetermined amount of blood. These animals were subjected to an exponential removal of either 50% of their calculated blood volume in 1 hour or a linear removal of 60% in 15 minutes. Our computer model indicates a hysteresis effect between the volume-pressure curves during and immediately following hemorrhage. The results emphasize the importance of venous capacitance changes as a compensatory response to blood loss.