Cardiorespiratory simulation for the evaluation of recovery following coronary artery bypass surgery

Abstract

The interpretation of a patient's status and recovery after coronary artery bypass surgery are difficult because of the complex interaction of many factors and because only relatively limited, non-specific measurements can be made. The objective of this study was to develop a simulation model of basic cardiorespiratory functions which would be useful as a clinical tool to obtain a refined characterization of a patient's cardiopulmonary interactions based on clinical measurements. The simulation was used to generate the same types of measurements obtained on patients. The basic approach was to adjust the simulation parameters so that the simulated measurements agreed with the patient's data. Thirty-five patients who had multiple coronary bypass surgery were simulated. The measurements agreed within clinical significance for a wide range of physiologic states. The resulting values of the simulation parameters provide functional indices of ventilation/perfusion disparity, diffusion gradients, venous-arterial pulmonary shunt, and respiratory dead space. The simulation model also offered a technique for estimating the efficacy of cardiorespiratory support maneuvers in changing blood gas and pH values in the critically ill post-coronary-bypass patient with an acute respiratory distress syndrome. © 1981.