Continuous, on-line, real-time measurement of cardiac output and derived cardiorespiratory variables in the critically ill.

A previously reported monitoring system provided continuous direct measurements of oxygen consumption and intravascular pressures. These data were combined with interval measurements of cardiac output and blood oxygen saturations to derive various hemodynamic and oxygen transport variables. This system has now been modified so that cardiac output is measured continuously in real-time.

Microcomputer-assisted monitoring system for measuring and processing cardiorespiratory variables: preliminary results of clinical trials.

A microcomputer-assisted monitoring system was developed for the continuous measuring and processing of cardiorespiratory variables, including: systemic and pulmonary arterial pressures, CVP, minute ventilation, inspired and expired O2 and CO2 concentrations, temperature, and heart rate. The primary data were converted to digital form, processed, displayed on a CRT monitor, and also stored for later evaluation. This system automatically calculated and displayed on-line and in real-time both primary measurements and derived cardiorespiratory variables, including: oxygen consumption, CO2 production, left and right ventricular stroke work, pulmonary venous admixture, and systemic and pulmonary vascular resistances. Printouts of the variables and trend graphs could be obtained for any desired time period. During its development, we tested this monitoring system in 30 critically ill patients, finding that the real-time calculation of cardiorespiratory variables was a great advantage during monitoring and treatment.