Clinical comparison of pressure-pulse and indicator-dilution cardiac output determination

Two clinical studies of cardiac output determination using the pressure-pulse technique are presented. The Warner pressure-pulse method of estimating cardiac output was compared with the dye-dilution technique in 17 patients. Both the Warner and a variation of the Bourgeosis pressure-pulse methods were compared with thermodilution in 13 patients. The Warner vs dye-dilution comparison resulted in a poor correlation coefficient (r = 0.61). Values for the Warner equation calibration constant (K) were nonstationary, varying with time from --69 to 135% of the initial value in individual patients. When thermodilution was compared with the two methods, the correlation was poor (r = 0.58 for the Warner method; r = 0.50 for the modified Bourgeois method). The Warner and a variation of the Bourgeois pressure-pulse methods for monitoring the cardiac output of critically ill patients with widely varying mean arterial pressures are not sufficiently reliable for clinical decision-making.