Study Objective: To compare cardiac index (CI) measurement by arterial pulse contour analysis using two different algorithms (CIPC, CIPCnew) with pulmonary arterial thermodilution values (CIPA) so as to evaluate the difference between the conventional algorithm, CIPC, and a new algorithm, CIPCnew, that accounts for patients' individual aortic compliance. Design: Prospective clinical study Setting: Intensive care unit of a university hospital. Patients: 20 ASA physical status II and III patients following elective cardiac surgery. Measurements and Main Results: 360 parallel triplicate determinations of CI (CIPA, CIPC, CIPCnew) were performed within a 90-minute period during the immediate postoperative period. Prior to the start of the study period, CIPC as well as CIPCnew were calibrated by triplicate femoral arterial thermodilution measurements. Regression analysis of CIPA and CIPC, as well as CIPA and CIPCnew revealed r = 0.89, p < 0.001, and r = 0.93, p < 0.001, respectively. Bland-Altman analysis was used for determining the accuracy and precision of CIPC and CIPCnew compared with CIPA. The mean differences (m) and standard deviation (SD) between CIPA and CIPC, as well as CIPA and CIPCnew resulted in m = -0.312 L/min/m(2), SD = 0.456 L/min/m(2), and m = -0.140 L/min/m(2), SD = 0.328 L/min/m(2), respectively. Conclusion: Arterial pulse contour analysis measurement of CI using either algorithm correlates well with CI values derived by pulmonary arterial thermodilution. However, the algorithm introduced in this study proved to be a more accurate predictor of values as derived by pulmonary artery catheter. (C) 2002 by Elsevier Science Inc.
