Effects of pulse pressure alterations on cardiac output measurements derived from analysis of arterial pressure waveform

Abstract

Background: Changes in pulse pressure (PP) may alter the morphology of arterial pressure waveforms, thereby affecting the accuracy of cardiac output (CO) measurements derived from such waveforms. This study evaluated the influence of PP on the accuracy of FloTrac/Vigileo™ system-measured CO (APCO). Pulmonary artery catheter (PAC) measured stat mode CO (SCO) is used as a reference standard. Methods: Hemodynamic variables were measured at various time points in 24 patients. APCO and SCO were compared using Bland-Altman analysis of the overall data pairs. The data pairs were divided into a low PP group and a high PP group, and subgroup analysis was conducted. Results: The mean APCO (5.3 ± 1.7 L/min) was higher than the mean SCO (5.1 ± 1.6 L/min) for all data pairs (P < 0.001). The Bland-Altman analysis revealed an overall percentage error of 41.7% between the APCO and SCO, which exceeds a 30% limit of agreement. There was a significant relationship between PP and the difference between APCO and SCO (P = 0.031, R = 0.151). In subgroup analysis, APCO and SCO showed reasonable agreement in the low PP group, with a percentage error of 28.2%, but decreased agreement in the high PP group, with a percentage error of 43.2%. Conclusions: Changes in PP affect the accuracy of APCO measurements. An acceptable level of agreement between APCO and SCO was observed only in a low range of PP.