Cardiac output measured by uncalibrated arterial pressure waveform analysis by recently released software version 3.02 versus thermodilution in septic shock

Abstract

To evaluate the 3.02 software version of the FloTrac/Vigileo™ system for estimation of cardiac output by uncalibrated arterial pressure waveform analysis, in septic shock. Nineteen consecutive patients in septic shock were studied. FloTrac/Vigileo™ measurements (COfv) were compared with pulmonary artery catheter thermodilution-derived cardiac output (COtd). The mean cardiac output was 7.7Lmin(-1) and measurements correlated at r=0.53 (P<0.001, n=314). In Bland-Altman plot for repeated measurements, the bias was 1.7Lmin(-1) and 95% limits of agreement (LA) were -3.0 to 6.5Lmin(-1), with a %error of 53%. The bias of COfv inversely related to systemic vascular resistance (SVR) (r=-0.54, P<0.001). Above a SVR of 700 dynscm(-5) (n=74), bias was 0.3 Lmin(-1) and 95% LA were -1.6 to 2.2Lmin(-1) (%error 32%). Changes between consecutive measurements (n=295) correlated at 0.67 (P<0.001), with a bias of 0.1% (95% limits of agreement -17.5 to 17.0%). All changes >10% in both COtd and COfv (n=46) were in the same direction. Eighty-five percent of the measurements were within the 30°-330° of the polar axis. COfv with the latest software still underestimates COtd at low SVR in septic shock. The tracking capacities of the 3.02 software are moderate-good when clinically relevant changes are considered.