Comparison of Single and Recalibrated Measurements of Cardiac Index Obtained by ProAQT-Pulsioflex with Those of FloTrac/Vigileo

TitelComparison of Single and Recalibrated Measurements of Cardiac Index Obtained by ProAQT-Pulsioflex with Those of FloTrac/VigileoBackgroundThe ProAQT-Pulsioflex™ is a minimally invasive method to obtain cardiac index (CI) using pulse contour analysis. According to the manufacturer, the device has to be calibrated at the start of every procedure and should be able to measure CI accurately without further calibration. However, recalibration of CI is possible, e.g. after major changes in vascular tone or volume. We compared these single calibrated measurements (CIPAsc) and recalibrated ones (CIPAcal) with our clinical standard, i.e. CI measured by FloTrac/Vigileo (CIFTV).MethodsThis prospective, observational single center study includes seventy patients undergoing off-pump coronary artery bypass surgery. The moments at which CI was documented were randomly chosen during surgery to resemble clinical practice. Values were compared by Bland-Altman analysis for repeated measures. Four-quadrant plots and polar plot methodology were used to evaluate CI trending ability for each method.ResultsCIPAsc overestimated CIFTV with an average of 23%. This overestimation increased over time, doubling in four hours from 15% to 30%. In contrast, CIPAcal consistently overestimated CIFTV by 13% (fig. A). Agreement analysis of CIPAsc (fig. B) and CIPAcal (fig. C) versus CIFTV revealed a bias of -0.76 and -0.23 l min-1m-2 and 95% limits of agreement of ± 1.37 and 0.95 l min-1m-2, respectively. The percentage error was 112% for CIPAsc and 79% for CIPAcal. Polar plot analysis showed moderate concordance to track CI changes in both methods (69% and 84% within 30º limits of agreement) (fig. D, E).ConclusionsThe ProAQT-Pulsioflex™ should be recalibrated at certain intervals to increase its accuracy and precision of measuring and tracking CI. Both CIPAsc and CIPAcal are not interchangeable with CIFTV