Accuracy of Cardiac Output Measured by Fourth-Generation FloTrac and LiDCOrapid, and Their Characteristics Regarding Systemic Vascular Resistance in Patients Undergoing Cardiac Surgery

Abstract

The clinical use of less-invasive devices that calculate the cardiac output from arterial pressure waveform is increasing. The authors aimed to evaluate the accuracy and characteristics of the systemic vascular resistance index (SVRI) of the cardiac index measured by 2 less-invasive devices, fourth-generation FloTrac (CIFT) and LiDCOrapid (CILR), compared with the intermittent thermodilution technique, using a pulmonary artery catheter (CITD). This was a prospective observational study. This study was conducted at a single university hospital. Twenty-nine adult patients undergoing elective cardiac surgery. Elective cardiac surgery was used as an intervention. Hemodynamic parameters, CIFT, CILR, and CITD, were measured after the induction of general anesthesia, at the start of cardiopulmonary bypass, after completion of weaning from cardiopulmonary bypass, 30 minutes after weaning, and at sternal closure (135 measurements in total). The CIFT and CILR had moderate correlations with CITD (r=0.62 and 0.58, respectively). Compared with CITD, CIFT, and CILR had a bias of -0.73 and -0.61 L/min/m2, limit of agreement of -2.14-to-0.68 L/min/m2 and -2.42-to-1.20 L/min/m2, and percentage error of 39.9% and 51.2%, respectively. Subgroup analysis for evaluating SVRI characteristics showed that the percentage errors of CIFT and CILR were 33.9% and 54.5% in low SVRI (<1,200 dyne×s/cm5/m), 37.6% and 47.9% in moderate SVRI (1,200-1,800 dyne×s/cm5/m), 49.3% and 50.6% in high SVRI (>1,800 dyne·s/cm5/m2), respectively. The accuracy of CIFT or CILR was not clinically acceptable for cardiac surgery. Fourth-generation FloTrac was unreliable in high SVRI. LiDCOrapid was inaccurate across a broad range of SVRI, and minimally affected by SVRI.