Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients

Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low. Fifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3-5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (COG2) and third-generation (COG3) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO). A total of 401 simultaneous measurements of iCO, COG2, COG3, and CCO were recorded. The mean (95%CI) biases between COG2 and iCO, COG3 and iCO, and CCO and iCO were -10 (-15 to -5)% [-0.8 (-1.1 to -0.4) L/min], 0 (-4 to 4)% [0 (-0.3 to 0.3) L/min], and 9 (6-13)% [0.7 (0.5-1.0) L/min], respectively. The percentage errors were 29 (20-37)% for COG2, 30 (24-37)% for COG3, and 28 (22-34)% for CCO. The difference between iCO and COG2 was significantly correlated with TSVR (r (2) = 0.37, p < 0.0001). A very weak (r (2) = 0.05) relationship was also observed for the difference between iCO and COG3. In patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software.