Comparison of cardiac output measurements between NICO and the pulmonary artery catheter during repeat surgery for total hip replacement

OBJECTIVE: The aim of this study was to compare cardiac output measurements of the non-invasive cardiac output and the pulmonary artery catheter during repeat surgery for hip replacement. METHODS: In this prospective observational study, patients undergoing repeat hip surgery who needed a pulmonary artery catheter were included. A standard protocol was followed for induction, endotracheal intubation and maintenance of anaesthesia (sufentanil, etomidate, sevoflurane, cisatracurium). After endotracheal intubation, the non-invasive cardiac output was connected and a pulmonary artery catheter was inserted. Data were collected every 3 min until patients were extubated. RESULTS: Ten patients were included and 2455 points of comparison recorded. Cardiac output from the pulmonary artery catheter varied from 1.7 to 8.9 L min(-1) (mean 4.1 L min(-1)) and the non-invasive cardiac output (using averaging mode) from 1.7 to 8.0 L min(-1) (mean 3.7 L min(-1)). There was a significant correlation between them (P < 0.01; bias 0.3 L min(-1); limits of agreement +1.9 and -2.5 L min(-1)), although these differed between patients. CONCLUSION: The perioperative bias was small and the non-invasive cardiac output slightly underestimated cardiac output intraoperatively compared to the pulmonary artery catheter. The bias was smaller when mean cardiac output was below 3 L min(-1). Core temperature between 34.4 degrees C and 37.6 degrees C had no influence on the differences.