Cardiac output measurements in off-pump coronary surgery: comparison between NICO and the Swan-Ganz catheter

Background: The aim. of this prospective study was to compare continuous cardiac output measurements of the non-invasive cardiac output system (NICO) with the pulmonary artery catheter during off-pump coronary bypass surgery. Methods: Twenty-two patients enrolled for off-pump coronary surgery received both a pulmonary artery catheter and a non-invasive cardiac output system for measurement of cardiac output. Data were compared by the Bland-Altman method to calculate the degree of agreement and to analyse if a significant difference existed between the two methods of cardiac output measurements. Results: Perioperatively, the non-invasive cardiac output underestimated cardiac output, but postoperatively overestimated it. The limits of agreement were larger during surgery compared to the postoperative period (-3.1; + 2.5 vs. -1.4; + 2.2 L min(-1)). Perioperatively, cardiac output measured with the pulmonary artery catheter varied from 0.5 to 7.5 L min(-1) (mean 3.6 L min(-1)) and with the non-invasive cardiac output from 0.5 to 8.4 L min(-1) (mean 3.9 L min(-1)). Postoperatively, these were 2.5-7.7 L min(-1) (mean 4.5 L min(-1)) and 2.3-8.4 L min(-1) (mean 4.9 L min(-1)), respectively. Conclusion: During off-pump cardiac surgery, the non-invasive cardiac output reliably measures cardiac output and does it more rapidly than a pulmonary artery catheter and may be more useful in order to detect rapid haemodynamic changes.