Cardiac output measurement by arterial waveform analysis in cardiac surgery--a comparison of measurements derived from waveforms of the radial artery versus the ascending aorta.

In cardiac surgery, perioperative haemodynamic management is often guided by cardiac output (CO) measurements. The Vigileo monitor offers uncalibrated CO measurement by arterial waveform analysis (CO(wave)). This validation study compared CO measurements derived from radial artery waveform analysis with those derived from the ascending aorta. CO measurements from the radial artery versus the ascending aorta showed a significant correlation before and after cardiopulmonary bypass (CPB). However, Bland-Altman analysis showed a mean bias of 0.1 l/min and 0.1 l/min, and limits of agreement (LOA) of +2.2 l/min and -1.9 l/min prior to CPB, and +2.5 l/min and -2.7 l/min after weaning from CPB. A comparison of these CO measurements showed a low mean bias, but wide LOA before and after CPB. Therefore measurements using uncalibrated CO(wave) have to be interpreted with caution in a clinical situation.