Noninvasive cardiac index estimation under general anaesthesia: comparison between the VenArt® device and...

VenArt® is a novel noninvasive cardiac output monitoring device which provides beat-by-beat Fick principle-based measurements of stroke volume and cardiac output. The study aim was to determine the accuracy of this device by comparing it with cardiac output measurements using transthoracic echocardiography in patients undergoing anaesthesia.

This prospective observational study included 55 women (ASA physical status classification I-III) undergoing laparoscopic gynaecological procedures. Cardiac output was assessed at five timepoints using the VenArt® device and transthoracic echocardiography. Primary endpoint was the agreement between the two methods regarding cardiac index, evaluated using Bland-Altman analysis to determine bias, precision, mean percentage error, and limits of agreement. Secondary endpoint was the ability of the device to track changes in cardiac index over time compared with echocardiography.

We analysed 273 pairs of cardiac index values from 55 patients. Bland-Altman analysis showed a bias of 0.02 (95% confidence interval [CI] 0-0.05) L min^-1 m^-2, with a precision of 0.20 and a mean percentage error of 14.7% (95% CI 13.2-16.2%). Limits of agreement ranged from -0.37 (95% CI -0.41 to -0.33) to 0.41 (95% CI 0.37-0.45) L min^-1 m^-2. Trending ability demonstrated good agreement: the four-quadrant plot revealed a concordance rate of 95.88%, and the polar plot showed a mean polar angle of 0.75°, with a standard deviation of 13.4° and radial limits of agreement within plus or minus 30°.

The VenArt® device showed negligible bias and acceptable differences. Trending ability was favourable, with clinically acceptable agreement and high concordance in tracking haemodynamic changes.

ISRCTN92565809.