Clinical evaluation of the Non-invasive Cardiac Output (NICO) monitor in the intensive care unit

The Non-invasive Cardiac Output (NICO) monitor (Novametrix Medical Systems Inc., Wallingford, CT, U.S.A.) utilizes a minimally-invasive partial rebrea thing methods to determine cardiac output by means of a differential form o f the Fick equation. We evaluated the NICO monitor by comparing its output to paired measurements obtained by the standard thermodilution (TD) techniq ue in patients who had recently undergone cardiac surgery. Forty-two paired measurements were carried out in 12 patients. The correlation between the two methods was moderate with a correlation coefficient of 0.691. Repeated measures ANOVA showed that TD measures of cardiac output were significantly higher than those obtained by the NICO monitor (P=0.0003). Comparison of t he two techniques using the methods described by Bland and Altman showed de creased correlation at higher values of cardiac output. We conclude that the NICO monitor may well have a place in intensive care m onitoring, provided patients are not breathing spontaneously and are able t o tolerate a 4 mmHg rise in PaCO2. It is less suitable for use in patients with a high cardiac output state.