Comparison between the Datex-Ohmeda M-COVX metabolic monitor and the Deltatrac II in mechanically ventilated patients.

Abstract

To compare the M-COVX and the Deltatrac II metabolic monitors under clinical conditions. Prospective clinical comparison. A general Intensive Care Unit of a university hospital. Twenty mechanically ventilated critically ill patients. The monitors were compared at FiO(2) 0.3, 0.5, and 0.7 in each patient where possible. Pulmonary gas exchange measurements were recorded using the two monitors sequentially (Deltatrac(before), M-COVX, Deltatrac(after)). Each measurement consisted of five consecutive 1-min readings of VO(2) and VCO(2). We compared the Deltatrac(before) with the Deltatrac(after) and the mean of the Deltatrac with the M-COVX. There was no clinically significant bias between the two monitors for VO(2) or VCO(2) but the limits of agreement (LOA) were wide (bias +/-95% LOA: VCO(2) -13 +/- 30 ml/min, -8 +/- 36 ml/min, 7 +/- 50 ml/min; VO(2) -7 +/- 50 ml/min, -5 +/- 56 ml/min, 6 +/- 64 ml/min, at FiO(2) 0.3, 0.5, and 0.7, respectively). The Deltatrac before and after measurements displayed good agreement for VCO(2) but poorer agreement for VO(2) (bias +/- 95% LOA: VCO(2) 0 +/- 18 ml/min, -6 +/- 16 ml/min, -1 +/- 12 ml/min; VO(2) 2 +/- 12 ml/min, 3 +/- 38 ml/min, 10 +/- 42 ml/min, at FiO(2) 0.3, 0.5, and 0.7, respectively). Using within-patient standard deviation as a measure of reproducibility suggested that for VO(2) the M-COVX performed better than the Deltatrac at high FiO(2), and for VCO(2) Deltatrac was better at lower FiO(2). The M-COVX is a suitable integrated device for measuring metabolic gas exchange in ventilated patients.