The performance of a new gas exchange monitor was assessed both in laboratory simulation and in ICU patients. Laboratory simulation using N2and CO2injections resulted in a mean error of 2 plusmn; 2percnt; in CO2production (OV0312;co2) and 4 plusmn; 47c in oxygen consumption (OV0312;o2) in respirator measurements (n = 55) and in a mean error of 3 plusmn; 2percnt; in OV0312;co2and 4 plusmn; 27c in OV0312;o2in canopy measurements (n = 25). The mean error in RQ during ethanol burning was 2 plusmn; 2percnt; in respirator measurements (n = 45) and 1 plusmn; 17c in canopy measurements. Fio2had little effect on the accuracy of OV0312;co2, whereas the accuracy on high rates of OV0312;o2(OV0312;o2= 400 ml/min) was reduced, when Fio2increased: the error ranged from 1 plusmn; 1percnt; to 6 plusmn; 17c, except at OV0312;o2400 ml/min during Fio20.8, where the error was 16 plusmn; 37c. Neither peak airway pressure (plus;13 to plus;63 cm H2O) nor PEEP (0 to plus;20 cm H2O) had an effect on the accuracy. The highest level of minute ventilation studied (22.5 L/min) reduced the accuracy slightly (mean error of OV0312;co24 plusmn; 1percnt; and OV0312;o27 plusmn; 27c). In patients during controlled mechanical ventilation, increasing Fio2from 0.4 to 0.6 had no effect on the results. OV0312;o2was consistently higher by gas exchange than by the Fick principle: 16 plusmn; 97c during controlled ventilation (n = 20), 21 plusmn; 87c on synchronized intermittent mandatory ventilation (n = 10) and 25 plusmn; 87c during spontaneous breathing. We conclude that the device proved to be accurate for gas exchange measurements in the ICU. (Crit Care Med 1989; 17:1041)
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