In vitro evaluation of a compact metabolic measurement instrument

The ability of the Datex Deltatrac (Sensor-Medics, Anaheim, CA) to accurately measure oxygen consumption (VO2v) and carbon dioxide production (VCO2) was examined in vitro using the carbon dioxide addition and nitrogen dilution methods. The accuracy of respiratory quotient (RQ = VCO2/VO2) measurements was assessed using methanol combustion (RQ = 0.67). Both in the canopy (blow-by) and respirator (FiO2: 0.21-0.6, PEEP: 0-12 cm H2O) modes the Deltatrac's measurements of VO2 and VCO2 were within +/- 7% of values predicted from CO2 and N2 simulations. Similar results were obtained with methanol combustion. In vitro testing revealed that the Deltatrac accurately measures VO2 and VCO2 under a variety of simulated clinical conditions.