Measurement of oxygen consumption in preterm infants: assessment of a method using a mass spectrometer.

A flow-through system for measurement of oxygen consumption (VO2), carbon dioxide (VCO2) and water (VH2O) production using a mass spectrometer for analysis of PO2, PCO2 and PH2O, was assessed with regard to the range expected for very small preterm infants. The technique was tested by burning ethanol, and close correlations were found between the measured and the theoretical VO2 (VCO2 and VH2O) values. Close correlation was also found between the measured and the theoretical VO2 when oxygen in the system was displaced by a gas mixture containing 10% O2 in nitrogen. The VO2 values found in a small number of infants compare well with values published in the literature. During all tests VO2 was also measured using a paramagnetic oxygen analyser. No significant difference in VO2 was found between the theoretical values and the values found with the two different methods or between the two methods, when the infants were studied.