A multipatient mass spectrometer based system for the measurement of metabolic gas exchange in artificially ventilated intensive care patients.

A commercially available multi-patient mass spectrometer based system [MPMS] has been evaluated for the measurement of metabolic gas exchange in artificially ventilated patients. The system automatically measures and displays oxygen uptake, (VO2) carbon dioxide output, (VCO2) respiratory quotient (RQ) expired minute volume, (Ve) and the percentage concentration of inspired gases. Measurements of VO2, VCO2, RQ and Ve, obtained using this system were compared with those determined by simultaneous Douglas bag collections. The measurement of carbon dioxide and oxygen concentrations was assessed separately by direct comparison with infra-red and paramagnetic analysis respectively. The MPMS measurements of metabolic gas exchange were found to have insignificant systematic errors with precisions of +/- 12 ml/min VO2, +/- 7 ml/min VCO2, +/- 0.03 RQ and +/- 0.1 l/min Ve; (2SD).