[Acquisition and elaboration of respiratory parameters by the use of analytical instruments with an electronic...

The measurement of oxygen uptake on a breath by breath basis has been obtained coupling the respiratory mass spectrometer (MS) for O2 and CO2 measurements, the pneumotachograph (PN) for flow rate and volume estimates to the computer. MS and PN output has been sampled at 50 Hz during the respiratory circle and each corresponding area has been integrated. From the volume of expired O2 subtracted from the amount of O2 inspired, O2 uptake of each breath has been obtained. Accordingly CO2 production and related respiratory variables have been assessed. O2 uptake referred to unit time calculated breath by breath has been compared to O2 consumed measured by open circuit method at steady state (from the 5th to the 6th min of exercise) in 5 male subjects pedalling on a bicycle ergometer in work rate range of 150-170 kpm/min. The difference of O2 consumption with the two methods was on the average less than +/- 5%. The proposed method is particularly suitable for O2 uptake kinetics at the onset and offset of exercise.