Properties of a combined sensor for dynamic measurement of oxygen in simulated respiration.

A combined sensor supplying momentary values of respiratory functions (flow, PO2, and temperature) for calculation of oxygen intake is tested in simulated respiration. Signal conditioning reduces the errors caused by the influence of CO2 on the sensitivity of the oxygen electrode, by the electrode response and time lag. Oxygen intake of 0.38 and 1.49 liters/min simulated by injection of N2 into the respiration pump (10--40 cycles/min) is analyzed by means of the combined sensor (signals conditioned; time constant about 40 msec) and calculated with a mean error of about -10%. The error rises with increase of the time constant as well as the respiration frequence.