Computerized breath-by-breath analysis of respiratory variables during exercise.

An on-line analysis of respiration with a breath-by-breath method during exercise is presented. Special emphasis is given to the computer processing of signals for gas flow rate and for O2 and CO2 concentrations. The validity and reliability of the method to measure oxygen uptake (VO2) was tested by ten subjects in repeated tests. Mean oxygen uptake was 2.3% less with the computerized breath-by-breath method than with the Douglas-bag method which was used as reference. The breath-by-breath method is planned to be used primarily for evaluating the work capacity of healthy and disabled persons. However, in addition to being suitable for such routine uses, the method described also yields respiratory data whose analysis can be valuable in a variety of clinical and research work.