On-line computer analysis and breath-by-breath graphical display of exercise function tests.

BEAVER, WILLIAM L., KARLMAN WASSERMAN, AND BRIAN J. WHIPP. On-line computer analysis and breath-by-breath graphical display of exercise fun&n tests. J. Appl. Physiol. 34(l): 128-132. 1973.The problem of making continuous calculations of respiratory variables over the duration of extended physiological studies is so difficult that observations of the breath-by-breath variations of derived quantities such as minute ventilation, oxygen consumption, and gas exchange ratio have not been possible until the recent advent of suitable computers. This paper describes a a method for obtaining breath-by-breath measurements of gas exchange using a mini-computer system for the on-line calculation of continuously measured respiratory and metabolic variables. These data are graphically displayed and/or stored on magnetic tape for future display for more extensive calculations. Special technical problems such as the handling of the dead space of the breathing valve, water vapor condensation, and characteristics of the transducers are described and treated. The results of the computer-processed data are compared with measurements made by standard techniques and have been found to be in good agreement. These procedures enable the investigator to analyze the kinetics of transient ventilatory and metabolic responses with precision.