Computer integrated measurement of respiratory compliance

Respiratory compliance is obtained from the ratio of lung volume change to change in differential pressure across the chest wall, and is classically derived from the slope of the static, transrespiratory pressure-volume relationship. The need to remove subjectivity from the derivation of respiratory compliance, has prompted the development of a computer-based system which facilitates compliance measurement with minimal experimenter error. This paper outlines the basic algorithms necessary to analyse static, quasi-static and dynamic pressure-volume data, and describes how these data may be entered into a graphics package (Sigmaplot) to derive best-fit polynomial curves.