The oxygen consumption and efficiency of the respiratory muscles in health and emphysema.

The work of moving the lung, chest wall, diaphragm and abdominal contents during spontaneous respiration is performed by the muscles of respiration. In order to obtain a better understanding of the disability present in pulmonary disease it would be advantageous to have, in normal and diseased states, a measure of the total work being done, the energy cost of performing this work and the efficiency of the muscles of respiration. There are few measurements of total mechanical work and efficiency of the respiratory muscles in the literature (1). A simple method for the determination of the oxygen consumption and efficiency of the respiratory muscles, as well as an indirect measurement of the total mechanical work, has recently been described (2). Reproducible results were obtained in both a normal and an emphysematous subject intensively studied. The purpose of this paper is to report further data on the oxygen cost, efficiency and the total mechanical work of the respiratory process in a series of normal and emphysematous subjects.