Role of the diaphragm in breathing in conscious normal man: an electromyographic study

Abstract

The electrical activity of the diaphragm was detected by means of electrodes placed, via the esophagus, at the level of the diaphragmatic esophageal orifice. This activity was synchronous with the respiratory variations of transdiaphragmatic pressure. The activity of the diaphragm, which occurred during inspiration and continued into expiration for a varying length of time, affected the shape of the pressure-volume diagrams of breathing cycles and of the expiratory flow curves. The relative importance of the antagonistic activity of inspiratory muscles opposing the expiratory elastic forces decreased with increasing ventilation. The implications of the antagonistic activity of the diaphragm on the mechanical efficiency of breathing are discussed. Submitted on April 11, 1960