Diaphragmatic command

Abstract

The control of breathing results from a complex interaction involving different respiratory centers, which feed signals to a central control mechanism that, in turn, provides output to the effector muscles. The dilators of the upper airway contract first, followed by the inspiratory muscles of the chest, including the diaphragm. This distribution of contraction of all the inspiratory muscles differs from rest to exercise. Afferent inputs arising from chemo- and mechanoreceptors, related to the physical status of the respiratory system and to the activation of the respiratory muscles, constantly modulate the respiratory command to adapt ventilation to the needs.

We review the various components of this system, focusing on the respiratory muscles and diaphragm. We discuss the differential inspiratory muscles contribution to breathing during the effort. We outline clinically relevant aspects of breathing control in two conditions, including the control of tidal volume under proportional assist ventilation and during respiratory entrainment called reverse triggering.