In Vivo Evaluation of Respiratory Muscles Mechanics

Respiratory muscle weakness (RMW) commonly occurs in acute or chronic illness as well as in primary neuromuscular diseases. Currently, global diagnosis of RMW is established by mouth pressure measurements during quasi-static maneuvers (Black and Hyatt, 1969, Ratnovsky et al., 1999) or imaging. Differentiation between the contributions of major muscle groups can be achieved by electromyogram (EMG) studies. The EMG of human respiratory muscles has been measured for many years with needle or surface electrodes, and was found to range from 50 to 500μV (Cala et al., 1992; McKenzie et al., 1988). However, these studies were mostly basic physiological ones and the resulting data were not utilized in the clinical setting. The objective of this study was to quantitatively explore the relative contribution of four major groups of respiratory muscles to global lung ventilation throughout a range of maneuvers in healthy subjects.