Recording of the diaphragm activity during anaesthesia

A computer based system for clinical on-line recording, analysis and display of diaphragm activity (transdiaphragmatic: pressure and diaphragmatic: EMG) Is described. The system includes two pressure channels and three EMG channels. We have used this system to study the behaviour or the diaphragm of anaesthetized patients undergoing surgical operations. We have shown an abolition of the activity of the central part of the diaphragm (crural) while the rest of the diaphragm (costal) remained active. This finding, of a differential response of the two parts of the diaphragm to anaesthetics, supports the theory that the diaphragm Is composed of two different muscles.