Comparison of Diaphragmatic EMG and Oesophageal Pressure in Obstructed and Unobstructed Breathing during Sleep. Korrelation von diaphragmalem EMG und Osophagusdruckmessung bei obstruierter und unobstruierter Atmung im Schlaf

Abstract

The importance of quantitative changes in respiratory effort during routine polysomnographic investigation has been recognized since the description of the upper airway resistance syndrome. In clinical settings, oesophageal manometry is rerely conducted on a routine basis. We therefore developed a new technique for semiquantitative assessment of respiratory effort using diaphragmatic EMG (EMGdi) monitoring and tested its efficacy. Five patients with obstructive sleep apnoea syndrome and five subjects without sleep-disordered breathing were investigated in a private sleep disorders laboratory. EMGdi was sampled at 0.25 kHz and processed to a moving average. For each inspiratory effort during apnoea/hypopnoea and unobstructed breathing, we calculated maximum EMGdi and Pes. Data were normalized calculating the percentage difference between the first obstructed and each subsequent inspiratory effort during respiratory events and control periods. A total of 583 periods with unobstructed breathing and 477 apnoeas and hypopnoeas were scored to compare the evolution between Pes and EMGdi. There was a significant difference in the evolution of both respiratory parameters in unobstructed breathing versus apnoeas and hypopnoeas. EMGdi and Pes evolution corresponded in each condition investigated. In unobstructed periods, the increase of Pes averaged +2.6±24.1% versus −1.1±37.4% for EMGdi (P=0.616). In apnoeas and hypopnoeas, the respective values were +90.2±38.0% for Pes and +82.4±31.6% for EMGdi (P=0.7330). EMGdi can be used in lieu of oesophageal manometry to describe relative changes in respiratory effort under conditions of normal and obstructed breathing during sleep.