Non-invasive estimation of esophageal pressure based on intercostal EMG monitoring.

Recording of esophageal pressure waveform is an important clinical tool to identify patients with sleep-disordered breathing. Commonly, esophageal pressure probes are not tolerated by patients undergoing sleep monitoring. We therefore developed a technique to non-invasively estimate esophageal pressure based on recording of intercostal EMG monitoring. A three step approach to modification of the intercostal EMG signal was created to closely match results obtained from esophageal pressure recording. The algorithm was then tested on 10 subjects with sleep-disordered breathing undergoing full polysomnography with simultaneous monitoring of esophageal pressure and intercostal EMG. Analysis of correlations between esophageal pressure and intercostal EMG were computed by sleep stages. The overall correlation coefficient in all subjects combined was r=0.896, p<0.00001. The results indicate that this method can be used reliably in clinical sleep studies where esophageal pressure recordings cannot be performed.