Figure 2: Example of abnormal increased inspiratory effort measured with esophageal manometry [Pes=esophageal pressure].This recording present 15 min of continuous recording. Fourteen channels of the recording have been selected for presentation of the figure from top to bottom. Electroencephalography, Chin electromyography, 2 eye movements, finger photoplethysmography (with sympathetic activation toward the bottom of figure), 2 leg electromyography, pulse oximetry with saturation reading, snore indicated by neck microphone measuring power, nasal cannula-pressure transducer wave contour, chest and abdomen plethysmographic bands, and esophageal manometry recording (bottom). Esophageal pressure has been calibrated before the beginning of recording. The negative peak is per convention placed toward the bottom of the recording. The end of the recording probe is placed in the lower esophagus. This segments of recording show a progressive increase in inspiratory efforts with peak esophageal pressure becoming more and more negative during the following 10 min. There is the presence of inspiratory flow limitation when looking at the nasal cannula wave contour, but no change indicating increase in effort. The electroencephalography analysis indicates the presence of cyclic alternating pattern phase A2, but a clear electroencephalography arousal is only noted at the end of the recording in association with return to normal breathing and important chin electromyography discharge. The investigation of the photoplethysmography indicates that during the entire segment, there are clear indications of several episodes of sympathetic activation that correlate with the cyclic alternating pattern phase A2 bursts, but these short arousals are not sufficient to lead to reopen the airway. A respiratory event- related arousal will be scored at the end of the event in association with the more than 3 s electroencephalography arousal, but the scoring will ignore the long abnormal breathing segment, the calculation of the “flow limitation” gives a better view of the duration and amount of disturbance than calculation of the respiratory -related arousal, moreover “respiratory event related arousals” are not taken into consideration when the apnea-hypopnea index is calculated, the figure indicates the limitations of many scoring systems.