[Airway occlusion pressure during sleep in normal subjects].

Sleep has been shown to be associated with a variety of changes in ventilatory mechanics. Recently, airway occlusion pressure (P0.1) has come to be widely used as an index of the neural output of the respiratory center, and is considered to be independent of lung mechanics. The purpose of this study was to analyze neural output of the respiratory center during sleep, utilizing an airway occlusion pressure procedure. Nine normal male subjects, 19 to 32 yrs of age, were used. Each subject was fitted with a face mask, and the area between the mask and the face was sealed with medical silicone rubber. They breathed through the mask, which was attached to a "J" valve that separated the inspiratory from the expiratory line. A radio-controlled camera shutter was joined to the "J" valve on the inspiratory line. The volume of dead space of this system was about 150 ml. Inspiratory pressure developing in the oral cavity was measured using a pressure transducer and a photocorder. Flow rate, tidal volume (VT) and inspiratory time (TI) were measured using a hot wire flow meter. Airway occlusion pressure (P0.1) was measured 0.1 second after the onset of the inspiratory effort by occluding the shutter on the inspiratory line during expiration. The onset of inspiration and expiration was detected by changes in airway pressure. Great care was taken to make the subjects as comfortable as possible during the procedure. Continuous recordings were made on a polygraph recorder of EEG, EOG, EMG and cardiorespiratory variables. Sleep stages were determined using the standard criteria.(ABSTRACT TRUNCATED AT 250 WORDS)