CHEST-WALL OSCILLATION AT 1HZ REDUCES SPONTANEOUS VENTILATION IN HEALTHY-SUBJECTS DURING SLEEP

Study objective: The objective was to determine whether external chest wall oscillation (ECWO) during sleep (1) reduced spontaneous ventilat ion while maintaining adequate gas exchange over several hours, (2) in fluenced the quality and distribution of sleep, and (3) increased the number of respiratory events, Design: Prospective controlled study wit h counterbalanced order of intervention. Setting: Pulmonary function s leep laboratory. Participants: Seven healthy volunteers. Intervention: One night of ECWO at 1 Hz (I:E=1:1; oscillation mean [SEM] from -11,1 [0.7] to 6.0 [0.7] cm H2O) and a night during which the cuirass was a pplied without ECWO. Measurements and results: ECWO resulted in a sign ificant decrease in spontaneous minute ventilation (V over dot E) in a ll stages of sleep, ECWO was associated with a reduction in the total sleep time and a reduction in rapid eye movement (REM) sleep, The numb er of stage changes and the sleep efficiency did not change significan tly. The mean PCO2 was similar between the control and cuirass nights (44 to 46 mm Hg), There was a significant decrease in the mean PCO2 du ring stage 1 (41 [2] mm Hg) and stage 2 (42 [2] mm Hg) sleep during th e ECWO night. The mean arterial oxygen saturation (SaO(2)) was maintai ned at 96 to 97% throughout sleep during the control, cuirass, and ECW O nights. The apnea+hypopnea index increased (p<0.05) during ECWO most ly due to an increase in the number of hypopneas in stage 2 sleep, Dur ing ECWO, 18 of 30 respiratory events were associated with an arousal, whereas only 2 events were associated with an arousal during the cont rol night. Conclusions: ECWO can be tolerated for several hours and wi ll assist ventilation while maintaining normal mean PCO2 and mean SaO( 2) during sleep, Monitoring of the apnea+hypopnea index and the SaO(2) is recommended at the time of application, Clinical trials to define the most appropriate indications for ECWO are now necessary.