Chest wall oscillation at 1 Hz reduces spontaneous ventilation in healthy subjects during sleep.
OBJECTIVE
The objective was to determine whether external chest wall oscillation (ECWO) during sleep (1) reduced spontaneous ventilation while maintaining adequate gas exchange over several hours, (2) influenced the quality and distribution of sleep, and (3) increased the number of respiratory events.


METHODS
Prospective controlled study with counterbalanced order of intervention.


METHODS
Pulmonary function sleep laboratory.


METHODS
Seven healthy volunteers.


METHODS
One night of ECWO at 1 Hz (I:E = I:I; oscillation mean [SEM] from - 11.1 [0.7] to 6.0 [0.7] cm H2O) and a night during which the cuirass was applied without ECWO.


RESULTS
ECWO resulted in a significant decrease in spontaneous minute ventilation (VE) in all stages of sleep. ECWO was associated with a reduction in the total sleep time and a reduction in rapid eye movement (REM) sleep. The number of stage changes and the sleep efficiency did not change significantly. 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 during stage 1 (41 [2] mm Hg) and stage 2 (42 [2] mm Hg) sleep during the ECWO night. The mean arterial oxygen saturation (SaO2) was maintained at 96 to 97% throughout sleep during the control, cuirass, and ECWO nights. The apnea + hypopnea index increased (p < 0.05) during ECWO mostly due to an increase in the number of hypopneas in stage 2 sleep. During ECWO, 18 of 30 respiratory events were associated with an arousal, whereas only 2 events were associated with an arousal during the control night.


CONCLUSIONS
ECWO can be tolerated for several hours and will assist ventilation while maintaining normal mean PCO2 and mean SaO2 during sleep. Monitoring of the apnea + hypopnea index and the SaO2 is recommended at the time of application. Clinical trials to define the most appropriate indications for ECWO are now necessary.
Dolmage
T E
TE
West Park Hospital, Mount Sinai Hospital, University of Toronto, Canada.
Eisenberg
H A
HA
Davis
L L
LL
Goldstein
R S
RS
D000328:Adult; D002245:Carbon Dioxide / Q000097:blood; D006612:High-Frequency Ventilation / Q000009:adverse effects / Q000379:methods; D006801:Humans; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012119:Respiration / Q000502:physiology*; D012890:Sleep / Q000502:physiology*
D002245:Carbon Dioxide; D010100:Oxygen