Breath-to-breath variability correlates with apnea-hypopnea index in obstructive sleep apnea.
BACKGROUND
Breathing in patients with obstructive sleep apnea (OSA) is frequently interrupted by periods of hypopnea and apnea. There is limited information regarding a possible disturbance of breathing outside these periods.


OBJECTIVE
To analyze the degree of breathing disturbance during nonocclusion.


METHODS
Prospective determination of breathing variability during full polysomnographic sleep studies.


METHODS
Breath-to-breath variation was monitored in 34 patients with OSA and in 9 healthy subjects.


RESULTS
All breath-to-breath intervals were automatically analyzed from flow signal, displayed, and manually corrected for artifacts. Distribution of all nonapneic breath intervals was analyzed for the extent of difference from a normal distribution pattern by specifying kurtosis. In untreated OSA patients, kurtosis was significantly reduced (0.0 +/- 0.5, mean +/- SD) compared to control subjects (0.8 +/- 0.5), indicating increased variability of nonoccluded breathing. This effect was present in all sleep stages, and the extent depended significantly on the degree of disease. Continuous positive airway pressure breathing was able to normalize kurtosis (1.0 +/- 0.9) immediately.


CONCLUSIONS
Breathing in OSA is not only characterized by interruptions of breathing during occlusion, but by a greater variation in the pattern of normal-length breaths.
Kowallik
P
P
Department of Medicine, University of Würzburg, Germany. kowallik@mail.uni-wuerzburg.de
Jacobi
I
I
Jirmann
A
A
Meesmann
M
M
Schmidt
M
M
Wirtz
H
H
D000328:Adult; D000368:Aged; D006801:Humans; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D012119:Respiration; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012895:Sleep, REM