Breath-to-Breath Variability Correlates With Apnea-Hypopnea Index in Obstructive Sleep Apnea

摘要

Background: Breathing in patients with obstructive sleep apnea (OSA) is frequently interruptednby periods of hypopnea and apnea. There is limited information regarding a possible disturbancenof breathing outside these periods.nStudy objective: To analyze the degree of breathing disturbance during nonocclusion.nDesign: Prospective determination of breathing variability during full polysomnographic sleepnstudies.nPatients: Breath-to-breath variation was monitored in 34 patients with OSA and in 9 healthynsubjects.nMeasurements and results: All breath-to-breath intervals were automatically analyzed from flownsignal, displayed, and manually corrected for artifacts. Distribution of all nonapneic breathnintervals was analyzed for the extent of difference from a normal distribution pattern bynspecifying kurtosis. In untreated OSA patients, kurtosis was significantly reduced (0.0 6 0.5,nmean 6 SD) compared to control subjects (0.8 6 0.5), indicating increased variability of nonoc-ncluded breathing. This effect was present in all sleep stages, and the extent depended signifi-ncantly on the degree of disease. Continuous positive airway pressure breathing was able tonnormalize kurtosis (1.0 6 0.9) immediately.nConclusions: Breathing in OSA is not only characterized by interruptions of breathing duringnocclusion, but by a greater variation in the pattern of normal-length breaths