New approaches to monitoring sleep-related breathing disorders.
Stradling JR., Davies RJ., Pitson DJ.
Conventional approaches to the analysis of sleep and sleep apnea do not describe all of the critical events that result from upper airway narrowing during sleep. The hypersomnolence that drives treatment is mainly due to microarousals, but these are poorly documented with conventional epoch-based sleep staging. The counting of apneas and hypopneas also fails to document other equally important events, such as the arousals due to increased respiratory effort in response to partial upper airway narrowing that may not cause significant hypopnea, hypoxemia, or even snoring. Modifications of conventional polysomnography, such as microarousal detection and analysis of the ribcage/abdominal paradox, may be an improvement. However, no system has been shown to be better than any other at identifying the critical events that produce symptoms of sleep-related breathing disorders, and thus be likely to respond to effective treatment. The time is right to explore innovative ways to characterize sleep-related breathing disorders, such as those derived from the cardiovascular change related to upper airway obstruction and arousal, without the shackles of conventional polysomnography. New monitoring techniques need to identify patients with events that will respond to treatment, not mimic the flawed gold standard of polysomnography.