The Upper Airway Resistance Syndrome: Surrogate Polysomnographic Markers

Excluding patients with snoring, occasional daytime sleepiness, or witnessed apneas did not change the mean frequency and increased the 95% confidence intervals. Wood-son also reported a pattern of crescendo snoring followed by transient EEG arousals in the absence of oxyhemoglobin desaturation as highly suggestive of UARS. He listed other criteria though, including nonobesity and a small retroglossal posterior airspace in somnolent patients. Improved daytime somnolence as well as increased SWS following treatment with nCPAP has also been cited in multiple publica-tions. birth control online

More recently, Lofaso and colleagues proposed beat-to-beat BP evaluation by infrared plethysmography as a more sensitive marker of IUAR than brief arousals. They studied six men with ESS scores of > 10, AHIs of < 5, and brief arousal indexes of > 10/h of sleep. The subjects were studied with Pes monitoring as well as with airflow measurement with a tight-fitting face mask and pneumotachograph to assess IUAR. The subjects demonstrated elevations in BP following respiratory events that correlated in magnitude with the intensity and duration of EEG arousal. However, the researchers also observed small BP elevations after IUAR events that elicited no detectable cortical arousal, and they postulated that increased subcortical brainstem activity was a cause of autonomic activation leading to these small hemodynamic changes. Of note, EEG monitoring during polysomnography included only two central derivations. Carley et al reported similar results when they found increases in respiratory rate and Vt after acoustic stimulation, regardless of whether detectable EEG arousals were seen in the central and occipital derivations. The authors concluded that a generalized arousal response is not a necessary precedent to a respiratory response. They hypothesized that regional or localized cortical responses or even subcortical responses may have gone undetected during these events. Therefore, evidence exists that standard polysomnographic EEG leads may miss subtle arousals and that criteria based on these devices may not attain the highest possible sensitivity.

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