Detection of increased upper airway resistance during overnight polysomnography.

STUDY
OBJECTIVES: To examine the utility of four methods used to detect increased upper airway resistance leading to arousal from sleep.
DESIGN: Ten overnight sleep studies were conducted on normal subjects who reported increased snoring and/or witnessed apneas following alcohol ingestion. Alcohol was used to increase upper airway resistance in these normal subjects before ovemight polysomnography. Four methods to detect the presence of increased upper airway resistance were used: esophageal pressure manometry; respiratory inductive plethysmography; a piezoelectrically treated stretch sensor adhered to the supraclavicular fossa; nasal flow measured with oxygen cannula and differential pressure transducer.
SETTING: Private Sleep Laboratory. PARTICIPANTS: Ten normal, healthy volunteers (5 male, 5 female).
INTERVENTIONS: Alcohol ingestion as red wine (14% alcohol), 180-540 mL one to two hours before overnight polysomnography. Esophageal catheterisation. MEASUREMENTS AND
RESULTS: Two hundred twenty-seven electroencephalogram arousals were preceded by inspiratory flow limitation and/or increased respiratory effort. Flattening of the nasal flow profile preceded all 227 arousals. In contrast, only 40% of arousals were preceded by an increase in the size of the stretch sensor signal, 22% by more-negative deflection of the esophageal pressure signal and 21% by increase in the signal size of respiratory inductance plethysmography.
CONCLUSION: These findings indicate that the most reliable method of detecting increased upper airway resistance leading to arousal from sleep is the nasal cannula/pressure transducer method and suggest that many arousals induced by increased upper airway resistance may be caused by mechanoreceptor afferents.