Objective: To compare upper airway pressures in snorers and nonsnorers during sleep and wakefulness.
Design: Case series of snorers and nonsnoring controls.
Setting: Sleep clinic of a university hospital.
Methods: We used open catheters to measure differential nasopharyngeal and hypopharyngeal pressures in 8 nonapneic snorers with excessive daytime tiredness and 10 healthy nonsnoring controls. Measurements were performed during sleep (with the mouth taped to ensure exclusively nasal breathing) and wakefulness. When awake, the subjects were either seated (with the head neutral, flexed, extended, or rotated) or recumbent (dorsal and lateral positions).
Main outcome measures: Comparison of pressures within the group as a function of body position and between the groups as a function of snoring.
Results: Differential nasal and pharyngeal pressures were similar in seated snorers and nonsnorers independently of head position. Assumption of recumbency resulted in significantly increased pharyngeal pressures in nonsnorers (26 +/- 18 Pa seated vs. 52 +/- 46 Pa recumbent, p < .05) and snorers (50 +/- 35 Pa seated vs. 93 +/- 38 recumbent, p < .01). The increase was higher in snorers than nonsnorers. During snoring, sleep differential pharyngeal pressures in snorers were markedly increased compared to quiet sleep (567 +/- 450 Pa during snoring epochs vs. 117 +/- 82 Pa during nonsnoring epochs, p < .01).
Conclusions: Compared to nonsnorers, recumbent nonapneic snorers have elevated differential pharyngeal pressures indicative of increased upper airway resistance and reduced airway patency; this is present during wakefulness and sleep.