Effect of REM sleep on retroglossal cross-sectional area and compliance innormal subjects

It has been proposed that the upper airway compliance should be highest dur ing rapid eye movement (REM) sleep. Evidence suggests that the increased co mpliance is secondary to an increased retroglossal compliance. To test this hypothesis, we examined the effect of sleep stage on the relationship of r etroglossal cross-sectional area (CSA; visualized with a fiber-optic scope) to pharyngeal pressure measured at the level of the oropharynx during eupn eic breathing in subjects without significant sleep-disordered breathing. B reaths during REM sleep were divided into phasic (associated with eye movem ent, PREM) and tonic (not associated with eye movements, TREM). Retroglossa l CSA decreased with non-REM (NREM) sleep and decreased further in PREM [wa ke 156.8 +/- 48.6 mm(2), NREM 104.6 +/- 65.0 mm(2) (P < 0.05 wake vs. NREM) , TREM 83.1 +/- 46.4 mm(2) (P = not significant NREM vs. TREM), PREM 73.9 /- 39.2 mm(2) (P < 0.05 TREM vs. PREM)]. Retroglossal compliance, defined a s the slope of the regression CSA vs. pharyngeal pressure, was the same bet ween all four conditions (wake -0.7 + 2.1 mm(2)/cmH(2)O, NREM 0.6 +/- 3.0 m m(2)/cmH(2)O, TREM -0.2 +/- 3.3 mm(2)/cmH(2)O, PREM -0.6 +/- 5.1 mm(2)/cmH( 2)O, P = not significant). We conclude that the intrinsic properties of the airway wall determine retroglossal compliance independent of changes in th e neuromuscular activity associated with changes in sleep state.