Pharyngeal Size in Snorers, Nonsnorers, and Patients with Obstructive Sleep Apnea

Abstract

We measured pharyngeal cross-sectional area and its change with alterations in lung volume in 10 subjects who snored and had obstructive sleep apnea, 6 subjects who snored and did not have obstructive sleep apnea, and 9 subjects who did not snore. Pharyngeal area was measured with use of an acoustic-reflection technique. We found that snorers with and without sleep apnea had a significantly smaller mean (+/- SE) pharyngeal cross-sectional area (4.1 +/- 0.2 and 3.7 +/- 0.9 cm2, respectively) at functional residual capacity than nonsnorers (5.4 +/- 0.5 cm2, P less than 0.025). When lung volume decreased from functional residual capacity to residual volume, both nonsnorers and snorers with sleep apnea had a decrease in pharyngeal area (from 5.4 +/- 0.5 to 4.5 +/- 0.4 cm2 and 4.1 +/- 0.2 to 3.4 +/- 0.2 cm2, respectively), whereas snorers without sleep apnea had no such decrease, suggesting that their pharynxes were less collapsible at low lung volumes. We conclude that snorers with and without sleep apnea have smaller pharyngeal cross-sectional areas than nonsnorers and that snorers with sleep apnea have a further decrease as lung volume falls.

Sleep-disordered breathing and upper airway size in pregnancy and post-partum

“…First, the results reported in this study were obtained during wakefulness. Measurements using this technique, however, correlate well with snoring and disturbed breathing during sleep [5,21,27]. …”

“…Differences measured during wakefulness do not necessarily predict differences during sleep, but this technique has shown narrower airways in awake patients with obstructive sleep apnoea-hypopnoea syndrome than in snorers [5,7,21], and also shows that awake snorers have narrower UAs than nonsnorers [5]. Thus, the results of acoustic reflection during wakefulness have been shown to predict differences in airway calibre and function during sleep [5,7,21,27].…”

“…BRADLEY et al [5] reported that snorers with or without obstructive sleep apnoea have narrower upper airways (UAs) than nonsnorers even when awake. In pregnancy, the physiological changes potentially predisposing to increased resistance [2] and reduced cross-sectional area of the UAs [4] include the following: weight gain [2,[6][7][8][9]; a decreased functional residual capacity (FRC) due to mass displacement of the diaphragm [9][10][11]; pharyngeal oedema of pregnancy [2][3][4]12]; and, possibly, the effect of sleep deprivation or fragmentation on pharyngeal dilator muscle activity [13] and UA collapsibility [14].…”

Sleep‐disordered breathing in heart failure: facts and numbers

“…Patients with OSA are often anatomically predisposed to smaller pharyngeal breathing tracts as a result of obesity, enlarged tonsils, adenoids, or tissue irregularities 6, 7. During sleep, the pharyngeal dilator muscle activity, which compensatory ensures a regular air passage during wakefulness, is diminished.…”

Effects of mandibular advancement on respiratory resistance

“…Obstructive respiratory events are generally explained by the inefficiency of the dilating muscles in counterbalancing the tendency of the pharyngeal airway to collapse, due to the inspiratory decrease in transmural pressure [1], and one of the main factors predisposing subjects to OSAS appears to be a reduction in upper airway calibre [2].…”