Dysfunctional mechanical coupling of upper airway tissues in sleep apnea syndrome.
The mechanical effect of musculus uvulae (MU) contraction on in vitro uvular shortening and/or displacement was measured in 15 patients with a sleep apnea hypopnea syndrome (SAHS) and in 8 snorers. Using freshly resected uvular tissues, passive and active uvular tissue-specific elastance and shortening were determined during stimulation of MU. No difference was found in maximum tetanic tension measured on uvular tissue between the two groups (47.2 +/- 14.8 g in SAHS and 39.1 +/- 16.5 g in snorers). Passive uvular-specific elastance was significantly less in snorers (0.36 +/- 0.27 g/% Lo) compared with patients with SAHS (0.84 +/- 0.39 g/% Lo) (p = 0.006). There was a negative correlation between uvular shortening and passive uvular specific elastance (r = 0.69, p = 0. 05). Maximal tetanic tension developed by isolated MU was higher in SAHS than in snorers (45.8 +/- 23.1 and 30.0 +/- 8.3 g, respectively, p = 0.04). A strong positive relationship was found between the apnea index and specific uvular elastance (r = 0.55, p = 0.007). We conclude that there is a significant difference between the uvular tissue elastance of SAHS and snorers, and that this difference influences the mechanical efficiency of MU contraction.
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Unité de Recherche, Centre de Pneumologie de l'Hôpital Laval, Quebec, Canada. Frederic.Series@med.ulaval.ca
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St Pierre
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D000328:Adult; D004548:Elasticity; D004558:Electric Stimulation; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D012044:Regression Analysis; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012913:Snoring / Q000503:physiopathology; D014609:Uvula / Q000503:physiopathology*