Le syndrome d'apnées du sommeil.

Abstract

Le syndrome des apnees obstructives du sommeil se manifeste par des symptomes banals (ronflement, somnolence, mictions nocturnes, hypertension arterielle) en rapport avec des obstructions completes (apnees) ou incompletes (hypopnees) iteratives des voies aeriennes superieures. Les apnees sont a l' origine d' hypoxie, d' hypercapnie, et d' efforts respiratoires suivis d' un bref eveil salvateur. L' instabilite des voies aeriennes est entretenue par des facteurs anatomiques (etroitesse du pharynx) et neurophysiologiques. Les muscles dilatateurs du pharynx, qui s' opposent a la pression negative engendree par le diaphragme en inspiration, sont en effet controles differemment pendant l' eveil et le sommeil. Cette maladie frequente, identifiee depuis peu, affecte plus volontiers l' homme d' age moyen en surpoids. Elle reste sous-estimee malgre une mortalite et une morbidite accrues par les troubles cardio-vasculaires et les accidents du travail et de la route.

Patients with obstructive sleep apnea syndrom (OSAS) demonstrate recurrent reduction (hypopnea) or cessation (apnea) of breathing during sleep due to narrowing or occlusion of the pharyngeal airway. Daytime sleepiness of various severity, loud snoring, thrashing in bed, nycturia, impaired daytime cognitive performance, dysphoric mood, impotence, and morning headaches are other symptoms of this condition, which is most commonly seen in middle-aged, obese males. This disease is often associated with overweight and has also been described in postmenopausal female, in people with upper airway anatomic abnormalities, and in association with endocrine or neuromuscular disorders. Prevalence surveys estimate that 4% of middle-aged men and 2% of middle-aged women are affected by OSAS. Several reports also indicate that patients have increased mortality and morbidity from cardiovascular events, such as systemic hypertension, myocardial infarction and stroke, and from road traffic accidents. Recurrent cessation of airflow is associated with hypoxia, hypercapnia, and increasing inspiratory effort against the obstructed airway, all of which ultimately lead to a brief arousal, restauration of airway patency, and recovery of blood gases. To explain this phenomenon, theory emphasizing both anatomic and functional abnormalities of the upper airways have been proposed. Structural narrowing may predispose the pharynx to collapse when pharyngeal dilator muscles fail to maintain sufficient force to counteract negative inspiratory pharyngeal pressure. Diagnosis of OSAS is performed during overnight polysomnography, which is an attended recording of sleep stage, respiratory and other parameters. The most effective and commonly used treatment for OSAS is nasal continuous positive airway pressure. Tracheostomy and mandibular advancement are the only effective surgical procedures in selected patients.