sleep apnea

sleep apnea. It is a sleep disorder characterized by repeated interruptions in breathing during sleep. These pauses, known as apneas, can last from a few seconds to minutes and occur many times per hour. The condition is broadly categorized into three main types, each with distinct underlying mechanisms. Left untreated, it is associated with significant cardiovascular and neurocognitive morbidity.

Definition and classification

The disorder is formally defined by the cessation of airflow for at least 10 seconds during sleep. The primary classification system recognizes three forms. The first, obstructive sleep apnea, involves a physical blockage of the upper airway despite respiratory effort, often at the level of the oropharynx or hypopharynx. The second, central sleep apnea, results from a failure of the brainstem to send appropriate signals to the respiratory muscles, as seen in conditions like Cheyne-Stokes respiration. The third category, complex sleep apnea, is a combination of the first two types, sometimes emerging during treatment with continuous positive airway pressure.

Signs and symptoms

Common nocturnal symptoms include loud, disruptive snoring, witnessed apneas reported by a bed partner, and abrupt awakenings accompanied by gasping or choking. Patients often experience non-restorative sleep, leading to excessive daytime sleepiness, which can be quantified by scales like the Epworth Sleepiness Scale. Morning headaches, dry mouth, and irritability are frequent. Cognitive impairments such as difficulties with memory, concentration, and executive function are well-documented. The condition is also a recognized risk factor for mood disorders including depression and anxiety.

Risk factors and causes

For the obstructive type, major anatomical risk factors include obesity, enlarged tonsils or adenoids, a thick neck circumference, and craniofacial abnormalities such as retrognathia. Lifestyle factors like alcohol consumption and sedative use can exacerbate airway collapse. The central type is often associated with underlying medical conditions affecting the central nervous system, such as congestive heart failure, stroke, or the use of long-term opioid therapy. Certain neuromuscular diseases like amyotrophic lateral sclerosis can also impair respiratory drive.

Diagnosis

Definitive diagnosis typically requires an overnight sleep study, or polysomnography, conducted in a laboratory accredited by the American Academy of Sleep Medicine. This test records multiple physiological parameters including brain waves, oxygen saturation, heart rate, and respiratory effort. A simplified home sleep apnea test may be used for uncomplicated cases with high pre-test probability. The severity is graded using the apnea-hypopnea index, which counts the number of breathing disturbances per hour of sleep. Differential diagnosis includes other sleep disorders like narcolepsy and idiopathic hypersomnia.

Treatment

First-line therapy for moderate to severe obstructive cases is continuous positive airway pressure, which uses pressurized air to stent the airway open. For patients intolerant of this device, alternative options include oral appliances fitted by a dentist, which advance the mandible. Surgical interventions, such as uvulopalatopharyngoplasty or maxillomandibular advancement, aim to modify the upper airway anatomy. Treatment for central sleep apnea may involve adaptive servo-ventilation or medications like acetazolamide. Significant weight loss through programs like the Look AHEAD trial can induce remission in some patients.

Epidemiology and prognosis

The prevalence is estimated to affect a substantial portion of the adult population, with higher rates reported among males and increasing with age. Landmark studies like the Wisconsin Sleep Cohort have helped establish its epidemiology. Untreated, it is an independent risk factor for the development of systemic hypertension, coronary artery disease, atrial fibrillation, and type 2 diabetes. It also increases the risk of motor vehicle accidents due to daytime sleepiness. With appropriate treatment, significant improvements in quality of life, cardiovascular outcomes, and neurocognitive function are typically observed. Category:Sleep disorders Category:Respiratory diseases