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Sleep Apnea

Obstructive sleep apnea syndrome is a sleep disturbance caused by complete or partial obstruction of the upper airway that is due to an anatomically small pharyngeal airway, increased inspiratory resistance and increased laxity of pharyngeal muscles. Collapse of pharyngeal muscles during sleep leads to increased resistance to airflow.

Numerous causes of upper airway obstruction exist, including: (1) tonsillar hypertrophy, which is more commonly seen in children and adolescents; (2) craniofacial abnormalities, such as retrognathia, micrognathia and nasal obstruction; 13) fatty infiltration of pharyngeal soft tissues; (4) macroglossia, which may be associated with hypothyroidism, acromegaly, amyloidosis or Down syndrome; (5) vocal cord paralysis, and (6) neuromuscular disorders, such as myotonic dystrophy.

Clinical Presentation. obstructive sleep apnea syndrome is a common disorder. The Wisconsin Sleep Cohort, a comprehensive epidemiologic study that investigated the prevalence of obstructive sleep apnea syndrome in middle-aged adults, found that 4 percent of men and 2 percent of women had obstructive sleep apnea syndrome based on clinical criteria and a sleep study. The prevalence of obstructive sleep apnea syndrome is comparable to that of asthma.

Members of a patient's family can best confirm the clinical symptoms of obstructive sleep apnea syndrome. The most prevalent complaint is daytime somnolence or fatigue. The severity of somnolence or fatigue may be gauged by the frequency and duration of naps and their occurrence during normally stimulating activities, such as reading, watching television.

Fragmentation of sleep and a cyclic pattern of arousal cause daytime somnolence. Hypoxemia in association with sleep fragmentation may lead to impairments in memory, attention and concentration, changes in mood and personality, loss of sexual drive or impotence and morning headaches (Table 13). Some patients report automatic behavior and retrograde amnesia, particularly when driving. Paradoxically, children with obstructive sleep apnea syndrome are more likely to present with hyperactivity, poor school performance.

Snoring is observed in about 80 percent of patients with obstructive sleep apnea syndrome but is not a requisite symptom. In one survey, snoring was already present in 68 percent of patients with obstructive sleep apnea syndrome by their late teens.

Symptoms of Obstructive Sleep Apnea Syndrome

Excessive daytime somnolence

Impaired memory, attention, concentration

Changes in mood or personality

Impaired libido

Morning headaches

Disruptive snoring

Restless sleep

Choking during sleep

Nocturia

Diaphoresis

early 20s but had worsened in proportion to weight gain.42 Snoring that becomes louder over time suggests increasing upper airway resistance. Disruptive snoring in all sleeping positions is more likely to be associated with obstructive sleep apnea syndrome than is snoring in the supine position only. Choking or gasping at the termination of an apneic episode.

Other manifestations of obstructive sleep apnea syndrome include enuresis and nocturia, which are caused by increased intra-abdominal pressure associated with respirations against a closed upper airway. Frequent movements of the limbs and trunk typically accompany apnea-associated arousals. Nocturnal diaphoresis, which is reported in 66 percent of patients with obstructive sleep apnea syndrome, is related to restlessness.

Several factors increase upper airway resistance and can exacerbate the frequency and duration of apneic episodes. Use of hypnotics, sedatives or alcohol promote collapse of pharyngeal musculature during sleep. Respiratory allergies produce inflammation of the nasopharynx and pharyngeal soft tissues and thereby increase upper airway resistance.

Complications. In severe or chronic cases of untreated obstructive sleep apnea syndrome, hematologic and cardiovascular complications may develop (Table 14). Polycythemia, a hallmark of chronic hypoxemia, occurs in 7 percent of patients with obstructive sleep apnea syndrome. The prevalence of hypertension in patients with obstructive sleep apnea syndrome is twice that seen in the general U.S. population, the prevalence of ischemic heart disease is increased threefold, and the prevalence of cerebrovascular disease is increased fourfold. The relationship between hypertension and obstructive sleep apnea syndrome.

Diagnostic Evaluation. The evaluation of a patient with obstructive sleep apnea syndrome must include a sleep study because the predictive value of symptoms and physical findings in establishing an accurate clinical diagnosis is limited. Two types of sleep studies are currently available: an overnight polysomnogram, which is performed in a laboratory setting.

Selected Causes of Excessive Sleepiness

Disturbed sleep

Sleep apnea syndromes

Esophageal reflux

Cardiopulmonary

Heart failure

Chronic obstructive pulmonary disorder

Pharmacologic

Hypnotics

Antihypertensives

Antidepressants

Alcohol

Tranquilizers

Other drugs of abuse

Psychotogic

Depression

Anxiety

Endocrine

Diabetes

Apathetic hyperthyroidism

Other disorders

Central nervous system

Multiple sclerosis

Other syndromes

Tumors

Definitions. An apnea is defined as cessation of airflow for at least 10 seconds. It may be associated with oxygen desaturation. Three types of apneas exist: obstructive, central and mixed. Obstructive apneas imply an absence of airflow in the presence of continued thoracic and abdominal effort [Figure 2). Central apneas are characterized by an absence of airflow.

Polysomnogram results should always be interpreted with the clinical history in mind. If the clinical assessment results are incongruent, diagnosis of obstructive sleep apnea syndrome must be reconsidered. Occasionally, the polysomnogram reveals frequent unexplained arousals or crescendo snoring immediately before an arousal, but shows no apneas.