apnea

Absence of breathing. [G. apnoia, want of breath]

- central a. a. as the result of medullary depression which inhibits respiratory movement.

- deglutition a. inhibition of breathing during swallowing.

- induced a. intentional respiratory arrest during general anesthesia produced by hypocapnia, a muscle relaxant drug, respiratory center depression, or sudden cessation of controlled respiration.

- obstructive sleep a. a disorder, first described in 1965, characterized by recurrent interruptions of breathing during sleep due to temporary obstruction of the airway by lax, excessively bulky, or malformed pharyngeal tissues (soft palate, uvula, and sometimes tonsils), with resultant hypoxemia and chronic lethargy.Symptoms of obstructive sleep a. are loud snoring, recurrent apneic episodes during sleep followed by gasping inspiration with partial or complete arousal, nocturnal restlessness, and daytime sleepiness. Apneic episodes last 10–120 seconds and may be accompanied by sinus bradycardia or atrioventricular block. The cumulative effect of recurrent spells of a. is hypoxemia and shallow, nonrefreshing sleep, which may lead to excessive drowsiness, personality change, impairment of intellectual function, and heightened tendency to accidents during waking hours. However, evidence establishing obstructive sleep a. as an independent risk factor for motor vehicle accidents, heart attack, stroke, and sudden death is weak. About 15% of persons with this disorder develop sustained pulmonary hypertension. Obstructive sleep a. affects about 4% of men and 2% percent of women between the ages of 30 and 60. Obesity, hypothyroidism, cigarette smoking, alcohol, and some hypnotics (particularly benzodiazepines) predispose to this disorder, and its incidence increases with advancing age. Diagnosis is confirmed by polysomnography (continuous measurement of airflow, respiratory activity, chin electromyography, ECG, EEG, electrooculogram, and arterial oxygen saturation during sleep) and by evaluation of the shape and size of the upper respiratory tract. Weight loss, smoking cessation, and avoidance of benzodiazepine hypnotics are advised for all patients. A mandibular advancement appliance worn inside the mouth at night reduces symptoms in some patients. An effective if somewhat cumbrous treatment is the nightly use of continuous positive airway pressure, which provides a steady flow of room air at low pressure through the nose to overcome intermittent upper respiratory obstruction. Selected patients benefit from surgical procedures such as uvulopalatopharyngoplasty (trimming and reshaping of the uvula and soft palate), which can be performed by laser or radiofrequency ablation under local anesthesia, and mandibular osteotomy with genioglossus muscle advancement.

- sleep a. central and/or peripheral a. during sleep, associated with frequent awakening and often with daytime sleepiness. Cf.:sleep-induced a..

- sleep-induced a. a. resulting from failure of the respiratory center to stimulate adequate respiration during sleep; divided into respiratory pause (cessation of air flow for less than 10 seconds) and apneic pause (cessation of air flow greater than 10 seconds).

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ap·nea or chiefly Brit ap·noea 'ap-nē-ə, ap-'nē- n

1) transient cessation of respiration whether normal (as in hibernating animals) or abnormal (as that caused by certain drugs) see sleep apnea

2) ASPHYXIA

ap·ne·ic or chiefly Brit ap·noe·ic ap-'nē-ik adj

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ap·nea (apґne-ə) [a-¹ + -pnea] cessation of breathing. apneic adj