THE SLEEP APNEA SYNDROME



The sleep apnea syndrome is characterized by daytime hypersomnolence in patients who dis­play at least 30 apneic episodes of 10 seconds or longer during six hours of nocturnal sleep. The apneic episodes are of two types: (1) central apnea due to decreased respiratory center output and manifested by cessation of breathing efforts (Fig. 25-4A) and (2] obstructive apnea due to upper airway obstruction and characterized by contin­ued respiratory efforts, indicated by paradoxical motion of the rib cage and abdomen, during the period of absent airflow . Commonly both types combine to give mixed apnea. The less common central type usually causes little phys­iological disturbance, whereas the obstructive va­riety is accompanied by severe 02 desaturation with occasional values below 50 per cent . Arrhythmias are common and may rarely result in sudden death.

The prevalence of this syndrome is unknown, but it probably affects more than 1 per cent of the general population. The major predisposing conditions can be grouped as (1) neurological states associated with impaired respiratory drive (pre­viously discussed) and (2) conditions associated with upper airway obstruction such as enlarged tonsils and adenoids, retrognathia, fat deposition in obesity, macroglossia associated with acro­megaly, myxedema, and Down’s syndrome, and nasal packing for nosebleeds or nasal surgery.

Characteristically, these patients have a long history of loud, sonorous snoring, often combined with thrashing movements of the limbs. Repeti­tive arousals produce sleep deprivation and lead to excessive daytime sleepiness. Many patients are obese, but this is not invariable, and only a small fraction can be classified as pickwickian. Other features of the sleep apnea syndrome in­clude hypertension, morning headache, intellec­tual deterioration, and reduced libido.
Polysomnography, including the monitoring of the electroencephalogram (EEG), electro-oculo-gram, motion of the rib cage and abdomen, and arterial 02 saturation, is required to make a def­inite diagnosis.

Treatment mav include respiratory stimulants, especially medroxyprogesterone, the application of continuous positive airway pressure [CFA^J to the nose, or tracheostomy to bypass the site ot upper airwav occlusion. In some obese patients, marked weight loss has led to an improvement in the obstruction.