Sleep apnea, a medical disorder with significant health and behavioral effects, is of particular interest to psychiatrists for its capacity to mimic or exacerbate symptoms of psychiatric disturbances such as depression, anxiety and panic disorder.
Apnea presents with cessation of breathing for at least 10 seconds during sleep. Three types of apneas have been described. In obstructive sleep apnea (OSA), cessation of breathing (gas exchange) occurs despite persistent respiratory efforts. In central apnea, there is no respiratory effort and thus no gas exchange. Mixed apnea usually begins with absent effort and terminates with obstruction.
Although most patients with obstructive and mixed apnea complain of excessive sleepiness, some OSA patients report midnocturnal awakenings. These patients may awaken with a startle or sense of panic, and complain of anxiety and insomnia at night as well as daytime sleepiness. Brief central apneas at sleep onset are fairly common and usually clinically unimportant. Sleep onset may be disrupted by central apnea, generating nonre-storative sleep and complaints of insomnia.
The majority of OSA patients are men age 50 and older. Virtually all report a history of loud, continuous snoring. Though they may be unaware of pauses in breathing, spouses or family members will describe gasping, choking or snorting breakthroughs for air concurrent with brief arousals. Although most such patients are moderately obese, relatively few have a classic Pickwickian habitus, and some are at or below a normal weight for their height. Thin individuals with significant apnea are likely to show upper airway abnormalities. These include, e.g., hypertrophic tonsils and adenoids, a low-set palate or palatal webbing, a large uvula, a large tongue or a small mandible.
Obstructive sleep apnea (OSA) is a very common disorder. A recent report by Young and colleagues generated a conservative estimate of 9 percent prevalence in working-age men and 4 percent in working-age women. In addition to sleepiness, OSA symptoms include restless sleep, headache, intellectual deterioration, impotence and mood changes, such as irritability, emotional lability and depression. Many obstructive apnea patients deny the severity of their symptoms.Serious Complications
Serious medical complications may develop in persistent apnea. Complications can include pulmonary and systemic hypertension, congestive heart failure and cardiac arrhythmias. The pathogenesis of this disorder probably relates both to disrupted nocturnal sleep and to brain and systemic anoxia. Even with severe disturbance, marked improvement and even complete cure may be attained with appropriate therapy.
Sleep position often influences OSA. Most patients snore more loudly in the supine position; bed partners often "encourage" them to move to their side while asleep.
Cartwright showed that some patients who have repetitive apneas while sleeping on their backs may breathe normally when they sleep on their side.Diagnostic PSG
Polysomnography (PSG) is a diagnostic procedure for sleep apnea, performed in a sleep disorders center. Although PSG is expensive, it provides critical diagnostic information. Typical PSG monitoring for sleep apnea would include recordings of electroencephalogram (EEG), electrocardiogram (EKG), eye movements or electrooculogram (EOG), body muscle tone (EMG) and body movement, respiratory effort from the chest and abdomen, airflow, snoring and blood oxygen saturation.
New diagnostic approaches have become available in recent years. Some use new technology; others have been developed in response to economic pressures of the managed care environment. Technology now allows patients to be recorded in a home or hospital setting without a technician in attendance, with remote monitoring capability via modem. Other limited recording approaches include montages without EEG or other typical "scoring" channels, or use of oximetry alone as a screening device.Treatment Approaches
Various medications have been explored as treatments for OSA. Acetazolamide(Drug information on acetazolamide) (Diamox) has respiratory stimulant properties, but is apparently not effective in the treatment of OSA. Whyte and associates showed that despite a reduction in apnea/hypopnea frequency with acetazolamide, there was no symptomatic benefit, and paresthesias were common. Medroxyprogesterone(Drug information on medroxyprogesterone) (Amen and others) also has some respiratory stimulant properties. Although it has been suggested as a treatment for OSA, studies performed by Cook and colleagues suggest that it provides little if any therapeutic benefit.
Protriptyline (Vivactil), a tricyclic antidepressant generally described as a more "stimulating" agent than other tricyclics, has been used in the treatment of several sleep disorders including narcolepsy and OSA. Brownell and colleagues proposed rapid eye movement (REM) sleep suppression to explain improvement in OSA severity, but Stepanski and associates interpreted improvement in oxygenation, respiratory events and arousals as not being caused by REM suppression.
Although mechanisms of protriptyline effects on sleep apnea are not known, Bonora and others focused on its capacity to raise skeletal muscle tone in sleep and, perhaps particularly in REM, preventing airway collapse and decreasing apnea severity. Séries and Cormier demonstrated that protriptyline treatment produced improvements in oxygen and carbon dioxide levels in patients with chronic obstructive pulmonary disease, suggesting a possible primary respiratory stimulant effect.
Nortriptyline (Pamelor) and desipramine (Norpramin) may provide alternatives to protriptyline. Sunderrajan and colleagues described effects of nortriptyline(Drug information on nortriptyline) treatment in a 61-year-old male with severe renal disease. Treatment of depression with nortriptyline at a dose of 125 mg provoked severe hyperventilation. Medication was stopped and restarted with similar results. In patients intolerant of protriptyline side effects, we have used nortriptyline with reported improvement in snoring and OSA symptoms.
A study comparing fluoxetine(Drug information on fluoxetine) (Prozac) with protriptyline in 12 OSA patients was performed by Hanzel and colleagues. Both drugs decreased the proportion of REM sleep time and decreased the number of apneas in non-REM sleep. For the entire group, no sig-nificant improvement was seen for either drug in oxygenation, desaturation events or arousals. Wide variability was seen in response to each medication, but six of the 12 patients had a good response to one or both medications. Fluoxetine was better tolerated overall.