Screen for apnea in patients with daytime sleepiness, guideline says

Doctors should assess the risk factors for and the symptoms of obstructive sleep apnea (OSA) in patients with unexplained daytime sleepiness, according to an ACP clinical practice guideline that appears in the Aug. 5 Annals of Internal Medicine.

The guideline recommends a sleep study for patients with unexplained daytime sleepiness (weak recommendation, low-quality evidence). To diagnose OSA in symptomatic patients, physicians should use full-night, attended, in-laboratory polysomnography (PSG). In patients without serious comorbidities for whom PSG is not available, a home-based portable monitor can be used as an alternative (weak recommendation, moderate-quality evidence).

Sleep study monitoring methods are classified by type. Type I monitoring is standard, attended, in-laboratory PSG; the other types are available for portable use. Type II monitors are portable comprehensive PSG with a minimum of 7 channels, including electroencephalogram, electrooculogram, electrocardiogram or heart rate, respiratory rate, respiratory effort and airflow, and oxygen saturation monitoring. Type III monitors have a minimum of 4 channels, including ventilation and airflow, heart rate, electrocardiogram or heart rate, and oxygen saturation. Type IV monitors have 1 or 2 channels, usually airflow and oxygen saturation.

The guideline writers found low-quality evidence showing that type II monitors may identify apnea-hypopnea index (AHI) scores that may suggest OSA. No study directly compared different portable monitors with each other, although current evidence supports greater diagnostic accuracy with type III monitors than type IV monitors. Most studies excluded patients with comorbid conditions, including chronic lung disease, congestive heart failure, or neurologic disorders, making the utility of portable monitors for diagnosing OSA in these patients uncertain. Also, compared with PSG, type II, III, and IV monitors had a wide range of difference in AHI estimates.

Type IV monitors cannot differentiate between obstructive apneas, where airflow is disrupted because of airway obstruction, and central apneas, which are caused by a temporary failure of the brain to regulate breathing. Continuous positive airway pressure (CPAP) may be contraindicated in patients with central sleep apnea. Patients with cardiac, respiratory, or neurologic disease may be at the greatest risk for central sleep apnea, and the American Academy of Sleep Medicine does not recommend the use of portable monitors for diagnosis in these patients.

Low-quality evidence indicated that the Berlin Questionnaire may be used to screen for OSA. However, questionnaires include subjective questions about sleepiness. Not all patients, even those with severe OSA, report sleepiness, which may limit applicability to the general population.

There was not enough evidence to determine the effectiveness of phased testing (screening tests or battery followed by a full test) for the diagnosis of OSA or the utility of preoperative screening for OSA to improve postsurgical outcomes.

A randomized trial showed that CPAP treatment did not reduce mortality or coronary heart disease events in patients with OSA who did not have daytime sleepiness. Although CPAP seems to reduce blood pressure in patients with symptomatic OSA, its effect on blood pressure in adults with OSA who do not have daytime sleepiness is less well established.