Chapter 242. Sleep Apnea and Obesity Hypoventilation Syndrome

1. How prevalent is sleep apnea?

2. What are the key distinguishing features between obstructive and central sleep apnea?

3. What are the consequences of untreated sleep apnea?

4. What are the indications for inpatient therapy for sleep apnea?

5. How should patients with suspected sleep apnea be managed at hospital discharge?

6. What is obesity hypoventilation syndrome and how is it best treated?

Sleep apnea is defined by repeated transient cessations of respiration during sleep. The more common type of this disorder, obstructive sleep apnea (OSA), has a prevalence approaching 5%. The burden of disease in the hospitalized patient is even greater than the general population because inpatients carry many predisposing risk factors for OSA: obesity, congestive heart failure, coronary artery disease, hypertension, stroke, and diabetes. Epidemiologic data suggest that the majority of patients with sleep apnea are undiagnosed. In 2004, national hospital discharge codes revealed fewer than 300,000 cases of sleep apnea amongst almost 35 million inpatient stays, yielding a prevalence of identified disease of less than 1%.

Although sleep apnea by itself is rarely a primary indication for hospitalization, recent evidence suggests that inpatient management of this disease needs to improve. Less than 6% of those identified as having sleep apnea in the 2004 National Hospital Discharge Survey received therapy with continuous positive airway pressure (CPAP) while in the hospital. Hospital Medicine physicians can ensure that OSA patients are identified and receive treatment. The key to identifying the possible presence of sleep apnea depends largely on an appreciation of risk factors and clinical features. Goring and Collop showed in 2008 that almost 80% of patients with suspected sleep apnea referred for a sleep study after an inpatient hospitalization were confirmed to have OSA. Therefore, inpatient identification and referral for evaluation can improve diagnosis rates and reduce the percentage of affected patients left untreated. This chapter will review the fundamentals of sleep apnea, address the management of patients with stable sleep apnea in the inpatient setting, delineate the necessity of preoperative screening in at-risk patients, and identify which patients should undergo further testing.

Sleep-disordered breathing includes two related diseases: obstructive sleep apnea and central sleep apnea—although as many as 90% of all cases are OSA. The distinction between OSA and central sleep apnea is an important one as the treatment options and responses to therapy are quite different. Obesity hypoventilation, also known as Pickwickian syndrome, is a condition in which patients afflicted with sleep apnea develop diurnal hypercapnia and hypoxemia.

Obstructive Sleep Apnea

The upper airway is a compliant structure that is also susceptible to collapse. Complex neurologic and musculoskeletal interactions cause a reduction in the cross-sectional area of the upper airway during sleep, which can result in a ...