Obstructive sleep apnea: a brief overview for the primary care physician.

Obstructive sleep apnea (OSA) affects 2% to 4% of middle-aged adults. It is even more common in the elderly. Although the primary care physician has the opportunity to play a pivotal role in the detection of this disorder, most physicians have had little or no formal training in OSA; and they frequently underdiagnose the disorder. The Walla Walla project demonstrated that with several educational interventions for physicians and patients, the OSA detection rate significantly increased. This article will review the typical presentation of OSA, diagnostic tests, and treatment options as well as follow-up once treatment is initiated. OSA is characterized by repetitive partial or complete closure of the upper airway during sleep despite continued respiratory drive (Figure 1A4). The patient demonstrates increasingly negative intrathoracic pressures as increasing ventilatory effort is generated to attempt to open the airway. These events are usually associated with a brief arousal and/or an oxygen desaturation and transient hypercapnea. These repetitive respiratory-related arousals result in significant sleep fragmentation, which, in combination with the oxygen desaturation, result in subsequent daytime sleepiness and fatigue An apnea refers to cessation of airflow for more than 10 seconds. An hypopnea is a reduction of airflow for 10 seconds. Both events are associated with continued respiratory effort. In contrast, central apneas have no airflow and no effort. The average number of apneas and hypopneas per hour of sleep is called the apnea-hypopnea index. The American Academy of Sleep Medicine (AASM) consensus statement suggests it is not necessary to distinguish between apneas and hypopneas. Instead, the term “respiratory events” should be used to refer to both because they have similar pathophysiology and consequence. More than five obstructed respiratory events per hour of sleep are considered abnormal. The AASM consensus statement includes both symptoms and sleep study data in the definition of the obstructive sleep apnea-hypopnea syndrome (OSAHS). OSAHS is defined as criteria A or B plus C. Criterion A: Excessive daytime sleepiness that is not better explained by other factors; Criterion B: two or more of the following that are not better explained by other factors: choking or gasping during sleep, recurrent awakenings from sleep, unrefreshing sleep, daytime fatigue, impaired concentration; Criterion C: overnight monitoring demonstrates five or more obstructed breathing events per hour during sleep. As these criteria suggest, fatigue and disrupted sleep are frequent symptoms of OSA. (Table 1) Several recent studies have suggested that certain key symptoms and associations are useful in predicting who will have OSA. Kump, et al found that the three symptoms most predictive of OSA are: Self-reported snoring, witnessed apnea, and sleepy driving. The positive predictive value of their model was enhanced by including body mass index (BMI) and gender. Netzer, et al found a simple self-administered patient questionnaire helped identify patients at high risk for OSA. Key symptoms include persistent symptoms (>3 to 4 times per week) in 2 or more questions regarding snoring, witnessed apnea or daytime sleepiness. Alternatively, persistent symptoms in conjunction with hypertension or obesity were suggestive of OSA. Simply adding questions regarding snoring, pauses, and daytime sleepiness to the primary care physician’s review of systems will increase the likelihood of detecting obstructive sleep apnea. If the patient has no reliable bed partner, the lack of a history of snoring, pauses, etc. has less significance. One may then need to rely on other symptoms and associated medical conditions The medical disorders most commonly associated with OSA include hypertension and upper body obesity. Approximately 50% of patients with obstructive sleep apnea have hypertension. Conversely, 25 to 30% of patients from a hypertension clinic will Table 1. Symptoms of Obstructive Sleep Apnea Snoring Witnessed Apnea/gasping Choking/shortness of breath arousals Recurrent awakenings Nocturia (three times per night) Morning headache Excessive daytime somnolence Automobile accident or near miss Decreased memory/concentration Depression/irritability Enuresis Sexual dysfunction