Obstructive Sleep Apnea: To Sleep, Perchance to Snore
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When to suspect and how best to diagnose obstructive sleep apnea?
It would be a mistake to minimize the syndrome of obstructive sleep apnea (OSA). It should not be characterized merely as obesity, a large neck, snoring, and daytime sleepiness; rather, it is a protean syndrome with serious cardiovascular, CNS, and endocrine ramifications. This month’s “Top Paper” is a valuable review of the diagnosis, prevalence, treatment, and complications of OSA.1
CLINICAL CONSEQUENCES OF OSA
OSA results in myriad cardiovascular problems, including a leading association with resistant hypertension.2 It independently increases both fatal and nonfatal cardiovascular events by 2.87 and 3.17 times, respectively. The prevalence of OSA among persons with an acute myocardial infarction is 65.7%! The syndrome also triples to quadruples the risk of tachyarrhythmias. Continuous positive airway pressure (CPAP) therapy mitigates many of these complications.
The brain is not immune to the consequences of OSA. In addition to cognitive impairment, hypersomnolence, and fatigue, the risk of stroke is 2.86 to 3.56 times higher in persons with OSA than in those who do not have the syndrome. If a patient with OSA survives a stroke, the risk of early death is increased by 75%. Again, CPAP use can decrease this disturbing risk.
Older adults with OSA have an increased likelihood of epilepsy. Not surprisingly, there is also a 2-fold increase in motor vehicle accidents in this cohort. Only 2 days of CPAP use results in a significant risk reduction in this arena as well. The OSA Expert Panel recommends conditional driving certification for commercial drivers with suspected OSA pending evaluation by a sleep specialist.
OSA carries an increased burden of insulin resistance, increased fasting and 2-hour postprandial glucose values, and frank diabetes. Combining these multiple target organ injuries eventuates in multiple perioperative risks. Patients with OSA who undergo surgery experience difficult intubations, respiratory depressions (from anesthetic and pain medications), more frequent re-intubations, and arrhythmias that result in lengthier hospital stays.
ROLE OF PRIMARY CARE
How should the primary care community diagnose and assist in the treatment of this increasingly prevalent syndrome? Among persons who have a body mass index of greater than 28, the incidence of OSA is 41%. A neck circumference in men of greater than 42 cm and in women of greater than 37 cm is suggestive of the diagnosis.1
Referral of such patients for sleep studies is important. Overnight polysomnography is the gold standard for diagnosis of OSA. Overnight oximetry is used increasingly; it is 98% sensitive but only 40% specific for the diagnosis.
Once OSA is diagnosed, CPAP use and compliance are critical. Documenting adherence is a primary care role and is defined as CPAP use 4 hours per night for at least 70% of nights during a 30-day period. OSA patients should see their primary care provider within the first 30 to 60 days of CPAP use after the initial diagnosis. The “Top Paper” also addresses further therapies such as oral appliances and surgery.
We must be vigilant in our efforts to diagnose OSA. Early diagnosis and intervention save lives. ■
1. Park JG, Ramar K, Olson EJ. Updates on definition, consequences, and management of obstructive sleep apnea. Mayo Clin Proc. 2011;86:549-555.
2. Wright BM, Adams M, Karwa R, et al. Extremely elevated blood pressures: an update on hypertensive urgencies and emergencies. Consultant. 2011;51:433-441.
Dr Rutecki reports that he has no relevant financial relationships to disclose.