Prognosis

High Blood Pressure. A number of studies have found a strong association between sleep apnea and high blood pressure (hypertension). (In the past, the link between sleep apnea and hypertension was thought to be due to obesity, a risk factor for both conditions, but more recent studies contradict that theory.) A 2000 study followed patients for 4 years; the more nightly apnea episodes they had in the first year, the more likely they were to develop hypertension by the fourth year. A weak, but still higher-than-normal association with high blood pressure has also been observed in those who snore, wake frequently during the night, or have mild sleep apnea.

A 2004 data analysis of over 200,000 patient records revealed that people who took both antidepressants and antihypertensives were 18 times more likely to be diagnosed with obstructive sleep apnea than those who did not take the medications. The probability was highest among adults aged 20-39 years. These drugs do not cause sleep apnea, but antidepressants may be prescribed to treat hypertensive patients’ complaints of fatigue even if sleep apnea is the real cause. The researchers recommended that patients being treated for high blood pressure, depression, and fatigue should also be evaluated for sleep apnea.

One way that apnea may directly affect blood pressure, regardless of other risk factors:

• Blood pressure fluctuates widely and suddenly in response to episodes of apnea and hypopnea (shallow nighttime breathing).
• Such fluctuations are possibly due to a sudden surge in the sympathetic nervous system, which controls involuntary muscle responses, importantly those in the blood vessels and heart, and may also play a role in sleep apnea.
• These fluctuations lead to transient constriction of blood vessels that, over time, could possibly lead to sustained hypertension and heart damage.
• Effective treatment of sleep apnea with continuous positive airway pressure (CPAP) may reduce blood pressure. Sleep apneas must be significantly reduced, however, to have any effect on blood pressure. Even a 50% reduction in apneas has no effect.