Latest posts by Michael Morgenstern, MD (see all)
Patients with high blood pressure should be evaluated for obstructive sleep apnea especially if they have resistant hypertension (HTN). Resistant hypertention is high blood pressure, despite 3 or more blood pressure medications. In the Heart Beat Study, Dr. Susan Redline, from Harvard Medical School, examined the risk of resistant hypertension in severe obstructive sleep apnea (OSA). While many studies on sleep apnea focus on individuals being seen in a sleep clinic, the focus of this study was on patients in cardiology clinics with heart disease. High blood pressure is one of the risk factors for cardiovascular disease. Good control can reduce the chances of heart attacks and stroke. But many people cannot get good control of their blood pressure. Resistant hypertension remains uncontrolled even after treatment with numerous medications. This is a video of Dr. Redline describing the Heart Beat Study in 2012:
Chances of OSA if you have high blood pressure
Research shows that the chances are good of having OSA even if your blood pressure is well controlled, around 50/50 or 1 in 2. In cases where blood pressure is not controlled such as in resistant hypertension, the chances of having OSA approach 80%. That is 80% of individuals with resistant hypertension or uncontrolled blood pressure after treatment with multiple medications will have sleep apnea.
Types of blood pressure measurements
Blood pressure measured in a doctors office is called resting blood pressure. Blood pressure may also be measured over a 24 hour period called ambulatory measurement. Recent evidence shows that a 24 hour ambulatory blood pressure measurement may be a better gauge of long-term blood pressure control. In this manner it is usually measured at home, every 15 to 30 minutes by a device that is worn all day. The device automatically takes measurements and an average blood pressure measurement is computed.
Resistant HTN commonly found in Severe OSA
The Heart Beat study found that patients with severe obstructive sleep apnea were about twice* as likely to have resistant resting high blood pressure after being prescribed 3 medications than patients who had less severe sleep apnea. [The same effect was not observed in 24 hour ambulatory monitoring.] The study provides good evidence to support the link between OSA and resistant hypertension. Other evidence suggests that controlling the OSA with CPAP might reduce their blood pressure even when medications do not.
Benefit of CPAP for Resistant high blood pressure
In a randomized control study published in the Journal of the American Medical Association, called the HIPARCO Trial, patients with resistant high blood pressure who received CPAP had substantial reductions in their 24-hour mean blood pressure after 12 weeks. [According to the author, HIPARCO is the Spanish name of a Greek scientist. He was the first in calculate the distance between the moon and the earth.] They were also about twice* as likely to have reductions in nighttime blood pressure. This is important because nighttime strokes and heart attacks are believed to be related to not having these “dips” in nighttime blood pressure.
It is essential that individuals with resistant hypertension be screened for OSA. Many times they will uncover sleep apnea. CPAP may be able to control their blood pressure when medication fails. It could be the difference between life and death.
*Reported as an odds ratio, converted using risk ratio calculation (for more information see reference 3)