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Are All Antihypertensive Agents Safe and Effective? More Evidence, For and Against: Nighttime Breathing Mask Lowers Blood Pressure in People With Sleep Apnea


Nighttime Breathing Mask Lowers Blood Pressure in People With Sleep Apnea

Patients with the nighttime breathing disorder known as obstructive sleep apnea who receive air through a mask while they sleep can significantly reduce their blood pressure, according to a study presented on May 22nd during the American Thoracic Society International Conference in San Diego, California.[13]

"Sleep apnea can have significant consequences on a person's physical health, and this study shows once again that treatment may lessen those risks," said lead researcher Daniel Norman, MD (University of California San Diego Medical Center, San Diego, California).

Obstructive sleep apnea is associated with recurrent episodes of nocturnal hypoxia and increased risk for development of systemic hypertension. Prior studies were limited in their ability to show reduction in blood pressure following continuous positive airway pressure (CPAP) therapy; and the effect of supplemental oxygen alone on blood pressure had not been evaluated.

In obstructive sleep apnea, the upper airway narrows, or collapses, during sleep. Periods of apnea end with a brief partial arousal that may disrupt sleep hundreds of times a night. More than half of those with sleep apnea also have high blood pressure, and their blood pressure does not fall during sleep as it does in most people.

The most widely used treatment for sleep apnea, a technique called nasal CPAP , delivers air through a mask while the patient sleeps. It has proved successful in many cases in providing a good night's sleep and preventing daytime accidents due to sleepiness. Supplementary oxygen is sometimes used as a treatment for sleep apnea.

Dr. Norman and colleagues studied 46 patients with moderate to severe obstructive sleep apnea in a randomized, double-blind, placebo-controlled study comparing the effects of 2 weeks of CPAP vs sham-CPAP vs supplemental nocturnal oxygen on 24-hour ambulatory blood pressure.

Two weeks of CPAP therapy resulted in a significant reduction in daytime mean arterial blood pressure and DBP, as well as nighttime SBP, DBP, and mean arterial blood pressure (all P < .05). Although nocturnal supplemental oxygen therapy improved oxyhemoglobin saturation, it did not affect blood pressure.

"There has been some controversy over how sleep apnea causes elevated blood pressure," Dr. Norman said. "Doctors do not know if it is due to drops in oxygen levels or arousals from sleep. Our study indicated that correcting drops in oxygen levels alone may not be enough to reduce blood pressure."

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