Study Suggests that Sleep-Disordered Breathing (SDB) Causes High Blood Pressure/Hypertension

Northbrook, IL - October 8, 2002

Nasal continuous positive airway pressure (CPAP), the usual treatment for sleep disordered breathing (SDB), was found to lower nocturnal blood pressure among men with hypertension. SDB is a condition of repeated episodes of breathing pauses lasting 10 seconds or more due to complete or partial collapse of the upper airway (apnea) or abnormal decrease in depth of respiration associated with lowering of blood oxygen level (hypopnea).

The study by the University of Wisconsin, which is reported in the October edition of CHEST, the peer-reviewed journal of the American College of Chest Physicians, looked at 24 men, ages 30 to 60 with mild to moderate untreated hypertension. The overall objective of the study was to find out if there was an independent causal effect of SDB on blood pressure.

"Our study was unique in that we studied patients with hypertension rather than patients who were already known to have sleep-disordered breathing," said lead study author K. Mae Hla, MD, MHS. "We also used CPAP treatment in the hypertensive patients with no sleep-disordered breathing to control for any other effect that CPAP itself potentially might have on blood pressure independent of its effect through correction of sleep-disordered breathing."

Participants were administered CPAP treatment for 14 days and each had blood pressure taken before, during, and after the CPAP treatment. The study found that the non-SBD participants had no significant change in blood pressure with CPAP meaning that the treatment itself does not alter blood pressure. In contrast, in patients with SDB, nocturnal blood pressure decreased with CPAP therapy. Therefore, SDB appears to have a causative effect in elevating nocturnal blood pressure in patients with hypertension.

Study subjects were recruited from the Employee Health and Primary Care Clinics at the University of Wisconsin Hospital. Among the 14 subjects who had SDB, the mean nighttime systolic blood pressure decreased by 10.3 mm Hg with CPAP treatment and remained reduced by 7.8 mm Hg the night after CPAP treatment was discontinued. The mean diastolic blood pressure decreased by 4.5 mm Hg with CPAP treatment and also remained reduced by 5.3 mm Hg the night after CPAP treatment was discontinued.

"Considering that sleep-disordered breathing is a very common problem yet often not diagnosed, it could be an unrecognized contributor to hypertension in some patients," said ACCP President-elect Udaya B.S. Prakash, MD, FCCP.

CHEST is a peer-reviewed journal published by the ACCP. It is available online each month at www.chestjournal.org. ACCP represents more than 15,000 members who provide clinical, respiratory, and cardiothoracic patient care in the U.S. and throughout the world. ACCP's mission is to promote the prevention and treatment of diseases of the chest through leadership, education, research and communication.

Source: Medwire