SLEEP-RELATED HYPOXEMIA IN HYPERTENSIVE AND NORMOTENSIVE MEN

Background-An association between hypertension and obstructive sleep a pnoea (OSA) has been found by some researchers but remains controversi al. Since such an association would have important implications for th e investigation and management of hypertension, the rate of nocturnal hypoxaemic episodes has been compared in hypertensive and normotensive men. Methods-The study was carried out in the community in Belfast an d its environs. Thirty four men with mild to moderate hypertension age d 40-64 years were identified from general practice and a hypertension clinic. Normotensive men, matched for age and body mass index, were s elected from a community survey. Subjects answered a sleep questionnai re and underwent overnight pulse oximetry at home. Computer analysis o f the results gave the number and magnitude of dips in oxygen saturati on (SaO2 dips, 4% or greater). Results-The median number of SaO2 dips/ hour for hypertensives was 2.0, and for normotensives was 0.8. Lowest SaO2 and mean SaO2 levels were significantly lower in the hypertensive group. Only one subject had a rate of SaO2 dips/hour greater than fiv e and symptoms suggestive of OSA. Conclusions-Both hypertensive and no rmotensive men had relatively few episodes of nocturnal hypoxaemia. Th e small increase in the rate of SaO2 dips in hypertensive subjects has not yet been fully explained. These results imply that OSA is not com mon in hypertensive subjects and is unlikely to be an important cause of hypertension.