Background: Several studies assessing the role of obstructive sleep apnea syndrome (OSAS) as an independent risk factor for hypertension have produced conflicting results. Although the sleep apnea syndrome is associated with hypertension, there are no references regarding the blood pressure response of normotensive OSAS patients during exercise.
Study objectives: The aim of this study was to investigate the relationship between diastolic blood pressure (DBP) response during exercise and the severity of OSAS.
Methods: We performed exercise testing a day after polysomnography in 17 normotensive males who were admitted for the first time because of OSAS and in 10 normal subjects who were members of the same families. During maximal incremental exercise test (bicycle ergometry) oxygen consumption (VO(2)) and the DBP were estimated at rest and at peak exercise. VO(2) was also measured when DBP were 100 and 110 mm Hg.
Results: At peak exercise DBP was significantly higher in OSAS patients (115.3 +/- 9.2 mm Hg) than in normal subjects (101 +/- 8.4 mm Hg, p < 0.01). OSAS patients reached a DBP of 110 mm Hg with a significantly lower VO(2) than normal subjects (1,881.5 +/- 703.4 vs. 1,972.3 +/- 108.6 ml/min, p = 0.045). VO(2) was not different between the two groups at a DBP of 100 mm Hg (1,211.2 +/- 371.7 vs. 1,536.6 +/- 267.2 ml/min, p = 0.089) but OSAS patients had a significantly lower heart rate than normals (111.2 +/- 13 vs. 118.6 +/- 27.6, p = 0.009). None of the aspects of quality of life, according to the Nottingham Health Profile Questionnaire, Part 1, were significantly different between patients and normal subjects.
Conclusions: Normotensive OSAS patients develop DBP elevation at an earlier stage during exercise compared to normal subjects. This hypertensive response was not correlated with the severity (apnea-hypopnea index, oxygen desaturation parameters) of OSAS. DBP elevation could be a limiting factor of physical performance in this group of patients.