24-HOUR AMBULATORY BLOOD-PRESSURE VARIABILITY IN OBSTRUCTIVE SLEEP-APNEA SYNDROME

The 24-h ambulatory blood pressure (24h-ABP) was examined in 21 men, a ged 38 to 65 years (mean 50.6), with obstructive sleep apnea syndrome (OSAS) and in 123 normal male control subjects, aged 40 to 60 years (m ean 48.1) who did not have OSAS, obesity, autonomic nervous system abn ormality, cardiac disease, or respiratory disease (group C), to assess the role of apneas in the circadian variation of blood pressure (BP). The 24h-ABP patterns in OSAS patients were classified into three type s as follow: normotensive OSAS patients with normal BP throughout the 24h period with nocturnal BP fall (type 1); hypertensive OSAS patients with progressive BP elevation from onset of sleep to early morning (t ype 2); and hypertensive OSAS patients with elevated BP (systolic BP g reater-than-or-equal-to 140 mm Hg or diastolic BP greater-than-or-equa l-to 90 mm Hg) at any time during a 24-h period (type 3). It was concl uded that the circadian BP variation in type 1 was almost identical to the level and pattern of group C; the circadian variations in types 2 and 3 were significantly different from that of group C; and the pati ents with types 2 and 3 BP patterns had more severe OSAS than type 1 p atients. The severity of OSAS was an important factor in nocturnal ele vation of BP, hence affecting the circadian variation of BP. Noninvasi ve 24h-ABP monitoring is a useful procedure for understanding the clin ical features of OSAS patients with or without hypertension.