Sleep-disordered breathing and hypotension

We investigated the presence of low blood pressure (BP) in 4,409 subjects r eferred for overnight polysomnography. A low resting arterial BP (systolic BP < 105 mm Hg, diastolic BP < 65 mm Hg) was present in 101 subjects (2.3%) . Low BP was more prevalent in subjects with upper airway resistance syndro me (LIARS) (23%) than in subjects with obstructive sleep apnea syndrome (OS AS) (0.06%), parasomnia (0.7%), restless leg syndrome (0.9%), or psychologi cal insomnia (0.9%). In order to investigate BP homeostasis, we conducted p olysomnography followed by tilt-table testing on IS subjects with orthostat ic intolerance (OI) and LIARS, five normotensive subjects with LIARS, five subjects with insomnia and low BP, 15 subjects with OSAS, and 15 healthy co ntrol subjects. Fifteen subjects with LIARS and OI and 15 healthy controls also underwent 24-h ambulatory BP monitoring. Subjects with OI and LIARS ha d lower mean daytime systolic (119 +/- 28 mm Hg) and diastolic (75 +/- 18 m m Hg) BP than did control subjects (131 +/- 35 mm Hg and 86 +/- 19 mm Hg, r espectively) (p < 0.05). During tilt-table testing, subjects with UARS and a history of OI had a greater decrease in systolic BP (27 +/- 3 mm Hg) than did control subjects (7.5 +/- 1.6 mm Hg), subjects with OSAS (6.8 +/- 1.2 mm Hg), normotensive subjects with LIARS (7.2 +/- 0.84 mm Hg), or hypotensi ve insomniacs (7.4 +/- 1.1 mm Hg) (p < 0.01). We conclude that approximatel y one fifth of subjects with LIARS have low BP and complain of OI. Tilt-tab le testing may be indicated to confirm orthostatic intolerance in subjects with UARS.