title: Arterial stiffness increases during obstructive sleep apneas.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) appears to be an independent risk factor for diurnal systemic hypertension, but the specific biologic markers for this association have not been well established. Increased arterial stiffness is an important measure of increased left ventricular load and a predictor of cardiovascular morbidity and may precede the onset of systemic hypertension in humans. However, arterial stiffness has not been measured in association with obstructive apneas in patients with OSA, nor related to systemic blood pressure (BP) activity in this setting. Our objective was to test the hypothesis that arterial stiffness may be utilized as a sensitive measure of arterial vasomotor perturbation during obstructive events in patients with OSA, by demonstrating that (1) arterial stiffness increases acutely in association with obstructive apnea and hypopnea, and that (2) such increased stiffness may occur in the absence of acute BP increase.
  
  
  METHODS
  Prospective, cross-sectional.
  
  
  METHODS
  A tertiary-care university-based sleep and ventilatory disorders center.
  
  
  METHODS
  Forty-four normo- and hypertensive adult patients (11 women, 33 men) with polysomnographically diagnosed moderate to severe OSA.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Beat-to-beat BP was recorded from the radial artery by applanation tonometry during nocturnal polysomnography. Arterial augmentation index (AAI), a measure of arterial stiffness, was calculated as the ratio of augmented systolic BP (SBP) to pulse pressure and expressed as a percentage for the following conditions: awake, the first 10 ("early apnea") and last 10 ("late apnea") cardiac cycles of obstructive events, and the first 15 cardiac cycles following apnea termination ("post apnea"). Mean AAI (+/-SD) for the group was significantly increased during NREM sleep from early apnea to late apnea (12.02 +/- 2.70% vs 13.35 +/- 3.54%, p<0.05, ANOVA). During REM (analyzed in 20 patients), MI again significantly increased from early apnea to late apnea (11.75 +/- 2.81% vs 13.43 +/- 4.97%). Conversely, neither mean SBP nor mean arterial BP was significantly changed from early apnea to late apnea in NREM (SBP 130 +/- 14 mmHg vs 129 +/- 14 mmHg) or REM (SBP 128 +/- 22 mmHg vs 127 +/- 21 mmHg).
  
  
  CONCLUSIONS
  Arterial stiffness increases acutely during obstructive apneas in both NREM and REM sleep, in the absence of measurable BP change. These data suggest that arterial stiffness may be a sensitive measure of acute arterial vasomotor perturbation in this setting and may have implications concerning cardiovascular sequelae in patients with OSA.
authors.affiliation: Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.
authors.forename: Sanja
authors.initials: S
authors.lastname: Jelic
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Bartels
authors.forename: Jason H
authors.initials: JH
authors.lastname: Mateika
authors.forename: Pakkay
authors.initials: P
authors.lastname: Ngai
authors.forename: Ronald E
authors.initials: RE
authors.lastname: DeMeersman
authors.forename: Robert C
authors.initials: RC
authors.lastname: Basner
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000209:etiology*; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods; D011446:Prospective Studies; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D012894:Sleep Stages / Q000502:physiology; D014851:Wakefulness / Q000502:physiology