title: Establishment of the cardio-ankle vascular index in patients with obstructive sleep apnea.
abstract: BACKGROUND
  An arterial stiffness parameter, the cardio-ankle vascular index (CAVI), has been developed. CAVI is adjusted for BP and can be used to measure arterial stiffness with little influence of BP. The purpose of this study was to evaluate the reproducibility, validity, and clinical usefulness of CAVI among patients with obstructive sleep apnea (OSA), who often have elevated BP during measurement.
  
  
  METHODS
  Overall, 543 consecutive patients with OSA were studied. CAVI was automatically calculated from the pulse volume record, BP, and the vascular length from the heart to the ankle. First, CAVI was measured three times on different days in 25 patients to evaluate its reproducibility. Second, the correlation between CAVI and BP was assessed. Third, patients were classified into two groups (mild OSA or moderate-to-severe OSA), and the CAVIs of these groups were compared. Fourth, the correlation between CAVI and carotid intima-media thickness (IMT) was also assessed in 74 patients.
  
  
  RESULTS
  The mean coefficient of variation was 2.8. CAVI demonstrated weak or no correlations with BP (with systolic BP, r = 0.184; with diastolic BP, r = 0.223). Patients with moderate-to-severe OSA (n = 469) had a significantly greater CAVI than patients with mild OSA (p = 0.034). CAVI was positively correlated with IMT (r = 0.487).
  
  
  CONCLUSIONS
  The measurement of CAVI demonstrated good reproducibility and was not affected by the BP during measurement. Additionally, CAVI was positively correlated with another arteriosclerosis indicator. CAVI was higher in patients with more severe OSA and is regarded as a clinically useful index for the progression of vascular damage.
authors: Department of Clinical Physiology, Toranomon Hospital, Tokyo, Japan.
authors: Takiko
authors: T
authors: Kumagai
authors: Sleep Center, Toranomon Hospital, Tokyo, Japan. Electronic address: kasai-t@mx6.nisiq.net.
authors: Takatoshi
authors: T
authors: Kasai
authors: Department of Clinical Physiology, Toranomon Hospital, Tokyo, Japan.
authors: Mitsue
authors: M
authors: Kato
authors: Sleep Center, Toranomon Hospital, Tokyo, Japan.
authors: Ryo
authors: R
authors: Naito
authors: Sleep Center, Toranomon Hospital, Tokyo, Japan.
authors: Ken-Ichi
authors: KI
authors: Maeno
authors: Sleep Center, Toranomon Hospital, Tokyo, Japan.
authors: Satoshi
authors: S
authors: Kasagi
authors: Department of Clinical Physiology, Toranomon Hospital, Tokyo, Japan.
authors: Fusae
authors: F
authors: Kawana
authors: Department of Clinical Physiology, Toranomon Hospital, Tokyo, Japan.
authors: Sugao
authors: S
authors: Ishiwata
authors: Sleep Center, Toranomon Hospital, Tokyo, Japan.
authors: Koji
authors: K
authors: Narui
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000842:Ankle / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000503:physiopathology; D001783:Blood Flow Velocity; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008297:Male; D010701:Phonocardiography; D017286:Polysomnography; D015203:Reproducibility of Results; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D014463:Ultrasonography