title: Validity of a novel wristband tonometer for measuring central hemodynamics and augmentation index.
abstract: BACKGROUND
  Central hemodynamic and augmentation indices are independent predictors of cardiovascular events and all-cause mortality that can be estimated noninvasively by pulse wave analysis. The purpose of this study was to assess the reliability and validity of a newly engineered wristband tonometer for acquiring radial artery pressure waveforms.
  
  
  METHODS
  Radial artery pulse pressure waveforms were evaluated with an established pencil-type and a novel wristband tonometer in 31 participants (aged 30.2±9.5 years) resting in a supine position. Pulse wave analysis was executed using the same validated generalized transfer function (SphygmoCor) for both tonometers.
  
  
  RESULTS
  A significant difference in time to data acquisition between tonometers was observed (-70.2±147.7 s; P < 0.05; wristband faster). The wristband tonometer had significantly lower within-subject coefficients of variation (CV) compared with the pencil-type tonometer in aortic pulse wave height (-2.67% ± 5.51%; P < 0.05) and time to reflection (-2.26% ± 6.16%; P < 0.01). No other differences in CV were observed. Slight but statistically significant mean differences between tonometers were observed in aortic systolic blood pressure (ASBP; 0.43±1.08 mm Hg; P < 0.05; wristband lower), aortic pulse pressure (APP; 0.43±0.96 mm Hg; P < 0.05; wristband lower), and round-trip travel time of the reflected pressure wave (Δtp; 3.58±12.86 ms; P < 0.05; wristband higher). However, ASBP, APP, and Δtp measurements were highly correlated (r = 0.9970, r = 0.9953, and r = 0.8838, respectively, P <0.0001) between tonometers; within-subject and between tonometer significant mean differences were within clinical ranges.
  
  
  CONCLUSIONS
  This novel, hands-free platform may be interchangeable with the commonly used pencil-type tonometer, heralding new directions in noninvasive in vivo vascular research and clinical application.
authors.affiliation: Department of Kinesiology, University of Rhode Island, Kingston, Rhode Island; darrentbeck@mail.uri.edu.
authors.forename: Darren T
authors.initials: DT
authors.lastname: Beck
authors.affiliation: Department of Biomedical Sciences, Quinnipiac University, Hamden, Connecticut;
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Martin
authors.affiliation: Division of Cardiovascular Medicine, University of Florida, Gainesville, Florida;
authors.forename: Wilmer W
authors.initials: WW
authors.lastname: Nichols
authors.affiliation: Department of Applied Medicine and Rehabilitation, Indiana State University, Terre Haute, Indiana;
authors.forename: Alvaro N
authors.initials: AN
authors.lastname: Gurovich
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida.
authors.forename: Randy W
authors.initials: RW
authors.lastname: Braith
mesh_terms: D000328:Adult; D001011:Aorta / Q000503:physiopathology; D001794:Blood Pressure; D006439:Hemodynamics; D006801:Humans; D008365:Manometry / Q000295:instrumentation*; D063177:Pulse Wave Analysis / Q000295:instrumentation*; D017534:Radial Artery / Q000503:physiopathology; D059289:Vascular Stiffness; D014953:Wrist
keywords: applanation tonometry; arterial stiffness; augmentation index; blood pressure; hypertension; pulse wave analysis