title: Measurement of central aortic pulse pressure: noninvasive brachial cuff-based estimation by a transfer function vs. a novel pulse wave analysis method.
abstract: BACKGROUND
  The prognostic value of central aortic pulse pressure (PP-C) may have been underestimated due to its measurement inaccuracy. We aimed to investigate the accuracy of noninvasive brachial cuff-based estimation of PP-C by a generalized transfer function (GTF) or a novel pulse wave analysis (PWA) approach to directly estimate PP-C.
  
  
  METHODS
  Invasive high-fidelity right brachial and central aortic pressure tracings, and left brachial pulse volume plethysmography (PVP) waveforms from an oscillometric blood pressure (BP) monitor were all digitized simultaneously in 40 patients during cardiac catheterization. An aortic-to-brachial GTF and a PWA multivariate prediction model using the PVP waveforms calibrated to brachial cuff systolic BP (SBP) and diastolic BP(DBP) were constructed. Accuracy of the two methods was examined in another 100 patients against invasively measured PP-C.
  
  
  RESULTS
  The error of cuff PP in estimating PP-C was 1.8 ± 12.4 mm Hg. Application of the GTF on noninvasively calibrated PVP waveforms produced reconstructed aortic pressure waves and PP-C estimates with errors of -3.4 ± 11.6 mm Hg (PP-C = reconstructed aortic SBP - aortic DBP) and -2.3 ± 11.4 mm Hg (PP-C = reconstructed aortic SBP - cuff DBP), respectively. The observed systematic errors were proportional to the magnitudes of PP-C. In contrast, the error of the PWA prediction model was 3.0 ± 7.1 mm Hg without obvious proportional systematic error.
  
  
  CONCLUSIONS
  Large random and systematic errors are introduced into the PP-C estimates when PP-C is calculated as the difference between the estimated central SBP and central or cuff DBP. The accuracy can be improved substantially with the novel PWA approach.
authors.affiliation: The Joanna Briggs Institute, The University of Adelaide, Adelaide, Australia.
authors.forename: Hao-Min
authors.initials: HM
authors.lastname: Cheng
authors.forename: Shih-Hsien
authors.initials: SH
authors.lastname: Sung
authors.forename: Yuan-Ta
authors.initials: YT
authors.lastname: Shih
authors.forename: Shao-Yuan
authors.initials: SY
authors.lastname: Chuang
authors.forename: Wen-Chung
authors.initials: WC
authors.lastname: Yu
authors.forename: Chen-Huan
authors.initials: CH
authors.lastname: Chen
mesh_terms: D001011:Aorta / Q000502:physiology*; D062186:Arterial Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D001916:Brachial Artery / Q000502:physiology*; D006801:Humans; D063177:Pulse Wave Analysis