title: Noninvasive assessment of central and peripheral arterial pressure (waveforms): implications of calibration methods.
abstract: OBJECTIVE
  Noninvasive estimation of central blood pressure (BP) from radial artery pressure waveforms is increasingly applied. We investigated the impact of radial artery waveform calibration on central BP assessment and calculated pressure amplification, with focus on the one-third rule used to estimate mean arterial BP (MAP).
  
  
  METHODS
  Pressure waveforms were noninvasively measured at the radial and carotid arteries in 1873 individuals (age 45.8+/-6.1 years). Radial and carotid artery waveforms were calibrated using brachial artery DBP and SBP, MAP estimated with the one-third rule and MAP estimated as brachial DBP along with 40% of brachial artery pulse pressure.
  
  
  RESULTS
  Central SBP obtained via a transfer function was 123.5 +/- 15.7, 117.8 +/- 14.2 and 126.0 +/- 15.4 mmHg (mean +/- SD) following above-mentioned three calibration schemes, respectively. Using the same calibration schemes, carotid artery SBP was 131.4 +/- 15.2, 118.4 +/- 14.4 and 126.8 +/- 15.7 mmHg, respectively. Central-to-brachial amplification was 13.0 +/- 3.6 mmHg using second method as compared with 4.6 +/- 3.8 mmHg with third method. Brachial-to-radial amplification was actually negative (-6.3 +/- 4.5 mmHg) using second method, whereas 3.4 +/- 5.5 mmHg was found with third method.
  
  
  CONCLUSIONS
  Both carotid artery SBP and central SBP obtained via a transfer function are highly sensitive to the calibration of the respective carotid artery and radial artery pressure waveforms. Our data suggest that the one-third rule to calculate MAP from brachial cuff BP should be avoided, especially when used to calibrate radial artery pressure waveforms for subsequent application of a pressure transfer function. Until more precise estimation methods become available, it is advisable to use 40% of brachial pulse pressure instead of 33% to assess MAP.
authors.affiliation: Department of Pharmacology, Belgium. dries.mahieu@ugent.be
authors.forename: Dries
authors.initials: D
authors.lastname: Mahieu
authors.forename: Jan
authors.initials: J
authors.lastname: Kips
authors.forename: Ernst R
authors.initials: ER
authors.lastname: Rietzschel
authors.forename: Marc L
authors.initials: ML
authors.lastname: De Buyzere
authors.forename: Francis
authors.initials: F
authors.lastname: Verbeke
authors.forename: Thierry C
authors.initials: TC
authors.lastname: Gillebert
authors.forename: Guy G
authors.initials: GG
authors.lastname: De Backer
authors.forename: Dirk
authors.initials: D
authors.lastname: De Bacquer
authors.forename: Pascal
authors.initials: P
authors.lastname: Verdonck
authors.forename: Luc M
authors.initials: LM
authors.lastname: Van Bortel
authors.forename: Patrick
authors.initials: P
authors.lastname: Segers
mesh_terms: D000328:Adult; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods* / Q000706:statistics & numerical data; D001916:Brachial Artery; D002138:Calibration; D002339:Carotid Arteries; D015331:Cohort Studies; D006801:Humans; D008875:Middle Aged; D017534:Radial Artery