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).
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.
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.
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.
aDepartment of Pharmacology, Belgium
bDepartment of Cardiovascular Diseases, Belgium
cDepartment of Nephrology, Belgium
dDepartment of Public Health, Ghent University Hospital, Belgium
eInstitute Biomedical Technology, Ghent University, Ghent, Belgium
Received 15 October, 2008
Revised 12 August, 2009
Accepted 9 October, 2009
Correspondence to Dries Mahieu, Department of Pharmacology, Ghent University Hospital, Ghent, Belgium Tel: +32 9 332 0034; fax: +32 9 332 4988; e-mail: email@example.com