Brachial and Central Blood Pressure Measurements

Office brachial BP measurement was performed using a mercury sphygmomanometer and a standard‐sized cuff (13 cm × 50 cm), after the person had been seated for at least 5 min.⁸ Brachial systolic and diastolic BP values represented the average of at least two consecutive measurements, separated by at least 5 min.
Office central BP measurement was performed using the carotid tonometry.⁹ Right carotid artery pressure waveforms were registered noninvasively by applanation tonometry using a high‐fidelity SPC‐301 micromanometer (Millar Instrument, Inc., Houston, Texas, USA).¹⁰, ¹¹ Five to ten consecutive carotid pressure waveforms were ensemble averaged to one waveform that was then calibrated to brachial mean and diastolic BPs.¹¹ The inter‐ and intra‐observer variabilities of the estimation of central systolic BP by carotid tonometry were .6% and .9%, respectively.⁸Ambulatory daytime brachial BP readings were calculated from multiple measurements of the oscillometric ABPM recorders (Model 90207; SpaceLabs Inc., Redmond, Washington, USA).⁷ Recorders were programmed to measure brachial BP at 20‐min intervals during the daytime (from 7 a.m. to 10 p.m.) and at 60‐min intervals during the nighttime (from 10 p.m. to 7 a.m.).⁸ The 24‐h BP readings were not edited manually, and only persons whose daytime ABPM records contained ≥ 70% of the total possible readings were included in the present analysis.
For the present study, office brachial hypertension was defined in retrospect as office brachial systolic BP ≥130 mmHg or diastolic BP ≥ 80 mmHg.¹ Office central hypertension was defined as office central systolic BP ≥130 mmHg or diastolic BP ≥ 80 mmHg. Ambulatory daytime brachial hypertension was defined as average brachial systolic BP ≥ 130 mmHg or average diastolic BP ≥ 80 mmHg during daytime.