Ambulatory daytime blood pressure versus tonometric blood pressure measurements in the laboratory : effect of posture

Objective To compare blood pressure (BP) in tonometric radial artery recordings during passive head-up tilt with ambulatory recordings and evaluate possible laboratory cutoff values for hypertension. Methods Laboratory BP and ambulatory BP were recorded in normotensive (n=69), unmedicated hypertensive (n=190), and medicated hypertensive (n=151) subjects. Results Mean age was 50.2 years, BMI 27.7kg/m2, ambulatory daytime BP 139/87mmHg, and 276 were male (65%). As supine-to-upright changes in SBP ranged from -52 to +30mmHg, and in DBP from -21 to +32mmHg, the mean values of BP supine and upright measurements were compared with ambulatory BP. The mean(supine+upright) systolic laboratory BP was corresponding to ambulatory level (difference +1mmHg), while mean(supine+upright) DBP was 4mmHg lower (P