RESUMO
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 (nâ =â 69), unmedicated hypertensive (nâ =â 190), and medicated hypertensive (nâ =â 151) subjects. RESULTS: Mean age was 50.2 years, BMI 27.7â kg/m 2 , ambulatory daytime BP 139/87â mmHg, and 276 were male (65%). As supine-to-upright changes in SBP ranged from -52 to +30â mmHg, and in DBP from -21 to +32â mmHg, 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 +1â mmHg), while mean(supine+upright) DBP was 4â mmHg lower ( P â <â 0.05) than ambulatory value. Correlograms indicated that laboratory 136/82â mmHg corresponded to ambulatory 135/85â mmHg. When compared with ambulatory 135/85â mmHg, the sensitivity and specificity of laboratory 136/82â mmHg to define hypertension were 71.5% and 77.3% for SBP, and 71.7% and 72.8%, for DBP, respectively. The laboratory cutoff 136/82â mmHg classified 311/410 subjects similarly to ambulatory BP as normotensive or hypertensive, 68 were hypertensive only in ambulatory, while 31 were hypertensive only in laboratory measurements. CONCLUSION: BP responses to upright posture were variable. When compared with ambulatory BP, mean(supine+upright) laboratory cutoff 136/82â mmHg classified 76% of subjects similarly as normotensive or hypertensive. In the remaining 24% the discordant results may be attributed to white-coat or masked hypertension, or higher physical activity during out-of-office recordings.