How long shall the patient rest before clinic blood pressure measurement?

Am J Hypertens. 2006 Jul;19(7):713-7. Sala C, Santin E, Rescaldani M, Magrini F. Istituto Medicina Cardiovascolare, Universita di Milano, Centro Interuniversitario di Fisiologia Clinica e Ipertensione-Fondazione Policlinico, Italy.

BACKGROUND: The optimal time at rest before clinic blood pressure (BP) measurement is still undefined. In this study in patients with essential hypertension, the time course of the hemodynamic changes during a 16-min rest in the chair-seated position was evaluated and compared with that observed in a stabilized postural condition, such as after a prolonged supine rest.

METHODS: In 55 untreated essential hypertensive patients, BP, heart rate, stroke volume (impedance cardiography), and systemic vascular resistances were measured every other minute during a 16-min rest in the chair-seated position and, in random sequence, in the last 16 min of a 60-min supine rest.

RESULTS: Overall, systolic BP (SBP) and diastolic BP (DBP) decreased by 11.6 and 4.3 mm Hg, respectively, during the chair-seated rest; only a 1.8-mm Hg decrease in SBP was observed in the control supine study. The chair-seated fall in BP was associated with a decrease in systemic vascular resistances, in the absence of significant changes in cardiac index. From the logarithmic curve of SBP and DBP decrements, a half-time of 5.8 and 5.5 min respectively, was calculated. Decrements in SBP, but not DBP, were inversely related to the corresponding baseline values.

CONCLUSIONS: In untreated essential hypertensive patients a significant decrease in SBP and DBP associated with a systemic vasodilation was observed during a 16-min rest in the chair-seated position. Because approximately 75% of the spontaneous fall in BP occurred within 10 min, it appears that this time at rest before clinic BP evaluation could improve the precision and accuracy of the measurement.




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