Abstract 072: Paradoxical Blood Pressure Increase After Brief Patient Rest Period

Abstract

Background: Office-based blood pressure (BP) measurement is subject to variations which may influence management. Objective: To assess the effect of rest period on repeat BP measurement. Methods: Clinic charts were review identified 200 encounters with BP re-measurement due to initial BP of > 130/80 mmHg. BP was measured initially by a nurse, with the patient in a sitting position and the arm resting at the level of the heart. If BP was > 130/80 mmHg, it was repeated by physician after resting the patient for 15 minutes. Mean age was 64 ± 12 years. Results: Among encounters with BP re-measurement, initial systolic BP (SBP) was 154 ± 25 mmHg, and diastolic BP 87 ± 15 mmHg. Upon re-measurement, 135 of 200 patients (68%) had lower SBP of 144 ± 21 mmHg compared with initial SBP of 161 ± 25 mmHg; a 17 mmHg drop (P < 0.01). However, 53 of 200 patients (27%) had higher SBP of 149 ± 17 mmHg compared with initial SBP of 138 ± 14 mmHg; an 11 mmHg increase (P < 0.01). Twelve patients (6%) had no BP change. In 47% (93/200) of encounters, BP re-measurement necessitated medication changes. Compared with the remaining patients, those with paradoxical increase in BP were younger (60 ± 9 years versus 66 ± 12 years; p < 0.01), and with lower initial SBP (138 ± 14 versus 161 ± 25, p < 0.01). Discussion: Hypertension is a major challenging public health problem. JNC 8 guidelines recommend that prior to BP measurement, patients should be seated quietly for at least 5 minutes in a chair, with feet on the floor, and arm supported at heart level; this may decrease initially elevated BP. However, 27% of our patients exhibited a paradoxical response, with elevation of the SBP after a 15 minute period of rest. The cause of this paradox is not clear, but may have resulted from white-coat hypertension during the rest period, which may be more common in younger patients, as noted in our study. This underscores the importance of ambulatory BP monitoring, especially in subsets of patients prone to having labile or white coat hypertension, to avoid the cost and side effects of BP overtreatment. Studying larger number of patients, and including patient with normal initial BP, may help clarify the mechanism and clinical significance of this observation.