P8.11 Supine Clinic Blood Pressure is Raised in Hypertensive Non-Dippers: A Novel Test to Determine Dipper Status?

Abstract

Introduction

Patients with nocturnal blood pressure (BP) that fails to decline ≥10% compared with daytime BP (non-dippers) have increased mortality risk. This may be related to increased arterial stiffness and raised central BP whilst supine. This study aimed to test this hypothesis. We also sought to determine if non-dippers could be identified by the BP change from seated-to-supine positions.

Methodology:

24-hour-ambulatory BP was recorded in 95 treated hypertensive patients (aged 62 ± 8 years), comprising 43 (45%) non-dippers and 52 (55%) dippers (nocturnal BP decline ≥10%). Brachial and central BP (SphygmoCor) were recorded in the seated and supine positions after ≈5 minutes rest in each position. Arterial stiffness was estimated by augmentation index and aortic pulse wave velocity.

Results:

Arterial stiffness was not significantly different between dippers and non-dippers, nor were brachial or central systolic BP (SBP) whilst seated (p > 0.05 for all). However, non-dippers had significantly higher supine brachial SBP (132 ± 14 vs 126 ± 11 mmHg: p < 0.05) and central SBP (121 ± 15 vs 115 ± 11 mmHg: p < 0.05). Moreover, the changes in both brachial and central SBP to the supine position were also higher in non-dippers (p < 0.05 for both). A brachial SBP increase of ≥8mmHg from the seated-to-supine position predicted non-dipper status with 87% specificity (p < 0.05). Night-time SBP correlated with clinic brachial SBP in the supine (r = 0.39; p < 0.001), but not seated (r = 0.19; p > 0.05) position (Z = 2.11; p < 0.05).

Conclusion:

Supine central SBP is elevated in non-dippers, which may contribute to cardiovascular risk. Increased supine, relative to seated, brachial SBP may be a useful clinical test to identify non-dipper status.