Chapter 75 - Orthostatic Hypertension

Abstract

This chapter describes orthostatic hypertension (OHT) as an increase in blood pressure on assumption of upright posture of 20/10 mmHg. It is often beneath the radar of physicians and nurses, because it is generally both unexpected and counterintuitive. OHT is usually defined as an increase in blood pressure with upright posture or tilt, but precise criteria have not been established. Furthermore few studies have entailed direct measurement of blood pressure in people with OHT. Such measurements would more faithfully reflect intra-arterial pressure and would avoid the introduction of potential artifacts. Patients presenting with acute baroreflex failure experience some of the highest blood pressures encountered in contemporary practice, sometimes with surges above 300 mmHg. In subsequent days and weeks after the acute event, the surges moderate, but substantial OHT may continue, though it usually declines somewhat with continued upright posture. Some patients with essential hypertension and abnormal diurnal variation in blood pressure exhibit OHT.