401 Cardiovascular Indices Measured by a Noninvasive Doppler Ultrasonography Cardiac Output Monitor in Patients With Stage 2 Hypertension

Abstract

Study Objective: Hypertensive patients either have increased systemic vascular resistance or increased cardiac output, or both. The exact prevalence of these pathophysiological derangements, and their relative contribution to hypertension, are not known. Study Objectives: To use a noninvasive Doppler ultrasonography cardiac output monitor to measure haemodynamic parameters and determine the relative derangements of cardiac output and systemic vascular resistance in emergency department patients with Stage 2 hypertension. Methods: Patients aged 18 years or above who attended the emergency department (ED) with systolic blood pressure> 160 or diastolic blood pressure >100 in 2 or more measurements at least 20 minutes apart were included. Research assistants collected demographic and clinical data and measured the cardiac output and systemic vascular resistance of these patients with a noninvasive Doppler ultrasonography cardiac output monitor. Patients were followed up within 2 weeks. Those who did not have documented increased blood pressure (Stage 2) in 2 or more different occasions were excluded. The patients' body surface area (BSA) was calculated to obtain the cardiac index (CI) and the systemic vascular resistance index (SVRI); where CI = cardiac output/BSA and SVRI = systemic vascular resistance/BSA. Results: Forty-nine patients were included. Mean age (+/− SD) was 66.5 +/− 12.5 years and 59.2% were females. 7 (14.3%) had either high cardiac output or high CI; 41(83.7%) had either high systemic vascular resistance or high SVRI; one had normal haemodynamics; 18 (36.7%) had either low cardiac output or low CI; and 3 (6.1%) had low SVRI. The prevalence of haemodynamic derangement subtypes was as follows: 4 (8.2%) with systemic vascular resistance normal, cardiac output high; 39 (79.5%) with systemic vascular resistance high, cardiac output normal; 4 (8.2%) with systemic vascular resistance and cardiac output normal; 2 (4.1%) with systemic vascular resistance high, cardiac output low. Conclusion: In ED patients with Stage 2 hypertension, about 80% have increased systemic vascular resistance. If clinicians choose anti-hypertensive therapy aiming at reducing systemic vascular resistance, it may result in a much higher likelihood of effective blood pressure control.