Hypertension in obese patients: hemodynamic and volume studies.

Distinct hemodynamic and volume characteristics have been suggested for established hypertension in severe obesity, namely, a high cardiac output, and expanded blood volume, and a normal peripheral resistance. To evaluate whether hypertension in moderately obese patients represents a separate entity that can be defined by hemodynamic and volume profiles, we studied these in 50 such patients and compared results with those obtained in 59 nonobese essential hypertensives and 25 normal subjects. Both obese and nonobese hypertensives had a normal cardiac index (men, 2.8 +/- 0.1 vs 2.8 +/- 0.09 liter/min/m2; women, 2.9 +/- 0.1 vs 2.8 +/- 0.1 liter/min/m2, respectively) and similarly elevated total peripheral resistance (men, 47.1 +/- 2.3 vs 46.5 +/- 1.9 U . m2; women, 45.0 +/- 2.4 vs 44.0 +/- 1.3 U . m2, respectively) as compared to normals (cardiac index: men, 2.9 +/- 0.09 liter/min/m2, women, 3.4 +/- 0.2 liter/min/m2; total peripheral resistance: men, 29.4 +/- 1.0 U . m2, women, 28.3 +/- 2.8 U. m2). Volume measurements corrected to body surface area showed that both obese and nonobese hypertensive patients had lower blood volume (men, 2.6 +/- 0.05 vs 2.5 +/- 0.05 liter/m2; women, 2.2 +/- 0.05 vs 2.3 +/- 0.05 liter/m2, respectively) than normals (men, 2.9 +/- 0.08 liter/m2; women, 2.5 +/- 0.08 liter/m2). The results of this study suggest that hypertension in moderately obese subjects is similar in its hemodynamic and volume profiles to hypertension in the nonobese and that the presence of obesity does not alter the hemodynamic characteristics of established essential hypertension.