Dependence of Arterial Pressure on Intravascular Volume in Treated Hypertensive Patients

Relations between plasma volume and arterial pressure were studied in 16 hypertensive patients during long-term antihypertensive treatment. In five patients who had responded poorly to combined adrenergic blocker and diuretic treatment, plasma volume was either expanded or normal. Intensified diuretic treatment reduced plasma volume below normal and arterial pressure nearly to normal. In 11, who had responded well to treatment either with the same combination (six patients) or with adrenergic blockers alone (five patients), plasma volume was below normal. In the 12 men both systolic and diastolic pressure correlated directly with plasma volume (p less than 0.01 for both). Although adrenergic blocking drugs interfere with cardiovascular adjustments to intravascular volume expansion, reasons for this quantitative relation between pressure and plasma volume did not emerge. However, this study emphasizes the importance of precise volume control in maintaining blood-pressure reductions during treatment.