The Blood Flow and Oxygen Consumption of the Brain in Patients with Essential Hypertension before and after Adrenalectomy1

Abstract

Cerebral blood flow (N2O) and arterial and internal jugular blood gases were measured in 7 patients with severe essential hypertension while supine before and after a reduction in blood pressure achieved by 90% adrenalectomy, alone or combined with sympathectomy. The tests were made between 1-15 mos. after adrenalectomy. At the time of the post-adrenalectomy tests all patients were ambulatory and outpatients, and most were receiving orally 6-25 mg. cortisone and 2 mg. desoxycorticosterone. Mean values of cerebral O2 consumption, jugular venous O2 content, and jugular venous O2 tension remained essentially unchanged, and cerebral blood flow increased slightly after adrenalectomy. The high cerebral vascular resistance (pressure/flow) of essential hypertension was lowered from 3.4 to 2.2. A compensated metabolic acidosis was observed after subtotal adrenalectomy (whole blood buffer base fell from 50 to 42 m.eq. per liter). This was in part related to a reduction in arterial pH and CO2 content. The changes in arterial CO2 content, tension, and pH in individual patients did not correlate well with the increased cerebral blood flow, reduced cerebral vascular resistance, or reduced mean arterial pressure. The mean reduction in cerebral vascular resistance as well as the mean decrease in mean arterial pressure (170-118 mm. Hg) appeared to be greater after combined sympathectomy-adrenalectomy than the reductions observed after sympathectomy alone as observed in a previous study.