The effect of hexamethonium upon cerebral blood flow and metabolism in patients with premalignant and malignant hypertension.

In 13 patients with grade III or grade IV hypertensive retinopathy the effect of intramuscular hexamethonium bromide on cerebral circulation and metabolism has been studied. The results have been compared with Dewar's study of hexamethonium in less severe hypertensive patients and with Kety's results following differential spinal sympathetic block. Sixty minutes after in-tramuscular hexamethonium, mean arterial blood pressure fell 39 per cent, cerebral vascular resistance was reduced 29 per cent, and cerebral blood flow decreased 16 per cent. Cerebral oxygen consumption was maintained at the expense of a reduction in cerebral venous oxygen saturation. HE EFFECT of hexamethonium upon blood flow in various organs of hyper-tensive patients has been reported by several investigators. Cardiac output was reduced in compensated patients.' Renal blood flow decreased initially but returned to control value despite a continued reduction in arterial blood pressure.' 2 Blood flow through the abdominal viscera decreased in proportion to the fall in arterial blood pressure.3 The present report concerns the effect of hexa-methonium upon cerebral hemodynamics and metabolism in 13 patients with severe hyper-tension.