The action of magnesium sulfate on cerebral circulation and metabolism in toxemia of pregnancy

Abstract

1.1. Studies of cerebral blood flow, cerebal vascular resistance, cerebral oxygen consumption, and respiratory quotient of the brain, as well as mean arterial blood pressure and the blood gases were made before and after intravenous administration of magnesium sulfate to 15 women with toxemia of pregnancy.2.2. Magnesium sulfate significantly lowers mean arterial blood pressure, but not to normal levels.3.3. Cerebral blood flow and oxygen utilization by the brain are slightly increased.4.4. Cerebral vascular resistance is decreased to a notable degree but not to the point where normal cerebral vascular tone is restored.5.5. A number of sedatives and vasodilators were compared and contrasted with the effects of magnesium sulfate on the brain. 5.1.A. Certain sedatives (intravenously administered barbiturates) depress cerebral oxygen metabolism in the same manner as does eclampsia. Cerebral blood flow is also decreased. None of the sedatives, other than magnesium sulfate, alleviated cerebral vasospasm.5.2.B. All of the vasodilators studied relieved the increased cerebral vascular resistance without compromising cerebral circulation and metabolism.6.6. It is concluded that magnesium sulfate with its exemplary action on the brain is a superior sedative and anticonvulsant in toxemia of pregnancy. Because its vasodilator action is not strong, it may be combined to great physiologic and therapeutic advantage with appropriate vasodilators when marked hypertension and vasospasm are present.