ORTHOSTATIC CIRCULATORY INSUFFICIENCY

Abstract

The maintenance of an adequate circulation despite change in posture, as from the horizontal to the vertical position, is accomplished by mechanisms which insure an equitable distribution of blood. In normal persons, the assumption of an erect position is attended by an increase in peripheral vasoconstriction, particularly in the arterioles of the splanchnic area,¹ by acceleration of the heart² and by a greater tonus of the skeletal musculature.³ Impairment of the capacity for postural adaptation, as a result of the failure of any of these factors, favors the development of orthostatic circulatory insufficiency, with stasis of blood in dependent areas and reduction of the cerebral blood supply. As a rule, this defect is temporary and occurs in patients weakened by illness.⁴ However, it is not uncommon in persons with low blood pressure,⁵ with a history of postural symptoms and a condition of noticeably subnormal weight