[Normal and abnormal response of the arterial pressure to standing (author's transl)]

Redistribution of blood volume during orthostatism is followed by a reduction in venous return and therefore cardiac output. A drop in the blood pressure following postural changes is normally prevented by the action of the baroreceptor reflex, which leads to an increase in total peripheral resistance and heart rate. Orthostatic hypotension may arise from a variety of causes. In some cases, the disorder of postural regulation is due to an autonomic nervous system disease, and various tests are available that enable the diagnosis to be confirmed and the mechanism of action to be elucidated. Certain of these investigations explore the function of the complete baroreceptor reflex arc, while others enable selective study of either the efferent parasympathetic or sympathetic pathways. Central zones and afferent pathways cannot be explored directly. Individual tests are of limited value only, and the results of overall investigations are necessary for a better understanding and therefore more effective therapy of orthostatic hypotension due to autonomic nervous system disease.