[Effect of body position on cerebral circulation in neurosurgical patients].

The mechanisms of the regulation of blood drainage from the brain were defined more precisely in 87 neurosurgical patients on the basis of comprehensive examination of cerebral circulation. The vertebral venous plexus was found to play the most important role in this process. Under normal conditions, when the patient is lying blood drains along the internal jugular veins, when he is sitting it drains mainly along the vertebral venous plexus. In patients remaining in a horizontal position for a long period of time the regulation of venous drainage is impaired. In such cases blood drains along the internal jugular veins and the vertebral venous plexus both when the person is lying and when he is sitting. This may cause a deterioration in the condition of bed-ridden patients during and after an operation performed with the patient in a sitting position.