Effect of “Dry” Immersion on Blood Flow in Jugular Veins and Cerebral Venous Sinus Characterized by Ultrasonic Methods of Investigation

Venous circulation in the brain was investigated in a three-day “dry” immersion experiment. The aim of the study was to estimate the influence of microgravity factors on venous drainage from the cranial cavity. Duplex scanning and Doppler ultrasound were used to record hemodynamic parameters of the cervical main veins and orbital and cerebral venous sinuses. A significant decrease in blood flow along the jugular pathway with the activation of additional pathways of both the extra- and intracranial divisions of the venous system of the brain was detected. These results suggest that microgravity triggers the mechanisms capable of compensating the increasing intracranial venous pressure. The fact that in some volunteers the intracranial venous blood flow did not accelerate may reflect anatomical features and require a more scrupulous investigation of their venous systems.