A Mathematical Model of Cerebral Perfusion Subjected to Gz Acceleration

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Authors
  1. Cirovic, S.
  2. Walsh, C.
  3. Fraser, W.D.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
When the human body is exposed to a high gravitational load, the blood supply to the brain is reduced and loss of consciousness may occur. Our goal is to identify the principal mechanical causes of reduced blood supply to the brain during high +Gz. We have developed a mathematical model to investigate the influence of Gz on the cerebral circulation. Blood flow is modeled using a one-dimensional flow approximation, in which the cross-sectional area of elastic vessels is determined as a non-linear function of the transmural (blood minus external) pressure. The intracranial vessels are subjected to cerebrospinal fluid pressure (PCSF) which is determined from the condition that the cranial volume is conserved. For a constant pressure difference of 100 mm Hg applied to the arterial and venous ends of the model, blood flow is diminished for +Gz. At approximately +5 Gz the blood flow predicted by the model is insufficient to maintain normal functioning of the brain. PCSF is approximately equal to the blood pressure in the large intracranial veins for all values of Gz. Extracranial arteries and the intracranial vessels to not collapse, even when Gz is substantially higher than normal. TRUNCATED
Keywords
Cerebral perfusion;+Gz;G-Induced Loss of Consciousness;G-LOC;Vascular pressure;Venous resistance;Transmural pressure;Tube law;Perfusion pressure;Cerebrospinal fluid pressure
Report Number
DCIEM-98-P-48 — Reprint
Date of publication
01 May 2000
Number of Pages
9
Reprinted from
Aviation, Space, and Enviornmental Medicine, vol 71, no 5, 2000, p 514-521
DSTKIM No
CA002082
CANDIS No
513877
Format(s):
Hardcopy;Document Image stored on Optical Disk

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