Modeling and numerical simulation of the cerebral blood flow under acceleration.
When fighter aircrafts change directions, the pilots are subject to a centrifuge force.  This force can be enough to induce the pilot loss of consciousness (LOC).  The physiological cause of this LOC is a brain hypoxia which results from the increase of the hydrostatic pressure.  Under gradual onset rate + Gz acceleration (GOR+Gz), the brain hypoxia occurs with visual prodromes familiar to fighter pilots.  In this case, they feel a reduction of the peripheral vision (Grey-out), followed by a loss of the central vision (Black-out).  The useful time of consciousness can be prolonged by using anti-G suit.  Under rapid onset rate +Gz acceleration, a new symptomatology of the LOC, characterized by the absence of a grey or black-out, has been observed.  The objective of this theoretical study is a better understanding of mechanisms which cause fighter pilot inflight LOC.  A physical model has been developed.  It allows to take into account the influence of the rate of change in acceleration on the cerebrovascular system behavior.
Gaffié
D
D
ONERA, Chatillon France.
Guillaume
A
A
Quandieu
P
P
D000054:Acceleration; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D008954:Models, Biological; D013575:Syncope / Q000209:etiology* / Q000503:physiopathology; D014474:Unconsciousness / Q000209:etiology / Q000503:physiopathology