Perfusion of the visual cortex during pressure breathing at different high-G stress profiles.
The effects of pressure breathing for G protection (PBG) on perfusion of the visual cortex were studied in a subject during various high-G stress profiles. Blood flow velocity was measured in the posterior cerebral artery using a transcranial Doppler (TCD) ultrasound instrument. The G profiles examined included gradual and rapid onset rates. Mean cerebral blood flow velocity (MCBFV) declined with increasing +Gz with G-suit protection alone. The MCBFV increased in direct proportion with increase in +Gz acceleration with PBG. The mediating mechanisms for the effects of PBG may include improved gaseous exchange, the diminished sympathicoadrenal discharges, and cardiopulmonary reflexes. A role for TCD in further research is indicated.
Noninvasive Flow Neurocybernetic Laboratory, Chidicon Medical Center, Owerri, Imo State Nigeria.
P C
PC
Njemanze
P J
PJ
Antol
C E
CE
Lundgren
D000328:Adult; D000337:Aerospace Medicine; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D006112:Gravitation; D005676:Gravity Suits; D006801:Humans; D008297:Male; D008889:Military Personnel; D012119:Respiration; D014793:Visual Cortex / Q000098:blood supply*