[Transcranial Doppler sonography in orthostasis].
Middle cerebral artery blood flow velocity was investigated by transcranial Doppler sonography in 20 healthy subjects during a 10 min orthostasis test. Mean maximal velocity proved to be significantly lower in upright compared to horizontal position, its mean amounting to 93 +/- 9% of the latter value over the first two minutes and to 89 +/- 9% during the remaining period of the test. The index of resistance calculated by dividing systolic by enddiastolic maximal velocity was significantly decreased to a mean of 96 +/- 11% and 97 +/- 11% respectively during the two periods of orthostasis, probably due to autoregulation.
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D005260:Female; D006706:Homeostasis; D006801:Humans; D007024:Hypotension, Orthostatic / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011187:Posture; D012212:Rheology; D014655:Vascular Resistance
Transkranielle Doppler-Sonographie in Orthostase.