段階的受動起立時の動的脳血流自動調節作用の変容 [in Japanese] Changes in Dynamic Cerebral Autoregulation During Graded Orthostatic Stress in Humans [in Japanese]
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To investigate the influence of orthostatic stress on dynamic cerebral autoregulation (DCA), thirteen healthy subjects underwent graded head-upright til (HUT; 0,15,30,45,60, 90° (degrees)) stress. Dynamic cerebral autoregulation was evaluated by transfer function gain (TFG) and coherence function (CF) between blood pressure (BP) fluctuation (input) measured by photoplethysmography (Finapres) and cerebral blood flow (CBF) velocity fluctuation (output) in the middle cerebral artery measured by transcranial Doppler. In the very-low-frequency range (0.02∼0.07 Hz), many (33.3%) of the CF values were under 0.5 and the average CF value did not change significantly during the graded HUT stress. CF values in the low-frequency (LF: 0.07∼0.2 Hz) and high-frequency (HF: 0.2∼ 0.3Hz) ranges were always over 0.5. TFG in the LF and HF ranges decreased significantly at HUT 45° and 90° and during HUT 45∼90° simultaneously. These results suggest that HUT stress generally activates DCA, although the modes of activation differ according to the frequency range of BP and CBF fluctuations.
Neurosonalogy 19(1), 17-24, 2006-05-30
The Japan Academy of Neurosonology