Acute reduction in cerebral blood velocity on supine-to-stand transition increases postural instability in young adults.

Acute reduction in cerebral blood velocity on supine-to-stand transition increases postural instability in young adults. Am J Physiol Heart Circ Physiol. 2019 Nov 01;: Authors: Fitzgibbon-Collins LK, Noguchi M, Heckman GA, Hughson RL, Robertson AD Abstract We tested the hypothesis that transient deficits in cerebral blood flow are associated with postural sway. In 19 young healthy adults, we examined the association between the drop in cerebral blood flow during supine-to-stand transitions (indexed by transcranial Doppler ultrasound (middle cerebral artery blood velocity at diastole; MCAdv) and near-infrared spectroscopy (tissue saturation index; TSI)) and the center of pressure displacement while standing. Participants performed transitions under 3 conditions aimed at progressively increasing the drop in MCAdv, in a randomized order: (i) a control transition (CON); (ii) a transition that coincided with deflation of bilateral thigh cuffs (TC); and (iii) a transition that coincided with both thigh cuff deflation and 90 sec of prior hyperventilation (HTC). The deficit in diastolic blood velocity (MCAdv deficit) was quantified as the difference between MCAdv and its preceding baseline value, summed over 10 sec beginning at the MCAdv nadir. Compared to CON, HTC led to greater drops in MCAdv (P = 0.003) and TSI (P < 0.001) at nadir. The MCAdv deficit was positively associated with the center of pressure displacement vector-average usin...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Tags: Am J Physiol Heart Circ Physiol Source Type: research