Effect of spinal sympathetic blockade upon postural changes of blood flow in human peripheral tissues

Publisher Website
Google Scholar
Abstract
The effect of head-up tilt on subcultaneous and skeletal muscle blood flow in the crus was studied before and during epidural blockade in 10 subjects. Relative changes in blood flow were estimated by the local 133Xe washout technique. In subcutaneous tissue head-up tilt induced a decrease in blood flow of .apprx. 40% and there was no difference in the vascular response to head-up tilt before and during epidural blockade. In skeletal muscle tissue essentially the same was found as head-up tilt decreased blood flow by .apprx. 26% the response being uninfluenced by epidural blockade. In 3 patients local nervous blockade was induced by lidocaine in 133Xe labeled subcutaneous tissue on 1 side. During epidural blockade and tilt blood flow increased by 12%; blood flow decreased by 30% on the control side. Epidural blockade had no influence on the vasoconstrictor response in subcutaneous tissue and skeletal muscle to head-up tilt local blockade was able to prevent the response. Local mechanisms including the local veno-arteriolar reflex appear to play an important role for the observed maintenance of arterial blood pressure in the tilted position during central sympathetic blockade.