Effect of hemorrhagic shock upon spinal cord blood flow and evoked potentials

Blood supply and vascular reactivity of the spinal cord under normal and pathological conditions

“…Resistance to flow through the upper branch is 278 times greater than in the downward branch, because the diameter of the ascending branch is much smaller (0.231 mm) than that of the descending branch (0.941 mm). 38 Under normal conditions in humans, the ascending branch of the artery of Adamkiewicz is required to supply the arterial domain of the upper 1-3 thoracolumbar segments, and its relatively small blood flow is sufficient. It is likely, however, that under the collateral demands of aortic crossclamping during surgery, the quantity of blood flow to the higher midthoracic area is unreliable.…”

“…In the ASA the blood flow may be modified by contraction of the conventional circular musculature of the tunica media, the generally longitudinally disposed layer of the intimal musculature, and the intimal cushions near and in the critical vascular junction just below the boundary between the thoracolumbar and midthoracic arterial domains. 38 …”

“…While the blood flow in the spinal cord is 40%-60% that of the brain, the tissue oxygen levels are the same (35)(36)(37)(38)(39). 23 The volume of blood perfusing the spinal cord increases when arterial CO 2 tension increases and falls when it decreases.…”

“…When MABP fell below 40 mm Hg, SCBF dropped significantly. 38 Kobrine and associates 45 found that when CO 2 pressure was between 10 to 50 mm Hg in monkeys, SCBF stayed constant. When the pressure of CO 2 surpassed 50 mm Hg, SCBF increased.…”