Relationship of brain blood flow and oxygen consumption to perfusion flow rate during profoundly hypothermic cardiopulmonary bypass. An experimental study.

A study was made of the relation of brain blood flow and oxygen consumption to changes in perfusion flow rate during cardiopulmonary bypass at 20° C in nine cynomolgus monkeys. Four perfusion flow rates varying from 0.25 to 1.75 L · min-1 · m-2 were randomly instituted, each for a 10 minute period. At the end of each period, brain arteriovenous oxygen content difference was measured and 15 μ radioactive microspheres were injected into the arterial perfusion line. The brain was then removed and sectioned into anatomic regions and radioactivity was counted. Regional and total brain blood flows were calculated, as was whole brain oxygen consumption. Brain perfusion continued in all areas at all perfusion flow rates. Whole brain blood flow decreased (p