Abstract

Background: Improved neurological outcome with postarrest hypertensive hemodilution in an earlier study could be the result of more homogeneous cerebral perfusion and improved O2 delivery. We explored global, regional, and local cerebral blood flow by stable xenon-enhanced computed tomography and global cerebral metabolism in our dog cardiac arrest model. Methods: Ventricular fibrillation cardiac arrest of 12.5 minutes was reversed by brief cardiopulmonary bypass, followed by life support to 4 hours postarrest We compared control group I (n=5; mean arterial blood pressure, 100 mm Hg; hematocrit, ^35%) with immediately postarrest reflow-promoted group II (n=5; mean arterial blood pressure, 140-110 mm Hg; hypervolemic hemodilution with plasma substitute to hematocrit, 20-25%). Results: After initial hyperemia in both groups, during the "delayed hypoperfusion phase " at 1-4 hours postarrest, global cerebral blood flow was 51-60 % of baseline in group I versus 85-100 % of baseline in group II (/><6.01). Percentages of brain tissue voxels with no flow, trickle flow, or low flow were lower (/?<0.01) and mean regional cerebral blood flow values were higher in group II (p<0.0l). Global cerebral oxygen uptake recovered to near baseline values at 3-4 hours postarrest in both groups. Postarrest arterial O2 content, however, in hemodiluted