Distribution and hierarchy of regional blood flow during hypothermic cardiopulmonary bypass.
BACKGROUND
Cardiopulmonary bypass (CPB) may decrease oxygen delivery relative to the nonbypass state. We predicted that a hierarchy of regional blood flow could be characterized under hypothermic (27 degrees C) CPB.


METHODS
Ten pigs underwent bypass at 27 degrees C. Fluorescent microspheres were administered before and during CPB at four randomized flows: 1.9, 1.6, 1.3, and 1.0 L x min(-1) x m(-2). At completion, tissue samples were obtained from brain, renal cortex and medulla, pancreas, small bowel, and limb muscle for regional blood flow determination.


RESULTS
Cerebral blood flow remained unchanged between CPB flows of 1.9 and 1.3 L x min(-1) x m(-2). Renal perfusion was stable between flows of 1.9 and 1.6 L x min(-1) x m(-2), whereas perfusion of small bowel decreased linearly with pump flow. Pancreatic perfusion was unchanged over the range of flows studied; muscle blood flow was profoundly reduced at the highest CPB flow and further decreased if pump flow was reduced below 1.6 L x min(-1) x m(-2).


CONCLUSIONS
This study characterizes the organ-specific hierarchy of blood flow and oxygen distribution during hypothermic CPB. These dynamics are relevant to clinical decisions for perfusion management.
Slater
J M
JM
Department of Anesthesiology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
Orszulak
T A
TA
Cook
D J
DJ
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002315:Cardiopulmonary Bypass; D006439:Hemodynamics / Q000502:physiology*; D007036:Hypothermia, Induced; D007421:Intestine, Small / Q000098:blood supply*; D007668:Kidney / Q000098:blood supply*; D018482:Muscle, Skeletal / Q000098:blood supply*; D009928:Organ Specificity; D010179:Pancreas / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology; D013552:Swine