Regional hemodynamics and oxygen supply during isovolemic hemodilution in the absence and presence of high-grade beta-adrenergic blockade.
Studies were performed in 16 pentobarbital-anesthetized dogs to evaluate regional circulatory effects of isovolemic hemodilution in the absence (group 1) and presence (group 2) of high-grade beta-adrenergic blockade with propranolol. Regional blood flow measured with 15 microm radioactive microspheres was used to calculate regional oxygen supply. In group 1, hemodilution with 5% dextran (40,000 molecular weight) reduced arterial hematocrit and oxygen content by approximately one half and had heterogeneous effects on regional blood flows. Blood flow was unchanged in the renal cortex, liver, and spleen, and it increased in the pancreas, duodenum, brain, and myocardium; however, only in the brain and myocardium were increases in blood flow sufficient to maintain oxygen supply at baseline (pre-hemodilution) levels. In group 2, intravenous administration of propranolol (1 mg/kg) itself decreased blood flow in the spleen and myocardium and had no other regional effects. Hemodilution after propranolol caused regional circulatory changes that were essentially similar to those in the absence of propranolol. It is concluded that (1) during isovolemic hemodilution, oxygen supply to the brain and myocardium is maintained at the expense of oxygen supply to less critical organs, and (2) this pattern of regional circulatory response during hemodilution remains intact in the presence of high-grade beta-adrenergic blockade with propranolol.
Crystal
G J
GJ
Department of Anesthesiology, Illinois Masonic Medical Center, 836 W Wellington Ave, Chicago, IL 60657, USA.
Ruiz
J R
JR
Rooney
M W
MW
Salem
M R
MR
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001810:Blood Volume; D001921:Brain / Q000378:metabolism; D004285:Dogs; D005260:Female; D006438:Hemodilution; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D012079:Renal Circulation / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D010100:Oxygen