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Regional blood flow during hyperoxic haemodilution.
Jens Meier1, Andreas Pape, Martin Kleen
1Department of Anesthesiology, Johann Wolfgang Goethe-University, Frankfurt, Germany. meier@em.uni-frankfurt.de
Clinical Physiology and Functional Imaging
|May 13, 2005
Summary
Hyperoxic ventilation during anemia redirects blood flow to vital organs like the kidneys and liver. While this improves oxygen supply to some areas, it reduces it in the heart, pancreas, and muscles without critical organ dysfunction.
Area of Science:
- Physiology
- Cardiovascular Research
- Anesthesiology
Background:
- Hyperoxic ventilation (HV) increases arterial oxygen content but may impair oxygen delivery due to arteriolar constriction.
- The effects of HV on regional blood flow (RBF) and oxygen supply during anemia are not fully understood.
Purpose of the Study:
- To investigate the impact of HV on RBF and oxygen supply to vital organs in a model of moderate normovolemic anemia.
Main Methods:
- Anesthetized dogs were hemodiluted to a hemoglobin of 7 g/dL under normoxia.
- Regional blood flow was measured using radioactive microspheres before and during HV.
- Calculations included relative RBF, RBF variation coefficient, and regional oxygen supply.
Main Results:
- HV led to a significant decrease in cardiac index and RBF to the myocardium, pancreas, and skeletal muscle.
- Renal, hepatic, and intestinal RBF remained unchanged, leading to an increased relative RBF in these organs.
- HV had minimal effect on the heterogeneity of RBF.
Conclusions:
- HV during moderate anemia causes a redistribution of blood flow, favoring oxygen supply to the kidneys, liver, and intestines.
- Oxygen supply decreased in the heart, pancreas, and muscles, but organ function was not critically compromised.