Comparison of acute cardiovascular effects and oxygen-supply following haemodilution with dextran, stroma-free haemoglobin solution and fluorocarbon suspension

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Abstract
Changes in haemodynamics and myocardial oxygen-supply were investigated in anaesthetised dogs, when the haematocrit was reduced to 18 to 22% by isovolaemic haemodilution with 8% stroma-free haemoglobin solution, 20% Fluosol-DA‡ and 6% dextran 70. Comparable haemodilution and comparable reduction in whole-blood viscosity was not followed by similar changes in cardiac output: dextran- and Fluosol-diluted dogs showed significantly elevated cardiac output, while haemoglobin-diluted dogs failed to do so. As a result, systemic O2-transport was better maintained with dextran and Fluosol. Myocardial blood flow, estimated by 15 μm microspheres, increased in all three haemodiluted groups, but oxygen-supply was not similar. The haemoglobin-diluted dogs showed inadequate O2-supply, suggested by a fall of coronary sinus pO2; dextran-diluted dogs exhibited adequate O2-supply suggested by maintained coronary sinus pO2, while the Fluosol-diluted group enjoyed excessive O2-supply, indicated by a markedly elevated pO2 in coronary sinus blood. The observations suggest that similar degrees of haemodilution may not be followed by comparable changes in haemodynamics and O2-supply, depending on O2-unloading characteristics.