Effects of haemodilution with fluorocarbons or dextran on oxygen tensions in the acutely ischaemic myocardium.

The effect of haemodilution with dextran or with oxygen transporting fluorocarbons (Fluosol-DA 20%) on myocardial oxygen tension (PmO2) during experimental myocardial ischaemia was studied in pigs. Polarographic oxygen microelectrodes were introduced 3 mm to the left ventricle wall and the distal one-third of the left anterior descending coronary artery (LAD) was occluded. Anaesthesia was maintained with 0.5% halothane in oxygen to ensure maximal oxygen content of the fluorocarbons. The animals were divided into three groups of five animals each. In group I no treatment was given and in groups II and III, after bleeding 20 ml kg-1, haemodilution was performed with Fluosol-DA 20% or 5% dextran respectively. Occlusion of the LAD caused no significant changes in cardiovascular vascular variables and only in group III (dextran) were significant effects of haemodilution observed. LAD occlusion caused highly significant decreases in PmO2. After haemodilution, PmO2 in the Fluosol group II (in contrast to groups I and III) was no longer significantly different from pre-occlusion values. After 5 h of occlusion, mean PmO2 in this group had returned to 92.2% of the pre-occlusion values, whereas in groups I and III it was 27.8% and 33.7%, respectively.