ISOLATED CAT HEAD PERFUSION BY DONOR DOG

Cerebral vascular resistance following platelet and leukocyte removal from perfusate

The rapid increases in cerebral vascular resistance (CVR) frequently observed during extracorporeal perfusion of isolated organs with whole or diluted blood have been investigated using the isolated canine brain preparation. Our data strongly suggest that these increases are caused by a vasoconstrictor that is present in the buffy coat. Plasma serotonin levels were measured and found to be insignificant after conditioning and storage. Conditioning the blood reduced the platelets and the potential for thromboxane A2 production to approximately 40% of normal. However, there was no correlation between thromboxane B2 levels and increases in CVR. Removal of the buffy coat effectively removed all of the leukocytes. Thus, one of the leukotrienes may have been responsible for the buffy coat-induced vasoconstriction.

The effect of shear, specific surface, and air interface on the development of blood emboli and hemolysis

Heparinized dog blood was exposed to shear and foreign surfaces in conicylindrical test cells. The cells were injection molded from polycarbonate and were filled using a technique that avoided contact of the blood with air. Particulate-matter formation was measured and was found to be dominated by the surface-to-blood-volume ratio and to be independent of shear rate. Hemolysis was also measured and was found to vary linearly with shear rate and to increase with increasing surface-to-blood volume ratio. Thus, at low shear rates and high specific surface conditions, the degree of hemolysis was found to be minimal while particulate-matter formation was high. The results suggest that the safety of extracoporeal perfusion procedures cannot be inferred from hemolysis measurements alone. In one series of tests, a gas-blood interface was generated at a rate equivalent to the rate of surface renewal in conventional disc oxygenators. The gas-blood interface failed to contribute significantly to the damage indices, which suggests that the apparent superiority of membrane oxygenators may be a result of factors other than the absence of a blood-gas interface.

Pulmonary microembolism after blood transfusion: an electron microscopic study

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