SCREEN FILTRATION PRESSURE OF HOMOLOGOUS AND HETEROLOGOUS BLOOD AND ELECTROENCEPHALOGRAM

Recovery of the electrocorticogram of canine brains after complete cerebral ischaemia at 37 degrees and 32 degrees C

Complete cerebral ischemia was produced in totally isolated dog heads, perfused from a donor dog. The temperature of the isolated brain was kept constant before, during and after the complete ischaemia, at either 37 degrees C or 32 degrees C. At a brain temperature of 37 degrees C electrocortical potentials were found to reappear spontaneously as long as complete ischaemia did not exceed 50 min. In canine brains kept at a temperature of 32 degrees C no reappearance of spontaneous electrical activity occurred if ischaemia exceeded 100 min.

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.

The recovery of the electrocorticogram of normothermic canine brains after complete cerebral ischemia

Complete cerebral ischaemias of 1 to 30 min duration were performed under normothermic conditions in completely isolated canine heads perfused from a donor dog. The electrocorticogram was found to return in the reperfusion period following these complete ischaemias. The latency of recovery, i.e. the interval between the end of the complete cerebral ischaemia and the reappearance of the first cortical potentials, increased with increasing duration of the complete cerebral ischaemia; thus, the latency of recovery after a complete ischaemia of 30 min amounted to 11 to 12 hours.

Pulmonary microembolism after blood transfusion: an electron microscopic study

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Effect of dipyridamole on microaggregate formation in the pump oxygenator

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