Title

Quantitative evaluation of blood-biomaterial interaction in hollow-fiber hemodialyser: In vitro vs in vivo

Date of Award

1995

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Mrinal K. Dewanjee, Committee Chair

Second Committee Member

Ned H. C. Hwang, Committee Member

Abstract

Prosthetic devices with large surface areas (oxygenators and hemodialyzers) consume circulating platelets by platelet thrombus formation, embolization, and platelet fragmentation. Protein adsorption and complement activation play an important role in this process. In previous studies, these parameters were evaluated using cumbersome techniques of scanning electron microscopy. The analysis of a representative surface for measurement of platelet density involved sampling errors, because the whole area of biomaterial under investigation could not be scanned. Also, the area of the test material used was small compared to the area of the connecting tube in the flow loop, giving a high signal to noise ratio.Although the dialyzer was the first successful artificial organ, platelet consumption by thrombus formation and embolization from the hemodialyzer were never quantified. In this dissertation, radioisotopic techniques, specifically $\sp{111}$In labeled platelets and neutrophils, and $\sp{125}$I labeled proteins were used to quantitate platelet, neutrophil and protein deposition on hemodialyzer. Effect of shear rate on cells and protein deposition has been quantified. Comparative thrombogenicity of platelets has been evaluated from three different species namely, canine, porcine and human blood.In order to analyze the effect of pulsatile flow and centrifugal flow on platelet deposition, studies were carried out with these flow configurations in vitro. Dynamics of deposition of platelets, neutrophils and proteins was studied by measuring the rate of deposition with a Geiger probe. Effect of shear rate on platelet fragmentation was measured by flow cytometry, and empirical equations have been developed to relate fragmentation and shear rate for pulsatile and centrifugal flow conditions.From the findings of the in vitro studies, an in vivo method for quantification of platelet deposition on the hemodialyzer and of emboli trapping in the organs has been developed, using Yorkshire pig as a model. The techniques used in this dissertation are potentially applicable to evaluate other blood contacting artificial devices, and a comparison between devices can be made, based on the quantitative results obtained from such studies.

Keywords

Engineering, Biomedical

Link to Full Text

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