Removal of Avitene microfibrillar collagen hemostat by use of suitable transfusion filters.

We assessed the ability of two commercial filters (Pall RC100 and Statlabs 20 microns) to filter out Avitene microfibrillar collagen hemostat from suspension. Quantitative determination of the collagen content as well as scanning electron and light microscopy, particle counting, and platelet aggregometry of filtrates revealed that these filters effectively remove potentially thrombogenic particles of Avitene microfibrillar collagen hemostat. The filters removed at least 97% of the total collagen, as determined by hydroxyproline analysis. The collagen that passed through the Pall filter did not pellet upon ultracentrifugation. Scanning electron and light microscopic analysis revealed no Avitene microfibrillar collagen hemostat particulates in the Pall filtrates but did reveal the presence of a significant number of approximately 1- to 8-microns particulates in the Statlabs filtrates. Concentrates of the filtrates from either of the two filters, however, did not promote platelet aggregation. Through ultracentrifugation and infrared analysis, the filtrates were found to consists of soluble, partially denatured collagen. The risk associated with the reintroduction of collagen particulates into the vasculature can be significantly reduced by use of appropriate, currently available blood-transfusion filters.