Blood–membrane interaction in continuous renal replacement therapies

Abstract

The biocompatibility of membranes used in continuous renal replacement therapies is multifaceted, determined by the membrane's polymer composition and structure. It is characterized by the membrane's interaction with bloodborne humoral and cellular defense mechanisms, including complement, contact, and coagulation pathways, and mononuclear and granulocyte activation. Several clinical studies, although not conclusive, suggest that the use of membranes that minimize blood–membrane interaction is likely to improve overall outcome, including rate and degree of renal recovery. Along with the debate regarding the relative merits of continuous hemofiltration versus intermittent hemodialysis, the use of biocompatible versus bioincompatible membranes in the management of acute renal failure has been a contentious issue for a number of years. This debate has been fueled by the fact that until recently no study has conclusively shown a clinical benefit to using biocompatible membranes; this is despite the ever-increasing evidence that the membranes used for dialyzing or filtering human blood vary greatly in their biologic interaction. The purpose of this review is to briefly discuss the known interactions and to consider their impact in the clinical setting. Older membranes, such as cuprophane, are part of the scope of this paper because they are still used to manage acute renal failure in intensive care units around the world