Blood lines should be considered in studies of biocompatibility during acetate haemodialysis.

In this one-year prospective study, the biocompatibility of blood lines used for acetate haemodialysis treatment was evaluated in 12 patients. These blood lines, polyvinyl chloride (PVC) and polyurethane extruded PVC (PE) respectively were compared in a schedule of four alternating three-month periods of treatment: PVC/PE/PVC/PE. White blood cell count, complement, IgE and thromboxane values were recorded monthly. A reduction in white blood cell and polymorphonuclear counts after 30 minutes of dialysis was significantly less during period 2 than period 1. Pre-dialysis eosinophil counts varied in a seasonally dependent pattern. We conclude that in spite of their small area, blood lines have some effect on biocompatibility and that the season of the year has to be considered in biocompatibility studies involving eosinophils.