title: Influence of different heparin concentrations on the results of in vitro investigations in plasmaseparation technology using capillary membrane filters.
abstract: Capillary membrane filters are devices commonly used for plasmapheresis and recirculating detoxification systems, including plasmaseparation units. Besides clinical trials and case reports, research on plasmafiltration techniques is carried out using in vitro systems. Notably, such hemoperfused in vitro systems require anticoagulation protocols suitable for investigating the clearance performance and hemocompatibility of a plasmafilter. This study analyzes how different heparin concentrations affect filtration performance and the hemocompatibility under conditions typically employed during in vitro experiments. Porcine blood from healthy slaughtered animals was used in an in vitro circuit. The blood collecting system was primed with heparin. Depending on the study group, blood was anticoagulated with either 2.5 IU/ml or 5 IU/ml heparin. The filters were n=10 PF1000N (effective membrane surface: 0.15 m2). For each experiment, the maximal permissible flow rate was established by determining the point where spontaneous hemolysis occurred and/or pressure values exceeded the highest limit of the pressure units on the apheresis monitor. Sieving coefficients of ten parameters, platelet counts, and coagulation patterns were determined at the lowest and highest blood flow (Qb) and filtration rates (Qf). Except for the activated clotting time (ACT), both anticoagulation protocols caused the blood to respond to its exposition to the plasmafilters concerning the activation and inhibition of the coagulation system. A significant decrease in platelet counts did not occur. There were sporadic differences in sieving properties between the groups. However, heparinization with 2.5 IU/ml resulted in unreproducible flow rate profiles, and pressure levels were higher than in the group with 5 IU/ml heparin. Compared to heparinization at 2.5 IU/ml, higher levels of heparinization stabilize rheological properties of the blood, and thereby increase the reliability of data obtained from plasmafiltration experiments carried out in vitro.
authors.affiliation: Department of Anesthesiology, University Hospital, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany.
authors.forename: Juliane Katharina
authors.initials: JK
authors.lastname: Unger
authors.forename: Claudia
authors.initials: C
authors.lastname: Haltern
authors.forename: Bernd
authors.initials: B
authors.lastname: Dohmen
authors.forename: Rolf
authors.initials: R
authors.lastname: Rossaint
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000008:administration & dosage*; D001780:Blood Coagulation Tests; D005374:Filtration / Q000295:instrumentation*; D006400:Hematocrit; D018056:Hemorheology; D006493:Heparin / Q000008:administration & dosage*; D066298:In Vitro Techniques; D010956:Plasmapheresis / Q000295:instrumentation* / Q000379:methods; D010976:Platelet Count; D012212:Rheology; D013552:Swine
chemical_list: D000925:Anticoagulants; D006493:Heparin