title: Simplified measurement of middle molecular toxin removal during continuous therapies.
abstract: The removal of middle molecules during continuous extracorporeal detoxification therapies is a scientific field of increasing attention. However, it is difficult to find suitable and inexpensive markers and methods regarding the in vitro clearance of molecules in a weight range between 10 and 20 kDa. We present an easy and reliable cytochrome C-based photometric method to compare the in vitro clearance of different hemofilters during hemodialysis therapy. Cytochrome C is an inexpensive globular protein that shows a relative absorption maximum at λ = 410 nm, allowing photometric concentration assessment in the dialysate outflow line. Various hemofilters were evaluated to assess the removal of cytochrome C during simulated continuous venovenous hemodialysis. Although reported sieving coefficients for globular proteins and surface area of all hemofilters were similar, clearance differences of up to 55% were observable at blood and dialysate flows of 150 ml/min and 4,000 ml/h, respectively. We found that even in a strict hemodialysis setting with moderate blood flow, a remarkable diffusive cytochrome C clearance can be achieved. Hereby, diffusion is eventually supported by transmembrane flow and backflow in the proximal and distal sections of the hollow fiber of a hemofilter.
authors.affiliation: Department of Physical Technology, RheinMain University, Ruesselsheim, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Lebau
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kleinekofort
mesh_terms: D000042:Absorption; D000818:Animals; D015415:Biomarkers; D001783:Blood Flow Velocity; D045304:Cytochromes c / Q000737:chemistry*; D015314:Dialysis Solutions; D004058:Diffusion; D006440:Hemofiltration / Q000379:methods*; D006736:Horses; D008970:Molecular Weight; D009206:Myocardium / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry; D010316:Particle Size; D010783:Photometry / Q000379:methods; D006435:Renal Dialysis / Q000379:methods*; D012995:Solubility; D013499:Surface Properties; D013696:Temperature; D001613:beta 2-Microglobulin / Q000737:chemistry
chemical_list: D015415:Biomarkers; D015314:Dialysis Solutions; D009211:Myoglobin; D001613:beta 2-Microglobulin; D045304:Cytochromes c