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Impact of Ultrafiltration on Back‐Diffusion in Hemodialyzer
Author(s) -
WANIEWSKI JACEK,
LUCJANEK PIOTR,
Weryriski Andrzej
Publication year - 1994
Publication title -
artificial organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.684
H-Index - 76
eISSN - 1525-1594
pISSN - 0160-564X
DOI - 10.1111/j.1525-1594.1994.tb03346.x
Subject(s) - ultrafiltration (renal) , chemistry , renal function , diffusion , creatinine , filtration (mathematics) , chromatography , thermodynamics , mathematics , biochemistry , physics , statistics
Ultrafiltration of water from blood to dialysate decreases the rate of back–diffusion of solutes from dialysate to blood. Therefore, back–clearance ( bK ) of hemodialyzers may be expressed as bK = bK o – bTrQ u , where bK o is the diffusive back–clearance, bTr is the “back–”transmittance coefficient, and Qu is the net ultrafiltration rate. A formula for bK was derived from the one–dimensional theory of hemodialyzer, and bTr was described as a function of bK o and the Staverman reflection coefficient. The transport parameters, bK o and bTr , for creatinine and vitamin B 12 were measured in two types of hemodialyzers with negligible back–filtration, using water solutions, and compared with the transport parameters, K o and Tr , for the case of both diffusion and ultrafiltration from blood to dialysate. bK o was in general equal to K o . bTr was not different from Tr for creatinine whereas bTr was lower than Tr for vitamin B 12 . Experimental values of bTr for vitamin B 12 were in general agreement with theoretical predictions. However, experimental values of bTr for creatinine were lower than predicted values. We conclude that the impact of ultrafiltration on back–clearance for slowly diffusing solutes is weaker than on their clearance.