Ultrafiltration and pressure profiles in continuous arterio-venous hemofiltration studied by computerized scintigraphic imaging
Ronco, C.; Lupi, A.; Brendolan, A.; Feriani, M.; Crepaldi, C.; La Greca, G.
International Journal of Artificial Organs 14(8): 457-462
1991
ISSN/ISBN: 0391-3988 PMID: 1937935 Document Number: 387168
Clotting of the filters in continuous arterio-venous hemofiltration (CAVH) has been frequently related to filtration pressure equilibrium (FPE). The geometry of the filter and the blood flow, together with filtration fraction, are the factors affecting FPE. A new method based on scintigraphic imaging of the filter is described to demonstrate FPE and identify the operational conditions influencing it. A radiolabelled marker molecule (albumin macroaggregates + Tc99) is added to the blood circulating at various flows through the filter. Changes in the concentration of this molecule detected by a gamma camera are used to calculate the water fluxes in different sections of the filter. When the curve reaches a plateau, no further changes occur and FPE is achieved. The study used Amicon D-30 hemofilters and FPE points were achieved for blood flows of 75, 110 and 150 ml/min respectively 8 cm, 12 cm and 18 cm from the inlet. The study not only demonstrates the occurrence of FPE, but also identifies the length of the filter required at a given blood flow to avoid FPE (achieving less clotting and lower heparin requirement). The Amicon diafilter family, having filters of different length, is useful for "personalizing" the filter in CAVH.