Abstract
Controlled ultrafiltration (UF) during hemodialysis may prevent dialysis associated hypotension. A prerequisite for controlled ultrafiltration is an accurate measurement of ultrafiltration. Volumetric measurement is the best currently available method for this purpose. In this study we compared in a clinical setting two volumetric ultrafiltration monitors (UFM): one device constructed in our hospital using oval flowmeters (UFM-N) and the other using electromagnetic flow transducers (UFM-G: UFM 10-2, Gambro Lund Sweden).
The UF measurements of both UFM's were compared with UF calculated from bedscales weight monitoring and standard scales determinations. During dual needle hemodialysis (n = 8) with a hollow fiber dialyzer the accuracy of the UFM-N was 91% and that of the UFM-G 97%. During dual needle dialysis with a parallel flow dialyzer the UFM-N appeared to be more sensitive for pulsatile changes in the dialysate flow due to the greater compliance of this type of dialyzer. The accuracy of the UFM-N in this setting was 80%, while that of the UFM-G was 87% (n = 11). During single needle dialysis with a parallel flow dialyzer (n = 14) only the UFM-G was tested and it measured UF with an accuracy of 92%. Finally the UFM-G can control UF actively by adjusting the TMP to obtain a given UF rate. The accuracy of the UFM-G in this setting was 94%, and the lineair regression correlation coefficient between planned UF and actually obtained UF was 0.974 (n - 61).
In conclusion volumetric monitoring of UF is accurate and reliable, but its accuracy is dependent on the type of dialyzer used. The UFM-G proved to be useful in every dialysis modality tested, while the UFM-N can be used in dual-needle dialysis using hollow fiber dialyzers.
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