Hydrodynamic analysis of the miniaturized hemofilter for a wearable ultrafiltration device

BACKGROUND/AIMS

Using a small wearable hemofiltration device, heart failure (HF) patients may have the possibility of eliminating acute hemodynamic changes and the freedom from spending many hours attached to a large stationary treatment system.

METHODS

We developed a miniaturized hemofilter for a vest-type wearable ultrafiltration device for the treatment of overhydration and congestive HF. In this study, we investigated the feasibility of the newly developed hemofilter based on dynamic CT imaging and in vitro evaluation of hydrodynamic properties.

RESULTS

The dynamic CT imaging technique showed development of uniform flow distribution and effective bubble removal in the hemofilter. Hydrodynamic performance of the hemofilter was also acceptable with a stable pressure drop in the blood compartment and ultrafiltration profiles in the intended operating ranges for the treatment of congestive HF patients.

CONCLUSIONS

The newly developed miniaturized hemofilter for a wearable ultrafiltration device meets the technical requirements of wearable medical devices and its structural design enables uniform blood flow distribution and stable hydrodynamics during operation.

Effect of fiber structure on dialysate flow profile and hollow-fiber hemodialyzer reliability: CT perfusion study

BACKGROUND

Uniform dialysate distributions in hollow-fiber hemodialyzers facilitate effective solute removal, and the fiber structure inside hemodialyzers plays a significant role in determining dialysate flow distribution and dialysis efficiency. The authors analyzed the effects of undulated fibers on dialysate flow profiles and hemodialyzer reliability using a perfusion CT technique.

METHOD

Using a multi-detector row CT unit, perfusion studies were performed on two different types of hemodialyzers: (A) straight fiber configuration; (B) undulated fiber configuration (wavy-shaped fibers). Deconvolution theory was used for image processing to derive dialysate flows, dialysate volumes, and mean transit time distributions. Three-dimensional perfusion maps for the two types of hemodialyzers were reconstructed using high resolution images and these parameters were compared at hemodialyzer midsections.

RESULTS

Dialysate maldistributions were observed in both types of hemodialyzer. However, dialysate flow distributions were more uniform in the undulated-fiber hemodialyzer, whereas more complex flow distributions developed in straight-fiber hemodialyzer. Reliability as determined using intraclass correlation coefficients was markedly higher for the hemodialyzer containing undulated fiber (0.968 vs. 0.496 for type A and type B, respectively).

CONCLUSIONS

The undulated-fiber type was found to have more uniform, consistent dialysate flow profiles. It is believed that this type of hemodialyzer will be found helpful for measurement and prescription of the delivered hemodialysis dose due to its better consistency.