Does Monitoring of Pre-/Post-Dialyzer Pressure Difference Improve Efficiency in Intermittent Hemodialysis?

Abstract

Background: Continuous monitoring of pre-/post-dialyzer pressure difference (ΔP) is widely used in continuous renal replacement therapies to monitor extracorporeal circuit function. The aim of this study was to verify whether ΔP may help to identify chronic subclinical worsening of dialysis quality due to incomplete dialyzer clotting in intermittent hemodialysis. Methods: Nine chronic hemodialysis patients were enrolled in the study and dialyzed twice (high-flux polysulfone dialyzer) with ΔP and urea-clearance monitoring: the first session with a standard anticoagulation and the second without. To verify whether a visible clotting of the dialyzer precedes or follows a significant ΔP increase, we checked the dialyzers for the presence of red clots after a saline flush performed when a 50% increase in ΔP was registered. Results: In the second dialysis session after a 50% increase in ΔP (documented in 7/9 patients), all dialyzers, after saline flush, showed a visible fiber clotting but not a significant reduction (>15%) in urea clearance. In the majority of the patients (6/7), until a few minutes before complete occlusion of the extracorporeal circuit, the urea clearance did not change significantly (–8.9 ± 12.7%). Conclusions: The usual check of the presence or absence of red clots in the dialyzer at the end of the dialysis session is enough, in the absence of red clots, to ensure that dialyzer efficiency is maintained during the whole treatment. Contrary to what is applied in CRRT, a continuous monitoring of ΔP during intermittent hemodialysis would not significantly help to unmask unnoticed inefficient hemodialysis sessions.

Citrate- vs. acetate-based dialysate in bicarbonate haemodialysis: consequences on haemodynamics, coagulation, acid-base status, and electrolytes

“…Despite the rapid clearance of citrate, the local consequences of removing calcium from the blood clotting cascade have measurable positive effects on the dialyser life-span in the "reuse" modality and on dialysis quality, as quantified by urea Kt/V [1,3]. The improvement in urea clearance has been correlated with an assumed favourable effect on dialyser fibre permeability mediated by the intradialyser anticoagulant properties of citrate [1,3,8]. Considering the importance of limiting the biocompatibility-related coagulation activation taking place in the extracorporeal circuit [9-17], the availability of a simple way to inhibit it without affecting systemic coagulation and bleeding risk [18] is very promising.…”

Extracorporeal circuit pressure profiles during continuous venovenous haemofiltration

“…These pressures can be potentially used to provide notification that clotting has begun in the haemofilter or that the haemofilter has clotted. The utility of pre‐/post‐dialyzer pressure differences to monitor efficiency in intermittent haemodialysis has been reported (Gabutti et al , 2003), but reports of its use in CVVH are scarce. In this study, we investigated the pattern of circuit pressure changes during CVVH treatments.…”

Real-Time Circuit Pressures Correlate Poorly with Circuit Longevity in Anticoagulant-Free, Predilution Continuous Venovenous Hemofiltration

“…The filter transmembrane pressure rise was used to detect filter clotting, a significant rise of which was seen in the group on heparin anticoagulation alone [8]. A study of pre- versus post-dialyzer pressure differences in intermittent hemodialysis concluded that such differences could not significantly unmask subclinical clotting resulting in inefficient hemodialysis [12]. Although the earlier study by Ejaz et al [11] asserted that it is the pattern of change in pressures rather than absolute pressure values that predict circuit outcome, Holt et al [13] observed that transfilter pressure gradient rise of >26 mm Hg accurately predicted circuit failure in CVVHD with anticoagulation.…”