Avoidance of systemic anticoagulation during intermittent haemodialysis with heparin-grafted polyacrilonitrile membrane and citrate-enriched dialysate: a retrospective cohort study

Can regional anticoagulation with calcium-free dialysate be extended to maintenance hemodialysis?

BACKGROUND

Regional anticoagulation in hemodialysis avoids the use of heparin, which is responsible for both hemorrhagic and non-hemorrhagic complications. Typically, blood is decalcified by injecting citrate into the arterial line of the extracorporeal circuit. Calcium-free dialysate improves anticoagulation efficacy but requires injection of a calcium-containing solution into the venous line and strict monitoring of blood calcium levels. Recent improvements have made regional anticoagulation with calcium-free dialysate safer and easier.

OBSERVATIONS

(1) Adjusting the calcium injection rate to ionic dialysance avoids the risk of dyscalcemia, thus making unnecessary the monitoring of blood calcium levels. This adjustment could be carried out automatically by the hemodialysis monitor. (2) As calcium-free dialysate reduces the amount of citrate required, this can be supplied by dialysate obtained from currently available concentrates containing citric acid. This avoids the need for citrate injection and the risk of citrate overload. (3) Calcium-free dialysate no longer needs the dialysate acidification required for avoiding calcium carbonate precipitation in bicarbonate-containing dialysate.

CONCLUSIONS

Regional anticoagulation with calcium-free dialysate enables an acid- and heparin-free procedure that is more biocompatible and environmentally friendly than conventional bicarbonate hemodialysis. The availability of specific acid-free concentrates and adapted hemodialysis monitors is required to extend this procedure to maintenance hemodialysis.

Calcium-Free Dialysate Hemodialysis: A Simplified Approach

Intermittent hemodialysis (HD) in high-bleeding-risk patients presents a challenge as circuit anticoagulation using heparin is contraindicated in such cases. Recently, the use of calcium-free citrate-containing dialysate with calcium supplementation emerged as a viable alternative to heparin-circuit anticoagulation. This is a retrospective, monocentric study to evaluate dialysis efficacy using calcium-free citrate-containing dialysate with calcium reinjection into the venous line in hemodialysis patients at risk of bleeding. A total of 53 patients were analyzed: 52 had a temporary contraindication to systemic anticoagulation (active bleeding or surgical intervention), and 1 chronic HD patient had prolonged bleeding time due to inoperable arteriovenous fistula stenosis. Only 7 out of 79 dialysis sessions performed were prematurely terminated (vascular access dysfunction). The median dialysis time was 240 min (range: 150-300). The chronic dialysis patient had 108 sessions with no premature termination. Frequent monitoring of ionized calcium was performed throughout the dialysis sessions: levels remained stable at T0 and T + 60 min (1.08 ± 0.08 mmol/L) and slightly increased at the end of the dialysis session (1.19 ± 0.13 mmol/L), remaining within normal limits. Target postfilter ionized calcium <0.4 mmol/L was achieved in all sessions (0.31 ± 0.07 mmol/L). There were no cases of symptomatic hypo-/hypercalcemia and no need for calcium infusion rate adjustment throughout the sessions. Hemodialysis with calcium-free citrate-containing dialysate and calcium reinjection into the venous line is efficient and safe in HD patients with contraindications to systemic anticoagulation.

Avoiding Systemic Heparinization During Hemodialysis: How the Dialysis Setup Might Help

Heparin is the most widely used anticoagulant for maintaining patency of the extracorporeal blood circuit during intermittent hemodialysis. Inadvertently, this leads to systemic heparinization of the patient. Repeated intermittent heparinization during hemodialysis has been associated with increased bleeding risks and metabolic and immunologic effects. Alternative strategies for minimizing systemic anticoagulation encompass dilution methods, regional citrate anticoagulation, priming of the extracorporeal circuit, and modifications to dialyzer membranes and dialysate composition. The effectiveness of these alternatives in maintaining patency of the extracorporeal circuit varies substantially. Although most studies have focused on particular changes in the hemodialysis setup, several combined interventions for adapting the hemodialysis setup are now being studied. This narrative review aims to present an overview of the current landscape of hemodialysis setup strategies aimed at limiting or avoiding systemic anticoagulation during treatment. Additionally, this review intends to shed light on the underlying pathophysiological mechanisms that contribute to variations observed in reported outcomes.

Immunologic Effects of Heparin Associated With Hemodialysis: Focus on Heparin-Induced Thrombocytopenia

Intermittent hemodialysis (HD) is almost invariably performed with heparin, and thus HD patients are at risk of developing the immune-mediated adverse effect heparin-induced thrombocytopenia (HIT), caused by anti-platelet factor 4/heparin IgG, which strongly activates platelets. HIT patients develop hypercoagulability with greatly increased risk of thrombosis, both venous and arterial. Certain HIT-associated complications are more likely to develop among HD patients, including hemofilter thrombosis despite heparin, intravascular catheter and/or arteriovenous fistula-associated thrombosis, post-heparin bolus anaphylactoid/anaphylactic reactions, and thrombotic stroke and acute limb artery thrombosis (reflecting the high frequency of underlying arteriopathy in many patients with renal failure). Management of HIT in HD usually requires use of an alternative (non-heparin) anticoagulant; for example, danaparoid sodium (outside the USA) or argatroban (USA and elsewhere). Whether heparin-grafted hemodialyzers (without systemic heparin) can be used safely in acute HIT is unknown. The HIT immune response is remarkably transient and usually not retriggered by subsequent heparin administration. Accordingly, since renal failure patients often require long-term HD, there may be the opportunity-following seroreversion (loss of platelet-activating HIT antibodies)-to restart heparin for HD, a practice that appears to have a low likelihood of retriggering HIT.

Regional Citrate Anticoagulation: A Tale of More Than Two Stories

Calcium is a key clotting factor, and several inorganic molecules that bind to calcium have been found to reduce the clotting propensity of blood. Citrate, a calcium chelator, is used as inhibitor of the coagulation cascade in blood transfusion. Also, it is used as an anaticoagulant during dialysis to maintain patency of the extracorporeal circuit, known as regional citrate anticoagulation (RCA). The amount of citrate should be chosen such that ionized calcium concentrations in the extracorporeal circuit are reduced enough to minimize propagation of the coagulation cascade. The dialytic removal of the calcium-citrate complexes combined with reduced ionized calcium concentrations makes necessary calcium supplementation of the blood returning to the patient. This can be achieved in different ways. In classical RCA, citrate and calcium are infused in the afferent and efferent tubing, respectively, whereas the dialysate does not contain calcium. This setup has been shown to be highly efficacious with a very low clotting propensity. Strict monitoring of blood electrolytes is required. Alternatively, the use of a high-calcium dialysate leads to calcium loading, obviating the need for a separate calcium infusion pump. The main advantages are simplified delivery of RCA and less fluctuation of systemic calcium concentrations. Currently, citric acid is sometimes added to the acid concentrate as a replacement for acetic acid. Differences and similarities between RCA and citrate-containing dialysate are discussed. RCA is an excellent alternative to heparin for patients at high risk of bleeding.

Detection and Scoring of Extracorporeal Circuit Clotting During Hemodialysis

Maintaining patency of the extracorporeal hemodialysis (HD) circuit is a prerequisite to perform HD. Unfractionated heparin and low-molecular-weight heparins are the most used anticoagulants in maintenance HD, but their administration comes with a major trade-off of bleeding complications. This narrative review article discusses technical factors impacting on HD circuit patency, such as tubings, dialyzer membranes, priming practices, and treatment settings. Strategies for monitoring extracorporeal circuit clotting during and after treatment are also reviewed, as these are essential tools for optimizing anticoagulation.

Recent advances in dialysis membranes

PURPOSE OF REVIEW

Improvement in hemodialysis treatment and membrane technology are focused on two aims: the first one is to achieve a better control of circulating uremic solutes by enhancing removal capacity and by broadening molecular weight spectrum of solutes cleared; the second one is to prevent inflammation by improving hemocompatibility of the global dialysis system.

RECENT FINDINGS

Despite impressive progresses in polymers chemistry few hazards are still remaining associated with leaching or sensitization to polymer additives. Research has focused on developing more stable polymers by means of additives or processes aiming to minimize such risks. Membrane engineering manufacturing with support of nanocontrolled spinning technology has opened up membrane to middle and large molecular weight substances, while preserving albumin losses. Combination of diffusive and enhanced convective fluxes in the same hemodialyzer module, namely hemodiafiltration, provides today the highest solute removal capacity over a broad spectrum of solutes.

SUMMARY

Dialysis membrane is a crucial component of the hemodialysis system to optimize solute removal efficacy and to minimize blood membrane biological reactions. Hemodialyzer is much more than a membrane. Dialysis membrane and hemodialyzer choice are parts of a treatment chain that should be operated in optimized conditions and adjusted to patient needs and tolerance, to improve patient outcomes.

How biocompatible haemodialysers can conquer the need for systemic anticoagulation even in post-dilution haemodiafiltration: a cross-over study

Background

While systemic anticoagulation is most widely used in haemodialysis (HD), contraindications to its use might occur in particular settings. The Solacea^™ haemodialyser with an asymmetric triacetate membrane claims improved biocompatibility and has already shown promising results when used in combination with only half dose of anticoagulation. To quantify the performance of the Solacea^™ when further decreasing anticoagulation to zero, fibre blocking was assessed by micro-computed tomography (micro-CT).

Methods

Ten maintenance HD patients underwent six dialysis sessions at midweek using a Solacea^™ 19H dialyser, consecutively in pre-dilution haemodiafiltration (pre-HDF), HD and post-dilution HDF (post-HDF). After the first three sessions with only a quarter of their regular anticoagulation dose (one-quarter), the last three sessions were performed without anticoagulation (zero). Dialyser fibre blocking was quantified in the dialyser outlet potting using a 3D micro-CT scanning technique post-dialysis.

Results

Even in case of reduced (one-quarter) anticoagulation, the relative number of open fibres post-dialysis was almost optimal, i.e. 0.96 (0.87-0.99) with pre-HDF, 0.99 (0.97-0.99) with HD and 0.97 (0.92-0.99) with post-HDF. Fibre patency was mildly decreased for pre-HDF and HD when anticoagulation was decreased from one-quarter to zero, i.e. to 0.76 (0.61-0.85) with pre-HDF (P = 0.004) and to 0.80 (0.77-0.89) with HD (P = 0.013). Comparing the results for zero anticoagulation, post-HDF [i.e. 0.94 (0.82-0.97)] performed as well as HD and pre-HDF.

Conclusions

The Solacea^™ dialyser provides promising results for use in conditions where systemic anticoagulation is contraindicated. Post-HDF, although inducing haemoconcentration in the dialyser, is equally effective for fibre patency in case of zero anticoagulation as pre-HDF and HD when using Solacea^™.

Dialyzer Performance During Hemodialysis Without Systemic Anticoagulation Using a Heparin-Grafted Dialyzer Combined With a Citrate-Enriched Dialysate: Results of the Randomized Crossover Noninferiority EvoCit Study

RATIONALE & OBJECTIVE

The EvoCit study was designed to evaluate performance of a heparin-grafted dialyzer during hemodialysis with and without systemic anticoagulation.

STUDY DESIGN

Randomized, crossover, noninferiority trial. Noninferiority was defined as a difference of≤10% for the primary outcome.

SETTING & PARTICIPANTS

Single hemodialysis center; 26 prevalent patients treated with 617 hemodialysis sessions.

INTERVENTIONS

Hemodialysis using a heparin-grafted dialyzer combined with a 1.0mmol/L citrate-enriched dialysate ("EvoCit") without systemic anticoagulation compared with hemodialysis performed with a heparin-grafted dialyzer with systemic heparin ("EvoHep"). Patients were randomly allocated to a first period of 4 weeks and crossed over to the alternative strategy for a second period of 4 weeks.

OUTCOMES

The primary end point was the difference in Kt/V_urea between EvoCit and EvoHep. Secondary end points were urea reduction ratio, middle molecule removal, treatment time, thrombin generation, and reduction in dialyzer blood compartment volume.

RESULTS

The estimated difference in Kt/V_urea between EvoCit and EvoHep was-0.03 (95% CI, -0.06 to-0.007), establishing noninferiority with mean Kt/V_urea of 1.47±0.05 (SE) for EvoCit and 1.50±0.05 for EvoHep. Noninferiority was also established for reduction ratios of urea and β₂-microglobulin. Premature discontinuation of dialysis was required for 4.2% of sessions among 6 patients during EvoCit and no sessions during EvoHep. Effective treatment time was 236±5 minutes for EvoCit and 238±1 minutes for EvoHep. Thrombin generation was increased and there was greater reduction in dialyzer blood compartment volume after treatments with EvoCit compared with EvoHep.

LIMITATIONS

The effects of avoiding systemic anticoagulation on clinical outcomes were not evaluated.

CONCLUSIONS

EvoCit is noninferior to EvoHep with respect to solute clearance but results in a greater number of shortened treatments, more membrane clotting, and greater thrombin generation TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT03887468.

Timed Controlled Repeated Rotation of the CAR-170-C NXSTAGE Chronic Cartridge Hemodialysis Filter: A Novel Approach to Enabling Heparin-Free Frequent Daily Home Hemodialysis

Heparin-free hemodialysis is often warranted in postoperative states, bleeding diathesis, and critically ill patients. Conventionally, this is achieved through normal saline flushes or regional citrate anticoagulation. An 87-year-old white man with end-stage renal disease and atrial fibrillation, who was taking warfarin and using maintenance home hemodialysis (HHD) with an NxStage machine, underwent laparoscopic appendicectomy. The procedure was complicated by intra-abdominal abscess, sepsis, and tamponade from a bloody pericardial effusion. He needed emergent therapeutic pericardiocentesis. Warfarin was promptly discontinued. He was discharged home with heparin-free HHD. Prior heparin anticoagulation for HHD was an initial bolus of 4000 units of heparin. He continued to clot his extracorporeal system with resultant very high venous pressures and compromised HHD. Heparin anticoagulation was still contraindicated. Flushes with 250-500 mL normal saline, delivered in aliquots every 15-30 minutes, failed to prevent the frequent clotting. The first author, our HD Senior Technician, had astutely observed that the horizontally placed hemodialysis filter exhibited early “clot” formation at the 12-o’clock position, despite the saline flushes. Through trial and error, he discovered that rotating the horizontally placed hemodialysis filter along its long axis, 60 degrees clockwise for 15 minutes, return to the neutral position for 15 minutes, rotating the filter another 60 degrees counterclockwise for 15 minutes, with this repeated cycle of rotations “did the trick.” It promptly and consistently resolved the clotting problem. The lines stopped clotting, and he has not needed saline flushes for smooth heparin-free HHD for more than 7 months. To our knowledge, this is the first such report. Further study is justified. We have hypothesized a mechanism and have named this the “Locke-Onuigbo Maneuver.”

Updates on hemodialysis techniques with a common denominator: The personalization of the dialytic therapy

Hemodialysis (HD) is a life-saving therapy for patients with end-stage renal disease. In dialyzed patients, the prevalence of multi-morbidity is rising driven by various factors, such as the population aging, the incomplete correction of uremia, and the side effects of the dialysis therapy itself. Each dialyzed patient has their own specific clinical and biochemical problems. It is therefore unthinkable that the same dialysis procedure can be able to meet the needs of every patient on chronic dialysis. We have very sophisticated dialysis machines and different dialysis techniques and procedures beyond conventional HD, such as hemodiafiltration (HDF) with pre- and post-dilution, acetate-free biofiltration (AFB), hemofiltration (HF), and expanded HD. Each of these techniques has its own specific characteristics. To solve some intradialytic clinical issues, such as arterial hypotension and arrhythmias, we have biofeedback systems with automatic regulation of the blood volume, body temperature, arterial pressure, as well as potassium profiling techniques in the dialysis bath. New technical innovations, such as citrate-containing dialysate or heparin-coated membranes, could reduce the risk of bleeding. To better address to patient needs, the strengths and weaknesses of each of these systems must be well-known, in order to have a personalized dialysis prescription for each patient.

Long-term mortality risk associated with citric acid- and acetic acid-based bicarbonate haemodialysis: a historical cohort propensity score-matched study in a large, multicentre, population-based study

Background

Citric acid-based bicarbonate dialysate (CiD) is increasingly used in haemodialysis (HD) to improve haemodynamic tolerance and haemocompatibility associated with acetic acid-based bicarbonate dialysate. Safety concerns over CiD have been raised recently after a French ecological study reported higher mortality hazard in HD clinics with high CiD consumption. Therefore, we evaluated the mortality risk associated with various acidifiers (AcD, CiD) of bicarbonate dialysate.

Methods

In this multicentre, historical cohort study, we included adult incident HD patients (European, Middle-East and Africa Fresenius Medical Care network; 1 January 2014 to 31 October 2018). We recorded acidifiers of bicarbonate dialysis and dialysate composition for each dialysis session. In the primary intention-to-treat analysis, patients were assigned to the exposed group if they received CiD in &gt;70% of sessions during the first 3 months (CiD70%), whereas the non-exposed group received no CiD at all. In the secondary analysis, exposure was assessed on a monthly basis for the whole duration of the follow-up.

Results

We enrolled 10 121 incident patients during the study period. Of them, 371 met the criteria for inclusion in CiD70%. After propensity score matching, mortality was 11.43 [95% confidence interval (CI) 8.86–14.75] and 12.04 (95% CI 9.44–15.35) deaths/100 person-years in the CiD0% and CiD70% groups, respectively (P = 0.80). A similar association trend was observed in the secondary analysis.

Conclusions

We did not observe evidence of increased mortality among patients exposed to CiD in a large European cohort of dialysis patients despite the fact that physicians were more inclined to prescribe CiD to subjects with worse medical conditions.

A randomized cross-over study with objective quantification of the performance of an asymmetric triacetate and a polysulfone dialysis membrane using different anticoagulation strategies

Background

Different strategies can be used to counteract coagulation of extracorporeal systems. Systemic anticoagulation is most widely used in routine clinical practice, but can be contraindicated in specific settings. The Solacea^™ dialyser, containing the asymmetric triacetate membrane, claims improved biocompatibility, which should result in decreased tendency for coagulation. We quantified the performance of the Solacea^™ versus the FX800CORDIAX dialyser regarding resistance to fibre blocking as assessed by micro-computed tomography (CT).

Methods

This cross-over study with four arms randomized consecutively 10 maintenance haemodialysis patients to a 4-h post-dilution haemodiafiltration session at midweek, using either Solacea^™ 19 H or FX800CORDIAX, with either regular or half dose of anticoagulation (EC2017/1459-NCT03820401). Dialyser fibre blocking was visualized in the dialyser outlet potting using a 3D CT scanning technique on micrometre resolution. Extraction ratios of middle molecules [myoglobin, lambda and kappa free light chains (FLCs)] were determined.

Results

The relative number of open fibres post-dialysis was lower in FX800CORDIAX versus Solacea^™ dialyser, and this was irrespective of the anticoagulation dose used or the threshold for counting open fibres. Extraction ratios of FLCs were not different at regular anticoagulation between Solacea^™ and FX800CORDIAX (21% ± 4% for kappa and 32% ± 8% for lambda with Solacea^™ versus 23% ± 7% and 38% ± 6% for FX800CORDIAX), but were superior with the Solacea^™ (34% ± 12% versus 22% ± 8% with FX800CORDIAX; P = 0.02) for myoglobin in case of halving anticoagulation dose. No clinically relevant albumin loss was detected.

Conclusions

The Solacea^™ dialyser seems to be promising for use in conditions where systemic anticoagulation is contraindicated, as even under conditions of low systemic anticoagulation, virtually no signs of fibre blocking could be observed using the sensitive micro-CT scanning technique. This finding is in line with its presumed good performance in terms of biocompatibility.

An evaluation of four modes of low-dose anticoagulation during intermittent haemodialysis

Introduction

Intensive care participants that need dialysis frequently suffer from increased risk of bleeding. Standard intermittent haemodialysis (SHD) includes anticoagulation to avoid clotting of the dialysis system. The aim of this study was to clarify which of four different low-dose anticoagulant modes was preferable in reducing the exposure to i.v. unfractionated heparin (heparin) and maintaining patency of the dialysis circuit.

Methods

Twenty-three patients on SHD were included to perform haemodialysis with four modes of low-dose anticoagulation. For comparative analyses, patients served as their own control. Haemodialysis with a single bolus of tinzaparin at the start was compared to haemodialysis initiated without i.v. heparin but priming with (1) heparin in saline (H), (2) heparin and albumin in saline (HA), (3) heparin and albumin in combination with a citrate-containing dialysate (HAC), (4) saline and usinga heparin-coated filters (Evodial®). The priming fluid was discarded before dialysis started. Blood samples were collected at 0, 30 and 180 min during haemodialysis. Smaller bolus doses of heparin (500 Units/dose) were allowed during the modes to avoid interruption by clotting.

Findings

The mean activated partial thromboplastin (APTT) time as well as the doses of anticoagulation administered was highest with SHD and least with HAC and Evodial®. Mode H versus SHD had the highest rate of prematurely interrupted dialyses (33%, p = 0.008). The urea reduction rate was less with Evodial® vs. SHD (p < 0.01). One hypersensitivity reaction occurred with Evodial®. Changes in blood cell concentrations and triglycerides differed between the modes.

Discussion

If intermittent haemodialysis is necessary in patients at risk of bleeding, anticoagulation using HAC and Evodial® appeared most preferable with least administration of heparin, lowest APTT increase and lowest risk for prematurely clotted dialyzers in contrast to the least plausible H mode.

Electronic supplementary material

The online version of this article (10.1007/s00228-017-2389-x) contains supplementary material, which is available to authorized users.

Heparin-Free Prolonged Intermittent Hemodialysis Using Calcium-Free Citrate Dialysate in Critically Ill Patients

OBJECTIVES

Critically ill patients who have a high risk of bleeding but require prolonged intermittent dialysis need a heparin-free easy-to-use alternative type of anticoagulation within the dialysis circuit. We assessed the safety and efficiency of heparin-free regional citrate anticoagulation of the dialysis circuit using a calcium-free citrate-containing dialysate, with calcium reinjected according to ionic dialysance.

DESIGN

Prospective cohort study.

SETTING

Critical care units.

PATIENTS

Critically ill patients who required renal replacement therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 101 dialysis sessions were performed in 35 patients (mechanical ventilation n = 78; norepinephrine n = 13). Median duration of dialysis was 294 minutes (interquartile range, 240-300), and median ultrafiltration volume was 2.3 L (1-2.8). Urea and β2-microglobulin reduction rates were 64.5% ± 0.4% and 48% ± 0.13%, respectively. Postfilter ionized calcium was 0.35 ± 0.17 and 0.38 ± 0.14 mmol/L at 1 and 3 hours, respectively, within the extracorporeal circuit. A major clotting event that led to premature termination of the session occurred in only three of 101 sessions. In these three cases, major catheter dysfunction occurred before clotting within the circuit. Prefilter ionized calcium remained within narrow ranges (before/after change +0.07 ± 0.006 mmol/L), and total-to-ionized calcium ratio, a surrogate marker for citratemia, was unchanged.

CONCLUSIONS

Dialysis anticoagulation with calcium-free citrate-containing dialysate and calcium reinjection according to ionic dialysance is an easy-to-use, efficient, and inexpensive form of heparin-free regional anticoagulation. It allows prolonged hemodialysis sessions in critically ill patients without the need to systemically monitor ionized calcium. Furthermore, sessions can be safely extended according to the hemodynamic tolerance to ensure an adequate dose of dialysis and a negative water balance, a major point in patients with severe acute kidney disease.

A noninferiority trial comparing a heparin-grafted membrane plus citrate-containing dialysate versus regional citrate anticoagulation: results of the CiTED study

Background

Anticoagulation is a prerequisite for successful haemodialysis. Heparin and low-molecular weight heparins are routinely used despite increased bleeding risk. Regional citrate anticoagulation (RCA) is efficacious, but is laborious and may induce metabolic disturbances. Heparin-grafted membranes are less efficacious. It is not known whether combining citrate-containing dialysate and a heparin-grafted membrane is a valid anticoagulation strategy.

Methods

We performed a randomized crossover noninferiority trial, with a prespecified noninferiority threshold of 10% in maintenance dialysis patients ( n  = 25). We compared the combination of citrate-containing dialysate plus a heparin-grafted membrane [CiTrate and EvoDial (CiTED) protocol] with RCA. The primary endpoint was completion of dialysis without significant clotting. Secondary endpoints included time to clotting, achieved Kt / V urea , loss of total cell volume, venous air chamber clotting score and systemic-ionized calcium concentration.

Results

In total, 1284 sessions were performed according to study protocol, 636 in the CiTED arm and 648 in the RCA arm. The primary outcome of preterm interruption due to clotting occurred in 36 (5.7%) of sessions in the CiTED arm, and in 40 (6.2%) sessions in the RCA arm, thereby meeting noninferiority criteria (P < 0.0001). Most of the clotting events occurred in the fourth hour of dialysis. Repetitive clotting occurred in four patients in the CiTED arm and one patient in the RCA arm. Time to preterm interruption due to clotting and achieved Kt / V urea was not significantly different. Systemic-ionized calcium levels during treatment were significantly lower in the RCA arm and clinically relevant hypocalcaemia was noted only in the RCA arm.

Conclusion

The combination of citrate-containing dialysate and a heparin-grafted membrane is a valid alternative to RCA.

Comparison of the AN69ST Membrane versus Citrate-Enriched Dialysate on Clotting Events during Hemodialysis without Systemic Anticoagulation

BACKGROUND

The optimal management of anticoagulation in hemodialyzed patients with a high risk of bleeding is controversial.

METHODS

We compared premature termination of dialysis caused by clotting events between AN69ST membranes (G1) and 0.8 mmol/L citrate-enriched dialysate (G2). The number of sessions that had increased venous pressure (VP) and variations in urea-reduction ratio (URR) were analyzed.

RESULTS

Six hundred and two sessions were analyzed in 259 patients: 22.4% had sessions that ended prematurely (25% in G1 and 19.1% in G2, p = ns, OR 0.60 [0.34-1.08], p = 0.08). The increase in VP was lower in G2 (23 vs. 70, p < 0.001). URR was higher in G2 (0.56 vs. 0.60, p < 0.001).

CONCLUSION

Clotting events that led to the termination of dialysis were comparable in the 2 groups. However, UUR was better in G2, and the number of patients with increased VP in the sessions was lower in G2.

SHORT SUMMARY

Our study compared the effects of the AN69ST membrane and citrate-enriched dialysate on clotting events during the dialysis of 259 patients with a high risk of bleeding. URR was significantly better and fewer cases of increased VP occurred in the citrate group compared to the AN69 ST group. No significant difference was observed regarding the need to prematurely terminate a dialysis session.

Cardiovascular disease in haemodialysis: role of the intravascular innate immune system

Haemodialysis is a life-saving renal replacement modality for end-stage renal disease, but this therapy also represents a major challenge to the intravascular innate immune system, which is comprised of the complement, contact and coagulation systems. Chronic inflammation is strongly associated with cardiovascular disease (CVD) in patients on haemodialysis. Biomaterial-induced contact activation of proteins within the plasma cascade systems occurs during haemodialysis and initially leads to local generation of inflammatory mediators on the biomaterial surface. The inflammation is spread by soluble activation products and mediators that are generated during haemodialysis and transported in the extracorporeal circuit back into the patient together with activated leukocytes and platelets. The combined effect is activation of the endothelium of the cardiovascular system, which loses its anti-thrombotic and anti-inflammatory properties, leading to atherogenesis and arteriosclerosis. This concept suggests that maximum suppression of the intravascular innate immune system is needed to minimize the risk of CVD in patients on haemodialysis. A potential approach to achieve this goal is to treat patients with broad-specificity systemic drugs that target more than one of the intravascular cascade systems. Alternatively, 'stealth' biomaterials that cause minimal cascade system activation could be used in haemodialysis circuits.

Citrate-Buffered Dialysis Solution (Citrasate) Allows Avoidance of Anticoagulation During Intermittent Hemodiafiltration-At the Cost of Decreased Performance and Systemic Biocompatibility

Reportedly, citrate-based dialysis solution enables heparin dose tapering or even complete exclusion, particularly in postdilution hemodiafiltration (HDF). The aim of the study was to verify this strategy in predilution setting and to assess its short-term safety, efficacy, and biocompatibility. Ten regular hemodialysis patients were assigned to predilution HDF on acetate- and citrate-based dialysis solutions (0.8 mmol/l trisodium citrate) at random order. Acetate HDF was performed using routine dose of heparin while citrate HDF was heparin free. Plasma calcium, thrombin-antithrombin complexes (TAT), and citrate levels were measured at 0, 30, 60, 120, and 240 min. Following each session, a semiquantitative dialyzer clotting score (DCT 1-5) was assessed and HDF adequacy was determined as spKt/V. Statistical relevance was tested by ANOVA with pP < 0.05 held significant, data are given as means ± standard deviations. All sessions were accomplished successfully, premature termination or circuit re-setting was not necessary. However, DCT was significantly higher in citrate-HDF compared to acetate-HDF regimen (3.4 ± 0.65 and 1.8 ± 0.79, respectively, P = 0.002) as well as TAT generation rate (increase per session by factor 11.0 ± 8.43 and 2.1 ± 1.26, respectively, P = 0.004 between regimens). Ionized calcium declined only by the end of citrate-HDF (from 1.09 ± 0.086 to 0.99 ± 0.030 mmol/L, P = 0.002) yet without accompanying clinical symptoms. Systemic citrate levels increased along the citrate-HDF session but stayed an order of magnitude below concentrations needed to establish citrate anticoagulation (peak at 0.276 ± 0.112 mmol/L). Dialysis adequacy estimated by spKt/V was found lower in citrate-HDF vs. acetate-HDF (1.48 ± 0.163 and 1.58 ± 0.165, respectively, P = 0.006). Although predilution HDF using citrate-based dialysate is feasible without heparin, both dialysis adequacy and biocompatibility is significantly compromised. Therefore, this approach can be adopted for a single procedure but is not acceptable on a regular basis.

Is Anticoagulation Discontinuation Achievable with Citrate Dialysate during HDF Sessions?

Citrate dialysate has been developed for few years to replace acetate and HCl concentrates. In Online Postdilution Hemodiafiltration (OL-POST-HDF), several issues are remaining concerning the possibility of stopping anticoagulation during sessions and the side effects of citrate solutions on calcium metabolism. This 1-year monocentric retrospective study included all patients exposed to citrate in OL-POST-HDF with nadroparin decrease for more than one month. Clotting events, serum calcium, PTH, hemoglobin, CRP, depuration parameters, and treatments administrated were recorded for analysis. 27 patients experienced nadroparin decrease and 5 did not receive nadroparin at the end of the study. Nadroparin decrease and withdrawal were both associated with more clotting events whereas the use of vitamin K antagonists was protective. No significant metabolic side effects were observed. Citrate dialysate does not allow anticoagulation discontinuation or decrease but has no significant side effects on mineral bone metabolism or erythropoiesis.

Inpatient citrate-based hemodialysis in pediatric patients

BACKGROUND

Citrate-based dialysate is an effective method of hemodialysis (HD) anticoagulation in adults. The objective of this study was to evaluate this therapy as an alternative to heparin anticoagulation in pediatric patients in the inpatient setting requiring HD.

METHODS

We performed a prospective, non-randomized study of citrate-based dialysate HD treatments (N = 119) over a 9-month period in 18 pediatric patients (age range 0-18 years) admitted to hospital. Primary outcome measures were thrombosis incidence rates that resulted in circuit loss, catheter loss or early dialysis termination. Secondary outcome measures were hypocalcemia incidence and heparin use. Data analysis was performed using descriptive and comparative statistics.

RESULTS

There was a thrombosis incidence rate of 2.5 % circuit loss, 2.5 % catheter loss and 5.9 % early dialysis termination due to the thrombosis risk. In 64 % of treatments a circuit clot developed but with no circuit loss, and mild asymptomatic hypocalcemia deveoped in 58 % of the monitored HD sessions . No patient required additional heparin during the citrate-based HD treatments, but 11.1 % were subsequently converted to heparin anticoagulation.

CONCLUSIONS

Our study showed a low percentage of thrombotic episodes resulting in catheter or circuit loss. Hypocalcemia was common but remained mild and asymptomatic. Citrate-based dialysate was well tolerated by our patients. We therefore conclude that citrate-based dialysate is a safe alternative to heparin-based hemodialysis anticoagulation.

Functionalized MWCNTs in improving the performance and biocompatibility of potential hemodialysis membranes

Functionalized multi-walled carbon nanotube incorporated polyetherimide mixed matrix membranes for blood purification application.

Effects of citrate dialysate in chronic dialysis: a multicentre randomized crossover study

BACKGROUND

Although citrate dialysate (CiDi) is regarded to be safe, dialysis modalities using higher dialysate volumes, like haemodiafiltration (HDF), may expose patients to higher citrate load and thus increase the risk of complications. We investigated the residual risk of CiDi compared with standard dialysate (StDi) in patients on different dialysis modalities and its effect on dialysis dose.

METHODS

In a multicentre randomized crossover study, 92 dialysis patients (HDF post-dilution: n = 44, HDF pre-dilution: n = 26, haemodialysis: n = 25) were treated for 4 weeks with each dialysate (StDi and CiDi). Hypocalcaemia (ionized calcium ≤0.9 mmol/L), alkalosis (pH ≥7.55), post-treatment bicarbonate ≥32 mmol/L, pre-treatment bicarbonate ≥27 mmol/L, intra-dialytic events (IEs) and adverse events (AEs) between dialysis sessions were investigated as primary end points. The secondary objective was dialysis efficacy, i.e. dose and removal ratios of urea, creatinine, phosphate and β-2-microglobulin.

RESULTS

Post-dialysis overcorrection of bicarbonate (>32 mmol/L) was less frequent with CiDi (P = 0.008). Other predefined calcium and acid-base disturbances did not vary. There was no significant difference in IE. However, more patients developed AEs such as fatigue, muscle spasms or pain using CiDi (StDi: 41 versus CiDi: 55 patients, P = 0.02), particularly in the first 2 weeks of exposure. Dialysis efficacy was comparable with both dialysates.

CONCLUSIONS

It can be confirmed that CiDi is not associated with the development of severe calcium and acid-base disorders, even when dialysis modalities with higher citrate loads are used. However, a refinement of the CiDi composition to minimize AEs is necessary.