Regional citrate anticoagulation in hemodialysis: an observational study of safety, efficacy, and effect on calcium balance during routine care

Hemodialysis without Systemic Anticoagulation: A Randomized Controlled Trial to Evaluate Five Strategies in Patients at a High Risk of Bleeding

BACKGROUND

There has been growing interest in exploring combined interventions to achieve a more effective heparin-free treatment approach.

AIM

to evaluate combination of interventions compared to standard practice (intermittent flushes) to prevent clotting and consequently reduce premature interruptions of hemodialysis.

METHODS

This open-label randomized controlled trial recruited chronic hemodialysis patients with contra-indication to systemic heparinization. Participants were randomized into one of five groups to receive different strategies of heparin-free hemodialysis treatment for up to three sessions.

PRIMARY ENDPOINT

the successful completion of hemodialysis without clotting.

SECONDARY OUTCOMES

the clotting of the air traps assessed by a semi-quantitative scale, online KT/V, and safety of the interventions.

RESULTS

Forty participants were recruited and randomized between May and December 2020. Participants showed similar baseline biochemistry results and coagulation profiles. The highest success rates were observed in group 3 (heparin-coated dialyzers combined with intermittent flushes) (100%) and group 5 (hemodiafiltration with online predilution combined with heparin-coated dialyzers), with 91% vs. the control (intermittent flushes) (64%). Group 2 (heparin-coated dialyzers alone) had the poorest success rate, with 38% of the sessions being prematurely terminated due to clotting. KT/V and clotting scores were similar between groups. No adverse events related to the trial interventions were observed.

CONCLUSIONS

The proposed combination of interventions may have had additive effects, leading to less frequent clotting and the premature termination of an HD/HDF session. Our study supports the feasibility of conducting a larger randomized controlled trial focusing on the efficacy of combined interventions for heparin-free HD in patients with a high risk of bleeding.

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.

Heparin anticoagulation versus regional citrate anticoagulation for membrane therapeutic plasma exchange in patients with increased bleeding risk

Background Heparin anticoagulation (HA) is commonly employed for membrane therapeutic plasma exchange (mTPE). However, for patients with increased bleeding risk, there were controversial opinions on the use of HA versus regional citrate anticoagulation (RCA) for mTPE. Our present study aimed to evaluate the efficacy and safety of HA vs. RCA for mTPE in patients with increased bleeding risk.Methods Patients with increased bleeding risk who underwent mTPE between 2014 and 2021 in our center were screened. Observations of anticoagulation efficacy and safety were used as the study endpoints.Results A total of 108 patients with 368 mTPE sessions were included. Of the included patients, 38 and 70 received HA and RCA mTPE, respectively. There was no significant difference in the clotting of extracorporeal circuits between the HA and RCA groups (4.1% vs. 4.4%, p = 0.605). More bleeding episodes were observed in the HA group compared to the RCA group (16.4% vs. 4.4% mTPE sessions, p < 0.001). The frequency of postoperative transfusion within 24 h (11% vs. 3.4%, p = 0.007) was significantly different in the HA and RCA group. Anticoagulation strategy (HA vs. RCA; OR 5.659, 95%CI 2.266-14.129; p < 0.001), and mean arterial pressure (prior treatment, OR 1.052, 95%CI 1.019-1.086; p = 0.002) were independent risk factors of bleeding episodes. At the end of mTPE treatment, the incidence of metabolic alkalosis (16.7% vs. 54.1%, p = 0.027) and hypocalcemia (41.7% vs. 89.2%, p = 0.001) was significantly different in the HA (n = 5, 12 sessions) and RCA (n = 22, 74 sessions) groups, respectively.Conclusion RCA is as effective as HA for mTPE. However, for patients with increased bleeding risk, RCA is associated with a lower risk of bleeding, compared with HA. With careful monitoring and timely adjustment, RCA most likely is a safe and effective anticoagulation option for mTPE in patients with increased bleeding risk.

Acute kidney injury and renal replacement therapy: terminology standardization

The Department of Acute Kidney Injury (IRA) of the Brazilian Society of Nephrology prepared this document for the purpose of standardizing AKI terminology and dialysis modalities in the Portuguese language for Brazil. Several terms with similar meanings have been used in AKI and its dialysis modalities, causing confusion and disparities among patients, nephrologists, health institutions, private care companies, insurance companies and government entities. These disparities can impact medical care, hospital organization and care, as well as the funding and reimbursement of AKI-related procedures. Thus, consensual nomenclature and definitions were developed, including the definitions of AKI, acute kidney disease (AKD) and chronic kidney disease (CKD). Additionally, we addressed all dialysis modalities and extracorporeal procedures related to AKI, currently approved and available in the country. The Brazilian Society of Nephrology hopes that this Consensus can standardize the terminology and provide technical support to all involved in AKI care in Brazil.

Injúria renal aguda e métodos de suporte: padronização da nomenclatura

Resumo O Departamento de Injúria Renal Aguda (IRA) da Sociedade Brasileira de Nefrologia elaborou o presente documento para fins de padronização da terminologia em IRA e modalidades dialíticas na língua portuguesa para o Brasil. Diversos termos com significados semelhantes têm sido empregados em IRA e suas modalidades dialíticas, causando confusão e disparidades entre pacientes, nefrologistas, instituições de saúde, empresas privadas de assistência, seguradoras e entidades governamentais. Essas disparidades podem impactar a assistência médica, a organização e o atendimento hospitalares, assim como o financiamento e reembolso dos procedimentos relacionados com a IRA. Assim, nomenclatura e definições consensuais foram elaboradas, incluindo-se as definições de IRA, doença renal aguda (DRA) e doença renal crônica (DRC). Adicionalmente, todas as modalidades dialíticas e os procedimentos extracorpóreos relacionados a IRA, atualmente aprovados e disponíveis no país, foram abordados. A Sociedade Brasileira de Nefrologia espera que este Consenso possa padronizar a nomenclatura e prover suporte técnico para todos os atores envolvidos na assistência à IRA no Brasil.

A simplified protocol for individualized regional citrate anticoagulation for hemodialysis: A single-center, randomized clinical study

INTRODUCTION

The lack of individualized treatment protocols and complicated procedures are important factors limiting the use of regional citrate anticoagulation (RCA) technology in hemodialysis. This study aims to validate the safety and efficacy of a simplified individualized RCA protocol for hemodialysis.

MATERIALS AND METHODS

From June 2019 to August 2019, 45 patients with active bleeding or bleeding tendency undergoing maintenance hemodialysis in the Nephrology Department of the First Affiliated Hospital of Nanchang University were randomly divided into a modified conventional RCA protocol group with a low-flux dialyzer, a simplified individualized RCA protocol group with a high-flux dialyzer, and a simplified individualized RCA protocol group with a low-flux dialyzer.

RESULTS

A total of 45 patients were included in this study. The mean age of the patients was 57.38 ± 19.05 years, and 78% were men. Forty-three patients completed 4 hours of hemodialysis, and the median total clotting scores in the 3 groups were 11, 12, and 12. Compared with the modified conventional RCA protocol group with a low-flux dialyzer, the 2 simplified individualized RCA protocol groups had better clotting scores for the dialyzer, arterial bubble trap, and single-pool urea clearance index (spKt/VBUN) and lower costs. Moreover, these parameters did not differ between the 2 simplified individualized RCA protocol groups. No electrolyte or acid-base imbalances or citrate poisoning was observed in any of the 3 groups. Adverse events did not differ significantly among the 3 groups.

CONCLUSIONS

The simplified individualized RCA protocol is safe, effective, and easy to implement. Therefore, this protocol can be promoted for clinical practice.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Study Registry under registration number ChiCTR1900023801.

Recent advances in heparinization of polymeric membranes for enhanced continuous blood purification

Continuous blood purification technology such as hemodiafiltration has been used worldwide for saving patients suffering from severe diseases or organ function failure, especially in the intensive care unit and emergency setting. The filters as core devices are commonly made of polymer materials as hollow fiber membranes. However, the membrane is often inductively blocked by blood clot formation due to its interactions with blood components. Heparin is the anticoagulant often used in clinical practice for anti-coagulation. Recently, heparin is also employed to modify the hollow fiber membranes either chemically or physically to improve the filtration performance. This review summarizes recent advances in methodology for surface heparinization of such hollow fiber membranes, and their filtration performance improvement. The review also provides expert opinions for further research in this rapidly expanding field.

Hemodialysis without anticoagulation: Less clotting in conventional hemodialysis than in predilution hemodiafiltration

INTRODUCTION

Hemodialysis patients with contraindication to systemic anticoagulation require a heparin-free hemodialysis technique. Among several alternatives to heparin, predilution hemodiafiltration (HDF) is often used, albeit without any confirmation of its effectiveness.

METHODS

Patients hospitalized in a nephrology ICU and hemodialysed for stage 5 CKD or AKI and with contraindication to systemic anticoagulation were randomized to either standard HD with a polysulfone membrane, or to predilution HDF with the same membrane. Coagulation activation was evaluated clinically by the need for premature termination and by the measurement of D-dimers.

FINDINGS

Two hundred dialysis sessions were performed in 155 patients. Survival curves showed better circuit survival in HD (P = 0.046). In HD, 12% of sessions were interrupted for coagulation versus 23% in predilution HDF (P = 0.04).

DISCUSSION

Predilution HDF was associated with more premature clotting than conventional HD without improvement in dialysis duration or performance epuration indices. When aiming for a 4-hour duration session, conventional heparin-free hemodialysis can be safely proposed in most patients with high bleeding risk.

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.

Calcium Mass Balance during Citrate Hemodialysis: A Randomized Controlled Trial Comparing Normal and Low Ionized Calcium Target Ranges

BACKGROUND

Regional citrate anticoagulation (RCA) during hemodialysis interferes with calcium homeostasis. Optimal ionized calcium (iCa) target range during RCA and consequent calcium balance are unknown.

METHODS

In a randomized controlled trial (ACTRN12613001029785) 30 chronic hemodialysis patients were assigned to normal (1.1-1.2 mmol/) or low (0.95-1.05 mmol/l) iCa target range during a single hemodialysis with RCA. The primary outcome was calcium mass balance during the procedure, using a partial spent dialysate collection method; magnesium mass balance was also measured. Intact parathormone (iPTH), total calcium (tCa) and magnesium were measured before and after procedures.

RESULTS

Mean iCa during procedures was significantly different in the two groups (1.12±0.06 in normal and 1.06±0.07 mmol/l in low iCa group, p <0.001), resulting in different tCa (2.18±0.22 vs. 1.95±0.17, p = 0.003) after the procedure. Mean delivered calcium during the procedure was 58.3±4.8 mmol in the normal and 51.5±8.2 mmol in the low iCa group (p = 0.010), which resulted in a significantly higher mean positive calcium mass balance of 14.6±8.3 mmol (584±333 mg) per procedure in normal as compared to 7.2±8.5 mmol (290±341 mg) in low iCa group (p = 0.024). Linear mixed effects model showed a significant interaction effect of time and iCa target range group on iPTH, i.e. a significant increase in iPTH in the low as compared to normal iCa target group (p = 0.008). Magnesium mass balance was mildly negative and comparable in both groups.

CONCLUSIONS

Low iCa target range resulted in a significantly less positive calcium mass balance, but in a significant increase in iPTH. To achieve a more neutral calcium balance, we recommend allowing a mild hypocalcemia during hemodialysis with RCA, especially when it is used for prolonged periods.

Stirred, shaken, or stagnant: What goes on at the blood-biomaterial interface

There is a widely recognized need to improve the performance of vascular implants and external medical devices that come into contact with blood by reducing adverse reactions they cause, such as thrombosis and inflammation. These reactions lead to major adverse cardiovascular events such as heart attacks and strokes. Currently, they are managed therapeutically. This need remains unmet by the biomaterials research community. Recognized stagnation of the blood-biomaterial interface research translates into waning interest from clinicians, funding agencies, and practitioners of adjacent fields. The purpose of this contribution is to stir things up. It follows the 2014 BloodSurf meeting (74th International IUVSTA Workshop on Blood-Biomaterial Interactions), offers reflections on the situation in the field, and a three-pronged strategy integrating different perspectives on the biological mechanisms underlying blood-biomaterial interactions. The success of this strategy depends on reengaging clinicians and on the renewed cooperation of the funding agencies to support long-term efforts.