Low-molecular weight heparin infusion as anticoagulation for haemodialysis

Anticoagulation for people receiving long-term haemodialysis

BACKGROUND

Haemodialysis (HD) requires safe and effective anticoagulation to prevent clot formation within the extracorporeal circuit during dialysis treatments to enable adequate dialysis and minimise adverse events, including major bleeding. Low molecular weight heparin (LMWH) may provide a more predictable dose, reliable anticoagulant effects and be simpler to administer than unfractionated heparin (UFH) for HD anticoagulation, but may accumulate in the kidneys and lead to bleeding.

OBJECTIVES

To assess the efficacy and safety of anticoagulation strategies (including both heparin and non-heparin drugs) for long-term HD in people with kidney failure. Any intervention preventing clotting within the extracorporeal circuit without establishing anticoagulation within the patient, such as regional citrate, citrate enriched dialysate, heparin-coated dialysers, pre-dilution haemodiafiltration (HDF), and saline flushes were also included.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to November 2023 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-randomised controlled studies (quasi-RCTs) evaluating anticoagulant agents administered during HD treatment in adults and children with kidney failure.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias using the Cochrane tool and extracted data. Treatment effects were estimated using random effects meta-analysis and expressed as relative risk (RR) or mean difference (MD) with 95% confidence intervals (CI). Evidence certainty was assessed using the Grading of Recommendation, Assessment, Development and Evaluation approach (GRADE).

MAIN RESULTS

We included 113 studies randomising 4535 participants. The risk of bias in each study was adjudicated as high or unclear for most risk domains. Compared to UFH, LMWH had uncertain effects on extracorporeal circuit thrombosis (3 studies, 91 participants: RR 1.58, 95% CI 0.46 to 5.42; I2 = 8%; low certainty evidence), while major bleeding and minor bleeding were not adequately reported. Regional citrate anticoagulation may lower the risk of minor bleeding compared to UFH (2 studies, 82 participants: RR 0.34, 95% CI 0.14 to 0.85; I2 = 0%; low certainty evidence). No studies reported data comparing regional citrate to UFH on risks of extracorporeal circuit thrombosis and major bleeding. The effects of very LMWH, danaparoid, prostacyclin, direct thrombin inhibitors, factor XI inhibitors or heparin-grafted membranes were uncertain due to insufficient data. The effects of different LMWH, different doses of LMWH, and the administration of LMWH anticoagulants using inlet versus outlet bloodline or bolus versus infusion were uncertain. Evidence to compare citrate to another citrate or control was scant. The effects of UFH compared to no anticoagulant therapy or different doses of UFH were uncertain. Death, dialysis vascular access outcomes, blood transfusions, measures of anticoagulation effect, and costs of interventions were rarely reported. No studies evaluated the effects of treatment on non-fatal myocardial infarction, non-fatal stroke and hospital admissions. Adverse events were inconsistently and rarely reported.

AUTHORS' CONCLUSIONS

Anticoagulant strategies, including UFH and LMWH, have uncertain comparative risks on extracorporeal circuit thrombosis, while major bleeding and minor bleeding were not adequately reported. Regional citrate may decrease minor bleeding, but the effects on major bleeding and extracorporeal circuit thrombosis were not reported. Evidence supporting clinical decision-making for different forms of anticoagulant strategies for HD is of low and very low certainty, as available studies have not been designed to measure treatment effects on important clinical outcomes.

How to Ensure Patency of the Extracorporeal Circuit in Hemodialysis: Global Perspectives

An adequate knowledge of anticoagulants used to prevent clotting in the extracorporeal circuit is crucial to provide optimal hemodialysis. Drugs can potentially prevent extracorporeal circuit clotting, but administration, half-life, and potential side effects differ. However, there is a lack of concise recommendations to guide anticoagulation and to avoid side effects. Because of the development of newer anticoagulant agents, direct thrombin inhibitors, and heparinoids, some of the side effects related to heparin may be overcome, but a deeper knowledge of these newer drugs is necessary. Moreover, types of heparin used, routes of administration, and health care economics vary around the world. We performed an extensive review of the literature, and the present article focuses on available anticoagulant drugs, exploring doses, side effects, particular use in hemodialysis, mechanism of action, pharmacokinetic properties, and use in special situations. Classical anticoagulants are still the standard of anticoagulation, but many questions remain unanswered; for example, is there real superiority of one treatment over another in terms of efficacy, safety, and health care economics? Anticoagulant protocols for hemodialysis need to be standardized and further studies performed to answer all of these questions.

The optimized anticoagulation strategy in prolonged hemodialysis

Background

During extended (nocturnal) hemodialysis (ENHD), the dose of low-molecular-weight heparin (LMWH) can be administered as a single injection or as a divided dose over different time points. Our hypothesis was that a single injection might be sufficient to maintain dialyzer fiber patency. In addition, we investigated whether the biochemical clotting parameter anti-Xa accurately predicts fiber blocking.

Methods

Our hypothesis was tested in 20 stable patients on ENHD in a random cross-over setting during two consecutive midweek sessions. The regular total dose of LMWH (i.e. enoxaparin, Clexane® 40-100  mg, Sanofi, Belgium) was either given (i) in a single injection at the dialysis start or (ii) divided over two injections, at the start and halfway the dialysis session. Blood samples were taken from the arterial blood line at different time points to determine plasma anti-Xa activity levels. Post-dialysis, the rinsed and dried hemodialyzers were scanned with a reference micro-computed tomography (µCT) scanning technique, and non-blocked fibers were counted in a central cross-section of the dialyzer outlet potting (ImageJ, NIH, USA).

Results

The percentage of open fibers in the dialyzers after a single injection of LMWH [91 (61-96)%] versus divided administration [94 (79-98)%] was not different. Time averaged anti-Xa activity levels were clinically not significantly different between both sessions. Anti-Xa activity levels correlated with the administered anticoagulation doses normalized for body weight, but not with the percentages open fibers in the dialyzers.

Conclusion

Our results indicate that there is no need to administer enoxaparin over two injections for ENHD up to 8 h. The usefulness of monitoring anti-Xa levels to predict fiber patency, assessed by µCT, can be questioned, but further clinical trials are needed.

The use of non-vitamin K oral anticoagulants in dialysis patients-A systematic review

Non-vitamin K oral anticoagulants (NOACs) are used for prevention of thromboembolic events, but their use in dialysis patients is debatable. This study investigated the available evidence for the use of NOACs in dialysis patients. Online databases were systematically searched for eligible studies including pharmacokinetic (PK) studies, cohort studies, and randomized control trials (RCTs) comparing NOAC with vitamin K antagonist (VKA) or no anticoagulant treatment. Newcastle Ottawa Scale and Cochrane Risk of bias tool were used for quality assessment. Twenty studies were identified (nine PK studies, two RCTs, and nine cohort studies). Most of the studies investigated apixaban or rivaroxaban. In dialysis patients, less accumulation was reported with apixaban and rivaroxaban compared to dabigatran and edoxaban. PK studies indicate that high dose apixaban or rivaroxaban should be avoided. The two RCTs (rivaroxaban/apixaban vs. VKA) were small and underpowered regarding stroke and bleeding outcomes. Most cohort studies found apixaban superior to VKA, whereas comparison of rivaroxaban with VKA yielded conflicting results. Cohort studies comparing apixaban high dose (5 mg) with low dose (2.5 mg) twice daily suggest a lower risk of stroke with high dose but also a higher risk of bleeding with high dose. Apixaban versus no anticoagulation was compared in one cohort study and did not lower the risk of stroke compared with non-treated regardless of apixaban dosage. Widespread use of NOACs in dialysis patients is limited by adequately sized RCTs. Available evidence suggests a potential for use of apixaban and rivaroxaban in reduced dose.

Arterial Versus Venous Port Site Administration of Nadroparin for Preventing Thrombosis of Extracorporeal Blood Circuits in Patients Receiving Hemodiafiltration Treatment

Introduction

Administration of low-molecular-weight heparins (LMWHs) is necessary for preventing extracorporeal circuit thrombosis during hemodialysis. A substantial amount of LMWH is removed with online hemodiafiltration (OL-HDF) when administered through the inlet site of the extracorporeal circuit. Consequently, administration of LMWH at the outlet site appears to be more efficient. In this study we aimed to compare the effects of nadroparin calcium (NAD) administered through the outlet versus the inlet port site in postdilution OL-HDF and assess the NAD dose reduction.

Methods

Forty-nine hemodialysis patients were included in 3 consecutive 6-week studies as follows: phase I, inlet port line; phase II, outlet port line; and phase III, outlet port line with reduced dose. We evaluated clotting in the hemodialyzer and venous bubble trap, the dialysis dose (K t/V), and substitution volume.

Results

Thirty four percent, 63%, and 66% were categorized as "white" during phases I, II, and III, respectively. During phases I, II, and III, 75%, 93%, and 95% of the venous bubble traps were "clean," and 9%, 0.6%, and 0.4% of the dialyzers clotted, respectively. Average NAD dose was 0.43 ml during phase I and 0.3 ml during phase II. During phase III, the LMWH dose was reduced by 33% to 50% in 15 patients. In phase III, Kt/V improved from 1.64 to 1.75 and substitution volume increased from 20.18 to 21.96 L.

Conclusions

When using OL-HDF, a single administration of NAD at the outlet port line allows for a significant dose reduction and was associated with improved dialysis performance.

Correlation between activated partial thromboplastin time and anti-Xa activity in patients who received low-molecular weight heparin as anticoagulation for haemodialysis

Plasma anti-Xa activity, the recommended test to monitor low-molecular weight heparin (LMWH) therapy, is not readily available in many laboratories. In our clinical trials on the use of LMWH as anticoagulation for haemodialysis, a consistent prolongation of APTT in addition to the elevated anti-Xa activity was observed in the patients after LMWH administration. Hence, the paired anti-Xa activity and APTT data were re-analyzed. The APTT ratio, which was the proportional change in APTT from the baseline value after LMWH administration, was found to have a strong correlation with anti-Xa activity (coefficient of determination, R ²  = 0.72, P < 0.001). In the receiver operating characteristic analysis, the APTT ratio was also found to be an excellent predictor of therapeutic anti-Xa activity ≧0.5 IU/mL (area under curve = 0.93, P < 0.001). The sensitivity was 88% and the specificity was 83.3% when an APTT ratio ≧1.4 was used as the cut point to predict the achievement of therapeutic anti-Xa activity. Our results illustrated that APTT is a potentially useful screening test to assess the degree of anticoagulation achieved by LMWH during haemodialysis, if the testing for plasma anti-Xa activity is not available.

Clinical study on low-molecular weight heparin infusion as anticoagulation for nocturnal home haemodialysis

AIM

This study was conducted to evaluate low-molecular weight heparin (LMWH) as anticoagulation for nocturnal home haemodialysis (NHHD). While its longer half-life may cause drug accumulation in frequent dialysis, the essential need of a supplementary intra-dialytic bolus for the sleeping patients also renders LMWH's use impractical.

METHODS

The recruited patients, who were on alternate-day 8 h haemodialysis, were randomized to receive either nadroparin or unfractionated heparin (UFH) for a week. They underwent crossover to receive the alternate anticoagulant in the next week. A nadroparin infusion regimen was adopted to enhance its practicability, which consisted of a loading dose of 35 IU/kg and a continuous infusion of 10 IU/kg per hour for 6 h.

RESULTS

A total of 12 NHHD patients were recruited. With nadroparin infusion, the mean anti-Xa levels at the 2^nd , 4^th , 6^th and 8^th hours of dialysis were 0.46 ± 0.11, 0.55 ± 0.14, 0.61 ± 0.15 and 0.45 ± 0.15 IU/mL respectively. Comparing to UFH, which offered satisfactory anticoagulation according to the activated partial thromboplastin time, nadroparin-treated dialysis achieved similar thrombus scores and dialyser urea/creatinine clearances at the end of haemodialysis. During the post-dialysis period, one patient demonstrated residual LMWH effect (anti-Xa level 0.09 IU/mL) on the next day, whereas none had detectable anti-Xa activities 2 days afterwards upon next dialysis.

CONCLUSIONS

Low-molecular weight heparin infusion is practical and effective as anticoagulation for NHHD. It can be safely used in an alternate-day haemodialysis schedule. A close monitoring for LMWH accumulation is recommended if long dialysis is performed daily.