Heparin versus prostacyclin in continuous hemodiafiltration for acute renal failure: Effects on platelet function in the systemic circulation and across the filter

Anticoagulation options for continuous renal replacement therapy in critically ill patients: a systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Continuous renal replacement therapy (CRRT) is a widely used standard therapy for critically ill patients with acute kidney injury (AKI). Despite its effectiveness, treatment is often interrupted due to clot formation in the extracorporeal circuits. Anticoagulation is a crucial strategy for preventing extracorporeal circuit clotting during CRRT. While various anticoagulation options are available, there were still no studies synthetically comparing the efficacy and safety of these anticoagulation options.

METHODS

Electronic databases (PubMed, Embase, Web of Science, and the Cochrane database) were searched from inception to October 31, 2022. All randomized controlled trials (RCTs) that examined the following outcomes were included: filter lifespan, all-cause mortality, length of stay, duration of CRRT, recovery of kidney function, adverse events and costs.

RESULTS

Thirty-seven RCTs from 38 articles, comprising 2648 participants with 14 comparisons, were included in this network meta-analysis (NMA). Unfractionated heparin (UFH) and regional citrate anticoagulation (RCA) are the most frequently used anticoagulants. Compared to UFH, RCA was found to be more effective in prolonging filter lifespan (MD 12.0, 95% CI 3.8 to 20.2) and reducing the risk of bleeding. Regional-UFH plus Prostaglandin I2 (Regional-UFH + PGI2) appeared to outperform RCA (MD 37.0, 95% CI 12.0 to 62.0), LMWH (MD 41.3, 95% CI 15.6 to 67.0), and other evaluated anticoagulation options in prolonging filter lifespan. However, only a single included RCT with 46 participants had evaluated Regional-UFH + PGI2. No statistically significant difference was observed in terms of length of ICU stay, all-cause mortality, duration of CRRT, recovery of kidney function, and adverse events among most evaluated anticoagulation options.

CONCLUSIONS

Compared to UFH, RCA is the preferred anticoagulant for critically ill patients requiring CRRT. The SUCRA analysis and forest plot of Regional-UFH + PGI2 are limited, as only a single study was included. Additional high-quality studies are necessary before any recommendation of Regional-UFH + PGI2. Further larger high-quality RCTs are desirable to strengthen the evidence on the best choice of anticoagulation options to reduce all-cause mortality and adverse events and promote the recovery of kidney function. Trial registration The protocol of this network meta-analysis was registered on PROSPERO ( CRD42022360263 ). Registered 26 September 2022.

Efficacy of Prostacyclin Anticoagulation in Critically Ill Patients Requiring Extracorporeal Support: A Systematic Review and Meta-Analysis

Extracorporeal support modalities are highly prothrombotic. Anticoagulation is frequently used for patients receiving Continuous Renal Replacement Therapy (CRRT), Molecular Adsorbent Recirculating System (MARS), and Extracorporeal Membrane Oxygenation (ECMO). The objective of this systematic review and meta-analysis is to determine if prostacyclin-based anticoagulation strategies are effective compared to other anticoagulation strategies, in critically ill children and adults who needs extracorporeal support, such as continuous renal replacement therapy. We conducted a systematic review and meta-analysis using multiple electronic databases and included studies from inception to June 1, 2022. Circuit lifespan, proportion of bleeding, thrombotic, and hypotensive events, and mortality were evaluated. Out of 2,078 studies that were screened, 17 studies (1,333 patients) were included. The mean circuit lifespan was 29.7 hours in the patients in the prostacyclin-based anticoagulation series and 27.3 hours in the patients in the heparin- or citrate-based anticoagulation series, with a mean difference of 2.5 hours (95%CI -12.0;16.9, p=0.74, I2=0.99, n=4,003 circuits). Bleeding occurred in 9.5% of the patients in the prostacyclin-based anticoagulation series and in 17.1% of the patients in the control series, which was a statistically significant decrease (LogOR -1.14 (95%CI -1.91;-0.37), p<0.001, I2=0.19, n=470). Thrombotic events occurred in 3.6% of the patients in the prostacyclin-based anticoagulation series and in 2.2% of the patients in the control series, which was not statistically different (LogOR 0.97 (95%CI -1.09;3.04), p=0.35, I2=0.0, n=115). Hypotensive events occurred in 13.4% of the patients in the prostacyclin-based anticoagulation series and in 11.0% of the patients in the control series, which was not statistically different (LogOR -0.56 (95%CI -1.87;0.74), p=0.40, I2=0.35, n=299). The mortality rate was 26.3% in the prostacyclin-based anticoagulation series, and 32.7% in the control series, which was not statistically different (LogOR -0.40 (95%CI -0.87;0.08), p=0.10, I2=0.00, n=390). The overall risk of bias was low to moderate. In this systematic review and meta-analysis of 17 studies, prostacyclin-based anticoagulation was associated with fewer bleeding events, but with similar circuit lifespans, thrombotic events, hypotensive events, and mortality rates. The potential benefits of prostacyclin-based anticoagulation should be explored in large randomized controlled trials.

Platelet Function in Acute Kidney Injury: A Systematic Review and a Cohort Study

Acute kidney injury (AKI) patients have increased bleeding risk, which could be partially due to acquired platelet dysfunction. We conducted a systematic review and a cohort study to investigate platelet function and count in AKI and their association with AKI-related bleeding and mortality. Through a systematic literature search in PubMed and Embase, we identified 9 studies reporting platelet function and 56 studies reporting platelet count or platelet indices in AKI patients. Overall, platelet aggregation was reduced in AKI patients in nonintensive care unit (ICU) settings but not in ICU settings, except that reduced aggregation was associated with renal replacement therapy. Thrombocytopenia in AKI was frequent and often predictive of mortality. In our cohort study, we prospectively included 54 adult ICU patients who developed AKI within 24 hours of ICU admission and 33 non-AKI ICU controls. Platelet function was measured with light transmission aggregometry and flow cytometry. AKI patients bled more frequently than non-AKI patients (p = 0.04), and bleeding was associated with increased 30-day mortality in AKI (p = 0.02). However, platelet function was not different between AKI and non-AKI patients (aggregation: all p > 0.52; flow cytometry: all p > 0.07) and platelet function was not associated with bleeding in AKI. In conclusion, a reduced platelet count is frequent in AKI, but the literature on platelet function in AKI is sparse. In a cohort study, we demonstrated that patients with AKI within 24 hours of ICU admission exhibited increased bleeding tendency but this was not associated with reduced platelet function.

Do anti-platelet drugs improve duration of continuous renal replacement therapy? A retrospective cohort study in cardiac ICU patients

OBJECTIVE

The objective of this study was to investigate the impact of anti-platelet drug/s on duration of continuous renal replacement therapy (CRRT) in those patients where anti-coagulants were not used due to certain contraindications and in cases where patients were on anti-platelet drugs and were given anti-coagulant during CRRT.

METHOD

This single-center, retrospective cohort study was conducted using the medical records patients treated with CRRT in the cardiac ICU of the inpatient urban facility, located in North India. Data was collected from only those patients who received CRRT for the duration of at least 12 h. Patient's in NAC group were not on any anti-platelet/s and did not receive anti-coagulant during CRRT. AC and AP group patients received anti-coagulant alone or were already on anti-platelet/s and did not receive anti-coagulant respectively while ACAP group patients were on anti-platelet drug/s and also received anti-coagulant during CRRT.

RESULT

Patients in AC, AP, or ACAP group showed significantly (p < 0.001) higher CRRT filter life compared to NAC group. The median CRRT filter life was significantly higher in the ACAP group compared to AC (p < 0.05) and AP (p < 0.001) groups.

CONCLUSION

This study indicates that systemic anti-platelet therapy can provide additional support in critical patients undergoing CRRT even with or without anti-coagulant therapy. However, the increase in CRRT filter life was more profound in patients who were on anti-platelet/s and also received anti-coagulant drug/s during CRRT.

Pharmacological interventions for preventing clotting of extracorporeal circuits during continuous renal replacement therapy

BACKGROUND

Acute kidney injury (AKI) is a major comorbidity in hospitalised patients. Patients with severe AKI require continuous renal replacement therapy (CRRT) when they are haemodynamically unstable. CRRT is prescribed assuming it is delivered over 24 hours. However, it is interrupted when the extracorporeal circuits clot and the replacement is required. The interruption may impair the solute clearance as it causes under dosing of CRRT. To prevent the circuit clotting, anticoagulation drugs are frequently used.

OBJECTIVES

To assess the benefits and harms of pharmacological interventions for preventing clotting in the extracorporeal circuits during CRRT.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 September 2019 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 Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs or cluster RCTs) and quasi-RCTs of pharmacological interventions to prevent clotting of extracorporeal circuits during CRRT.

DATA COLLECTION AND ANALYSIS

Data were abstracted and assessed independently by two authors. Dichotomous outcomes were calculated as risk ratio (RR) with 95% confidence intervals (CI). The primary review outcomes were major bleeding, successful prevention of clotting (no need of circuit change in the first 24 hours for any reason), and death. Evidence certainty was determined using the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach.

MAIN RESULTS

A total of 34 completed studies (1960 participants) were included in this review. We identified seven ongoing studies which we plan to assess in a future update of this review. No included studies were free from risk of bias. We rated 30 studies for performance bias and detection bias as high risk of bias. We rated 18 studies for random sequence generation,ààsix studies for the allocation concealment, three studies for performance bias, three studies for detection bias,à nine studies for attrition bias,à14 studies for selective reporting and nine studies for the other potential source of bias, as having low risk of bias. We identified eight studies (581 participants) that compared citrate with unfractionated heparin (UFH). Compared to UFH, citrate probably reduces major bleeding (RR 0.22, 95% CI 0.08 to 0.62; moderate certainty evidence) and probably increases successful prevention of clotting (RR 1.44, 95% CI 1.10 to 1.87; moderate certainty evidence). Citrate may have little or no effect on death at 28 days (RR 1.06, 95% CI 0.86 to 1.30, moderate certainty evidence). Citrate versus UFH may reduce the number of participants who drop out of treatment due to adverse events (RR 0.47, 95% CI 0.15 to 1.49; low certainty evidence). Compared to UFH, citrate may make little or no difference to the recovery of kidney function (RR 1.04, 95% CI 0.89 to 1.21; low certainty evidence). Compared to UFH, citrate may reduceàthrombocytopenia (RR 0.39, 95% CI 0.14 to 1.03; low certainty evidence). It was uncertain whether citrate reduces a cost to health care services because of inadequate data. For low molecular weight heparin (LMWH) versus UFH, six studies (250 participants) were identified. Compared to LMWH, UFH may reduce major bleeding (0.58, 95% CI 0.13 to 2.58; low certainty evidence). It is uncertain whether UFH versus LMWH reduces death at 28 days or leads to successful prevention of clotting. Compared to LMWH, UFH may reduce the number of patient dropouts from adverse events (RR 0.29, 95% CI 0.02 to 3.53; low certainty evidence). It was uncertain whether UFH versus LMWH leads to the recovery of kidney function because no included studies reported this outcome. It was uncertain whether UFH versus LMWH leads to thrombocytopenia. It was uncertain whether UFH reduces a cost to health care services because of inadequate data. For the comparison of UFH to no anticoagulation, one study (10 participants) was identified. It is uncertain whether UFH compare to no anticoagulation leads to more major bleeding. It is uncertain whether UFH improves successful prevention of clotting in the first 24 hours, death at 28 days, the number of patient dropouts due to adverse events, recovery of kidney function, thrombocytopenia, or cost to health care services because no study reported these outcomes. For the comparison ofàcitrate to no anticoagulation,àno completed study was identified.

AUTHORS' CONCLUSIONS

Currently,àavailable evidence does not support the overall superiority of any anticoagulant to another. Compared to UFH, citrate probably reduces major bleeding and prevents clotting and probably has little or no effect on death at 28 days. For other pharmacological anticoagulation methods, there is no available data showing overall superiority to citrate or no pharmacological anticoagulation. Further studies are needed to identify patient populations in which CRRT should commence with no pharmacological anticoagulation or with citrate.

Pharmacological interventions for preventing clotting of extracorporeal circuits during continuous renal replacement therapy

BACKGROUND

Acute kidney injury (AKI) is a major comorbidity in hospitalised patients. Patients with severe AKI require continuous renal replacement therapy (CRRT) when they are haemodynamically unstable. CRRT is prescribed assuming it is delivered over 24 hours. However, it is interrupted when the extracorporeal circuits clot and the replacement is required. The interruption may impair the solute clearance as it causes under dosing of CRRT. To prevent the circuit clotting, anticoagulation drugs are frequently used.

OBJECTIVES

To assess the benefits and harms of pharmacological interventions for preventing clotting in the extracorporeal circuits during CRRT.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 September 2019 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 Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs or cluster RCTs) and quasi-RCTs of pharmacological interventions to prevent clotting of extracorporeal circuits during CRRT.

DATA COLLECTION AND ANALYSIS

Data were abstracted and assessed independently by two authors. Dichotomous outcomes were calculated as risk ratio (RR) with 95% confidence intervals (CI). The primary review outcomes were major bleeding, successful prevention of clotting (no need of circuit change in the first 24 hours for any reason), and death. Evidence certainty was determined using the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach.

MAIN RESULTS

A total of 34 completed studies (1960 participants) were included in this review. We identified seven ongoing studies which we plan to assess in a future update of this review. No included studies were free from risk of bias. We rated 30 studies for performance bias and detection bias as high risk of bias. We rated 18 studies for random sequence generation,  six studies for the allocation concealment, three studies for performance bias, three studies for detection bias,  nine studies for attrition bias, 14 studies for selective reporting and nine studies for the other potential source of bias, as having low risk of bias. We identified eight studies (581 participants) that compared citrate with unfractionated heparin (UFH). Compared to UFH, citrate probably reduces major bleeding (RR 0.22, 95% CI 0.08 to 0.62; moderate certainty evidence). Citrate may have little or no effect on death at 28 days (RR 1.06, 95% CI 0.86 to 1.30, moderate certainty evidence), while citrate versus UFH may have little or no effect on successful prevention of clotting (RR 1.01, 95% CI 0.77 to 1.32; moderate certainty evidence). Citrate versus UFH may reduce the number of participants who drop out of treatment due to adverse events (RR 0.47, 95% CI 0.15 to 1.49; low certainty evidence). Compared to UFH, citrate may make little or no difference to the recovery of kidney function (RR 0.95, 95% CI 0.66 to 1.36; low certainty evidence). Compared to UFH, citrate may reduce thrombocytopenia (RR 0.39, 95% CI 0.14 to 1.03; low certainty evidence). It was uncertain whether citrate reduces a cost to health care services because of inadequate data. For low molecular weight heparin (LMWH) versus UFH, six studies (250 participants) were identified. Compared to LMWH, UFH may reduce major bleeding (0.58, 95% CI 0.13 to 2.58; low certainty evidence). It is uncertain whether UFH versus LMWH reduces death at 28 days or leads to successful prevention of clotting. Compared to LMWH, UFH may reduce the number of patient dropouts from adverse events (RR 0.29, 95% CI 0.02 to 3.53; low certainty evidence). It was uncertain whether UFH versus LMWH leads to the recovery of kidney function because no included studies reported this outcome. It was uncertain whether UFH versus LMWH leads to thrombocytopenia. It was uncertain whether UFH reduces a cost to health care services because of inadequate data. For the comparison of UFH to no anticoagulation, one study (10 participants) was identified. It is uncertain whether UFH compare to no anticoagulation leads to more major bleeding. It is uncertain whether UFH improves successful prevention of clotting in the first 24 hours, death at 28 days, the number of patient dropouts due to adverse events, recovery of kidney function, thrombocytopenia, or cost to health care services because no study reported these outcomes. For the comparison of citrate to no anticoagulation, no completed study was identified.

AUTHORS' CONCLUSIONS

Currently, available evidence does not support the overall superiority of any anticoagulant to another. Compared to UFH, citrate probably reduces major bleeding and probably has little or no effect on preventing clotting or death at 28 days. For other pharmacological anticoagulation methods, there is no available data showing overall superiority to citrate or no pharmacological anticoagulation. Further studies are needed to identify patient populations in which CRRT should commence with no pharmacological anticoagulation or with citrate.

Prostacyclin as an Anticoagulant for Continuous Renal Replacement Therapy in Children

Effective delivery of continuous renal replacement therapy (CRRT) depends on the longevity of the filter and circuit used in the CRRT machine. Safe and effective anticoagulation is crucial for maintaining the patency of these circuits. In children, heparin and citrate are the commonly used anticoagulants but they are limited by serious side effects and thus calls for meticulous monitoring. In conditions where neither of these can be used, prostacyclin can be an effective alternative. Prostacyclin is a platelet inhibitor that can be safely used as an efficient anticoagulant in CRRT. When combined with heparin, it induces a heparin-sparing effect, which can reduce the dosage and side effects of heparin. Furthermore, there is no need for performing time-consuming monitoring tests. Although prostacyclin seems to be an attractive option, there is scanty evidence about its use as an anticoagulant in CRRT in children. We review the evidence and practicalities, and propose a guideline for the use of prostacyclin as an anticoagulant in children requiring CRRT.

Factors affecting circuit life during continuous renal replacement therapy in children with liver failure

Despite abnormal clotting, circuits clot during continuous renal replacement therapy (CRRT) in children with acute liver failure (ALF). We report our experience. All children with ALF needing CRRT were studied over 2 years. Patient and circuit factors associated with circuit use were evaluated. Thirty-one children in liver failure (median age 7.4 years) underwent CRRT, of which 17 (54.8%) died. A total of 98 filtration episodes were used. The smallest access catheter was 6.5 Fr, while the largest was 13.5 Fr. The most common filter used was HFO7 (63%). Mean duration (SD) of circuit use was 33.13(30.83) hours. Of the 98 filtration episodes, circuits blocked in 25, whereas the access catheter blocked in 25. Fifty-two circuits were changed electively for a variety of reasons. Prostacyclin was the anticoagulant in 62 filtration episodes. The remaining filtration episodes had either no anticoagulation or heparin. The mean (SD) "downtime" was 5.13 (9.15) hours. We found a significant association between fresh frozen plasma (FFP) use with circuit blockade. Neither the duration of CRRT nor the "downtime" influenced mortality. The CRRT circuits blocked in children despite deranged clotting in liver disease. Circuits are changed for a variety of reasons other than clotting. The use of FFP reduces circuit life.

Coagulation management in patients undergoing mechanical circulatory support

The incidence of bleeding and thrombo-embolic complications in patients undergoing mechanical circulatory support therapy remains high and is associated with bad outcomes and increased costs. The need for anticoagulation and anti-platelet therapy varies widely between different pulsatile and non-pulsatile ventricular-assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) systems. Therefore, a unique anticoagulation protocol cannot be recommended. Notably, most thrombo-embolic complications occur despite values of conventional coagulation tests being within the targeted range. This is due to the fact that conventional coagulation tests such as international normalised ratio (INR), activated partial thromboplastin time (aPTT) and platelet count cannot detect hyper- or hypofibrinolysis, hypercoagulability due to tissue factor expression on circulating cells or increased clot firmness, and platelet aggregation as well as response to anti-platelet drugs. By contrast, point-of-care (POC) whole blood viscoelastic tests (thromboelastometry/-graphy) and platelet function tests (impedance or turbidimetric aggregometry) reflect in detail the haemostatic status of patients undergoing mechanical circulatory support therapy and the efficacy of their anticoagulation and antiaggregation therapy. Therefore, monitoring of haemostasis using POC thromboelastometry/-graphy and platelet function analysis is recommended during mechanical circulatory support therapy to reduce the risk of bleeding and thrombo-embolic complications. Notably, these haemostatic tests should be performed repeatedly during mechanical circulatory support therapy since thrombin generation, clot firmness and platelet response may change significantly over time with a high inter- and intra-individual variability. Furthermore, coagulation management can be hampered in non-pulsatile VADs by acquired von Willebrand syndrome, and in general by acquired factor XIII deficiency as well as by heparin-induced thrombocytopenia. In addition, POC testing can be used in bleeding patients to guide calculated goal-directed therapy with allogeneic blood products, haemostatic drugs and coagulation factor concentrates to optimise the haemostasis and to minimise transfusion requirements, transfusion-associated adverse events and to avoid thrombo-embolic complications, as well. However, coagulation management in patients undergoing mechanical circulatory support therapy is somehow like navigating between Scylla and Charybdis, and development of protocols based on POC testing seems to be beneficial.