Renal replacement therapy and anticoagulation

Clinical guidance for unfractionated heparin dosing and monitoring in critically ill patients

INTRODUCTION

Unfractionated heparin is a widely used anticoagulant in critically ill patients. It has a well-established safety profile and remains an attractive option for clinicians due to its short half-life and reversibility. Heparin has a unique pharmacokinetic profile, which contributes to significant inter-patient and intra-patient variability in effect. The variability in anticoagulant effect combined with heparin's short half-life mean close monitoring is required for clinical efficacy and preventing adverse effects. To optimize heparin use in critically ill patients effective monitoring assays and dose adjustment strategies are needed.

AREAS COVERED

This paper explores the use of heparin as an anticoagulant and optimal approaches to monitoring in critically ill patients.

EXPERT OPINION

Conventional monitoring assays for heparin dosing have significant limitations. Emerging data appears to favor using anti-Xa assay monitoring for heparin anticoagulation which many centers have successfully adopted as the standard. The anti-Xa assay appears have important benefits relative to the aPTT for heparin monitoring in critically ill patients, and should be considered for broader use.

Bleeding during tooth extraction in patients with chronic kidney disease: A cross-sectional pilot study

OBJECTIVE

This work measures the intra-operative bleeding in end-stage renal disease patients and assesses whether laboratory coagulation tests and nitrogenous compounds are related to a higher bleeding risk.

METHODS

Laboratory tests were performed on the day of surgery and some patients with thrombocytopenia and values above the normal levels of international normalised ratio (INR), thrombin time (TT) and activated partial thromboplastin time (aPTT) were identified.

RESULTS

Haemostatic time ranged from 2 to 35 min (mean of 8.51 min) after suture. Bleeding volume ranged from 0.02 to 67.06 mL (mean of 4.38 mL) and the bleeding volume per minute ranged from 0.05 to 2.10 mL/min (median of 0.6 mL/min). Only seven patients (16.27%) had abnormal bleeding (more than 0.6 mL/min). Spearman's coefficient showed weak correlations between bleeding volume (mL/min) and serum urea (r = 0.226), TT (r = 0.227), plasma urea (r = 0.148) and creatinine (r = 146), as well as very weak correlations with all other variables (r < 0.140) such as age, haemodialysis time, glycaemia, glycated haemoglobin, platelets, INR, aPTT and fibrinogen.

CONCLUSION

It was not possible to associate any laboratory test or nitrogenous compounds present in the blood and saliva with an increased bleeding.

Global Scientific Trends in Continuous Renal Replacement Therapy from 2000 to 2023: A Bibliometric and Visual Analysis

INTRODUCTION

Continuous renal replacement therapy (CRRT) is one of the most widely used blood purification and organ support methods in the ICU. However, the development process, the current status, hotspots, and future trends of CRRT remain unclear.

METHOD

The WoSCC database was used to analyze CRRT research evolution and theme trends. VOSviewer was used to construct coauthorship, co-occurrence, co-citation, and network visualizations. CiteSpace is used to detect bursts for co-occurrence items. Several important subtopics were reviewed and discussed in more detail.

RESULTS

Global publications increased from 56 in 2000 to 398 in 2023, a 710.71% increase. Blood Purification published the most manuscripts, followed by the International Journal of Artificial Organs. The USA, the San Bortolo Hospital, and Bellomo were the most productive and impactful institution, country, and author, respectively. Based on co-occurrence cluster analysis, five clusters emerged: (1) clinical applications and management of CRRT; (2) sepsis and CRRT; (3) CRRT anticoagulant management; (4) CRRT and antibiotic pharmacokinetics and pharmacodynamics; and (5) comparison of CRRT and intermittent hemodialysis. COVID-19, initiation, ECOMO, cefepime, guidelines, cardiogenic shock, biomarker, and outcome were the latest high-frequency keywords or strongest bursts, indicating the emerging frontiers of CRRT.

CONCLUSIONS

There has been widespread publication and citation of CRRT research in the past 2 decades. We provide an overview of current trends, global collaboration patterns, basic knowledge, research hotspots, and emerging frontiers.

Nafamostat mesylate versus regional citrate anticoagulation for continuous renal replacement therapy in patients at high risk of bleeding: a retrospective single-center study

PURPOSE

The choice of continuous renal replacement therapy (CRRT) anticoagulation program for patients at high risk of bleeding has always been a complex problem in clinical practice. Clinical regimens include regional citrate anticoagulation (RCA) and nafamostat mesylate (NM). This study aimed to evaluate the efficacy and safety of these two anticoagulants for CRRT in patients at high risk of bleeding to guide their clinical use better.

PATIENTS AND METHODS

Between January 2021 and December 2022, 307 patients were screened for this study. Forty-six patients were finally enrolled: 22 in the regional citrate anticoagulation group and 24 in the nafamostat mesylate group. We collected patients' baseline characteristics, laboratory indicators before CRRT, and CRRT-related data. We then performed a statistical analysis of the data from both groups of patients.

RESULTS

In our study, the baseline characteristics did not differ significantly between the two groups; the baseline laboratory indicators before CRRT of patients in the two groups were not significantly different. The duration of CRRT was 600 min in the regional citrate anticoagulation (RCA) group, 615 min in the nafamostat mesylate (NM) group; the success rate was 90.7% in the RCA group, and 85.6% in the NM group, the anticoagulant efficacy between the two groups was comparable. There was no significant difference in the safety of anticoagulation between the two groups. We used Generalized Estimating Equations (GEE) to test whether different anticoagulation methods significantly affected the success rate of CRRT and found no statistical difference between RCA and NM.

CONCLUSION

Our study suggests that nafamostat mesylate's anticoagulant efficacy and safety are not inferior to regional citrate anticoagulation for continuous renal replacement therapy in patients at high risk of bleeding.

Quality indicators in prolonged hemodialysis with regional citrate anticoagulation with the genius system: retrospective cohort of critical patients with acute kidney injury

BACKGROUND

Prolonged hemodialysis (HD) is performed from 6 to 12 h and can last up to 24 h. To prevent system clotting some studies suggest that Regional Citrate Anticoagulation (RCA) use reduces bleeding rates relative to systemic heparin. However, there may be difficulties in the patient's clinical management and completing the prescribed HD with Genius system using RCA.

OBJECTIVE

To analyze safety Quality Indicators (IQs) and follow up on prolonged HD with 4% sodium citrate solution in a Genius® hybrid system.

METHODS

This is a retrospective cohort conducted in an intensive care unit.

RESULTS

53 random sessions of prolonged HD with 4% sodium citrate solution of critically ill patients with AKI assessed. Evaluated safety indicators were dysnatremia and metabolic alkalosis, observed in 15% and 9.4% of the sessions, respectively. Indicators of effectiveness were system clotting which occurred in 17.3%, and the minimum completion of the prescribed HD time, which was 75.5%.

CONCLUSION

The assessment of the indicators showed that the use of RCA with a 4% sodium citrate solution in prolonged HD with the Genius system in critically ill patients with AKI can be performed in a simple, safe, and effective way.

Influence of continuous renal replacement therapy on the plasma concentration of tigecycline in patients with septic shock: A prospective observational study

Objective: The influence of continuous renal replacement therapy (CRRT) on the steady-state plasma concentration of high-dose tigecycline was investigated in septic shock patients to provide references for drug dosing.

Methods: In this prospective observational study, 17 septic shock patients presenting with severe infections needing a broad-spectrum antibiotic therapy with high-dose tigecycline (100 mg per 12 h) in the intensive care unit were included and divided into CRRT group (n = 6) or non-CRRT group (n = 11). The blood samples were collected and plasma drug concentration was determined by SHIMADZU LC-20A and SHIMADZU LCMS 8040. The steady-state plasma concentration was compared between groups using unpaired t-test. Furthermore, between-groups comparisons adjusted for baseline value was also done using multivariate linear regression model.

Results: Peak concentration (Cmax) of tigecycline was increased in CRRT group compared to non-CRRT group, but there were no statistical differences (505.11 ± 143.84 vs. 406.29 ± 108.00 ng/mL, p-value: 0.129). Trough concentration (Cmin) of tigecycline was significantly higher in CRRT group than in non-CRRT group, with statistical differences (287.92 ± 41.91 vs. 174.79 ± 33.15 ng/mL, p-value: 0.000, adjusted p-value: 0.000). In safety, Cmin was reported to be a useful predictor of hepatotoxicity with a cut-off of 474.8 ng/mL. In our studies, Cmin of all patients in CRRT group was lower than 474.8 ng/mL.

Conclusion: The plasma concentration of tigecycline was increased in septic shock patients with CRRT treatment and only Cmin shown statistical differences. No dose adjustment seems needed in the view of hepatotoxicity.

Clinical Trial Registration:https://www.chictr.org.cn/, identifier ChiCTR2000037475.

Continuous renal replacement therapy and extracorporeal membrane oxygenation: implications in the COVID-19 era

The novel severe acute respiratory syndrome coronavirus 2, SARS-CoV-2 (coronavirus Disease 19 (COVID-19)) was identified as the causative agent of viral pneumonias in Wuhan, China in December 2019, and has emerged as a pandemic causing acute respiratory distress syndrome (ARDS) and multiple organ dysfunction. Interim guidance by the World Health Organization states that extracorporeal membrane oxygenation (ECMO) should be considered as a rescue therapy in COVID-19-related ARDS. International registries tracking ECMO in COVID-19 patients reveal a 21%-70% incidence of acute renal injury requiring renal replacement therapy (RRT) during ECMO support. The indications for initiating RRT in patients on ECMO are similar to those for patients not requiring ECMO. RRT can be administered during ECMO via a temporary dialysis catheter, placement of a circuit in-line hemofilter, or direct connection of continuous RRT in-line with the ECMO circuit. Here we review methods for RRT during ECMO, RRT initiation and timing during ECMO, anticoagulation strategies, and novel cytokine filtration approaches to minimize COVID-19's pathophysiological impact.

Anticoagulation in patients with acute kidney injury undergoing kidney replacement therapy

Kidney replacement therapy (KRT) is used to provide supportive therapy for critically ill patients with severe acute kidney injury and various other non-renal indications. Modalities of KRT include continuous KRT (CKRT), intermittent hemodialysis (HD), and sustained low efficiency daily dialysis (SLED). However, circuit clotting is a major complication that has been investigated extensively. Extracorporeal circuit clotting can cause reduction in solute clearances and can cause blood loss, leading to an upsurge in treatment costs and a rise in workload intensity. In this educational review, we discuss the pathophysiology of the clotting cascade within an extracorporeal circuit and the use of various types of anticoagulant methods in various pediatric KRT modalities.

Double Pump Sequential Constant Citrate Anticoagulation in General Hemodialysis

Objective

To investigate the safety and efficacy of single-pump and double-pump sequential anticoagulation in general hemodialysis under the condition of constant citrate.

Methods

A total of 32 patients with end-stage renal disease complicated with hemorrhage admitted by Zigong Third People's Hospital from December 2019 to December 2020 were collected. Randomly divided into single pump group (n = 17) and double pump group (n = 15). The coagulation of dialyzer and intravenous pot was compared between the two groups. Then, the changes of serum calcium before treatment, after 2 h treatment, and after the completion of the treatment, and the front of the blood pump and intravenous pot, as well as behind the intravenous pot were observed and recorded in the two groups. Then, single-pool clearance of urea/volume (spKt/V) was compared between the two groups.

Results

There were few differences in dialyzer coagulation between the single pump group and double pump group. However, the single pump group had a significant increase in the number of intravenous pot coagulations than the double pump group. At 2 h for dialysis, the serum calcium level behind the intravenous pot in the double pump group was notably lower than that in the single pump group. And after the completion of dialysis, the serum calcium returned to pretreatment level. The Kt/v in both groups reached the normal standard without statistically significant difference. And there were no adverse reactions in the patients of both groups after dialysis.

Conclusion

For hemodialysis patients with bleeding, dual-pump segmented anticoagulation is superior to single-pump anticoagulation in intravenous pot anticoagulation. Double pump segmented sequential constant citrate anticoagulation can be utilized as a new simple and effective anticoagulation method for clinical hemodialysis.

A Cohort Study on the Safety and Efficacy of Warfarin and Rivaroxaban in Anticoagulant Therapy in Patients with Atrial Fibrillation Study

Objective. To observe the safety and efficacy of warfarin and rivaroxaban in anticoagulation therapy in patients with atrial fibrillation (AF). Methods. A total of 96 patients with AF treated in our hospital from June 2019 to February 2021 were enrolled in this study. According to the different modes of drug administration, the patients were divided into the warfarin group and rivaroxaban group. Demographic and clinical data such as age, body weight, and previous drug use were collected. The blood routine, liver and kidney function, blood coagulation routine, and cardiac color ultrasound were accessed. The valvular atrial fibrillation and anticoagulant taboos were excluded, and the risk of embolism and bleeding was evaluated. Among them, 48 patients in the warfarin group were given warfarin once a day, and the international ratio (INR) was used to adjust the dose, and the INR was controlled between 2.0 and 3.0. In contrast, 48 patients in the rivaroxaban group received a fixed dose of rivaroxaban 20 mg or 15 mg once a day. After administration, regular telephone or outpatient follow-up was given once a month, to monitor patients’ drug compliance and ask if there was bleeding, and to detect blood routine, urine routine, fecal routine+occult blood, and liver and kidney function. In addition, at the beginning of 3, 6, and 12 months of follow-up, each patient was given cardiac color Doppler ultrasound, peripheral vascular color ultrasound, and brain CT to determine whether there were mural thrombosis, stroke, and peripheral arterial thromboembolism. The INR attainment rate, coagulation index, thromboembolism, bleeding, and adverse reactions were compared between the two groups. Results. There was no significant difference in serum Dmurd and NT-proBNP levels between the two groups before treatment and 3, 6, and 9 months after treatment. There was no significant difference in the number of venous embolism, pulmonary embolism, cerebral embolism, and total embolism between the two groups ( $P>0.05$ ). There was no significant difference in the number of mild, moderate, and severe bleeding between the two groups ( $P>0.05$ ), but the total number of bleeding in the rivaroxaban group was lower than that in the warfarin group ( $P<0.05$ ). During the treatment, side effects such as nausea and vomiting, elevated transaminase, glutamyl transpeptidase, and diarrhea occurred between the two groups, and there was no significant difference in the number of adverse reactions between the two groups ( $P>0.05$ ). Conclusion. Compared with warfarin, rivaroxaban anticoagulant therapy has the same advantage in tolerance and prevention of thromboembolism in patients with AF, but rivaroxaban can effectively reduce the risk of bleeding in patients with AF.

Regional citrate versus heparin anticoagulation for CRRT in critically ill patients: a meta-analysis of RCTS

INTRODUCTION

This study aimed to compare the efficacy and safety of citrate and heparin in continuous renal replacement therapy (CRRT) for critically ill patients.

METHODS

Searched in PubMed, Embase, and Cochrane Library databases.

RESULTS

Analyses showed that there no difference existed in mortality, metabolic alkalosis, circuit loss, and the number of transfused between the two group(RR=0.95, P=0.40; RR=1.73, P=0.40; RR=0.64, P=0.09; RR=1.05, P=0.70). The filter life of the citrate group was longer than heparin group(MD=16.98, P<0.0001). The risk of bleeding and HIT was significantly lower in the citrate(RR=0.32, P<0.00001; RR=0.55, P=0.04). The citrate group was more susceptible to hypocalcemia(RR=4.85, P=0.0004).

CONCLUSION

Citrate anticoagulant therapy should have priority for CRRT in most critically ill patients. This article is protected by copyright. All rights reserved.

Heparin versus citrate anticoagulation for continuous renal replacement therapy in intensive care: the RRAM observational study

BACKGROUND

In the UK, 10% of admissions to intensive care units receive continuous renal replacement therapy with regional citrate anticoagulation replacing systemic heparin anticoagulation over the last decade. Regional citrate anticoagulation is now used in > 50% of intensive care units, despite little evidence of safety or effectiveness.

AIM

The aim of the Renal Replacement Anticoagulant Management study was to evaluate the clinical and health economic impacts of intensive care units moving from systemic heparin anticoagulation to regional citrate anticoagulation for continuous renal replacement therapy.

DESIGN

This was an observational comparative effectiveness study.

SETTING

The setting was NHS adult general intensive care units in England and Wales.

PARTICIPANTS

Participants were adults receiving continuous renal replacement therapy in an intensive care unit participating in the Intensive Care National Audit & Research Centre Case Mix Programme national clinical audit between 1 April 2009 and 31 March 2017.

INTERVENTIONS

Exposure - continuous renal replacement therapy in an intensive care unit after completion of transition to regional citrate anticoagulation. Comparator - continuous renal replacement therapy in an intensive care unit before starting transition to regional citrate anticoagulation or had not transitioned.

OUTCOME MEASURES

Primary effectiveness - all-cause mortality at 90 days. Primary economic - incremental net monetary benefit at 1 year. Secondary outcomes - mortality at hospital discharge, 30 days and 1 year; days of renal, cardiovascular and advanced respiratory support in intensive care unit; length of stay in intensive care unit and hospital; bleeding and thromboembolic events; prevalence of end-stage renal disease at 1 year; and estimated lifetime incremental net monetary benefit.

DATA SOURCES

Individual patient data from the Intensive Care National Audit & Research Centre Case Mix Programme were linked with the UK Renal Registry, Hospital Episode Statistics (for England), Patient Episodes Data for Wales and Civil Registrations (Deaths) data sets, and combined with identified periods of systemic heparin anticoagulation and regional citrate anticoagulation (survey of intensive care units). Staff time and consumables were obtained from micro-costing. Continuous renal replacement therapy system failures were estimated from the Post-Intensive Care Risk-adjusted Alerting and Monitoring data set. EuroQol-3 Dimensions, three-level version, health-related quality of life was obtained from the Intensive Care Outcomes Network study.

RESULTS

Out of the 188 (94.9%) units that responded to the survey, 182 (96.8%) use continuous renal replacement therapy. After linkage, data were available from 69,001 patients across 181 intensive care units (60,416 during periods of systemic heparin anticoagulation use and 8585 during regional citrate anticoagulation use). The change to regional citrate anticoagulation was not associated with a step change in 90-day mortality (odds ratio 0.98, 95% confidence interval 0.89 to 1.08). Secondary outcomes showed step increases in days of renal support (difference in means 0.53 days, 95% confidence interval 0.28 to 0.79 days), advanced cardiovascular support (difference in means 0.23 days, 95% confidence interval 0.09 to 0.38 days) and advanced respiratory support (difference in means, 0.53 days, 95% CI 0.03 to 1.03 days) with a trend toward fewer bleeding episodes (odds ratio 0.90, 95% confidence interval 0.76 to 1.06) with transition to regional citrate anticoagulation. The micro-costing study indicated that regional citrate anticoagulation was more expensive and was associated with an estimated incremental net monetary loss (step change) of -£2376 (95% confidence interval -£1912 to £911). The estimated likelihood of cost-effectiveness at 1 year was less than 0.1%.

LIMITATIONS

Lack of patient-level treatment data means that the results represent average effects of changing to regional citrate anticoagulation in intensive care units. Administrative data are subject to variation in data quality over time, which may contribute to observed trends.

CONCLUSIONS

The introduction of regional citrate anticoagulation has not improved outcomes for patients and is likely to have substantially increased costs. This study demonstrates the feasibility of evaluating effects of changes in practice using routinely collected data.

FUTURE WORK

(1) Prioritise other changes in clinical practice for evaluation and (2) methodological research to understand potential implications of trends in data quality.

TRIAL REGISTRATION

This trial is registered as ClinicalTrials.gov NCT03545750.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 13. See the NIHR Journals Library website for further project information.

Non-anticoagulation pediatric continuous renal replacement therapy methods to increase circuit life

INTRODUCTION

Acute kidney injury (AKI) is a clinical condition characterized by an abrupt increase in serum creatinine levels due to functional changes in the kidneys from a newfound insult or injury. For supportive treatment, continuous renal replacement therapy (CRRT) is one of the most widely used modalities due to its precise control of fluid balance over extended periods of time. However, its complications include circuit clotting, the most frequent cause for CRRT interruption. Vascular access and circuit management were found to be major determinants of performance efficiency. Anticoagulation required to prevent clotting has the downside of increasing the risk of bleeding, especially in the setting of overdosage. Hence, a delicate balance needs to be maintained consistently.

METHODS

This study explores the adequacy of non-anticoagulation measures in the prevention of circuit clotting. A comprehensive literature search was conducted using PubMed/Medline and Embase databases to include all relevant studies.

FINDINGS

The most-effective CRRT catheter would be made of nonthrombogenic material, noncuffed and nontunneled with separate lumens for arterial and venous blood. Further, studies show that blood flow during the process is optimized at 200 ml/min, which can be lowered in the pediatric population due to more narrow catheters. Platelet count and hematocrit need to be closely monitored as levels above 450,000 × 10⁶ /L and 0.40, respectively, increase risk of clotting. Predilution is a non-anticoagulation technique to reduce the risk of clotting by returning replacement solution to the blood before it reaches the filter. Also, biocompatible membranes such as polyacrylonitrile or polysulfone activate the coagulation cascade significantly less than the conventional cellulose-based membranes, thereby reducing clotting chances.

DISCUSSIONS

With the advent of such techniques and maneuvers, anticoagulation can be efficiently maintained in patients undergoing CRRT without increasing the risk of bleeding.

The importance of anticoagulation in COVID-19-related acute kidney injury requiring continuous renal replacement therapy

Introduction/Objective. In Serbia, the pandemic of the coronavirus disease 2019 (COVID-19) began in early March 2020. The aim of this study is to summarize clinical experience in the treatment of COVID-19-associated acute kidney injury (AKI) by methods of continuous renal replacement therapy (CRRT) with the focus on the amount of the administered dose of unfractionated heparin (UFH). Methods. The study covers 12 patients treated with CRRT at the Clinic for Infectious Diseases at the Clinical Center of Vojvodina from March 6, 2020 to May 20, 2020. Antithrombotic prophylaxis, risk of venous thromboembolism (VTE), applied therapy, biochemical parameters before and after CRRT, anticoagulation and other CRRT parameters were analyzed. Results. The mean age of the patients was 61.54 ? 10.37 years and seven (58.3%) were men. All the patients received standard thromboprophylaxis. Nine (75%) patients had Padua Prediction Score for Risk of VTE ? 4, but none developed a thrombotic event. Seven critically ill patients with multi-organic dysfunction developed AKI dependent on CRRT. The mean CRRT dose was 36.6 ml/kg/h, the mean bolus dose of unfractionated heparin was 3250 ? 1138.18IU, and the continuous dose was 1112.5 ? 334.48IU/kg/h. Discontinuation of CRRT due to the clotting circuit was necessary in only one patient. The values of leukocytes, AST, ALT, GGT, aPTT, PT were significantly higher after CRRT compared to urea, creatinine, potassium, chlorine and magnesium, whose values were significantly lower. Conclusion. In our COVID-19 patients who had high inflammatory parameters and D-dimer and an estimated risk of developing DVT, the implementation pre-dilution CVVHDF with antithrombotic membrane and 1/3 to 1/2 higher UFH doses than the recommended one, the filter life lasted longer with no complications.

Antithrombotic and anticoagulation therapies in cardiogenic shock: a critical review of the published literature

Cardiogenic shock (CS) is a complex multifactorial clinical syndrome, developing as a continuum, and progressing from the initial insult (underlying cause) to the subsequent occurrence of organ failure and death. There is a large phenotypic variability in CS, as a result of the diverse aetiologies, pathogenetic mechanisms, haemodynamics, and stages of severity. Although early revascularization remains the most important intervention for CS in settings of acute myocardial infarction, the administration of timely and effective antithrombotic therapy is critical to improving outcomes in these patients. In addition, other clinical settings or non-acute myocardial infarction aetiologies, associated with high thrombotic risk, may require specific regimens of short-term or long-term antithrombotic therapy. In CS, altered tissue perfusion, inflammation, and multi-organ dysfunction induce unpredictable alterations to antithrombotic drugs' pharmacokinetics and pharmacodynamics. Other interventions used in the management of CS, such as mechanical circulatory support, renal replacement therapies, or targeted temperature management, influence both thrombotic and bleeding risks and may require specific antithrombotic strategies. In order to optimize safety and efficacy of these therapies in CS, antithrombotic management should be more adapted to CS clinical scenario or specific device, with individualized antithrombotic regimens in terms of type of treatment, dose, and duration. In addition, patients with CS require a close and appropriate monitoring of antithrombotic therapies to safely balance the increased risk of bleeding and thrombosis.

Development and External Validation of a Model for Predicting Sufficient Filter Lifespan in Anticoagulation-Free Continuous Renal Replacement Therapy Patients

Background

Anticoagulation-free continuous renal replacement therapy (CRRT) was recommended by the current clinical guideline for patients with increased bleeding risk and contraindications of citrate. Nevertheless, anticoagulation-free CRRT yielded heterogeneous filter lifespan. Furthermore, the specific cutoff values for traditional coagulation parameters to predict sufficient filter lifespan of anticoagulation-free CRRT have not yet been determined. The purpose of our present study was to develop and validate a model for predicting sufficient filter lifespan in anticoagulation-free CRRT patients.

Methods

Patients who underwent anticoagulation-free CRRT in our center between June 2013 and June 2019 were retrospectively included. The primary outcome was sufficient filter lifespan (≥24 h). Thirty-seven predictors were included for modeling based on their clinical significance and previous reports. The final model was developed by using multivariable logistic regression analysis and was validated in a separate external cohort.

Results

The development cohort included 170 patients. Sufficient filter lifespan was observed in 80 patients. Thirteen variables were independent predictors for sufficient filter lifespan by logistic regression: body temperature, mean arterial pressure, activated partial thromboplastin time, direct bilirubin, alkaline phosphatase, blood urea nitrogen, vasopressor use, body mass index, white blood cell, platelet count, D-dimer, uric acid, and pH. The area under the curve (AUC) of the stepwise model and internal validation model was 0.82 (95% confidence interval [CI] [0.76–0.88]) and 0.8 (95% CI [0.74–0.87]), respectively. The positive predictive value and the negative predictive value of the stepwise model were 0.77 and 0.79, respectively. The validation cohort included 44 eligible patients and the AUC of the external validation model was 0.82 (95% CI [0.69–0.96]).

Conclusions

The use of a prediction model instead of an assessment based only on coagulation parameters could facilitate the identification of the patients with filter lifespan of ≥24 h when they accepted anticoagulation-free CRRT.

Comparison of the Clinical Effectiveness of AN69-oXiris versus AN69-ST Filter in Septic Patients: A Single-Centre Study

INTRODUCTION

The clinical effectiveness of AN69-oXiris remains unclear. This study aimed to compare the effects of AN69-oXiris and AN69-ST filters on cytokine levels and clinical improvement in septic patients.

METHODS

This prospective observational study recruited septic patients who underwent blood purification in the First Affiliated Hospital of Soochow University between December 2019 and May 2020. Patients were assigned to an AN69-oXiris (oXiris) or AN69-ST (ST) group based on their preferred filter. Patients' clinical data, cytokine levels, and prognostic indicators were analysed at baseline (T0), 24 h after treatment (T1), and at the end of the treatment (T2).

RESULTS

Forty-four patients participated in this study (22 patients in each group). Participants in both groups showed improvements in mean arterial pressure (MAP) values, oxygenation indices, and urinary output, and decreased vasoactive-inotropic scores (VISs), heart rates, lactic acid levels, and serum creatinine levels after blood purification. Reductions in cytokine levels were observed at T1 in both groups. Improvement the haemodynamic status was higher in the oXiris group than in the ST group at T2 (MAP: 79.0 [76.0, 85.0] vs. 77.0 [72.75, 79.25] mm Hg, p = 0.04; VISs: 9.10 [0.00, 16.69] vs. 19.05 [10.60, 26.33], p = 0.03, respectively). Patients in the oXiris group also had lower cytokine levels than those in the ST group at T1 (tumour necrosis factor-α: 24.55 [16.9, 30.15] vs. 30.15 [23.38, 34.13] pg/mL, p = 0.04; interleukin (IL)-6: 66.63 [46.21, 102.20] vs. 125.48 [79.73, 167.97] pg/mL, p = 0.01; IL-8: 53.59 [35.10, 66.01] vs. 63.60 [45.58, 83.37] pg/mL, p = 0.04; IL-10: 13.50 [10.35, 18.68] vs. 17.15 [13.80, 21.95] pg/mL, p = 0.04, respectively). There were no significant differences between the 2 groups regarding hospital mortality, intensive care unit length of stay (LOS), and hospital LOS.

CONCLUSION

Blood purification using the AN69-oXiris or AN69-ST filter proved useful for septic patients, which was associated with reduced cytokine levels and improved clinical condition. Patients treated with AN69-oXiris had a more remarkable improvement in haemodynamic status and lower cytokine levels than those treated with AN69-ST filter, but there were no differences in clinical outcomes. Further investigations are needed to prove this finding.

Continuous renal replacement therapy in COVID-19-associated AKI: adding heparin to citrate to extend filter life-a retrospective cohort study

BACKGROUND

Coronavirus disease 2019 (COVID-19) may predispose patients to thrombotic events. The best anticoagulation strategy for continuous renal replacement therapy (CRRT) in such patients is still under debate. The purpose of this study was to evaluate the impact that different anticoagulation protocols have on filter clotting risk.

METHODS

This was a retrospective observational study comparing two different anticoagulation strategies (citrate only and citrate plus intravenous infusion of unfractionated heparin) in patients with acute kidney injury (AKI), associated or not with COVID-19 (COV + AKI and COV - AKI, respectively), who were submitted to CRRT. Filter clotting risks were compared among groups.

RESULTS

Between January 2019 and July 2020, 238 patients were evaluated: 188 in the COV + AKI group and 50 in the COV - AKI group. Filter clotting during the first filter use occurred in 111 patients (46.6%). Heparin use conferred protection against filter clotting (HR = 0.37, 95% CI 0.25-0.55), resulting in longer filter survival. Bleeding events and the need for blood transfusion were similar between the citrate only and citrate plus unfractionated heparin strategies. In-hospital mortality was higher among the COV + AKI patients than among the COV - AKI patients, although it was similar between the COV + AKI patients who received heparin and those who did not. Filter clotting was more common in patients with D-dimer levels above the median (5990 ng/ml). In the multivariate analysis, heparin was associated with a lower risk of filter clotting (HR = 0.28, 95% CI 0.18-0.43), whereas an elevated D-dimer level and high hemoglobin were found to be risk factors for circuit clotting. A diagnosis of COVID-19 was marginally associated with an increased risk of circuit clotting (HR = 2.15, 95% CI 0.99-4.68).

CONCLUSIONS

In COV + AKI patients, adding systemic heparin to standard regional citrate anticoagulation may prolong CRRT filter patency by reducing clotting risk with a low risk of complications.

Influence of recombinant human-soluble thrombomodulin on extracorporeal circuit clotting in septic patients undergoing blood purification: a propensity-matched cohort study

Blood purification has been widely performed for critically ill patients, even in cases without renal failure. Effective anticoagulation of the extracorporeal circuit is necessary to prevent circuit clotting. We hypothesized that administration of recombinant human-soluble thrombomodulin (rhsTM) to septic patients undergoing blood purification may prevent circuit clotting, because this agent regulates coagulation. We performed a retrospective, single-center, propensity-matched cohort study in the intensive care unit of Nishichita General Hospital. We included septic patients admitted to the intensive care unit from May 2015 to August 2020 who underwent blood purification. Patients who received rhsTM during intensive care unit admission to the end of the first blood purification (rhsTM group) were matched 1:1 with other patients (control group). The primary outcome was the occurrence of circuit clotting during the first blood purification. A total of 138 patients were included in the study [43 patients (31%) in the rhsTM group and 95 patients (69%) in the control group]. After propensity score matching, 42 pairs of patients were selected, and patients in the rhsTM group had a lower incidence of circuit clotting (21 vs. 55%, P = 0.003). One case of major bleeding occurred in the rhsTM group, but there was no difference in the incidence of major bleeding between groups (2 vs. 0%, P = 1.0). In conclusion, this propensity-matched cohort study indicated that the administration of rhsTM to septic patients undergoing blood purification may prevent extracorporeal circuit clotting.

A Meta-Analysis of Extracorporeal Anticoagulants in Pediatric Continuous Kidney Replacement Therapy

OBJECTIVE

Continuous kidney replacement therapy (CKRT) is the primary therapeutic modality utilized in hemodynamically unstable patients with severe acute kidney injury. As the circuit is extracorporeal, it poses an increased risk of blood clotting and circuit loss; frequent circuit losses affect the provider's ability to provide optimal treatment. The objective of this meta-analysis is to evaluate the safety and efficacy of the extracorporeal anticoagulants in the pediatric CKRT population.

DATA SOURCES

We conducted a literature search on PubMed/Medline and Embase for relevant citations.

STUDY SELECTION

Studies were included if they involved patients under the age of 18 years undergoing CKRT, with the use of anticoagulation (heparin, citrate, or prostacyclin) as a part of therapy. Only English articles were included in the study.

DATA EXTRACTION

Initial search yielded 58 articles and a total of 24 articles were included and reviewed. A meta-analysis was performed focusing on the safety and effectiveness of regional citrate anticoagulation (RCA) vs unfractionated heparin (UFH) anticoagulants in children.

DATA SYNTHESIS

RCA had statistically significantly longer circuit life of 50.65 hours vs. UFH of 42.10 hours. Two major adverse effects metabolic alkalosis and electrolyte imbalance seen more commonly in RCA compared to UFH. There was not a significant difference in the risk of systemic bleeding when comparing RCA vs. UFH.

CONCLUSION

RCA is the preferred anticoagulant over UFH due to its significantly longer circuit life, although vigilant circuit monitoring is required due to the increased risk of electrolyte disturbances. Prostacyclin was not included in the meta-analysis due to the lack of data in pediatric patients. Additional studies are needed to strengthen the study results further.

Measurement of the Concentration of Citrate in Human Biofluids in Patients Undergoing Continuous Renal Replacement Therapy Using Regional Citrate Anticoagulation: Application of a Two-Step Enzymatic Assay

BACKGROUND

Continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA) is now commonly used to treat acute kidney injury in critically ill patients. The concentration of citrate is not routinely measured, with citrate accumulation and/or toxicity primarily assessed using surrogate measures.

OBJECTIVES

The aim of this study was to measure the concentration of citrate in plasma and ultrafiltrate in patients receiving CRRT with RCA using a modified commercial enzymatic assay.

METHODS

After meeting inclusion criteria, blood was sampled from 20 patients before, during, and after episodes of filtration. Using spectrophotometry, samples were tested for citrate concentration. Demographic and other clinical and biochemical data were also collected. Throughout, a 15 mmol/L solution of trisodium citrate was used as the prefilter anticoagulant. Results were analysed using STATA (v15.0) and presented as mean (SD), median (IQR), or simple proportion. Comparisons were made using either the Student t test or the Wilcoxon rank-sum test. Correlation was assessed using Pearson's r.

RESULTS

Twenty patients (17 males) were enrolled in the study. Mean (SD) age was 63.7 years (9.9). Median (IQR) ICU length of stay was 281 h (199, 422) with 85% undergoing intermittent positive pressure ventilation. Median APACHE 3 score was 95 (87, 117) with an overall 30% mortality rate. Median filtration time was 85 h (46, 149). No difference was found between pre- and post-filtration plasma citrate concentrations (79 µmol/L [50] vs. 71 µmol/L [42], p = 0.65). Mean citrate concentration during filtration was 508 µmol/L (221) with a maximum of 1,070 µmol/L. This was significantly higher than the pre/post levels (p < 0.001).

CONCLUSIONS

Plasma concentrations of citrate rose significantly during episodes of CRRT using RCA returning back to normal after cessation of treatment.

Precision renal replacement therapy

PURPOSE OF REVIEW

This article reviews the current evidence supporting the use of precision medicine in the delivery of acute renal replacement therapy (RRT) to critically ill patients, focusing on timing, solute control, anticoagulation and technologic innovation.

RECENT FINDINGS

Precision medicine is most applicable to the timing of RRT in critically ill patients. As recent randomized controlled trials have failed to provide consensus on when to initiate acute RRT, the decision to start acute RRT should be based on individual patient clinical characteristics (e.g. severity of the disease, evolution of clinical parameters) and logistic considerations (e.g. organizational issues, availability of machines and disposables). The delivery of a dynamic dialytic dose is another application of precision medicine, as patients may require different and varying dialysis doses depending on individual patient factors and clinical course. Although regional citrate anticoagulation (RCA) is recommended as first-line anticoagulation for continuous RRT, modifications to RCA protocols and consideration of other anticoagulants should be individualized to the patient's clinical condition. Finally, the evolution of RRT technology has improved precision in dialysis delivery through increased machine accuracy, connectivity to the electronic medical record and automated reduction of downtime.

SUMMARY

RRT has become a complex treatment for critically ill patients, which allows for the prescription to be precisely tailored to the different clinical requirements.

Application of regional citrate anticoagulation in membrane therapeutic plasma exchange

BACKGROUND

Both regional citrate anticoagulation (RCA) and heparin are used as anticoagulants during membrane therapeutic plasma exchange (mTPE). However, there are few reports of comparisons of the two methods. The aim of this study was to compare different anticoagulants in mTPE and observe the effectiveness, safety, and advantages of RCA.

METHODS

We retrospectively included 85 patients who underwent mTPE in the past 1 year, and divided them into three groups. Patients with no bleeding tendency were administered heparin anticoagulation; patients with bleeding tendency/with liver dysfunction/who had undergone an operation were treated with RCA, or did not receive anticoagulation. In the heparin group, low-dose heparin anticoagulation was administered; in the RCA group, 4% sodium citrate solution was administered, and 10% calcium gluconate solution was pumped from the venous circuit tube. The peripheral blood platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), and electrolytes were detected before and after treatment in all patients.

RESULTS

A total of 255 sessions of mTPE were performed in 85 patients (2-7 times/case) with 120 sessions of heparin anticoagulation, 93 sessions of RCA, and 42 sessions of no anticoagulation. Compared with pretreatment values, the platelet count decreased by 53.7% and the PT and APTT increased (p < 0.05) in the heparin group after treatment. There were no differences in platelet count and PT before and after treatment in the RCA group. In the RCA group, the patients did not experience hypocalcemia or hypercalcemia, and no separator clotting occurred.

CONCLUSION

RCA is safe, feasible, and effective in mTPE, especially for patients with bleeding tendency and frequent monitoring is needed. It is worth widely developing and applying it in clinical practice.

Monitoring Anticoagulation with Unfractionated Heparin on Renal Replacement Therapy. Which is the Best aPTT Sampling Site?

BACKGROUND

Controlled anticoagulation is key to maintaining continuous blood filtration therapies. Objective: The study aimed to compare different blood sampling sites for activated partial thromboplastin time (aPTT) to evaluate anticoagulation with unfractionated heparin (UFH) in continuous renal replacement therapy (CRRT) and identify the most appropriate sampling site for safe patient anticoagulation and increased filter life span.

METHOD

The study was a prospective observational single-centre investigation targeting intensive care unit (ICU) patients on CRRT using an anticoagulation protocol based on patient characteristics and a weight-based modified nomogram. Eighty-four patients were included in the study. Four sampling sites were assessed: heparin free central venous nondialysis catheter (CVC), an arterial line with heparinised flush (Artery), a circuit access line (Access), and a circuit return line (Postfilter). Blood was sampled from each of four different sites on every patient, four hours after the first heparin bolus. aPTT was determined using a rapid clot detector, point of care device.

RESULTS

A high positive correlation was obtained for aPTT values between CVC and Access sampling sites (r (84) =0.72; p <0 .05) and a low positive correlation between CVC and Arterial sampling site (r (84) =0.46, p < 0.05). When correlated by artery age, the young Artery (1-3 day old) correlates with CVC, Access and Postfilter (r (45) = 0.74, p >0.05). The aPTT values were significantly higher at Postfilter and Arterial sampling site, older than three days, compared to the CVC sampling site (p<0.05).

CONCLUSION

Considering patient bleeding risks and filter life span, the optimal sampling sites for safe assessment of unfractionated heparin anticoagulation on CRRT during CVVHDF were the central venous catheter using heparin free lavage saline solution, a heparinised flushed arterial catheter not older than three days, and a circuit access line.

Acute cardiorenal syndrome in acute heart failure: focus on renal replacement therapy

Almost half of hospitalised patients with acute heart failure develop acute cardiorenal syndrome. Treatment consists of optimisation of fluid status and haemodynamics, targeted therapy for the underlying cardiac disease, optimisation of heart failure treatment and preventive measures such as avoidance of nephrotoxic agents. Renal replacement therapy may be temporarily needed to support kidney function, mostly in case of diuretic resistant fluid overload or severe metabolic derangement. The best timing to initiate renal replacement therapy and the best modality in acute heart failure are still under debate. Several modalities are available such as intermittent and continuous renal replacement therapy as well as hybrid techniques, based on two main principles: haemofiltration and haemodialysis. Although continuous techniques have been associated with less haemodynamic instability and a greater chance of renal recovery, cohort data are conflicting and randomised controlled trials have not shown a difference in recovery or mortality. In the presence of diuretic resistance, isolated ultrafiltration with individualisation of ultrafiltration rates is a valid option for decongestion in acute heart failure patients. Practical tools to optimise the use of renal replacement therapy in acute heart failure-related acute cardiorenal syndrome were discussed.

Elimination of glycopeptide antibiotics by cytokine hemoadsorption in patients with septic shock: A study of three cases

Sepsis and septic shock are characterized by a release of cytokines into the circulation. These mediators contribute to the detrimental hemodynamic and metabolic effects in the early phase of septic shock. Recently, a new polystyrene-based hemoadsorption device was introduced into clinical practice (CytoSorb®). The adsorber binds a variety of molecules including cytokines and removes them from the circulation. Studies in septic patients have shown an improved clinical course following hemoadsorption but no increased survival. We hypothesize that not only cytokines but also antibiotics may be removed which potentially may negate any beneficial effect of the adsorber. To test this hypothesis, we performed polystyrene-based hemoadsorption in three patients in septic shock and analysed glycopeptide elimination by measuring serum levels pre- and post-adsorber. We administered both teicoplanin and vancomycin via a 60-min infusion and vancomycin via continuous infusion, additionally. When applied as 60 min infusion, vancomycin and teicoplanin were removed immediately by the adsorber. However, the adsorptive capacity of the device was saturable. Serum levels of vancomycin, but not teicoplanin, decreased to subtherapeutic levels. With continuous infusion of vancomycin, removal was less and serum levels remained in the therapeutic range. In conclusion, we show effective glycopeptide adsorption using a polystyrene-based hemoadsorber in septic patients. The dose of these antibiotics should be adjusted appropriately and early therapeutic drug monitoring is highly recommended.

Therapeutic Anticoagulation with Argatroban and Heparins Reduces Granulocyte Migration: Possible Impact on ECLS-Therapy?

Introduction

Anticoagulants such as argatroban and heparins (low-molecular-weight and unfractionated) play an immense role in preventing thromboembolic complications in clinical practice. Nevertheless, they can also have a negative effect on the immune system. This study is aimed at investigating the influence of these substances on polymorphonuclear neutrophils (PMNs), whose nonspecific defense mechanisms can promote thrombogenesis.

Methods

Blood samples from 30 healthy volunteers were investigated, whereby PMNs were isolated by density gradient centrifugation and incubated with 0.8 μg/mL of argatroban, 1.0 U/mL of low-molecular-weight heparin (LMWH), 1.0 U/mL of unfractionated heparin (UFH), or without drug (control). A collagen-cell mixture was prepared and filled into 3D μ-slide chemotaxis chambers (IBIDI® GmbH, Germany). Stimulation was initiated by using a chemokine gradient of n-formyl-methionine-leucyl-phenylalanine (fMLP), and microscopic observation was conducted for 4.5 hours. The cells' track length and track straightness, as well as the number of attracted granulocytes, level of ROS (reactive oxygen species) production, and NET (neutrophil extracellular traps) formation, were analyzed and categorized into migration distances and time periods.

Results

All three anticoagulants led to significantly reduced PMN track lengths, with UFH having the biggest impact. The number of tracks observed in the UFH group were significantly reduced compared to the control group. Additionally, the UFH group demonstrated a significantly lower track straightness compared to the control. ROS production and NET formation were unaffected.

Conclusion

Our data provide evidence that anticoagulants have an inhibitory effect on the extent of PMN migration and chemotactic migration efficiency, thus indicating their potential immune-modulatory and prothrombotic effects.

Renal replacement anticoagulant management: Protocol and analysis plan for an observational comparative effectiveness study of linked data sources

Acute kidney injury is common in critical illness. In patients with severe acute kidney injury, renal replacement therapy is needed to prevent harm from metabolic and electrolyte disturbances and fluid overload. In the UK, continuous renal replacement therapy (CRRT) is the preferred modality, which requires anticoagulation. Over the last decade, conventional systemic heparin anticoagulation has started being replaced by regional citrate anticoagulation for CRRT, which is now used in approximately 50% of ICUs. This shift towards regional citrate anticoagulation for CRRT is occurring with little evidence of safety or longer term effectiveness. Renal replacement anticoagulant management (RRAM) is an observational comparative effectiveness study, utilising existing data sources to address the clinical and cost-effectiveness of the change to regional citrate anticoagulation for CRRT in UK ICUs. The study will use data from approximately 85,000 patients who were treated in adult, general ICUs participating in the case mix programme national clinical audit between 1 April 2009 and 31 March 2017. A survey of health service providers’ anticoagulation practices will be combined with treatment and hospital outcome data from the case mix programme and linked with long-term outcomes from the Civil Registrations (deaths), Hospital Episodes Statistics for England, Patient Episodes Data for Wales, and the UK Renal Registry datasets. The primary clinical effectiveness outcome is all-cause mortality at 90-days. The study will incorporate an economic evaluation with micro-costing of both regional citrate anticoagulation and systemic heparin anticoagulation.

Study registration: NCT03545750

Regional citrate anticoagulation for continuous renal replacement therapy

PURPOSE OF REVIEW

The delivery of an effective dialysis dose in continuous renal replacement therapy (CRRT) depends on adequate anticoagulation of the extracorporeal circuit. In most patients, either systemic heparin anticoagulation (SHA) or regional citrate anticoagulation (RCA) is used. This review will outline the basics and rationale of RCA and summarize data on safety and efficacy of both techniques.

RECENT FINDINGS

The basic principle of RCA is to reduce the level of ionized calcium in the extracorporeal circuit via infusion of citrate. This way, effective anticoagulation restricted to the extracorporeal circuit is achieved. SHA and RCA were compared in a variety of studies. RCA significantly prolonged filter lifetime, reduced bleeding complications and provided excellent control of uremia and acid-base status. RCA was also safe in the majority of patients with impaired liver function, whereas caution must be exerted in those with severe multiorgan failure and persistent hyperlactatemia.

SUMMARY

RCA per se is safe and effective for anticoagulation of CRRT. Compared to SHA, efficacy of anticoagulation is improved and adverse effects are reduced. RCA can be recommended as the anticoagulation mode of choice for CRRT in most ICU patients.

Feasibility and safety of combined cytokine adsorption and continuous veno-venous hemodialysis with regional citrate anticoagulation in patients with septic shock

INTRODUCTION

Septic shock is characterized by severe metabolic and hemodynamic alterations. It is often accompanied by acute kidney injury. A new adjunct treatment is hemoadsorption using a cytokine adsorber in line with continuous veno-venous renal replacement therapy. We studied the feasibility, efficacy, and safety of cytokine adsorption with citrate-anticoagulated continuous veno-venous hemodialysis (regional citrate anticoagulation-continuous veno-venous hemodialysis).

METHODS

In 11 patients with septic shock and acute kidney injury stage 3, we studied 12 cycles of cytokine adsorption and regional citrate anticoagulation-continuous veno-venous hemodialysis. We monitored parameters of citrate anticoagulation, circuit lifetime, laboratory parameters, hemodynamics, and vasopressor demand.

RESULTS

Ten out of 12 adsorber/continuous veno-venous hemodialysis circuits reached the target lifetime of 24 h for the adsorber. One system clotted and one was stopped for non-device-related reasons. Nine of the remaining continuous renal replacement therapy circuits reached 72 h lifetime. With default settings for regional citrate anticoagulation, serum ionized calcium and pH were in the normal range. Urea and creatinine were reduced significantly, and norepinephrine dose decreased from 0.47 (±0.09) to 0.16 (±0.04) µg/kg/min (p = 0.016) after 24 h.

DISCUSSION

We show that combined cytokine adsorption/continuous veno-venous hemodialysis is effective to control pH, to reduce urea and creatinine, and to improve hemodynamics by reducing norepinephrine doses in patients with septic shock. It can be applied safely with standard settings of regional citrate anticoagulation rendering sufficiently long filter lifetimes for the adsorber and the continuous veno-venous hemodialysis circuit. Further studies are on the way to investigate whether these effects translate into improved outcomes in septic shock patients.

Renal replacement therapy: a practical update

Acute kidney injury (AKI) is defined as an abrupt decrease in kidney function, with the most severe form requiring some method of renal replacement therapy (RRT). The use of RRT is required in 5-10% of critically ill patients who develop severe AKI. Renal replacement therapy can be provided as either intermittent hemodialysis or one of the various modes of continuous renal replacement therapy (CRRT), with CRRT potentially conferring an advantage with respect to renal recovery and dialysis independence. There is no difference in mortality when comparing low (< 25 mL·kg^-1·hr^-1) vs high (> 40 mL·kg^-1·hr^-1) RRT dosing. Continuous renal replacement therapy may be run in different modes of increasing complexity depending on a given patient's clinical needs. Regional citrate anticoagulation is recommended as the therapy of choice for the majority of critically ill patients requiring CRRT.

Tigecycline in critically ill patients on continuous renal replacement therapy: a population pharmacokinetic study

Background

Tigecycline is a vital antibiotic treatment option for infections caused by multiresistant bacteria in the intensive care unit (ICU). Acute kidney injury (AKI) is a common complication in the ICU requiring continuous renal replacement therapy (CRRT), but pharmacokinetic data for tigecycline in patients receiving CRRT are lacking.

Methods

Eleven patients mainly with intra-abdominal infections receiving either continuous veno-venous hemodialysis (CVVHD, n = 8) or hemodiafiltration (CVVHDF, n = 3) were enrolled, and plasma as well as effluent samples were collected according to a rich sampling schedule. Total and free tigecycline was determined by ultrafiltration and high-performance liquid chromatography (HPLC)-UV. Population pharmacokinetic modeling using NONMEM® 7.4 was used to determine the pharmacokinetic parameters as well as the clearance of CVVHD and CVVHDF. Pharmacokinetic/pharmacodynamic target attainment analyses were performed to explore the potential need for dose adjustments of tigecycline in CRRT.

Results

A two-compartment population pharmacokinetic (PK) model was suitable to simultaneously describe the plasma PK and effluent measurements of tigecycline. Tigecycline dialysability was high, as indicated by the high mean saturation coefficients of 0.79 and 0.90 for CVVHD and CVVHDF, respectively, and in range of the concentration-dependent unbound fraction of tigecycline (45–94%). However, the contribution of CRRT to tigecycline clearance (CL) was only moderate (CL_CVVHD: 1.69 L/h, CL_CVVHDF: 2.71 L/h) in comparison with CL_body (physiological part of the total clearance) of 18.3 L/h. Bilirubin was identified as a covariate on CL_body in our collective, reducing the observed interindividual variability on CL_body from 58.6% to 43.6%. The probability of target attainment under CRRT for abdominal infections was ≥ 0.88 for minimal inhibitory concentration (MIC) values ≤ 0.5 mg/L and similar to patients without AKI.

Conclusions

Despite high dialysability, dialysis clearance displayed only a minor contribution to tigecycline elimination, being in the range of renal elimination in patients without AKI. No dose adjustment of tigecycline seems necessary in CRRT.

Trial registration

EudraCT, 2012–005617-39. Registered on 7 August 2013.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2278-4) contains supplementary material, which is available to authorized users.