Circuit lifespan during continuous renal replacement therapy for combined liver and kidney failure

Development and external validation of a prediction model for the premature circuit clotting of continuous renal replacement therapy in critically ill patients

OBJECTIVE

This study aimed to develop and validate a prediction model for premature circuit clotting of continuous renal replacement therapy (CRRT) in critically ill patients.

DESIGN

A retrospective cohort study was conducted on ICU patients undergoing CRRT. The Medical Information Mart for Intensive Care-III Clinical Database CareVue subset and Medical Information Mart for Intensive Care-IV were utilized for model development, while the eICU Collaborative Research Database was employed for external validation. Predictive factors were selected through Least Absolute Shrinkage and Selection Operator Regression and univariate logistic regression. A prediction model was then developed using binary logistic regression. Internal and external validations assessed the model's discrimination, calibration, and clinical net benefit.

RESULTS

This study encompassed 2531 patients overall, with a premature circuit clotting rate of 31.88 %. The prediction model comprises five variables: body temperature, anticoagulation, mean arterial pressure, maximum transmembrane pressure change within two hours, and vasopressor. The model demonstrated robust predictive performance, achieving an area under the receiver operating characteristic curve of 0.897 (95 % CI: 0.879-0.915) in the training set and 0.877 (95 % CI: 0.852-0.902) in the external validation set. Internal validation yielded a Brier score of 0.087, while external validation showed a Brier score of 0.120. Calibration curves indicated good model calibration for both validations. The decision curve analysis indicates that the model yields a clinical net benefit across a wide range of decision thresholds.

CONCLUSION

The model demonstrates robust discrimination, calibration, and clinical net benefit, with readily available variables indicating substantial potential for valuable clinical applications.

IMPLICATIONS FOR CLINICAL PRACTICE

Healthcare providers in the ICU can leverage the model to evaluate the risk of premature circuit clotting in critically ill patients undergoing continuous renal replacement therapy, facilitating timely intervention to mitigate its incidence.

Regional Citrate Anticoagulation versus No Anticoagulation for CKRT in Patients with Liver Failure with Increased Bleeding Risk

BACKGROUND

The opinions on the efficacy and safety of no anticoagulation versus regional citrate anticoagulation for continuous KRT (CKRT) were controversial in patients with severe liver failure with a higher bleeding risk. We performed a randomized controlled trial to assess no anticoagulation versus regional citrate anticoagulation for CKRT in these patients.

METHODS

Adult patients with liver failure with a higher bleeding risk who required CKRT were considered candidates. The included participants were randomized to receive regional citrate anticoagulation or no-anticoagulation CKRT. The primary end point was filter failure.

RESULTS

Of the included participants, 44 and 45 were randomized to receive regional citrate anticoagulation and no-anticoagulation CKRT, respectively. The no-anticoagulation group had a significantly higher filter failure rate (25 [56%] versus 12 [27%], P = 0.003), which was confirmed by cumulative incidence function analysis and sensitive analysis including only the first CKRT sessions. In the cumulative incidence function analysis, the cumulative filter failure rates at 24, 48, and 72 hours of the no-anticoagulation and regional citrate anticoagulation groups were 31%, 58%, and 76% and 11%, 23%, and 35%, respectively. Participants in the regional citrate anticoagulation group had significantly higher incidences of Ca 2+tot /Ca 2+ion >2.5 (7% versus 57%, P < 0.001), hypocalcemia (51% versus 82%, P = 0.002), and severe hypocalcemia (13% versus 77%, P < 0.001). However, most (73%) of the increased Ca 2+tot /Ca 2+ion ratios were normalized after the upregulation of the calcium substitution rate. In the regional citrate anticoagulation group, there was no significant additional increase in the systemic citrate concentration after 6 hours.

CONCLUSIONS

For patients with liver failure with a higher bleeding risk who required CKRT, regional citrate anticoagulation resulted in significantly longer filter lifespan than no anticoagulation. However, regional citrate anticoagulation in patients with liver failure was associated with a significantly higher risk of hypocalcemia, severe hypocalcemia, and Ca 2+tot /Ca 2+ion >2.5.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

RCA for CRRT in Liver Failure and High Risk Bleeding Patients, NCT03791190 .

Factors affecting continuous renal replacement therapy duration in critically ill patients: A retrospective study

INTRODUCTION

This study aimed to analyze the factors affecting continuous renal replacement therapy (CRRT) duration in critically ill patients and provide a reference for clinical treatment.

MATERIAL AND METHODS

We divided patients into regional citrate anti-coagulation (RCA) and low-molecular-weight-heparin (LMWH) groups according to the anti-coagulation method and collected the relevant data, to analyze the factors associated with CRRT time.

RESULTS

Compared with the LMWH group, the RCA group had a longer mean treatment time (55.36 ± 22.57 vs. 37.65 ± 27.09 h, p < 0.001), lower transmembrane pressure, and lower filter pressure, regardless of vascular access site. Multivariable linear regression analysis showed a significant correlation between anti-coagulation patterns, filter pressure at CRRT discontinuation, nurses' level of intensive care unit experience, pre-machine fibrinogen level, and CRRT time.

CONCLUSION

Anti-coagulation is the most important factor affecting CRRT duration. Filter pressure, nurses' level of intensive care unit experience, and fibrinogen level also affecting CRRT duration.

Continuous KRT: A Contemporary Review

AKI is a common complication of critical illness and is associated with substantial morbidity and risk of death. Continuous KRT comprises a spectrum of dialysis modalities preferably used to provide kidney support to patients with AKI who are hemodynamically unstable and critically ill. The various continuous KRT modalities are distinguished by different mechanisms of solute transport and use of dialysate and/or replacement solutions. Considerable variation exists in the application of continuous KRT due to a lack of standardization in how the treatments are prescribed, delivered, and optimized to improve patient outcomes. In this manuscript, we present an overview of the therapy, recent clinical trials, and outcome studies. We review the indications for continuous KRT and the technical aspects of the treatment, including continuous KRT modality, vascular access, dosing of continuous KRT, anticoagulation, volume management, nutrition, and continuous KRT complications. Finally, we highlight the need for close collaboration of a multidisciplinary team and development of quality assurance programs for the provision of high-quality and effective continuous KRT.

Regional Citrate Anticoagulation or Heparin Anticoagulation for Renal Replacement Therapy in Patients With Liver Failure: A Systematic Review and Meta-Analysis

In patients with liver failure complicated by acute kidney injury, renal replacement therapy (RRT) is often required to improve the internal environment. The use of anticoagulants for RRT in patients with liver failure remains controversial. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases for studies. The methodological quality of the included studies was assessed using the Methodological Index for Nonrandomized Studies. A meta-analysis was performed using R software (version 3.5.1) and Review Manager (version 5.3.5). During RRT, 348 patients from 9 studies received regional citrate anticoagulation (RCA), and 127 patients from 5 studies received heparin anticoagulation (including heparin and LMWH). Among patients who received RCA, the incidence of citrate accumulation, metabolic acidosis, and metabolic alkalosis were 5.3% (95% confidence interval [CI]: 0%-25.3%), 26.4% (95% CI: 0-76.9), and 1.8% (95% CI: 0-6.8), respectively. The potassium, phosphorus, total bilirubin (TBIL), and creatinine levels were lower, whereas the serum pH, bicarbonate, base excess levels, and total calcium/ionized calcium ratio were higher after treatment than before treatment. Among patients who received heparin anticoagulation, the TBIL levels were lower, whereas the activated partial thromboplastin clotting time and D-dimer levels were higher after treatment than before treatment. The mortality rates in the RCA and heparin anticoagulation groups were 58.9% (95% CI: 39.2-77.3) and 47.4% (95% CI: 31.1-63.7), respectively. No statistical difference in mortality was observed between the 2 groups. For patients with liver failure, the administration of RCA or heparin for anticoagulation during RRT under strict monitoring may be safe and effective.

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.

Circuit haemodynamics during non-citrate and regional citrate continuous renal replacement, and impact of blood flow on filter life

BACKGROUND

During continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA), blood flow (Qb) might affect vascular access dysfunction (AD) and, thereby, circuit life.

METHODS

Circuit life and circuit haemodynamics were studied in three intensive care units (ICUs) by analysing hemofilter device data (Prismaflex^®, Baxter, Chicago, IL). The three sites shared similar RCA protocols but differed in Qb (120-130 vs 150-200 mL/h). Non-RCA circuits were compared with RCA circuits in which the impact of Qb was also assessed.

RESULTS

About 3,981,906 min of circuit pressures were analysed in 2568 circuits in 567 patients. High-Qb RCA was associated with more extreme pressures, and greater AD (IRR 3.7 (1.93-7.08) as well as reduced filter life 21.1 (10.2-42.6) vs 27.0 (14.8-41.6) h). AD in high-Qb RCA circuits was associated with a 49% reduction in filter life, versus 24% reduction in low-Qb RCA, associated with a rise in the rate of increase in transfilter pressure.

CONCLUSIONS

High-Qb RCA-CRRT was associated with greater access dysfunction, earlier filter loss and increased haemodynamic impacts of access dysfunction, suggesting low-Qb RCA-CRRT may improve circuit mechanics, function and longevity.

Management of acute renal replacement therapy in critically ill cirrhotic patients

Renal replacement therapy (RRT) in cirrhotic patients encompasses a number of issues related to the particular characteristics of this population, especially in the intensive care unit (ICU) setting. The short-term prognosis of cirrhotic patients with acute kidney injury is poor, with a mortality rate higher than 65% in patients with RRT requirement, raising questions about the futility of its initiation. Regarding the management of the RRT itself, there is still no consensus with respect to the modality (continuous versus intermittent) or the anticoagulation required to improve the circuit life, which is shorter than similar at-risk populations, despite the altered haemostasis in traditional coagulation tests frequently found in these patients. Furthermore, volume management is one of the most complex issues in this cohort, where tools used for ambulatory dialysis have not yet been successfully reproducible in the ICU setting. This review attempts to shed light on the management of acute RRT in the critically ill cirrhotic population based on the current evidence and the newly available tools. We will discuss the timing of RRT initiation and cessation, the modality, anticoagulation and fluid management, as well as the outcomes of the RRT in this population, and provide a brief review of the albumin extracorporeal dialysis from the point of view of a nephrologist.

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.

Low Blood Flow Continuous Veno-Venous Haemodialysis Compared with Higher Blood Flow Continuous Veno-Venous Haemodiafiltration: Effect on Alarm Rates, Filter Life, and Azotaemic Control

TITLE

Low blood flow continuous veno-venous haemodialysis (CVVHD) compared with higher blood flow continuous veno-venous haemodiafiltration (CVVHDF): effect on alarm rates, filter life, and azotaemic control.

INTRODUCTION

Continuous renal replacement therapy (CRRT) can be delivered via convective, diffusive, or mixed approaches. Higher blood flows have been advocated for convective clearance efficiency and promotion of filter life. It is unclear whether a lower blood flow predominantly diffusive approach may benefit filter life and alarm rates.

MATERIALS AND METHODS

Sequential cohort study of 284 patients undergoing 874 CRRT circuits from January 2015 to August 2018 in a single university-associated tertiary referral hospital in Australia. Patients underwent a protocol of either CVVHDF at blood flow 200-250 mL/min or CVVHD at blood flow 100-130 mL/min. Machine and patient data were analysed. Outcomes of azotaemic control, filter life, and warning alarm rates were log transformed and analysed with mixed linear modelling with patient as a random effect.

RESULTS

Both groups had similar azotaemic control (effect estimate on log creatinine CVVHD vs. CVVHDF 1.04 [0.87-1.25], p = 0.68) and median filter life (CVVHDF 16.8 [8.4-90.5] h and CVVHD 16.4 [9.4-82.3] h, p = 0.97). However, circuit pressures were less extreme with a narrower distribution during CVVHD. Multivariate analysis showed CVVHD had a reduced risk of warning alarms (incidence risk ratio [IRR] 0.51 [0.38-0.70]) and femoral access placement also had a reduced risk of alarms (IRR 0.55 [0.41-0.73]).

CONCLUSION

Low blood flow CVVHD and femoral vascular access reduce alarms while maintaining azotaemic control and circuit patency thus minimizing bedside clinician workload.

Decreased CRRT Filter Lifespan in COVID-19 ICU Patients

(1) Background: Increased thromboembolic events and an increased need for continuous renal replacement therapy (CRRT) have been frequently reported in COVID-19 patients. Our aim was to investigate CRRT filter lifespan in intensive care unit (ICU) COVID-19 patients. (2) Methods: We compared CRRT adjusted circuit lifespan in COVID-19 patients admitted for SARS-CoV-2 infection to a control group of patients admitted for septic shock of pulmonary origin other than COVID-19. Both groups underwent at least one session of CRRT for AKI. (3) Results: Twenty-six patients (13 in each group) were included. We analysed 117 CRRT circuits (80 in the COVID-19 group and 37 in the control group). The adjusted filter lifespan was shorter in the COVID-19 group (17 vs. 39 h, p < 0.001). This trend persisted after adjustment for confounding factors (-14 h, p = 0.037). Before CRRT circuit clotting, the COVID-19 group had a more procoagulant profile despite higher heparin infusion rates. Furthermore, we reported a decreased relation between activated partial thromboplastin time (aPTT) and cumulative heparin dose in COVID-19 patients when compared to historical data of 23,058 patients, suggesting a heparin resistance. (4) Conclusion: COVID-19 patients displayed a shorter CRRT filter lifespan that could be related to a procoagulant profile and heparin resistance.

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.

Filter life and safety of heparin-grafted membrane for continuous renal replacement therapy - A randomized controlled trial

Polyethyleneimine-layered membrane with grafted heparin (oXiris) may improve filter life during continuous renal replacement therapy (CRRT) in addition to its immunoadsorptive capability, compared with that of conventional membrane. In this single center, prospective, open-label pilot study, we randomized critically ill patients with bleeding risk who underwent anticoagulation-free CRRT, to commence with oXiris or M150 filter with sequential crossover. We examined the filter life with each circuit and its effect on systemic coagulation parameters. We randomized 11 and nine patients to commence CRRT with oXiris and M150 respectively, with 19 oXiris and 20 M150 filter-circuits in all. Patient profiles in both arms were comparable for illness severity and comorbidities. Median filter lives for oXiris versus M150 circuits were 13 h versus 18 h (p = 0.10). Among 11 patients with paired crossover filters, filter lives for 14 oXiris-M150 circuit pairs were 13 h versus 16 h (p = 0.27), and corresponding transmembrane pressures increased to 111 mmHg versus 75 mmHg by 12 h (p = 0.02). Patients' coagulation parameters were comparable following both filter-circuits. CRRT with oXiris (vs. M150) was independently associated with shorter filter life, adjusted for prescribed dose, vascular access, and coagulopathy. Use of oXiris did not prolong filter life over conventional membrane with no evidence of systemic heparin exposure; significant membrane clogging is observed by 12 h with oXiris.

Continuous renal replacement therapy without anticoagulation in critically ill patients at high risk of bleeding: A systematic review and meta-analysis

The current clinical guideline recommends continuous renal replacement therapy (CRRT) proceed without anticoagulation in patients with contraindication to citrate and increased bleeding risk. Nevertheless, the efficacy of anticoagulation-free CRRT remains inconsistent. The purpose of our present systematic review is to evaluate the efficacy and safety of anticoagulant-free CRRT based on the current literatures. The primary outcomes were filter lifespan and risk factors for filter failure. Seventeen observational studies and three randomized controlled trials were included in our present meta-analysis. There was no significant difference in filter lifespan and azotemic control between the anticoagulation-free and systemic heparin group. The regional citrate anticoagulation (RCA) protocol seems to be superior to the anticoagulation-free protocol in terms of filter lifespan (WMD -23.01, 95% CI [-28.62, -17.39], p < 0.001; I²  = 0%, p = 0.53) and azotemic control. Nafamostat protocol could significantly prolong filter lifespan (WMD -8.4, 95% CI [-9.9, -6.9], p < 0.001; I²  = 33.7%, p = 0.21) as compared with anticoagulation-free protocol without better azotemic control. The conventional coagulation parameters showed poor predictive performence for filter failure and the necessity of anticoagulants use before CRRT. Currently, the optimal choice of anticoagulation strategy for critically ill patients with increased bleeding risk could be RCA under close monitoring.

Renal Dysfunction in Cirrhosis: Critical Care Management

Cirrhotic patients with manifestations of the end-stage liver disease have a high risk for developing renal dysfunction even with minor insults. The development of renal dysfunction increases the morbidity and mortality of these patients. Causes of renal dysfunction in cirrhotics can be due to hepatorenal syndrome (HRS) or acute kidney injury (AKI) resulting from prerenal, renal, and postrenal causes. Development of pretransplant renal dysfunction has been shown to affect post-liver transplantation outcomes. Early detection and aggressive strategies for the prevention of further progression of renal dysfunction seem to decrease the morbidity and improve survival in this group of patients. This article aims to outline the pathogenesis of renal dysfunction in cirrhosis, etiological factors, and evaluation of renal dysfunction, strategies for aggressive therapy for renal dysfunction, the indications of renal replacement therapy (RRT) in this group of patients, and the various modalities of RRT with their merits and demerits. A thorough understanding of the pathogenesis, early detection, and aggressive corrective measures for AKI can prevent further progression. In conclusion, a good knowledge of treatment modalities available for renal dysfunction in cirrhosis and institution of timely interventions can significantly improve survival in this group of patients.

Ensuring Sustainability of Continuous Kidney Replacement Therapy in the Face of Extraordinary Demand: Lessons From the COVID-19 Pandemic

With the exponential surge in patients with coronavirus disease 2019 (COVID-19) worldwide, the resources needed to provide continuous kidney replacement therapy (CKRT) for patients with acute kidney injury or kidney failure may be threatened. This article summarizes subsisting strategies that can be implemented immediately. Pre-emptive weekly multicenter projections of CKRT demand based on evolving COVID-19 epidemiology and routine workload should be made. Corresponding consumables should be quantified and acquired, with diversification of sources from multiple vendors. Supply procurement should be stepped up accordingly so that a several-week stock is amassed, with administrative oversight to prevent disproportionate hoarding by institutions. Consumption of CKRT resources can be made more efficient by optimizing circuit anticoagulation to preserve filters, extending use of each vascular access, lowering blood flows to reduce citrate consumption, moderating the CKRT intensity to conserve fluids, or running accelerated KRT at higher clearance to treat more patients per machine. If logistically feasible, earlier transition to intermittent hemodialysis with online-generated dialysate, or urgent peritoneal dialysis in selected patients, may help reduce CKRT dependency. These measures, coupled to multicenter collaboration and a corresponding increase in trained medical and nursing staffing levels, may avoid downstream rationing of care and save lives during the peak of the pandemic.

The Effect of Patient- and Treatment-Related Factors on Circuit Lifespan During Continuous Renal Replacement Therapy in Critically Ill Children

OBJECTIVES

To examine the effects of patient and treatment variables on circuit lifespan in critically ill children requiring continuous renal replacement therapy.

DESIGN

Retrospective observational study based on a prospective registry.

SETTING

Tertiary referral 30-bed PICU.

PATIENTS

One hundred sixty-one critically ill children undergoing continuous renal replacement therapy during an 8-year period (2007-2014) were included in the study.

INTERVENTIONS

Continuous renal replacement therapy.

MEASUREMENTS AND MAIN RESULTS

During the study period, 161 patients received a total of 22,190 hours of continuous renal replacement therapy, with a median duration of 74.75 hours (interquartile range, 32-169.5) per patient. Of the 572 filter circuits used, 276 (48.3%) were changed due to circuit clotting and 262 (45.8%) were electively changed. Median circuit life was 24.62 hours (interquartile range, 10.6-55.3) for all filters and significantly longer for those electively removed as compared to those prematurely removed because of clotting (35.50 hr [interquartile range, 16.9-67.6] vs 22.00 hr [interquartile range, 13.8-42.5]; p < 0.001). Multivariate regression analyses revealed that admission diagnosis (p < 0.001), anticoagulation type (p < 0.001), access type (p = 0.016), and circuit size (p = 0.027) were associated with prolonged circuit life, as well as, in patients on heparin anticoagulation, with higher doses of heparin (p < 0.001) and a prolonged activated partial thromboplastin time (p < 0.001).

CONCLUSIONS

In this study, circuit lifespan in pediatric continuous renal replacement therapy was low and appeared to depend upon the patient's diagnosis, the type of access and anticoagulation used as well as the size of the circuit used.

Circuit Hemodynamics and Circuit Failure During Continuous Renal Replacement Therapy

OBJECTIVES

To study hemodynamic changes within continuous renal replacement therapy circuits and evaluate their relationship with continuous renal replacement therapy longevity.

DESIGN

Analysis of downloaded variables recorded by continuous renal replacement therapy machines during multiple episodes of clinical care.

SETTING

Tertiary ICU in Melbourne, Australia.

PATIENTS

Cohort of 149 ICU patients: 428 episodes of continuous renal replacement therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Indices of continuous renal replacement therapy function representing 554,991 minutes were assessed including blood flow, access pressure, effluent pressure, prefilter pressure, and return pressure. We defined three patterns of artificial kidney failure: early (≤ 12 hr), intermediate (> 12-24 hr), and late (> 24 hr) in 35%, 31%, and 34% of circuits, respectively. Mean access pressure in late artificial kidney failure was 7.5 mm Hg (7.1-7.9 mm Hg) less negative than early failing circuits and pressures demonstrated lower variability in such late failing circuits. Access dysfunction, defined as access pressure less than or equal to -200 mm Hg occurred in the first 4 hours in 118 circuits (27%) which had a shorter (median [interquartile range]) life at 12.9 hr [5.5-21.3 hr]) hours than access dysfunction-free circuits (18.8 hr [10.1-33.4 hr]; p < 0.0001). Multivariate analysis found the first occurrence of access dysfunction (as a time-varying covariate) was independently associated with increased hazard of subsequent failure (hazard ratio, 1.75; 1.36-2.26). Classification and regression tree analysis of summary pressure indices in the first 2 hours confirmed minimum access pressure to be a significant predictor, as well as indices of transmembrane pressure and return pressure. A pressure-based predictor correctly identified early and late failing circuits (86.2% and 93.6% specificity, respectively).

CONCLUSIONS

Access dysfunction is a predictor of continuous renal replacement therapy circuit failure. Future monitoring of continuous renal replacement therapy hemodynamics may facilitate remedial actions to improve circuit function.

Regional citrate anticoagulation versus no-anticoagulation for continuous venovenous hemofiltration in patients with liver failure and increased bleeding risk: A retrospective case-control study

Objective

There are controversial opinions on anticoagulation for continuous venovenous hemofiltration (CVVH) in patients with liver failure (LF) and increased bleeding risk. Therefore, we conducted a retrospective study to evaluate the efficacy and safety of regional citrate anticoagulation (RCA) versus no-anticoagulation for CVVH in these patients.

Methods

The included patients were divided into RCA and no-anticoagulation group according to the CVVH anticoagulation strategy they accepted for CVVH. Filter lifespan, bleeding, citrate accumulation, catheter occlusion, and totCa/ionCa ratio were evaluated as outcomes.

Results

In the original cohort, the filter lifespan of the RCA group (41 patients, 79 filters) was significantly longer than the no-anticoagulation group (62 patients, 162 filters) (> 72 hours vs 39.5 hours (IQR 31.2–47.8), P = 0.002). The adjusted results demonstrated that RCA could significantly reduce the risk of filter failure (HR = 0.459, 95%CI 0.26–0.82, P = 0.008). Four episodes of totCa/ionCa > 2.5 were observed in the RCA group and continuously accepted RCA-CVVH after the reduction of citrate dose and blood flow. No obvious citrate accumulation was observed in these patients. In the matched cohort, the filter lifespan of the RCA group was significantly longer than the no-anticoagulation group (P = 0.013) as well. No significant difference in the episodes of totCa/ionCa > 2.5 was observed between the two matched groups (P = 0.074). Both in the original cohort and the matched cohort, the bleeding, acidosis, alkalosis, and catheter occlusion incidences were not significantly different between the two groups.

Conclusions

In LF patients with increased bleeding risk who underwent CVVH, RCA could prolong the filter lifespan and be safely used with careful blood gas monitoring and citrate dose adjusting. Further prospective, randomized, control studies are warranted to obtain robust evidences.

Net Ultrafiltration Prescription and Practice Among Critically Ill Patients Receiving Renal Replacement Therapy: A Multinational Survey of Critical Care Practitioners

OBJECTIVES

To assess the attitudes of practitioners with respect to net ultrafiltration prescription and practice among critically ill patients with acute kidney injury treated with renal replacement therapy.

DESIGN

Multinational internet-assisted survey.

SETTING

Critical care practitioners involved with 14 societies in 80 countries.

SUBJECTS

Intervention: MEASUREMENT AND MAIN RESULTS:: Of 2,567 practitioners who initiated the survey, 1,569 (61.1%) completed the survey. Most practitioners were intensivists (72.7%) with a median duration of 13.2 years of practice (interquartile range, 7.2-22.0 yr). Two third of practitioners (71.0%; regional range, 55.0-95.5%) reported using continuous renal replacement therapy with a net ultrafiltration rate prescription of median 80.0 mL/hr (interquartile range, 49.0-111.0 mL/hr) for hemodynamically unstable and a maximal rate of 299.0 mL/hr (interquartile range, 200.0-365.0 mL/hr) for hemodynamically stable patients, with regional variation. Only a third of practitioners (31.5%; range, 13.7-47.8%) assessed hourly net fluid balance during continuous renal replacement therapy. Hemodynamic instability was reported in 20% (range, 20-38%) of patients and practitioners decreased the rate of fluid removal (70.3%); started or increased the dose of a vasopressor (51.5%); completely stopped fluid removal (35.8%); and administered a fluid bolus (31.6%), with significant regional variation. Compared with physicians, nurses were most likely to report patient intolerance to net ultrafiltration (73.4% vs 81.3%; p = 0.002), frequent interruptions (40.4% vs 54.5%; p < 0.001), and unavailability of trained staff (11.9% vs 15.6%; p = 0.04), whereas physicians reported unavailability of dialysis machines (14.3% vs 6.1%; p < 0.001) and costs associated with treatment as barriers (12.1% vs 3.0%; p < 0.001) with significant regional variation.

CONCLUSIONS

Our study provides new knowledge about the presence and extent of international practice variation in net ultrafiltration. We also identified barriers and specific targets for quality improvement initiatives. Our data reflect the need for evidence-based practice guidelines for net ultrafiltration.

High-Fidelity Simulation Nurse Training Reduces Unplanned Interruption of Continuous Renal Replacement Therapy Sessions in Critically Ill Patients: The SimHeR Randomized Controlled Trial

BACKGROUND

Although continuous renal replacement therapy (CRRT) is common, unplanned interruptions (UI) often limit its usefulness. In many units, nurses are responsible for CRRT management. We hypothesized that a nurse training program based on high-fidelity simulation would reduce the rate of interrupted sessions.

METHODS

We performed a 2-phase (training and evaluation), randomized, single-center, open study: During the training phase, intensive care unit nurses underwent a 6-hour training program and were randomized to receive (intervention) or not (control) an additional high-fidelity simulation training (6 hours). During the evaluation phase, management of CRRT sessions was randomized to either intervention or control nurses. Sessions were defined as UI if they were interrupted and the interruption was not prescribed in writing more than 3 hours before.

RESULTS

Study nurses had experience with hemodialysis, but no experience with CRRT before training. Intervention nurses had higher scores than control nurses on the knowledge tests (grade, median [Q1-Q3], 14 [10.5-15] vs 11 [10-12]/20; P = .044). During a 13-month period, 106 sessions were randomized (n = 53/group) among 50 patients (mean age 70 ± 13 years, mean simplified acute physiology II score 69 [54-96]). Twenty-one sessions were not analyzed (4 were not performed and 17 patients died during sessions). Among the 42 intervention and 43 control sessions analyzed, 25 (59%) and 38 (88%) were labeled as UI (relative risk [95% CI], 0.67 [0.51-0.88]; P = .002). Intervention nurses required help significantly less frequently (0 [0-1] vs 3 [1-4] times/session; P < .0001). The 2 factors associated with UI in multilevel mixed-effects logistic regression were Sequential Organ Failure Assessment score (odds ratio [95% CI], 0.81 [0.65-99]; P = .047) and the intervention group (odds ratio, 0.19 [0.05-0.73]; P = .015).

CONCLUSIONS

High-fidelity simulation nurse training reduced the rate of UI of CRRT sessions and the need for nurses to request assistance. This intervention may be particularly useful in the context of frequent nursing staff turnover.

Anemia, Blood Transfusion, and Filter Life Span in Critically Ill Patients Requiring Continuous Renal Replacement Therapy for Acute Kidney Injury: A Case-Control Study

Background

Filter clotting is frequent during continuous renal replacement therapy (CRRT), which increases anemia risk. We studied anemia and blood transfusion in critically ill patients requiring CRRT for acute kidney injury and assessed the relationship between CRRT filter life span and PRBC transfusion.

Methods

A case-control study was conducted at a tertiary-care intensive care unit (ICU) where CRRT cases were matched with controls for age, gender, admission category, and severity of illness. Daily hemoglobin levels, blood transfusions, and life span of CRRT filter were noted. CCRT patients were categorized according to the median of the filter life span (20 hours).

Results

Ninety-five cases and 102 controls were enrolled. The hemoglobin level on admission was similar in the two groups, yet cases had significantly lower hemoglobin levels than controls (72.8 ± 15.3 versus 82.5 ± 20.7 g/L, p < 0.001) during ICU stay. Anemia <70 g/L occurred in 50% of cases and 19% of controls (p < 0.001). Most (56.3%) cases were transfused compared with 29.9% for controls (p < 0.001) with higher number of transfused packed red blood cell (PRBC) units in cases (2.6 ± 4.0 versus 1.5 ± 3.2 units per patient, p=0.03). Patients with shorter versus longer filter life had similar hemoglobin level in the first 7 days of CRRT with no difference in PRBC transfusion requirement. Prefilter heparin use and hemodialysis access location were not associated with longer filter life span. The mortality was similar in patients with shorter versus longer filter life.

Conclusions

CRRT in ICU was associated with larger drop in hemoglobin and more PRBC transfusion. Shorter (<20 hours) versus longer CCRT filter life was not associated with increased PRBC transfusion.

Safety and efficacy of regional citrate anticoagulation for continuous renal replacement therapy in liver failure patients: a systematic review and meta-analysis

Background

Regional citrate anticoagulation (RCA) is a widely used strategy for continuous renal replacement therapy (CRRT). Most of the current guidelines recommend liver failure as one of the contraindications for citrate anticoagulation. However, some studies suggested that the use of citrate for CRRT in liver failure patients did not increase the risk of citrate-related complications. The purpose of this systematic review is to summarize the current evidences on the safety and efficacy of RCA for CRRT in liver failure patients.

Methods

We performed a comprehensive search on PubMed, Embase, and the Cochrane Library databases from the inception to March 1, 2018. Studies enrolled adult (age > 18 years) patients with various levels of liver dysfunction underwent RCA-CRRT were included in this systematic review.

Results

After the study screening, 10 observational studies with 1241 liver dysfunction patients were included in this systematic review. The pooled rate of citrate accumulation and bleeding was 12% [3%, 22%] and 5% [2%, 8%], respectively. Compared with the baseline data, the serum pH, bicarbonate, and base excess (BE), the rate of metabolic alkalosis, the serum ionized calcium (ionCa) and total calcium (totCa) level, and the ratio of total calcium/ionized calcium (totCa/ionCa) significantly increased at the end of observation. However, no significant increase was observed in serum citrate (MD − 65.82 [− 194.19, 62.55]), lactate (MD 0.49 [− 0.27, 1.26]) and total bilirubin concentration (MD 0.79 [− 0.70, 2.29]) at the end of CRRT. Compared with non-liver failure patients, the live failure patients showed no significant difference in the pH (MD − 0.04 [− 0.13, 0.05]), serum lactate level (MD 0.69 [− 0.26, 1.64]), and totCa/ionCa ratio (MD 0.03 [− 0.12, 0.18]) during CRRT. The median of mean filter lifespan was 55.9 h, with a range from 22.7 to 72 h.

Conclusions

Regional citrate anticoagulation seems to be a safe anticoagulation method in liver failure patients underwent CRRT and could yield a favorable filter lifespan. Closely monitoring the acid base status and electrolyte balance may be more necessary during RCA-CRRT in patients with liver failure.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2317-9) contains supplementary material, which is available to authorized users.

Continuous Renal Replacement Therapy and Anticoagulation: What Are the Options?

Continuous renal replacement therapy is currently used as a standard treatment for acute kidney injury in the intensive care unit, particularly for patients with unstable hemodynamic status. Because this therapy is continuous, for days or weeks, and the extracorporeal blood circuit is large, the circuit is prone to clotting. Several methods of keeping the extracorporeal circuit patent are available, including heparin infusion, flushes with physiological saline, use of thrombin inhibitors, and citrate. This article reviews methods for continuous renal replacement therapy, anticoagulation, efficacy, and implications for bedside critical care.

Hyperlactatemia Predicts Citrate Intolerance With Regional Citrate Anticoagulation During Continuous Renal Replacement Therapy

PURPOSE:

We aim to determine whether hyperlactatemia, which suggests multi-organ dysfunction and impaired organic substrate metabolism, may predict intolerance to regional citrate anticoagulation (RCA) during continuous venovenous hemofiltration (CVVH).

METHODS:

We performed a single-center, retrospective observational study in critically ill patients with acute kidney injury or end-stage renal disease and evaluated the association of peak serum lactate levels with citrate intolerance (CI) during the initial 72 hours of RCA-CVVH, defined by serum total-to-ionized calcium >2.5 plus systemic hypocalcemia.

RESULTS:

Eighty-eight patients were studied (aged 59 ± 14 years, 66% males, Acute Physiology and Chronic Health Evaluation II: 31 ± 8). Citrate was dosed at median 2.1 mmol/L of blood flow, with citrate load of 30 mmol/h, and CVVH effluent of 43 mL/kg/h. Twenty patients developed CI. Comparing patients with CI versus none, peak lactate levels were 8 (5-11) versus 3 (2-6) mmol/L, calcium replacement was 13 (10-17) versus 11 (8-12) mmol/h, and standard base excess was -4 (-12 to 1) versus 2(-4 to 7) mmol/L, respectively ( P < .05). Citrate intolerance developed in 38%, 44%, and 55%, in patients with peak lactate >4, >6, >7 mmol/L, respectively, versus 7% in those with peak lactate ≤4 mmol/L ( P ≤ .001), despite comparable citrate load and effluent rates across all categories. On multivariate analysis, hyperlactatemia and hyperbilirubinemia predicted CI ( P ≤ .01), which was associated with increasing calcium infusion requirement. Higher peak lactate from >4 to >7 mmol/L predicted CI with graded increase in odds ratio and specificity from 59% to 87%, but the corresponding negative predictive value from 93% to 87%. Area under nonparametric receiver operating characteristic curve for peak lactate and CI was 0.78.

CONCLUSION:

Hyperlactatemia predicts CI during RCA-CVVH with reasonable discriminatory performance in critically ill patients. Serum lactate surveillance may help preempt issues with citrate toxicity.

Non anti-coagulant factors associated with filter life in continuous renal replacement therapy (CRRT): a systematic review and meta-analysis

BACKGROUND

Optimising filter life and performance efficiency in continuous renal replacement therapy has been a focus of considerable recent research. Larger high quality studies have predominantly focussed on optimal anticoagulation however CRRT is complex and filter life is also affected by vascular access, circuit and management factors. We performed a systematic search of the literature to identify and quantify the effect of vascular access, circuit and patient factors that affect filter life and presented the results as a meta-analysis.

METHODS

A systematic review and meta-analysis was performed by searching Pubmed (MEDLINE) and Ovid EMBASE libraries from inception to 29th February 2016 for all studies with a comparator or independent variable relating to CRRT circuits and reporting filter life. Included studies documented filter life in hours with a comparator other than anti-coagulation intervention. All studies comparing anticoagulation interventions were searched for regression or hazard models pertaining to other sources of variation in filter life.

RESULTS

Eight hundred nineteen abstracts were identified of which 364 were selected for full text analysis. 24 presented data on patient modifiers of circuit life, 14 on vascular access modifiers and 34 on circuit related factors. Risk of bias was high and findings are hypothesis generating. Ranking of vascular access site by filter longevity favours: tunnelled semi-permanent catheters, femoral, internal jugular and subclavian last. There is inconsistency in the difference reported between femoral and jugular catheters. Amongst published literature, modality of CRRT consistently favoured continuous veno-venous haemodiafiltration (CVVHD-F) with an associated 44% lower failure rate compared to CVVH. There was a trend favouring higher blood flow rates. There is insufficient data to determine advantages of haemofilter membranes. Patient factors associated with a statistically significant worsening of filter life included mechanical ventilation, elevated SOFA or LOD score, elevations in ionized calcium, elevated platelet count, red cell transfusion, platelet factor 4 (PF-4) antibodies, and elevated fibrinogen. Majority of studies are observational or report circuit factors in sub-analysis. Risk of bias is high and findings require targeted investigations to confirm.

CONCLUSION

The interaction of patient, pathology, anticoagulation, vascular access, circuit and staff factors contribute to CRRT filter life. There remains an ambiguity from published data as to which site and side should be the first choice for vascular access placement and what interaction this has with patient factors and timing. Early consideration of tunnelled semi-permanent access may provide optimal filter life if longer periods of CRRT are anticipated. There remains an absence of robust evidence outside of anti-coagulation strategies despite over 20 years of therapy delivery however trends favour CVVHD-F over CVVH.

A retrospective review of fluid balance control in CRRT

INTRODUCTION

An effect of severe acute kidney injury (AKI) is the development of oliguria and subsequent retention of fluid. Recent studies have reported an association between fluid overload and increased mortality in critically ill patients. Achieving fluid balance control through haemofiltration is an important part of dialysis dose delivery in continuous renal replacement therapy (CRRT).

AIMS

(1) Compare the prescribed dose with the delivered dose of dialysis and haemofiltration for CRRT. (2) Identify how interruptions and delays in treatment delivery impact on fluid balance management.

METHOD

A retrospective cohort study was undertaken of daily fluid balance and fluid removal for patients who required CRRT. Each observation chart and prescription order for every treatment day was reviewed. Each patient was exposed to the same treatment mode, predilutional continuous veno-venous haemodiafiltration (CVVHDf). A comparison was made of fluid balance control delivered to the patient over 24h against the dose of fluid removal prescribed.

RESULTS

The observation charts of 46 consecutive patients were reviewed for total of 288 treatment days. Median number of days patients received CRRT was 5 (range 1-31). Median circuit life was 16h (range 0-66). Fluid removal targets did not occur in 75 (26%) treatment days. Median daily fluid removal shortfall was 300mL (range 25-3800mL). Mean number of daily treatment interruptions 1.25, SD±0.49. The most frequent cause of treatment downtime was circuit clotting (45%). Mean length of treatment down time was 3.71, SD±4.36h excluding delays attributed to assessment of renal function.

CONCLUSION

In over a quarter of treatment days prescribed fluid removal was not achieved. Frequency of interruptions and delays in resumption of treatment compromised fluid balance control. Daily targets for fluid removal which are not achieved contribute to fluid overload and may compromise the outcome of patients who require CRRT.

The effect of continuous elimination methods on the hemostatic profile of a cardiac surgery patient monitored using thromboelastography

INTRODUCTION

This work is focused on mapping issues of hemostasis in patients during continuous renal replacement therapy, or the possible impact of the use of anticoagulants.

METHODS

The study included 30 consecutive patients requiring continuous renal replacement therapy following cardiac surgery in the period of 2009 to 2012. Patients were placed into 2 branches according to the selected method of anticoagulation (regional citrate anticoagulation-RCA, unfractionated heparin UFH). According to the given scheme (t1-t7) thromboelastography and laboratory testing related to the testing of blood clotting during continuous renal replacement therapy were performed.

RESULTS

The average lifespan of a hemofilter during continuous renal replacement is 58.13 ± 9.968 hours. During continuous renal replacement therapy there are significant changes in the initiation of coagulation according to thromboelastographic parameters (R, K, alpha angle) in both branches of anticoagulation. The maximum image changes in hemostasis occur around 24 hours (t4) from the start of the procedure. The nature of the changes is the procoagulant activity in these parameters. In the branch of regional citrate anticoagulation a higher value of functional fibrinogen is apparent. There was no significant difference in the activation of native blood between UFH and RCA.

CONCLUSIONS

During continuous renal replacement therapy significant changes occur in the thromboelastographic image and the laboratory parameters in blood clotting. The nature of the change is the procoagulant activity. The question remains about the complexity of the changes that TEG is not able to detect, especially in the cellular area.