Ultrafiltration in critically ill patients treated with kidney replacement therapy

Kidney Replacement Therapies in Advanced Heart Failure - Timing, Modalities, and Clinical Considerations

Acute kidney dysfunction is commonly encountered in advanced heart failure and carries significant prognostic implications, often leading to poorer outcomes and increased mortality. It can alter the course of decision making for left ventricular assist device (LVAD) and cardiac transplantation candidacy. Kidney replacement therapies (KRT) offer a critical intervention in this context but require careful consideration of timing, various types of KRT modalities, individual patient preferences and circumstances. This review discusses the intricacies of KRT in advanced heart failure, examining how to optimize timing and choose among the various KRT modalities. It also provides a detailed discussion on the unique clinical scenarios that clinicians may face when treating this vulnerable patient group.

Behind the scenes: Key lessons learned from the RELIEVE-AKI clinical trial

Continuous kidney replacement therapy (CKRT) is commonly used to manage critically ill patients with severe acute kidney injury. While recent trials focused on the correct dosing and timing of CKRT, our understanding regarding the optimum dose of net ultrafiltration is limited to retrospective data. The Restrictive versus Liberal Rate of Extracorporeal Volume Removal Evaluation in Acute Kidney Injury (RELIEVE-AKI) trial has been conducted to assess the feasibility of a prospective randomized trial in determining the optimum net ultrafiltration rate. This paper outlines the relevant challenges and solutions in implementing this complex ICU-based trial. Several difficulties were encountered, starting with clinical issues related to conducting a trial on patients with rapidly changing hemodynamics, low patient recruitment rates, increased nursing workload, and the enormous volume of data generated by patients undergoing prolonged CKRT. Following several brainstorming sessions, several points were highlighted to be considered, including the need to streamline the intervention, add more flexibility in the trial protocols, ensure comprehensive a priori planning, particularly regarding nursing roles and their compensation, and enhance data management systems. These insights are critical for guiding future ICU-based dynamically titrated intervention trials, leading to more efficient trial management, improved data quality, and enhanced patient safety.

Relative Blood Volume Monitoring during Continuous Renal Replacement Therapy: A Prospective Observational Study

INTRODUCTION

Hematocrit monitoring during continuous renal replacement therapy (CRRT) allows the continuous estimation of relative blood volume (RBV). This may enable early detection of intravascular volume depletion prior to clinical sequelae. We aimed to investigate the feasibility of extended RBV monitoring and its epidemiology during usual CRRT management by clinicians unaware of RBV. Moreover, we studied the association between changes in RBV and net ultrafiltration (NUF) rates.

METHODS

In a cohort of adult intensive care unit patients receiving CRRT, we continuously monitored hematocrit and RBV using a pre-filter noninvasive optical sensor. We analyzed temporal changes in RBV and investigated the association between RBV change and NUF rates, using the classification of NUF rates into low, moderate, or high based on predefined cut-offs.

RESULTS

We obtained >60,000 minute-by-minute measurements in >1,000 CRRT hours in 36 patients. The median RBV change was negative (decrease) in 69% of patients and the median peak change in RBV was -9.3% (interquartile range: -3.9% to -14.3%). Moreover, the median RBV decreased from baseline by >5% in 40.2% of measurements and by >10% in 20.6% of measurements. Finally, RBV decreased significantly more when patients received a high NUF rate (>1.75 mL/kg/h) compared to low or moderate NUF rates (5.32% vs. 1.93% or 1.97%, p < 0.001).

CONCLUSION

Continuous hematocrit and RBV monitoring during CRRT was feasible. RBV decreased significantly during CRRT, and decreases were greater with higher NUF rates. RBV monitoring may help optimize NUF management and prevent the occurrence of intravascular volume depletion.

Haematocrit monitoring and blood volume estimation during continuous renal replacement therapy

BACKGROUND

Continuous haemoglobin, venous blood oxygen saturation, and haematocrit (Hct) monitoring is currently not applied during continuous renal replacement therapy (CRRT). Such Hct monitoring enables estimation of changes in blood volume as percentage change (ΔBV%) from therapy start time and is incorporated into intermittent haemodialysis machines but not CRRT machines despite its potential to optimise fluid management in CRRT patients.

METHODS

To overcome this problem, we used a standalone monitor (CRIT-LINE®IV, Fresenius Medical Care, Concord, USA) with an associated in-line blood chamber (CRIT-LINE®IV Blood Chamber, Fresenius Medical Care, Concord, USA) and designed our own adaptor connection piece (TekMed and Morriset, Melbourne and Brisbane, Australia) to allow these readings at the vascular access outflow and recorded data for estimated Hct and derived ΔBV% during CRRT.

RESULTS

We report on this technique with an illustrative case example and 12 h of CRRT data on the fluid loss rate prescribed, hourly net patient fluid loss (range: 0-308 mL/h), mean arterial pressure, norepinephrine dose (range: 5-14 mcg/min), estimated continuous Hct and ΔBV%, and the otherwise undetected diagnosis of an approximate 15 % decrease in blood volume during the CRRT.

CONCLUSION

We have described a technical CRRT circuit modification that can facilitate a previously unavailable assessment of fluid shifts during CRRT. Further application in clinical trials is now possible.

Factors associated with successful liberation from continuous renal replacement therapy in children and young adults: analysis of the worldwide exploration of renal replacement outcomes collaborative in Kidney Disease Registry

PURPOSE

Continuous renal replacement therapy (CRRT) is used for supportive management of acute kidney injury (AKI) and disorders of fluid balance (FB). Little is known about the predictors of successful liberation in children and young adults. We aimed to identify the factors associated with successful CRRT liberation.

METHODS

The Worldwide Exploration of Renal Replacement Outcomes Collaborative in Kidney Disease study is an international multicenter retrospective study (32 centers, 7 nations) conducted from 2015 to 2021 in children and young adults (aged 0-25 years) treated with CRRT for AKI or FB disorders. Patients with previous dialysis dependence, tandem extracorporeal membrane oxygenation use, died within the first 72 h of CRRT initiation, and those who never had liberation attempted were excluded. Patients were categorized based on first liberation attempt: reinstituted (resumption of any dialysis within 72 h) vs. success (no receipt of dialysis for ≥ 72 h). Multivariable logistic regression was used to identify factors associated with successful CRRT liberation.

RESULTS

A total of 622 patients were included: 287 (46%) had CRRT reinstituted and 335 (54%) were successfully liberated. After adjusting for sepsis at admission and illness severity parameters, several factors were associated with successful liberation, including higher VIS (vasoactive-inotropic score) at CRRT initiation (odds ratio [OR] 1.35 [1.12-1.63]), higher PELOD-2 (pediatric logistic organ dysfunction-2) score at CRRT initiation (OR 1.71 [1.24-2.35]), higher urine output prior to CRRT initiation (OR 1.15 [1.001-1.32]), and shorter CRRT duration (OR 0.19 [0.12-0.28]).

CONCLUSIONS

Inability to liberate from CRRT was common in this multinational retrospective study. Modifiable and non-modifiable factors were associated with successful liberation. These results may inform the design of future clinical trials to optimize likelihood of CRRT liberation success.

Knowledge, attitude, practice, needs, and implementation status of intensive care unit staff toward continuous renal replacement therapy: a survey of 66 hospitals in central and South China

BACKGROUND

Continuous renal replacement therapy (CRRT) is a commonly utilized form of renal replacement therapy (RRT) in the intensive care unit (ICU). A specialized CRRT team (SCT, composed of physicians and nurses) engage playing pivotal roles in administering CRRT, but there is paucity of evidence-based research on joint training and management strategies. This study armed to evaluate the knowledge, attitude, and practice (KAP) of ICU staff toward CRRT, and to identify education pathways, needs, and the current status of CRRT implementation.

METHODS

This study was performed from February 6 to March 20, 2023. A self-made structured questionnaire was used for data collection. Descriptive statistics, T-tests, Analysis of variance (ANOVA), multiple linear regression, and Pearson correlation coefficient tests (α = 0.05) were employed.

RESULTS

A total of 405 ICU staff from 66 hospitals in Central and South China participated in this study, yielding 395 valid questionnaires. The mean knowledge score was 51.46 ± 5.96 (61.8% scored highly). The mean attitude score was 58.71 ± 2.19 (73.9% scored highly). The mean practice score was 18.15 ± 0.98 (85.1% scored highly). Multiple linear regression analysis indicated that gender, age, years of CRRT practice, ICU category, and CRRT specialist panel membership independently affected the knowledge score; Educational level, years of CRRT practice, and CRRT specialist panel membership independently affected the attitude score; Education level and teaching hospital employment independently affected the practice score. The most effective method for ICU staff to undergo training and daily work experience is within the department.

CONCLUSION

ICU staff exhibit good knowledge, a positive attitude and appropriately practiced CRRT. Extended CRRT practice time in CRRT, further training in a general ICU or teaching hospital, joining a CRRT specialist panel, and upgraded education can improve CRRT professional level. Considering the convenience of training programs will enhance ICU staff participation. Training should focus on basic CRRT principles, liquid management, and alarm handling.

Fluid Balance in Continuous Renal Replacement Therapy: Prescribing, Delivering, and Review

BACKGROUND

Historically IV and enteral fluids given during acute kidney injury (AKI) were restricted before the introduction of continuous renal replacement therapies (CRRTs) when more liberal fluids improved nutrition for the critically ill. However, fluid accumulation can occur when higher volumes each day are not considered in the fluid balance prescribing and the NET ultrafiltration (NUF) volume target.

KEY MESSAGES

The delivered hours of CRRT each day are vital for achievement of fluid balance and time off therapy makes the task more challenging. Clinicians inexperienced with CRRT make this aspect of AKI management a focus of rounding with senior oversight, clear communication, and "precision" a clinical target. Sepsis-associated AKI can be a complex patient where resuscitation and admission days are with a positive fluid load and replacement mind set. Subsequent days in ICU requires fluid regulation, removal, with a comprehensive multilayered assessment before prescribing the daily fluid balance target and the required hourly NET plasma water removal rate (NUF rate). Future machines may include advanced software, new alarms - display metrics, messages and association with machine learning and "AKI models" for setting, monitoring, and guaranteeing fluid removal. This could also link to current hardware such as on-line blood volume assessment with continuous haematocrit measurement.

SUMMARY

Fluid balance in the acutely ill is a challenge where forecasting and prediction are necessary. NUF rate and volume each hour should be tracked and adjusted to achieve the daily target. This requires human and machine connections.

Engineered Extracellular Vesicles in Wound Healing: Design, Paradigms, and Clinical Application

The severe quality of life and economic burden imposed by non-healing skin wounds, infection risks, and treatment costs are affecting millions of patients worldwide. To mitigate these challenges, scientists are relentlessly seeking effective treatment measures. In recent years, extracellular vesicles (EVs) have emerged as a promising cell-free therapy strategy, attracting extensive attention from researchers. EVs mediate intercellular communication, possessing excellent biocompatibility and stability. These features make EVs a potential tool for treating a plethora of diseases, including those related to wound repair. However, there is a growing focus on the engineering of EVs to overcome inherent limitations such as low production, relatively fixed content, and targeting capabilities of natural EVs. This engineering could improve both the effectiveness and specificity of EVs in wound repair treatments. In light of this, the present review will introduce the latest progress in the design methods and experimental paradigms of engineered EVs applied in wound repair. Furthermore, it will comprehensively analyze the current clinical research status and prospects of engineered EVs within this field.

Accuracy of Crit-Line® monitors in predicting hematocrit and change in blood volume of dogs during hemodialysis

BACKGROUND

Ultrafiltration (UF) is an extracorporeal technique for treating fluid overload and is monitored with noninvasive blood volume monitors.

HYPOTHESIS/OBJECTIVES

The primary objective was to determine the accuracy of Crit-Line® III and IV noninvasive blood volume monitors to estimate canine packed cell volume (PCV) and changes in blood volume during UF. A secondary aim was to determine accuracy of targeted ultrafiltration rates (UFR) compared to calculated delivered UFR.

METHODS

An ex vivo study with a single Phoenix® X36 platform and canine packed red blood cells (pRBC) was performed. Through dilution and UF, clinically applicable PCV values were obtained and compared to Crit-Line® hematocrit (Hct). Blood volume was constantly measured and compared to targeted UFR. Systematic and proportional bias were calculated using a Bayes method.

RESULTS

Crit-Line® III and IV reported Hct was significantly lower than PCV (n = 140, median 26%, range, 8%-50%) when PCV was >25% and >30%, respectively. Crit-Line® III and IV calculated change in blood volume (ΔBV%) was significantly different from measured blood volume changes at ΔBV% ±20% and >-20%, respectively. Comparing targeted and delivered UFR (mL/h), less than targeted UFR was removed at UFR100 through UFR400 and UFR0 adding volume.

CONCLUSIONS AND CLINICAL IMPORTANCE

Crit-Line® III and IV monitors provide accurate estimates of canine PCV and UF volume change within specific ranges and are useful in monitoring canine UF and hemodialysis. Veterinary hemodialysis services should evaluate individual machines for UFR inaccuracies, which can meaningfully affect small animals.

A Polymeric Nanosponge as a Broad-Spectrum Reactive Oxygen Species Scavenger for Acute Kidney Injury Treatment

Acute kidney injury (AKI) is closely associated with the overproduction of reactive oxygen species (ROS), which can cause multiple organ dysfunctions without timely treatment. However, only supportive treatments are currently available for AKI in clinics. Here, we developed nanomaterials of hyperbranched polyphosphoester (PPE) containing abundant thioether (S-PPE NP) and thioketal bonds (TK-PPE NP). Our data demonstrates that S-PPE NP exhibits an excellent capability of absorbing and scavenging multiple types of ROS, including H2O2, •OH, and •O2-, via thioether oxidation to sulfone or sulfoxide; it was also determined that S-PPE NP efficiently eliminates intracellular ROS, thus preventing cellular damage. Moreover, S-PPE NP was able to efficiently accumulate in the injured kidneys of AKI-bearing mice. As a result, the administration of S-PPE NP provided a superior therapeutic effect in AKI-bearing mice by downregulating ROS- and inflammation-related signaling pathways, thus reducing cell apoptosis. This thioether-containing polymer represents a promising broad-spectrum ROS scavenger that can be used for effective AKI treatments.

Prevention of Intradialytic Hypotension in Hemodialysis Patients: Current Challenges and Future Prospects

Intradialytic hypotension, defined as rapid decrease in systolic blood pressure of greater than or equal to 20 mmHg or in mean arterial pressure of greater than or equal to 10 mmHg that results in end-organ ischemia and requires countermeasures such as ultrafiltration reduction or saline infusion to increase blood pressure to improve patient's symptoms, is a known complication of hemodialysis and is associated with several potential adverse outcomes. Its pathogenesis is complex and involves both patient-related factors such as age and comorbidities, as well as factors related to the dialysis prescription itself. Key factors include the need for volume removal during hemodialysis and a suboptimal vascular response which compromises the ability to compensate for acute intravascular volume loss. Inadequate vascular refill, incorrect assessment or unaccounted changes of target weight, acute illnesses and medication interference are further potential contributors. Intradialytic hypotension can lead to compromised tissue perfusion and end-organ damage, both acutely and over time, resulting in repetitive injuries. To address these problems, a careful assessment of subjective symptoms, minimizing interdialytic weight gains, individualizing dialysis prescription and adjusting the dialysis procedure based on patients' risk factors can mitigate negative outcomes.

Restrictive versus Liberal Rate of Extracorporeal Volume Removal Evaluation in Acute Kidney Injury (RELIEVE-AKI): a pilot clinical trial protocol

INTRODUCTION

Observational studies have linked slower and faster net ultrafiltration (UFNET) rates during kidney replacement therapy (KRT) with mortality in critically ill patients with acute kidney injury (AKI) and fluid overload. To inform the design of a larger randomised trial of patient-centered outcomes, we conduct a feasibility study to examine restrictive and liberal approaches to UFNET during continuous KRT (CKRT).

METHODS AND ANALYSIS

This study is an investigator-initiated, unblinded, 2-arm, comparative-effectiveness, stepped-wedged, cluster randomised trial among 112 critically ill patients with AKI treated with CKRT in 10 intensive care units (ICUs) across 2 hospital systems. In the first 6 months, all ICUs started with a liberal UFNET rate strategy. Thereafter, one ICU is randomised to the restrictive UFNET rate strategy every 2 months. In the liberal group, the UFNET rate is maintained between 2.0 and 5.0 mL/kg/hour; in the restrictive group, the UFNET rate is maintained between 0.5 and 1.5 mL/kg/hour. The three coprimary feasibility outcomes are (1) between-group separation in mean delivered UFNET rates; (2) protocol adherence; and (3) patient recruitment rate. Secondary outcomes include daily and cumulative fluid balance, KRT and mechanical ventilation duration, organ failure-free days, ICU and hospital length of stay, hospital mortality and KRT dependence at hospital discharge. Safety endpoints include haemodynamics, electrolyte imbalance, CKRT circuit issues, organ dysfunction related to fluid overload, secondary infections and thrombotic and haematological complications.

ETHICS AND DISSEMINATION

The University of Pittsburgh Human Research Protection Office approved the study, and an independent Data and Safety Monitoring Board monitors the study. A grant from the United States National Institute of Diabetes and Digestive and Kidney Diseases sponsors the study. The trial results will be submitted for publication in peer-reviewed journals and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

This trial has been prospectively registered with clinicaltrials.gov (NCT05306964). Protocol version identifier and date: 1.5; 13 June 2023.

Acute Kidney Injury: Gaps and Opportunities for Knowledge and Growth

Acute kidney injury (AKI) occurs frequently in hospitalized patients, regardless of age or prior medical history. Increasing awareness of the epidemiologic problem of AKI has directly led to increased study of global recognition, diagnostic tools, both reactive and proactive management, and analysis of long-term sequelae. Many gaps remain, however, and in this article we highlight opportunities to add significantly to the increasing bodies of evidence surrounding AKI. Practical considerations related to initiation, prescription, anticoagulation, and monitoring are discussed. In addition, the importance of AKI follow-up evaluation, particularly for those surviving the receipt of renal replacement therapy, is highlighted as a push for global equity in the realm of critical care nephrology is broached. Addressing these gaps presents an opportunity to impact patient care directly and improve patient outcomes.

Fluid Therapy for Critically Ill Adults With Sepsis: A Review

Importance

Approximately 20% to 30% of patients admitted to an intensive care unit have sepsis. While fluid therapy typically begins in the emergency department, intravenous fluids in the intensive care unit are an essential component of therapy for sepsis.

Observations

For patients with sepsis, intravenous fluid can increase cardiac output and blood pressure, maintain or increase intravascular fluid volume, and deliver medications. Fluid therapy can be conceptualized as 4 overlapping phases from early illness through resolution of sepsis: resuscitation (rapid fluid administered to restore perfusion); optimization (the risks and benefits of additional fluids to treat shock and ensure organ perfusion are evaluated); stabilization (fluid therapy is used only when there is a signal of fluid responsiveness); and evacuation (excess fluid accumulated during treatment of critical illness is eliminated). Among 3723 patients with sepsis who received 1 to 2 L of fluid, 3 randomized clinical trials (RCTs) reported that goal-directed therapy administering fluid boluses to attain a central venous pressure of 8 to 12 mm Hg, vasopressors to attain a mean arterial blood pressure of 65 to 90 mm Hg, and red blood cell transfusions or inotropes to attain a central venous oxygen saturation of at least 70% did not decrease mortality compared with unstructured clinical care (24.9% vs 25.4%; P = .68). Among 1563 patients with sepsis and hypotension who received 1 L of fluid, an RCT reported that favoring vasopressor treatment did not improve mortality compared with further fluid administration (14.0% vs 14.9%; P = .61). Another RCT reported that among 1554 patients in the intensive care unit with septic shock treated with at least 1 L of fluid compared with more liberal fluid administration, restricting fluid administration in the absence of severe hypoperfusion did not reduce mortality (42.3% vs 42.1%; P = .96). An RCT of 1000 patients with acute respiratory distress during the evacuation phase reported that limiting fluid administration and administering diuretics improved the number of days alive without mechanical ventilation compared with fluid treatment to attain higher intracardiac pressure (14.6 vs 12.1 days; P < .001), and it reported that hydroxyethyl starch significantly increased the incidence of kidney replacement therapy compared with saline (7.0% vs 5.8%; P = .04), Ringer lactate, or Ringer acetate.

Conclusions and Relevance

Fluids are an important component of treating patients who are critically ill with sepsis. Although optimal fluid management in patients with sepsis remains uncertain, clinicians should consider the risks and benefits of fluid administration in each phase of critical illness, avoid use of hydroxyethyl starch, and facilitate fluid removal for patients recovering from acute respiratory distress syndrome.

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.

Efficacy of Continuous Renal Replacement Therapy and Intermittent Hemodialysis in Patients with Renal Failure in Intensive Care Unit: A Systemic Review and Meta-analysis

Objective

This study aimed to compare the clinical efficacy of continuous renal replacement therapy (CRRT) and intermittent hemodialysis (IHD) in patients with renal failure in intensive care unit (ICU).

Methods

Relevant studies were searched in the databases including EMBASE, Cochrane Library, and MEDLINE (PubMed) from inception to January 04, 2021. The inclusion of available studies and the collection of data were independently conducted by two authors after reviewing the full text. Pooled analyses of relative risk (RR) and weighted mean difference (WMD) were performed to compare the outcomes of renal recovery, short-term mortality, length of ICU stays, and length of in-hospital stays between the two different treatment groups. Publication bias was assessed by the funnel plot.

Results

A total of 11 RCT studies including 1740 patients with renal failure were eligible for final analysis. Among them, 894 patients (51.4%) underwent CRRT and 846 patients (48.6%) received IHD. Pooled analysis did not find significant differences in renal recovery and short-term mortality between the two groups. Interestingly, patients underwent CRRT showed significantly shorter length of ICU stay and in-hospital stay than those who underwent IHD (ICU stay: RR: -0.61, 95%CI: -1.10--0.11, P < 0.05; I² = 93.6%; in-hospital stay: RR: -0.56, 95%CI: -1.41-0.28, P < 0.05; I² = 97.7%). No significant publication biases were observed on the funnel plots.

Conclusion

Compared with IHD, CRRT had similar effects on renal recovery and short-term mortality in patients with renal failure in ICU. As a promising technique in clinical practice, CRRT could significantly reduce the length of ICU stay and in-hospital stay of patients, which was of great significance for the reduction of medical costs and the long-term benefits of patients, thereby reducing the burden on society and individuals.

Perfusion-based deresuscitation during continuous renal replacement therapy: A before-after pilot study (The early dry Cohort)

BACKGROUND

Active fluid removal has been suggested to improve prognosis following the resolution of acute circulatory failure. We have implemented a routine care protocol to guide fluid removal during continuous renal replacement therapy (CRRT). We designed a before-after pilot study to evaluate the impact of this deresuscitation strategy on the fluid balance.

METHODS

Consecutive ICU patients suffering from fluid overload and undergoing CRRT for acute kidney injury underwent a perfusion-based deresuscitation protocol combining a restrictive intake, net ultrafiltration (UFnet) of 2 mL/kg/h, and monitoring of perfusion (early dry group, N = 42) and were compared to a historical group managed according to usual practices (control group, N = 45). The primary outcome was the cumulative fluid balance at day 5 or at discharge.

RESULTS

Adjusted cumulative fluid balance was significantly lower in the early dry group (median [IQR]: -7784 [-11,833 to -2933] mL) compared to the control group (-3492 [-9935 to -1736] mL; p = 0.04). The difference was mainly driven by a greater daily UFnet (31 [22-46] mL/kg/day vs. 24 [15-32] mL/kg/day; p = 0.01). There was no significant difference between both groups regarding hemodynamic tolerance.

CONCLUSION

Our perfusion-based deresuscitation protocol achieved a greater negative cumulative fluid balance compared to standard practices and was hemodynamically well tolerated.

Proportion of Hemodialysis Treatments with High Ultrafiltration Rate and the Association with Mortality

Background

Rapid fluid removal during hemodialysis has been associated with increased mortality. The limit of ultrafiltration rate (UFR) monitored by the Centers for Medicare & Medicaid Services is 13 ml/kg per hour. It is not clear if the proportion of treatments with high UFR is associated with higher mortality. We examined the association of proportion of dialysis treatments with high UFR and mortality in end stage kidney failure patients receiving hemodialysis.

Methods

This was a retrospective study of incident patients initiating hemodialysis between January 1, 2010, and December 31, 2019, at Emory dialysis centers. The proportion of treatments with high UFR (>13 ml/kg per hour) per patient was calculated using data from the initial 3 months of dialysis therapy. Patients were categorized on the basis of quartiles of proportion of dialysis sessions with high UFR. Risk of death and survival probabilities were calculated and compared for all quartiles.

Results

Of 1050 patients eligible, the median age was 59 years, 56% were men, and 91% were Black. The median UFR was 6.5 ml/kg per hour, and the proportion of sessions with high UFR was 5%. Thirty-one percent of patients never experienced high UFR. Being a man, younger age, shorter duration of hemodialysis sessions, lower weight, diabetic status, higher albumin, and history of heart failure were associated with a higher proportion of sessions with high UFR. Patients in the higher quartile (26% dialysis with high UFR, average UFR 9.8 ml/kg per hour, median survival of 5.6 years) had a higher risk of death (adjusted hazard ratio 1.54; 95% CI, 1.13 to 2.10) compared with those in the lower quartile (0% dialysis with high UFR, average UFR 4.7 ml/kg per hour, median survival 8.8 years).

Conclusions

Patients on hemodialysis who did not experience frequent episodes of elevated UFR during the first 3 months of their dialysis tenure had a significantly lower risk of death compared with patients with frequent episodes of high UFR.

A Positive Fluid Balance in the First Week Was Associated With Increased Long-Term Mortality in Critically Ill Patients: A Retrospective Cohort Study

Introduction

Early fluid balance has been found to affect short-term mortality in critically ill patients; however, there is little knowledge regarding the association between early cumulative fluid balance (CFB) and long-term mortality. This study aims to determine the distinct association between CFB day 1-3 (CFB 1-3) and day 4-7 (CFB 4-7) and long-term mortality in critically ill patients.

Patients and Methods

This study was conducted at Taichung Veterans General Hospital, a tertiary care referral center in central Taiwan, by linking the hospital critical care data warehouse 2015-2019 and death registry data of the Taiwanese National Health Research Database. The patients followed up until deceased or the end of the study on 31 December 2019. We use the log-rank test to examine the association between CFB 1-3 and CFB 4-7 with long-term mortality and multivariable Cox regression to identify independent predictors during index admission for long-term mortality in critically ill patients.

Results

A total of 4,610 patients were evaluated. The mean age was 66.4 ± 16.4 years, where 63.8% were men. In patients without shock, a positive CFB 4-7, but not CFB 1-3, was associated with 1-year mortality, while a positive CFB 1-3 and CFB 4-7 had a consistent and excess hazard of 1-year mortality among critically ill patients with shock. The multivariate Cox proportional hazard regression model identified that CFB 1-3 and CFB 4-7 (with per 1-liter increment, HR: 1.047 and 1.094; 95% CI 1.037-1.058 and 1.080-1.108, respectively) were independently associated with high long-term mortality in critically ill patients after adjustment of relevant covariates, including disease severity and the presence of shock.

Conclusions

We found that the fluid balance in the first week, especially on days 4-7, appears to be an early predictor for long-term mortality in critically ill patients. More studies are needed to validate our findings and elucidate underlying mechanisms.

miR-3587 Inhibitor Attenuates Ferroptosis Following Renal Ischemia-Reperfusion Through HO-1

Renal ischemia-reperfusion (IR) is frequently observed in patients who are critically ill, yet there are no reliable or effective approaches for the treatment of this condition. Ferroptosis, a form of programmed cell death, is regulated by key genes such as glutathione peroxidase 4 (GPX4) and heme oxygenase-1 (HMOX1) and participates in the injury of renal tubular epithelial cells during IR. This study aimed to investigate the miRNA-mRNA regulatory networks involved in ferroptosis following renal IR. Using bioinformatics analysis, HMOX1 was found to be significantly upregulated during the early stages of renal IR injury, and microRNA-3587 (miR-3587) was identified as a putative regulator of HMOX1. When a miR-3587 inhibitor was applied in a hypoxia-reoxygenation (HR) model system using renal tubular epithelial cells, HO-1 protein (encoded by HMOX1) expression was significantly increased relative to that observed in the HR group, with concomitant increases in GPX4 protein levels, enhanced cell viability, a reduction in malondialdehyde content, decreased Fe²⁺ level, and the restoration of normal mitochondrial membrane potential. Transmission electron microscopy showed a reduced or absent mitochondrial crest and a damaged mitochondrial outer membrane. Targeting of HMOX1 by miR-3587 was confirmed by luciferase reporter gene assay. In conclusion, these preliminary results indicate that inhibition of miR-3587 promotes HO-1 upregulation, thereby protecting renal tissues from IR-induced ferroptosis.

Ultrafiltration in Japanese critically ill patients with acute kidney injury on renal replacement therapy

A recent worldwide survey indicates an international diversity in net ultrafiltration (UF^NET) practices for the treatment of fluid overload in critically ill patients with acute kidney injury (AKI) requiring renal replacement therapy (RRT). The sub-analysis of the survey has demonstrated that maximum doses of furosemide used before determination of diuretic resistance are lower in Japan than those prescribed worldwide and UF^NET is lower but is initiated earlier. In contrast, the interval during which practitioners evaluate fluid balance is longer. The characterization of RRT in critically ill patients in Japan should unveil more appropriate approaches to the successful treatment of AKI.

Prediction of hemodynamic tolerance of intermittent hemodialysis in critically ill patients: a cohort study

The evaluation and management of fluid balance are key challenges when caring for critically ill patients requiring renal replacement therapy. The aim of this study was to assess the ability of clinical judgment and other variables to predict the occurrence of hypotension during intermittent hemodialysis (IHD) in critically ill patients. This was a prospective, observational, single-center study involving critically ill patients undergoing IHD. The clinical judgment of hypervolemia was determined by the managing nephrologists and critical care physicians in charge of the patients on the basis of the clinical data used to calculate the ultrafiltration volume and rate for each dialysis treatment. Seventy-nine (31.9%) patients presented with hypotension during IHD. Patients were perceived as being hypervolemic in 109 (43.9%) of the cases by nephrologists and in 107 (43.1%) by intensivists. The agreement between nephrologists and intensivists was weak (kappa = 0.561). Receiver operating characteristic curve analysis yielded an AUC of 0.81 (95% CI 0.75 to 0.84; P < 0.0001), and a cutoff value of 70 mm for the vascular pedicle width (VPW) had the highest accuracy for the prediction of the absence of hypotension. The clinical judgment of hypervolemia did not predict hypotension during IHD. The high predictive ability of the VPW may assist clinicians with critical thinking.

The Association of an Early Net Ultrafiltration Rate and 28-Day Mortality in Patients Receiving Continuous Kidney Replacement Therapy

Background: An early net ultrafiltration (NUF) rate may be associated with prognosis in patients receiving continuous kidney replacement therapy (CKRT). In this study, we tested whether high or low early NUF rates in patients treated with CKRT were associated with increased mortality. Methods: We conducted a retrospective, observational study among all patients in the Medical Information Mart for Intensive Care IV database who received CKRT for more than 24 h within 14 days after intensive care unit admission. We defined the early (initial 48 h) NUF rate as the amount of fluid removal per hour adjusted by the patients' weight and took it as a classified variable (low rate: <1.6, moderate rate: 1.6-3.1 and high rate: > 3.1 ml/kg/h). The association between 28-day mortality and the NUF rate was analyzed by logistic regression and mediation analyses. Results: A total of 911 patients were included in our study. The median NUF rate was 2.71 (interquartile range 1.90-3.86) ml/kg/h and the 28-day mortality was 40.1%. Compared with the moderate NUF rate, the low NUF rate (adjusted odds ratio 1.56, 95% CI 1.04-2.35, p = 0.032) and high NUF rate (adjusted odds ratio 1.43, 95% CI 1.02-2.01, p = 0.040) were associated with higher 28-day mortality. The putative effect of high or low NUF rates on 28 day mortality was not direct [adjusted average direct effects (ADE) for a low NUF rate = 0.92, p = 0.064; adjusted ADE for a high NUF rate = 1.03, p = 0.096], but mediated by effects of the NUF rate on fluid balance during the same period [adjusted average causal mediation effects (ACME) 0.96, p = 0.010 for a low NUF rate; adjusted ACME 0.99, p = 0.042 for a high NUF rate]. Moreover, we found an increase trend in the NUF rate corresponding to the lowest mortality when fluid input increased. Conclusion: Compared with NUF rates between 1.6-3.1 ml/kg/h in the first 48 h of CKRT, NUF rates > 3.1 and <1.6 ml/kg/h were associated with higher mortality.

Survey of U.S. Critical Care Practitioners on Net Ultrafiltration Prescription and Practice among Critically Ill Patients Receiving Kidney Replacement Therapy

INTRODUCTION

The current prescription and practice of net ultrafiltration among critically ill patients receiving kidney replacement therapy in the U.S. are unclear.

AIM OF THE STUDY

To assess the attitudes of U.S. critical care practitioners on net ultrafiltration (UFNET) prescription and practice among critically ill patients with acute kidney injury treated with kidney replacement therapy.

METHODS

A secondary analysis was conducted of a multinational survey of intensivists, nephrologists, advanced practice providers, and ICU and dialysis nurses practising in the U.S.

RESULTS

Of 1,569 respondents, 465 (29.6%) practitioners were from the U.S. Mainly were nurses and advanced practice providers (58%) and intensivists (38.2%). The median duration of practice was 8.7 (IQR, 4.2-19.4) years. Practitioners reported using continuous kidney replacement therapy (as the first modality in 60% (IQR 20%-90%) for UFNET. It was found that there was a significant variation in assessment of prescribed-to-delivered dose of UFNET, use of continuous kidney replacement therapy for UFNET, methods used to achieve UFNET, and assessment of net fluid balance during continuous kidney replacement therapy. There was also variation in interventions performed for managing hemodynamic instability, perceived barriers to UFNET, belief that early and protocol-based fluid removal is beneficial, and willingness to enroll patients in a clinical trial.

CONCLUSIONS

There was considerable practice variation in UFNET among critical care practitioners in the U.S., reflecting the need to generate evidence-based practice guidelines for UFNET.

Early restrictive fluid balance is associated with lower hospital mortality independent of acute disease severity in critically ill patients on CRRT

Fluid overload (FO) with coincident acute kidney injury has been associated with increased mortality. However, it is unclear whether FO is an independent determinant of mortality for disease severity. We aimed to explore whether the development of fluid balance (FB) during the first 72 h of continuous renal replacement therapy (CRRT) is independently associated with hospital mortality. All patients admitted to a single centre ICU requiring CRRT for at least 24 h between years 2010–2019 were included. Extracted data included patient demographics and clinical parameters including daily cumulative fluid balance (FB^cum), lactate, SOFA score and vasoactive requirement at the initiation and during the first 72 h of CRRT. 399 patients were included in the analysis. Hospital survivors had a significantly lower FB^cum at CRRT initiation compared to non-survivors (median 1382 versus 3265 ml; p = 0.003). Hourly fluid balance per bodyweight (FB^net) was lower in survivors at 0–24, 24–48 and 48–72 h after initiation of CRRT (p < 0.008 for all comparisons). In the survival analysis (analyzed with counting process model) significant time-dependent explanatory variables for hospital mortality were FB^net (per ml/kg/h: HR: 1.319, 95% CI 1.038–1.677, p = 0.02), lactate (HR: 1.086, 95% CI 1.030–1.145, p = 0.002) and SOFA score (per ml/kg/h: HR: 1.084, 95% CI 1.025–1.146, p = 0.005) during the first 72 h of CRRT. Even after careful adjustment for repeated measures of disease severity, FB^net during the first 72 h of CRRT remains independently associated with hospital mortality, in critically ill patients with AKI.

Increased 28-day mortality due to fluid overload prior to continuous renal replacement in sepsis associated acute kidney injury

Patients with sepsis are prone to fluid overload (FO) due to fluid resuscitation, irrespective of stage of acute kidney injury (AKI). The aim of our study was to analyze the association between FO at continuous renal replacement therapy (CRRT) initiation and 28-day mortality in patients with sepsis associated AKI (S-AKI). In this retrospective study, data for patient characteristics were collected and 28-day mortality were studied. We also analyze association of variables, including FO degrees with 28-day mortality. Earlier commencement of CRRT showed better outcome. Non-survivors had higher FO than survivor (9.17% vs. 5.20%; p = 0.016). Survival in patients with FO > 10% over 28 days was significantly worse compared to those with FO ≤ 10% (p = 0.006). Multivariate analysis showed, FO > 10% (95%CI [1.721, 17.195], p = 0.004) was significantly associated with increased 28-day mortality. In S-AKI requiring CRRT, FO > 10% at CRRT initiation was independently associated with 28-day mortality.