Effect of Frequent Dialysis on Renal Recovery: Results From the Acute Renal Failure Trial Network Study

A model of hemodialysis after acute kidney injury in rats

BACKGROUND

Acute kidney injury (AKI) is frequent among critically ill patients. Renal replacement therapy (RRT) is often required to deal with severe complications of AKI. This technique is however associated with side effects such as hemodynamic instability and delayed renal recovery. In this study, we aimed to describe a novel model of hemodialysis in rats with AKI and depict a dialysis membrane performance.

METHODS

Eighteen Sprague-Dawley rats received 0.75% adenine-rich diet to induce AKI. After 2 weeks, nine underwent an arterio-venous extracorporeal circulation (ECC) (ECC group) for 2 h without a dialysis membrane on the circuit and nine received a hemodialysis session (HD group) for 2 h with an ECC circuit. All rats were hemodynamically monitored, and glomerular filtration rate (GFR) was measured by transcutaneous fluorescence after the injection of FITC-Sinistrin. Blood samples were collected at different time points to assess serum creatinine and serum urea concentrations and to determine the Kt/V. Sinistrin concentration was also quantified in both plasma and dialysis effluent.

RESULTS

After 2 weeks of adenine-rich diet, rats exhibited a decrease in GFR. Both serum urea and serum creatinine concentrations increased in the ECC group but remained stable in the HD group. We found no significant difference in serum creatinine and serum urea concentrations between groups. At the end of experiments, mean serum urea was 36.7 mmol/l (95%CI 19.7-46.9 mmol/l) and 23.6 mmol/l (95%CI 15.2-33.5 mmol/l) in the ECC and HD groups, respectively (p = 0.15), and mean serum creatinine concentration was 158.0 µmol/l (95%CI 108.1-191.9 µmol/l) and 114.0 µmol/l (95%CI 90.2-140.9 µmol/l) in the ECC and HD groups, respectively (p = 0.11). The Kt/V of the model was estimated at 0.23. Sinistrin quantity in the ultrafiltrate raised steadily during the dialysis session. After 2 h, the median quantity was 149.2 µg (95% CI 99.7-250.3 µg).

CONCLUSIONS

This hemodialysis model is an acceptable compromise between the requirement of hemodynamic tolerance which implies reducing extracorporeal blood volume (using a small dialyzer) and the demonstration that diffusion of molecules through the membrane is achieved.

Impact of Continuous Renal Replacement Therapy Initiation on Urine Output and Fluid Balance: A Multicenter Study

INTRODUCTION

The effect of continuous renal replacement therapy (CRRT) on renal function is poorly understood. However, the initiation of CRRT may induce oliguria. We aimed to investigate the impact of CRRT commencement on urine output (UO).

METHODS

This was a retrospective cohort study in two intensive care units. We included all patients who underwent CRRT and collected data on hourly UO and fluid balance before and after CRRT commencement. We performed an interrupted time series analysis using segmented regression to assess the relationship between CRRT commencement and UO.

RESULTS

We studied 1,057 patients. Median age was 60.7 years (interquartile range [IQR], 48.3-70.6), and the median APACHE III was 95 (IQR, 76-115). Median time to CRRT was 17 h (IQR, 5-49). With start of CRRT, the absolute difference in mean hourly UO and mean hourly fluid balance was -27.0 mL/h (95% CI: -32.1 to -21.8; p value < 0.01) and - 129.3 mL/h (95% CI: -169.2 to -133.3), respectively. When controlling for pre-CRRT temporal trends and patient characteristics, there was a rapid post-initiation decrease in UO (-0.12 mL/kg/h; 95% CI: -0.17 to -0.08; p value < 0.01) and fluid balance (-78.1 mL/h; 95% CI: -87.9 to -68.3; p value < 0.01), which was sustained over the first 24 h of CRRT. Change in UO and fluid balance were only weakly correlated (r -0.29; 95% CI: -0.35 to -0.23; p value < 0.01).

CONCLUSION

Commencement of CRRT was associated with a significant decrease in UO that could not be explained by extracorporeal fluid removal.

Disparities in Deceased Donor Kidney Offer Acceptance: A Survey of Canadian Transplant Nephrologists, General Surgeons and Urologists

Background

Significant variability in organ acceptance thresholds have been demonstrated across the United States, but data regarding the rate and rationale for kidney donor organ decline in Canada are lacking.

Objective

To examine decision making regarding deceased kidney donor acceptance and non-acceptance in a population of Canadian transplant professionals.

Design

A survey study of theoretical deceased donor kidney cases of increasing complexity.

Setting

Canadian transplant nephrologists, urologists, and surgeons making donor call decisions responding to an electronic survey between July 22 and October 4, 2022.

Participants

Invitations to participate were distributed to 179 Canadian transplant nephrologists, surgeons, and urologists through e-mail. Participants were identified by contacting each transplant program and requesting a list of physicians who take donor call.

Measurements

Survey respondents were asked whether they would accept or decline a given donor, assuming there was a suitable recipient. They were also asked to cite reasons for donor non-acceptance.

Methods

Donor scenario-specific acceptance rates (total acceptance divided by total number of respondents for a given scenario and overall) and reasons for decline were determined and presented as a percentage of the total cases declined.

Results

In all, 72 respondents from 7 provinces completed at least one question of the survey, with considerable variability between acceptance rates for centers; the most conservative center declined 60.9% of donor cases, whereas the most aggressive center declined only 28.1%, P-value < .001. There was an increased risk of non-acceptance with advancing age, donation after cardiac death, acute kidney injury, chronic kidney disease, and comorbidities.

Limitations

As with any survey, there is the potential for participation bias. In addition, this study examines donor characteristics in isolation, however, asks respondent to assume there is a suitable candidate available. In reality, whenever donor quality is considered, it should be considered in the context of the intended recipient.

Conclusion

In a survey of increasingly medically complex deceased kidney donor cases, there was significant variability in donor decline among Canadian transplant specialists. Given relatively high rates of donor decline and apparent heterogeneity in acceptance decisions, Canadian transplant specialists may benefit from additional education regarding the benefits achieved from even medically complex kidney donors for appropriate candidates relative to remaining on dialysis on the transplant waitlist.

Management of Intermittent Hemodialysis in the Critically Ill Patient

Intermittent hemodialysis remains a cornerstone of extracorporeal KRT in the intensive care unit, either as a first-line therapy for AKI or a second-line therapy when patients transition from a continuous or prolonged intermittent therapy. Intermittent hemodialysis is usually provided 3 days per week in this setting on the basis that no clinical benefits have been demonstrated with more frequent hemodialysis. This should not detract from the importance of continually assessing and refining the hemodialysis prescription (including the need for extra treatments) according to dynamic changes in extracellular volume and other parameters, and ensuring that an adequate dose of hemodialysis is being delivered to the patient. Compared with other KRT modalities, the cardinal challenge encountered during intermittent hemodialysis is hemodynamic instability. This phenomenon occurs when reductions in intravascular volume, as a consequence of ultrafiltration and/or osmotic shifts, outpace compensatory plasma refilling from the extravascular space. Myocardial stunning, triggered by intermittent hemodialysis, and independent of ultrafiltration, may also contribute. The hemodynamic effect of intermittent hemodialysis is likely magnified in patients who are critically ill due to an inability to mount sufficient compensatory physiologic responses in the context of multiorgan dysfunction. Of the many interventions that have undergone testing to mitigate hemodynamic instability related to KRT, the best evidence exists for cooling the dialysate and raising the dialysate sodium concentration. Unfortunately, the evidence supporting routine use of these and other interventions is weak owing to poor study quality and limited sample sizes. Intermittent hemodialysis will continue to be an important and commonly used KRT modality for AKI in patients with critical illness, especially in jurisdictions where resources are limited. There is an urgent need to harmonize the definition of hemodynamic instability related to KRT in clinical trials and robustly test strategies to combat it in this vulnerable patient population.

Renal outcomes according to renal replacement therapy modality and treatment protocol in the ATN and RENAL trials

Background

In critically ill patients with acute kidney injury, renal replacement therapy (RRT) modality and treatment protocols may affect kidney recovery. This study explored whether RRT modality and treatment protocol affected RRT dependence in the ‘Randomized Evaluation of Normal versus Augmented Level of RRT’ and the ‘Acute Renal Failure Trial Network’ (ATN) trials.

Methods

Primary outcome was 28-day RRT dependence. Secondary outcomes included RRT dependence among survivors and in different SOFA-based treatment protocol groups. We used the Fine-Gray competing-risk model sub-distribution hazard ratio (SHR) to assess the primary outcome. Analyses were adjusted for confounders.

Results

Of 2542 patients, 2175 (85.5%) received continuous RRT (CRRT) and 367 (14.4%) received intermittent hemodialysis (IHD) as first RRT modality. CRRT-first patients had greater illness severity. After adjustment, there was no between-group difference in 28-day RRT dependence (SHR, 0.96 [95% CI 0.84–1.10]; p = 0.570) or hospital mortality (odds ratio [OR], 1.14 [95% CI 0.86–1.52]; p = 0.361) However, among survivors, CRRT-first was associated with decreased 28-day RRT dependence (OR, 0.54 [95% CI 0.37–0.80]; p = 0.002) and more RRT-free days (common OR: 1.38 [95% CI 1.11–1.71]). Moreover, among CRRT-first patient, the ATN treatment protocol was associated with fewer RRT-free days, greater mortality, and a fourfold increase in RRT dependence at day 28.

Conclusions

There was no difference in RRT dependence at day 28 between IHD and CRRT. However, among survivors and after adjustment, both IHD-first and the ATN treatment protocol were strongly associated with greater risk of RRT dependence at 28 days after randomization.

Trial registration NCT00221013 registered September 22, 2005, and NCT00076219 registered January 19, 2004.

Intermittent Online Postdilution Hemodiafiltration versus High-Flux Hemodialysis in Non-critical Acute Kidney Injury: A Pilot Randomized Controlled Trial

The preferential use of convective modes of hemodialysis (HD) for targeting hyper-cytokinemia state in sepsis-related acute kidney injury (AKI) has been questioned for its efficacy. Several studies have used predilution hemodiafiltration (HDF) in critically ill AKI patients with mixed results. In this study, we compared intermittent online postdilution HDF with the standard high-flux (HF) intermittent HD in non-critically ill patients with community-acquired (CA) AKI. In this pilot study, stable patients with CA AKI and systemic inflammatory response syndrome were included and given either postdilution online-HDF (OL-HDF) or standard HF HD outside intensive care units. The primary objectives were to assess the feasibility of conducting the study at a larger scale and to detect the differential impact of convective clearance on the rates of independence from dialysis at discharge or after 30 days. Plasma cytokine clearance was assessed as a secondary objective. Eighty consecutive AKI patients were randomized to receive dialysis in one of the treatment arms after fulfilling the eligibility criteria. The baseline parameters of clinical severity, etiology, and indications of dialysis, plus the baseline plasma cytokine profiles, were comparable. Moreover, 83% in the control arm and 71.1% in the intervention arm became independent from dialysis at discharge or at 30 days (P = 0.189). No survival advantage of postdilution OL-HDF was observed (P >0.05). Similar plasma cytokine clearance levels were noted in both arms. The current study confirms the feasibility; however, it does not support the preferential use of postdilution OL-HDF over HF-HD in non-critical patients.

The conundrum of the complex relationship between acute kidney injury and cardiac arrhythmias

Acute kidney injury (AKI) is defined by a rapid increase in serum creatinine levels, reduced urine output, or both. Death may occur in 16%-49% of patients admitted to an intensive care unit with severe AKI. Complex arrhythmias are a potentially serious complication in AKI patients with pre-existing or AKI-induced heart damage and myocardial dysfunction, fluid overload, and especially electrolyte and acid-base disorders representing the pathogenetic mechanisms of arrhythmogenesis. Cardiac arrhythmias, in turn, increase the risk of poor renal outcomes, including AKI. Arrhythmic risk in AKI patients receiving kidney replacement treatment may be reduced by modifying dialysis/replacement fluid composition. The most common arrhythmia observed in AKI patients is atrial fibrillation. Severe hyperkalemia, sometimes combined with hypocalcemia, causes severe bradyarrhythmias in this clinical setting. Although the likelihood of life-threatening ventricular arrhythmias is reportedly low, the combination of cardiac ischemia and specific electrolyte or acid-base abnormalities may increase this risk, particularly in AKI patients who require kidney replacement treatment. The purpose of this review is to summarize the available epidemiological, pathophysiological, and prognostic evidence aiming to clarify the complex relationships between AKI and cardiac arrhythmias.

Prolonged exposure to continuous renal replacement therapy in patients with acute kidney injury

BACKGROUND

Little is known about the process of deciding to discontinue continuous renal replacement therapy (CRRT) in patients with acute kidney injury (AKI) and the impact of CRRT duration on outcomes.

METHODS

We report the clinical parameters of prolonged CRRT exposure and predictors of doubling of serum creatinine or need for dialysis at 90 days after CRRT with propensity score matching, including covariates that were likely to influence patients in the prolonged CRRT group.

RESULTS

Among 104 survey responders, most use urine output (87%) to guide CRRT discontinuation, 24% use improvement in clinical or hemodynamic status. In the cohort study, of 854 included patients, 465 participated in the assessment of kidney recovery. Patients with prolonged CRRT had higher SOFA scores (11.9 vs. 11.2) and were more likely to be mechanically ventilated (99% vs. 84%) at CRRT initiation compared to patients without prolonged CRRT, p-value < 0.05. In multivariable logistic regression, daily urine output and cumulative fluid balance leading to CRRT discontinuation or day seven were independently associated with lower [OR 0.87 per 200 ml/day increase] and higher odds [OR 1.03 per 1-L increase] of requiring prolonged CRRT, respectively. After propensity score matching, prolonged exposure to CRRT was independently associated with increased risk of doubling serum creatinine or dialysis at 90 days, OR 3.1 (95% CI 1.23-8.3 p = 0.017).

CONCLUSIONS

Resolution of critical illness and signs of kidney recovery are important factors when considering CRRT discontinuation. Prolonged CRRT exposure may be associated with less chance of kidney recovery among survivors.

Recovery after Critical Illness and Acute Kidney Injury

AKI is a common complication in hospitalized and critically ill patients. Its incidence has steadily increased over the past decade. Whether transient or prolonged, AKI is an independent risk factor associated with poor short- and long-term outcomes, even if patients do not require KRT. Most patients with early AKI improve with conservative management; however, some will require dialysis for a few days, a few weeks, or even months. Approximately 10%-30% of AKI survivors may still need dialysis after hospital discharge. These patients have a higher associated risk of death, rehospitalization, recurrent AKI, and CKD, and a lower quality of life. Survivors of critical illness may also suffer from cognitive dysfunction, muscle weakness, prolonged ventilator dependence, malnutrition, infections, chronic pain, and poor wound healing. Collaboration and communication among nephrologists, primary care physicians, rehabilitation providers, physical therapists, nutritionists, nurses, pharmacists, and other members of the health care team are essential to create a holistic and patient-centric care plan for overall recovery. Integration of the patient and family members in health care decisions, and ongoing education throughout the process, are vital to improve patient well-being. From the nephrologist standpoint, assessing and promoting recovery of kidney function, and providing appropriate short- and long-term follow-up, are crucial to prevent rehospitalizations and to reduce complications. Return to baseline functional status is the ultimate goal for most patients, and dialysis independence is an important part of that goal. In this review, we seek to highlight the varying aspects and stages of recovery from AKI complicating critical illness, and propose viable strategies to promote recovery of kidney function and dialysis independence. We also emphasize the need for ongoing research and multidisciplinary collaboration to improve outcomes in this vulnerable population.

Hypocalcemia is associated with hypotension during CRRT: A secondary analysis of the Acute Renal Failure Trial Network Study

PURPOSE

We investigated the effect of potentially modifiable continuous renal replacement therapy (CRRT)-related treatment factors on the risk of severe hypotension.

MATERIALS AND METHODS

We carried out a secondary statistical analysis of the Acute Renal Failure Trial Network (ATN) trial. The primary exposures of interest were CRRT treatment dose, ultrafiltration rate, blood flow rate, ionized calcium level and type of anti-coagulation used. The primary outcome was severe hypotension, defined as vasopressor-inotropic score > 18 and calculated based on treatment doses of vasopressor and inotropic agents.

RESULTS

Of 1124 individuals enrolled in the ATN Trial, 786 were managed with CRRT. 265/786 (33.7%) patients experienced severe hypotension during the trial. A serum ionized calcium <1.02 mmol/l was associated with a higher risk of severe hypotension compared to a serum calcium >1.02 mmol/l (hazard ratio 2.9; 95% CI 1.5-5.7). There was no significant difference in the risk of hypotension associated with other CRRT treatment factors.

CONCLUSIONS

Of the CRRT treatment factors studied, hypocalcemia with a serum ionized calcium <1.02 mmol/l was associated with a significantly increased risk of treatment-associated hypotension. Further studies will be required to assess whether treatment targets for serum calcium improve the risk of hypotension during CRRT.

Determinants of Outcomes of Acute Kidney Injury: Clinical Predictors and Beyond

Acute kidney injury (AKI) is a common clinical syndrome characterized by rapid impairment of kidney function. The incidence of AKI and its severe form AKI requiring dialysis (AKI-D) has been increasing over the years. AKI etiology may be multifactorial and is substantially associated with increased morbidity and mortality. The outcome of AKI-D can vary from partial or complete recovery to transitioning to chronic kidney disease, end stage kidney disease, or even death. Predicting outcomes of patients with AKI is crucial as it may allow clinicians to guide policy regarding adequate management of this problem and offer the best long-term options to their patients in advance. In this manuscript, we will review the current evidence regarding the determinants of AKI outcomes, focusing on AKI-D.

Current Approach to Successful Liberation from Renal Replacement Therapy in Critically Ill Patients with Severe Acute Kidney Injury: The Quest for Biomarkers Continues

Recovery of sufficient kidney function to liberate patients with severe acute kidney injury (AKI-D) from renal replacement therapy (RRT) is recognized as a vital patient-centred outcome. However, no clinical consensus guideline provides specific recommendations on when and how to stop RRT in anticipation of renal recovery from AKI-D. Currently, wide variations in clinical practice regarding liberation from RRT result in early re-start of RRT to treat uraemia after premature liberation or in the unnecessary prolonged exposure of unwell patients after late liberation. Observational studies, predominantly retrospective in nature, have attempted to assess numerous surrogate markers of kidney function or of biomarkers of kidney damage to predict successful liberation from RRT. However, a substantial heterogeneity in the timing of measurement and cut-off values of most biomarkers across studies allows no pooling of data, and impedes the comparison of outcomes from such studies. The accuracy of most traditional and novel biomarkers cannot be assessed reliably. Currently, the decision to discontinue RRT in AKI-D patients relies on daily clinical assessments of the patient’s status supplemented by measurement of creatinine clearance (> 15 ml/min) and 24-h urine output (> 2000 ml/min with diuretics). Clinical trials objectively comparing the success of validated biomarkers for guiding optimal timed liberation from RRT in AKI-D will be required to provide high-quality evidence for guidelines.

Intensity of renal replacement therapy and outcomes in critically ill patients with acute kidney injury: Critical appraisal of the dosing recommendations

The current care of critically ill patients with severe acute kidney injury requiring dialysis (AKI-D) is limited to supportive management in which renal replacement therapy (RRT) plays a central role. Renal replacement techniques are invasive bioincompatible procedures and are therefore associated with complications that may prove harmful to fragile patients. Inexperience with the standards and lacking or misinterpreted recommendations for the delivery of the RRT dose increases the risk of serious complications. Neither the optimal doses of intermittent or continuous RRTs nor the minimal or maximal effective doses are known. The Kidney Disease Improving Global outcomes (KDIGO) AKI guidelines for RRT dosing recommendations are inflexible, based on limited research, and may be at least partially outdated. High-intensity therapy may be associated with clinically relevant alterations in systemic and renal hemodynamics, profound electrolyte imbalances, the loss of nutrients or thermal energy, and underdosing of antimicrobial agents. However, higher doses of continuous renal replacement therapy (CRRT) may confer a survival benefit for certain subgroups of intensive care patients with severe AKI. Lower CRRT doses than the recommended adequate dosage may not lead to negative health outcomes, at least in Asian patients. Future research should evaluate the demand-capacity concept, recognizing that the delivery of the RRT dose is dynamic and should be modified in response to patient-related factors. There is a need for large-scale studies evaluating whether precision RRT dose modifications may improve patient-centered outcomes in subgroups of critically ill patients.

Narrative Review of Incremental Hemodialysis

The prescription of hemodialysis (HD) in patients with incident end-stage kidney disease (ESKD) is fundamentally empirical. The abrupt transition from nondialysis chronic kidney disease (CKD) to thrice-weekly in-center HD of much the same dialysis intensity as in those with prevalent ESKD underappreciates the progressive nature of kidney disease whereby the decline in renal function has been gradual and ongoing-including at the time of HD initiation. Adjuvant pharmacologic treatment (i.e., diuretics, acid buffers, potassium binders), coupled with residual kidney function (RKF), can complement an initial HD regimen of lower intensity. Barriers to less intensive HD in incident ESKD include risk of inadequate clearance of uremic toxins due to variable and unexpected loss of RKF, lack of patient adherence to assessments of RKF or adjustment of HD intensity, increased burden for all stakeholders in the dialysis units, and negative financial repercussions. A stepped dialysis regimen with scheduled transition from time-delineated twice-weekly HD to thrice-weekly HD could represent an effective and safe strategy to standardize incremental HD in patients with CKD transitioning to early-stage ESKD. Patients' adherence and survival as well as other clinical outcomes should be rigorously evaluated in clinical trials before large-scale implementation of different incremental schedules of HD. This review discusses potential benefits of and barriers to alternative dialysis regimens in patients with incident ESKD, with emphasis on twice-weekly HD with pharmacologic therapy, and summarizes in-progress clinical trials of incremental HD schedules.

A Pilot Study Evaluating the Effect of Cooler Dialysate Temperature on Hemodynamic Stability During Prolonged Intermittent Renal Replacement Therapy in Acute Kidney Injury

OBJECTIVES

Acute kidney injury requiring renal replacement therapy is associated with high morbidity and mortality. Complications of renal replacement therapy include hemodynamic instability with ensuing shortened treatments, inadequate ultrafiltration, and delay in renal recovery. Studies have shown that lowering dialysate temperature in patients with end-stage renal disease is associated with a decrease in the frequency of intradialytic hypotension. However, data regarding mitigation of hypotension by lowering dialysate temperature in patients with acute kidney injury are scarce. We conducted a prospective, randomized, cross-over pilot study to evaluate the effect of lower dialysate temperature on hemodynamic status of critically ill patients with acute kidney injury during prolonged intermittent renal replacement therapy.

DESIGN

Single-center prospective, randomized, cross-over study.

SETTING

ICUs and a step down unit in a tertiary referral center.

PATIENTS

Acute kidney injury patients undergoing prolonged intermittent renal replacement therapy.

INTERVENTIONS

Participants were randomized to start prolonged intermittent renal replacement therapy with dialysate temperature of 35°C or dialysate temperature of 37°C.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was the number of hypotensive events, as defined by any of the following: decrease in systolic blood pressure greater than or equal to 20 mm Hg, decrease in mean arterial pressure greater than or equal to 10 mm Hg, decrease in ultrafiltration, or increase in vasopressor requirements. The number of events was analyzed by Poisson regression and other outcomes with repeated-measures analysis of variance. Twenty-one patients underwent a total of 78 prolonged intermittent renal replacement therapy sessions, 39 in each arm. The number of hypotensive events was twice as high during treatments with dialysate temperature of 37°C, compared with treatments with the cooler dialysate (1.49 ± 1.12 vs 0.72 ± 0.69; incidence rate ratio, 2.06; p ≤ 0.0001). Treatment sessions with cooler dialysate were more likely to reach prescribed ultrafiltration targets.

CONCLUSIONS

Patients with acute kidney injury undergoing prolonged intermittent renal replacement therapy with cooler dialysate experienced significantly less hypotension during treatment. Prevention of hemodynamic instability during renal replacement therapy helped to achieve ultrafiltration goals and may help to prevent volume overload in critically ill patients.

Outpatient Dialysis for Acute Kidney Injury: Progress and Pitfalls

Dialysis-requiring acute kidney injury (AKI) has increased markedly in the United States. At the same time, mortality rates have recently improved. As such, increasing numbers of patients with AKI are surviving to hospital discharge, including up to 30% who will continue to require outpatient dialysis. In recent years, policy changes have significantly affected the care of this high-risk population. Beginning in 2017, new legislation reversed a previous Centers for Medicare & Medicaid Services policy that prohibited dialysis for AKI at end-stage renal disease (ESRD) facilities. This has improved dialysis options for patients, but the impact on patient outcomes remains uncertain. Unfortunately, there is currently a lack of evidence basis to guide management of this vulnerable patient population. Moving forward, additional data reporting and analyses will be required, analogous to how the US Renal Data System has helped inform ESRD care. As the dialysis setting for patients with AKI shifts to the ESRD setting, it is incumbent on the nephrology community to identify best practices to promote kidney recovery, recognizing that these practices will differ from standard ESRD protocols.

A swan song for Kt/Vurea

Dialyzer clearance of urea multiplied by dialysis time and normalized for urea distribution volume (Kt/V_urea or simply Kt/V) has been used as an index of dialysis adequacy since more than 30 years. This article reviews the flaws of Kt/V, starting with a lack of proof of concept in three randomized controlled hard outcome trials (RCTs), and continuing with a long list of conditions where the concept of Kt/V was shown to be flawed. This information leaves little room for any conclusion other than that Kt/V, as an indicator of dialysis adequacy, is obsolete. The dialysis patient might benefit more if, instead, the nephrology community concentrates in the future on pursuing the optimal dialysis dose that conforms with adequate quality of life and on factors that are likely to affect outcomes more than Kt/V. These include residual renal function, volume status, dialysis length, ultrafiltration rate, the number of intra-dialytic hypotensive episodes, interdialytic blood pressure, serum potassium and phosphate, serum albumin, and C reactive protein.