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

Successful Liberation from Acute Kidney Replacement Therapy in Critically Ill Patients: A Prospective Cohort Study

INTRODUCTION

Recovery of kidney function to liberate patients from acute kidney replacement therapy (AKRT) is recognized as a vital patient-centered outcome. The lack of specific guidelines providing specific recommendations on therapy interruption is an important obstacle. We aimed to determine the prevalence of successful discontinuation of AKRT and its predictive factors after the elaboration of clinical protocol with these recommendations.

METHODOLOGY

A prospective cohort study was performed with 156 patients at a public Brazilian university hospital between July 2020 and July 2021.

RESULTS

Success and hospital discharge were achieved for most patients (84.6% and 89%, respectively). Multivariable logistic regression analysis showed that C-reactive protein (CRP), urine output, and creatinine clearance at the time of interruption were variables associated with discontinuation success (OR: 0.943, CI: 0.905-0.983, p = 0.006; OR: 1.078, CI: 1.008-1.173, p = 0.009 and OR: 1.091, CI: 1.012-1.213, p = 0.004; respectively). The areas under the curve for CRP, urine output, and creatinine clearance at the time of interruption were 0.78, 0.62, and 0.82, respectively. Both CRP and creatinine clearance were good predictors of successful liberation of AKRT. The optimal cutoff value of them had sensitivity and specificity of 0.88 and 0.87, 0.91 and 0.90, respectively. The use of noradrenalin at the time of interruption (OR: 0.143, CI: 0.047-0.441, p = 0.001) and successful discontinuation (OR: 3.745, CI: 1.047-13.393, p = 0.042) were identified as variables associated with hospital discharge.

CONCLUSION

Our results show the factors related to success in discontinuing AKRT are the CRP, creatinine clearances, and urinary output at the time of AKRT interruption and it was associated with lower mortality.

Different Roles of Functional and Structural Renal Markers Measured at Discontinuation of Renal Replacement Therapy for Acute Kidney Injury

INTRODUCTION

Severe acute kidney injury (AKI) requiring renal replacement therapy (RRT) has been associated with an unacceptably high mortality of 50% or more. Successful discontinuation of RRT is thought to be linked to better outcomes. Although functional and structural renal markers have been evaluated in AKI, little is known about their roles in predicting outcomes at the time of RRT discontinuation.

METHODS

In this prospective single-center cohort study, we analyzed patients who received continuous RRT (CRRT) for AKI between August 2016 and March 2018 in the intensive care unit of the University of Tokyo Hospital (Tokyo, Japan). Clinical parameters and urine samples were obtained at CRRT discontinuation. Successful CRRT discontinuation was defined as neither resuming CRRT for 48 h nor receiving intermittent hemodialysis for 7 days from the CRRT termination. Major adverse kidney events (MAKEs) were defined as death, requirement for dialysis, or a decrease in the estimated glomerular filtration rate (eGFR) of more than 25% from the baseline at day 90.

RESULTS

Of 73 patients, who received CRRT for AKI, 59 successfully discontinued CRRT and 14 could not. Kinetic eGFR, urine volume, urinary neutrophil gelatinase-associated lipocalin (NGAL), and urinary L-type fatty acid binding protein were predictive for CRRT discontinuation. Of these factors, urine volume had the highest area under the curve (AUC) 0.91 with 95% confidence interval [0.80-0.96] for successful CRRT discontinuation. For predicting MAKEs at day 90, the urinary NGAL showed the highest AUC 0.76 [0.62-0.86], whereas kinetic eGFR and urine volume failed to show statistical significance (AUC 0.49 [0.35-0.63] and AUC 0.59 [0.44-0.73], respectively).

CONCLUSIONS

Our prospective study confirmed that urine volume, a functional renal marker, predicted successful discontinuation of RRT and that urinary NGAL, a structural renal marker, predicted long-term renal outcomes. These observations suggest that the functional and structural renal makers play different roles in predicting the outcomes of severe AKI requiring RRT.

Neutrophil-to-lymphocyte ratio-a new diagnostic and prognostic marker of acute kidney injury. Barriers to broad clinical application

Hospital-acquired acute kidney injury is a heterogeneous clinical syndrome that has multiple aetiologies, widely differing pathogeneses, variable clinical manifestations, and diverse outcomes. There is a persistent unmet need for novel biomarkers that offer timely diagnosis and accurate prediction of the short- and long-term sequelae of acute kidney injury (AKI). AKI is associated with systemic and intrarenal inflammation. The neutrophil-to-lymphocyte ratio (NLR), a readily available marker of inflammation and physiologic stress, has gained increasing attention as universal marker in AKI patients. Numerous retrospective cross-sectional studies assessed the clinical usefulness of this test in high-risk patients with a known time point of the renal injury (surgery, radiological procedures). Strong associations have been demonstrated between high NLR and early onset, progression or recovery of AKI, and the in-hospital and post-discharge mortality of these patients. However, the results were contradictory. The huge heterogeneity of reporting concerning the timing and numbers of blood samples, calculation of the optimal cut-off and the demographic and clinical features of the patient cohorts were confounders. Uncertainty in the optimal cut-off values defining high NLR, the lack of prospective validation of this test and limited understanding of the strengths of associations between NLR and clinical outcomes were further barriers for the clinical adoption of NLR as a valid diagnostic and prognostic test in AKI patients.

Consensus-Based Recommendations on Priority Activities to Address Acute Kidney Injury in Children: A Modified Delphi Consensus Statement

IMPORTANCE

Increasing evidence indicates that acute kidney injury (AKI) occurs frequently in children and young adults and is associated with poor short-term and long-term outcomes. Guidance is required to focus efforts related to expansion of pediatric AKI knowledge.

OBJECTIVE

To develop expert-driven pediatric specific recommendations on needed AKI research, education, practice, and advocacy.

EVIDENCE REVIEW

At the 26th Acute Disease Quality Initiative meeting conducted in November 2021 by 47 multiprofessional international experts in general pediatrics, nephrology, and critical care, the panel focused on 6 areas: (1) epidemiology; (2) diagnostics; (3) fluid overload; (4) kidney support therapies; (5) biology, pharmacology, and nutrition; and (6) education and advocacy. An objective scientific review and distillation of literature through September 2021 was performed of (1) epidemiology, (2) risk assessment and diagnosis, (3) fluid assessment, (4) kidney support and extracorporeal therapies, (5) pathobiology, nutrition, and pharmacology, and (6) education and advocacy. Using an established modified Delphi process based on existing data, workgroups derived consensus statements with recommendations.

FINDINGS

The meeting developed 12 consensus statements and 29 research recommendations. Principal suggestions were to address gaps of knowledge by including data from varying socioeconomic groups, broadening definition of AKI phenotypes, adjudicating fluid balance by disease severity, integrating biopathology of child growth and development, and partnering with families and communities in AKI advocacy.

CONCLUSIONS AND RELEVANCE

Existing evidence across observational study supports further efforts to increase knowledge related to AKI in childhood. Significant gaps of knowledge may be addressed by focused efforts.

Anticipation of recovery of native renal function and liberation from renal replacement therapy in critically ill patients with severe acute kidney injury

Background

Renal replacement therapy (RRT) is used to manage critically ill patients with severe acute kidney injury (AKI-D), and it is undoubtedly life-sustaining for most patients. However, the prolonged unnecessary use of these techniques may be harmful. At present, no consensus guidelines provide specific recommendations for clinicians on when (optimal timing of discontinuation) and how (liberation or weaning) to stop RRT in intensive care unit (ICU) patients with recovering native kidney function.

Methods and results

Numerous variables such as clinical parameters, classical surrogate markers for glomerular filtration rate, novel biomarkers of kidney function and damage, and new imaging techniques in AKI-D have been described to predict successful discontinuation of RRT. Most available studies are limited by study design, heterogeneity of variable assessment and thresholds of biomarkers, and lack of prospective validation. At present, the decision on discontinuation of RRT in ICU patients is based on three clinical scenarios: (a) intrinsic kidney function (defined as spontaneous urine output > 500 ml/24 h, timed creatinine clearance > 15 to 20 ml/min) has adequately improved to match the demands and continued RRT is no longer consistent with goals of care (transition to intermittent RRT); (b) the acute illness that prompted RRT has improved; (c) the clinical practice of switching haemodynamic stable patients with persistent AKI-D from continuous RRTs to intermittent RRTs is variable, but de-escalation of RRT (frequency, dose) may facilitate mobilization and discharge of ICU patients.

Conclusions

The predictive ability of novel kidney biomarkers, surrogate markers of kidney function, and direct measurements of kidney function should be evaluated in future studies.