Purpose The incidence, patient features, risk factors and outcomes of surgery-associated postoperative acute kidney injury (PO-AKI) across different countries and health care systems is unclear. Methods We conducted an international prospective, observational, multi-center study in 30 countries in patients undergoing major surgery (> 2-h duration and postoperative intensive care unit (ICU) or high dependency unit admission). The primary endpoint was the occurrence of PO-AKI within 72 h of surgery defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Secondary endpoints included PO-AKI severity and duration, use of renal replacement therapy (RRT), mortality, and ICU and hospital length of stay. Results We studied 10,568 patients and 1945 (18.4%) developed PO-AKI (1236 (63.5%) KDIGO stage 1500 (25.7%) KDIGO stage 2209 (10.7%) KDIGO stage 3). In 33.8% PO-AKI was persistent, and 170/1945 (8.7%) of patients with PO-AKI received RRT in the ICU. Patients with PO-AKI had greater ICU (6.3% vs. 0.7%) and hospital (8.6% vs. 1.4%) mortality, and longer ICU (median 2 (Q1-Q3, 1–3) days vs. 3 (Q1-Q3, 1–6) days) and hospital length of stay (median 14 (Q1-Q3, 9–24) days vs. 10 (Q1-Q3, 7–17) days). Risk factors for PO-AKI included older age, comorbidities (hypertension, diabetes, chronic kidney disease), type, duration and urgency of surgery as well as intraoperative vasopressors, and aminoglycosides administration. Conclusion In a comprehensive multinational study, approximately one in five patients develop PO-AKI after major surgery. Increasing severity of PO-AKI is associated with a progressive increase in adverse outcomes. Our findings indicate that PO-AKI represents a significant burden for health care worldwide. Supplementary Information The online version contains supplementary material available at 10.1007/s00134-023-07169-7.

Background Renal replacement therapy (RRT) remains the key rescue therapy for critically ill patients with severe acute kidney injury (AKI). However, there are currently no tools available to predict successful liberation from RRT. Biomarkers may allow for risk stratification and individualization of treatment strategies. Proenkephalin A 119–159 (penKid) has been suggested as a promising marker of kidney function in the context of AKI, but has not yet been evaluated for RRT liberation in critically ill patients with AKI. Methods This post hoc analysis included 210 patients from the randomized clinical ELAIN trial and penKid levels were measured in the blood of these patients. Competing risk time-to-event analyses were performed for pre-RRT penKid at initiation of RRT and in a landmark analysis at day 3 after initiation of RRT. Competing risk endpoints were successful liberation from RRT or death without prior liberation from RRT. Results Low pre-RRT penKid levels (penKid ≤ 89 pmol/l) at RRT initiation were associated with early and successful liberation from RRT compared to patients with high pre-RRT penKid levels (subdistribution hazard ratio (sHR) 1.83, 95%CI 1.26–2.67, p = 0.002, estimated 28d-cumulative incidence function (28d-CIF) of successful liberation from RRT 61% vs. 45%, p = 0.022). This association persisted in the landmark analysis on day 3 of RRT (sHR 1.78, 95%CI 1.17–2.71, p = 0.007, 28d-CIF of successful liberation from RRT 67% vs. 47%, p = 0.018). For both time points, no difference in the competing event of death was detected. Conclusions In critically ill patients with RRT-dependent AKI, plasma penKid appears to be a useful biomarker for the prediction of shorter duration and successful liberation from RRT and may allow an individualized approach to guide strategies of RRT liberation in critically ill patients with RRT-dependent AKI. Trial registration: The ELAIN trial was prospectively registered at the German Clinical Trial Registry (Identifier: DRKS00004367) on 28th of May 2013. Graphical Abstract

OBJECTIVES: Optimal timing of renal replacement therapy (RRT) initiation in severe acute kidney injury (AKI) remains controversial. Initiation of treatment early in the course of AKI may lead to some patients undergoing unnecessary RRT, whereas delayed treatment is associated with increased mortality. This study aims to investigate whether the combination of the furosemide stress test (FST) and AKI-associated biomarkers can predict the development of indications for RRT. DESIGN: Single-center, prospective, observational study. SETTING: University Hospital of Muenster, Germany. PATIENTS: Critically ill, postoperative patients with moderate AKI (Kidney Disease: Improving Global Outcomes stage 2) and risk factors for further progression (vasopressors and/or mechanical ventilation) receiving an FST. INTERVENTIONS: Sample collection and measurement of different biomarkers (chemokine [C-C motif] ligand 14 [CCL14], neutrophil gelatinase-associated lipocalin, dipeptidyl peptidase 3). MEASUREMENT AND MAIN RESULTS: The primary endpoint was the development of greater than or equal to one predefined RRT indications (hyperkalemia [≥ 6 mmol/L], diuretic-resistant hypervolemia, high urea serum levels [≥ 150 mg/dL], severe metabolic acidosis [pH ≤ 7.15], oliguria [urinary output < 200 mL/12 hr], or anuria). Two hundred eight patients were available for the primary analysis with 108 having a negative FST (urine output < 200 mL in 2 hr following FST). Ninety-eight patients (47%) met the primary endpoint, 82% in the FST negative cohort. At the time of inclusion, the combination of a negative FST test and high urinary CCL14 levels had a significantly higher predictive value for the primary endpoint with an area under the receiver operating characteristic curve (AUC) of 0.87 (95% CI, 0.82–0.92) compared with FST or CCL14 alone (AUC, 0.79; 95% CI, 0.74–0.85 and AUC, 0.83; 95% CI, 0.77–0.89; p < 0.001, respectively). Other biomarkers showed lower AUCs. CONCLUSIONS: The combination of the FST with the renal biomarker CCL14 predicts the development of indications for RRT.

Introduction Recent evidence suggests an association of plasma Proenkephalin A 119–159 (penKid) with early and successful liberation from continuous renal replacement therapy (CRRT) in critically ill patients with acute kidney injury. However, these exploratory results are derived from a monocentric trial and therefore require external validation in a multicenter cohort. Methods Data and plasma samples from the “Effect of Regional Citrate Anticoagulation versus Systemic Heparin Anticoagulation During Continuous Kidney Replacement Therapy on Dialysis Filter Life Span and Mortality Among Critically Ill Patients With Acute Kidney Injury—A Randomized Clinical Trial” (RICH Trial) were used for this validation study. PenKid was measured in all plasma samples available at CRRT initiation and at day 3 of CRRT. Patients were categorized into low and high penKid groups with a cutoff at 100 pmol/l. Competing-risk time-to-event analyses were performed. Competing risk endpoints were successful and unsuccessful liberation from CRRT, the latter meaning death or initiation of a new RRT within one week of discontinuation of primary CRRT. Then penKid was compared to urinary output. Results Low pre-CRRT penKid levels at CRRT initiation were not associated with early and successful liberation from CRRT compared to patients with high pre-CRRT penKid levels [subdistribution hazard ratio (sHR) 1.01, 95% CI 0.73–1.40, p = 0.945]. However, the landmark analysis on day 3 of ongoing CRRT demonstrated an association between low penKid levels and successful liberation from CRRT (sHR 2.35, 95% CI 1.45–3.81, p < 0.001) and an association between high penKid levels and unsuccessful liberation (sHR 0.46, 95% CI 0.26–0.80, p = 0.007). High daily urinary output (> 436 ml/d) was even stronger associated with successful liberation (sHR 2.91, 95% CI 1.80–4.73, p < 0.001) compared to penKid. Discussion This study suggests that penKid may be a competent biomarker to monitor the recovery of kidney function during CRRT. This is in line with previous findings and investigated this concept in a multicenter cohort. Again, low penKid was associated with early and successful CRRT liberation, but was outperformed by high daily urinary output. The findings of this study now warrant further evaluation in prospective studies or a randomized controlled trial. Trial registration The RICH Trial was registered at clinicaltrials.gov: NCT02669589. Registered 01 February 2016.

BACKGROUND: Sepsis remains the leading cause of mortality in critically ill patients, and mortality is increased when acute kidney injury (AKI) occurs. The Kidney Disease: Improving Global Outcomes (KDIGO) guideline recommends the implementation of supportive measures in patients at high risk for AKI. However, it remains unclear to what extent these nephroprotective measures are implemented in daily clinical practice in critically ill patients, especially those with high-risk exposures such as sepsis. METHODS: We analyzed the Medical Information Mart for Intensive Care IV (MIMIC-IV) database to identify septic patients with and without AKI. The primary outcome of interest was the adherence to the KDIGO bundle consisting of avoidance of nephrotoxic agents, implementation of a functional hemodynamic monitoring, optimization of perfusion pressure and volume status, close monitoring of renal function, avoidance of hyperglycemia, and avoidance of radiocontrast agents. Secondary outcomes included the development of AKI, progression of AKI, the use of renal replacement therapy (RRT), mortality, and a composite end point consisting of progression of AKI and mortality within 7 days. RESULTS: Our analysis included 34,679 patients with sepsis with 1.6% receiving the complete bundle (10% received 5, 42.3% 4, 35.4% 3, and 9.8% 2 bundle components). In 56.4%, nephrotoxic agents were avoided, and hemodynamic optimization was reached in 86.5%. Secondary end points were improved in patients with bundle adherence. Avoidance of nephrotoxic drugs and optimization of hemodynamics were significantly associated with lower rates of AKI and improved patient outcomes, including 30-day mortality. CONCLUSIONS: Implementation of the KDIGO bundle is poor in patients with sepsis but may be associated with improved outcomes.