Acute Kidney Injury in Mechanically Ventilated Patients: The Risk Factor Profile Depends on the Timing of Aki Onset

Acute kidney disease beyond day 7 after major surgery: a secondary analysis of the EPIS-AKI trial

PURPOSE

Acute kidney disease (AKD) is a significant health care burden worldwide. However, little is known about this complication after major surgery.

METHODS

We conducted an international prospective, observational, multi-center study among patients undergoing major surgery. The primary study endpoint was the incidence of AKD (defined as new onset of estimated glomerular filtration rate (eCFR) < 60 ml/min/1.73 m2 present on day 7 or later) among survivors. Secondary endpoints included the relationship between early postoperative acute kidney injury (AKI) (within 72 h after major surgery) and subsequent AKD, the identification of risk factors for AKD, and the rate of chronic kidney disease (CKD) progression in patients with pre-existing CKD.

RESULTS

We studied 9510 patients without pre-existing CKD. Of these, 940 (9.9%) developed AKD after 7 days of whom 34.1% experiencing an episode of early postoperative-AKI. Rates of AKD after 7 days significantly increased with the severity (19.1% Kidney Disease Improving Global Outcomes [KDIGO] 1, 24.5% KDIGO2, 34.3% KDIGO3; P < 0.001) and duration (15.5% transient vs 38.3% persistent AKI; P < 0.001) of early postoperative-AKI. Independent risk factors for AKD included early postoperative-AKI, exposure to perioperative nephrotoxic agents, and postoperative pneumonia. Early postoperative-AKI carried an independent odds ratio for AKD of 2.64 (95% confidence interval [CI] 2.21-3.15). Of 663 patients with pre-existing CKD, 42 (6.3%) had worsening CKD at day 90. In patients with CKD and an episode of early AKI, CKD progression occurred in 11.6%.

CONCLUSION

One in ten major surgery patients developed AKD beyond 7 days after surgery, in most cases without an episode of early postoperative-AKI. However, early postoperative-AKI severity and duration were associated with an increased rate of AKD and early postoperative-AKI was strongly associated with AKD independent of all other potential risk factors.

The effects of timing onset and progression of AKI on the clinical outcomes in AKI patients with sepsis: a prospective multicenter cohort study

BACKGROUND

Limited studies are available concerning on the earlier identification of AKI with sepsis. The aim of the study was to identify the risk factors of AKI early which depended on the timing onset and progression of AKI and investigate the effects of timing onset and progression of AKI on clinical outcomes.

METHODS

Patients who developed sepsis during their first 48-h admission to ICU were included. The primary outcome was major adverse kidney events (MAKE) consisted of all-cause mortality, RRT-dependence, or an inability to recover to 1.5 times of the baseline creatinine value up to 30 days. We determined MAKE and in-hospital mortality by multivariable logistic regression and explored the risk factors of early persistent-AKI. C statistics were used to evaluate model fit.

RESULTS

58.7% sepsis patients developed AKI. According to the timing onset and progression of AKI, Early transient-AKI, early persistent-AKI, late transient-AKI, late persistent-AKI were identified. Clinical outcomes were quite different among subgroups. Early persistent-AKI had 3.0-fold (OR 3.04, 95% CI 1.61 - 4.62) risk of MAKE and 2.6-fold (OR 2.60, 95%CI 1.72 - 3.76) risk of in-hospital mortality increased compared with the late transients-AKI. Older age, underweight, obese, faster heart rate, lower MAP, platelet, hematocrit, pH and energy intake during the first 24 h on ICU admission could well predict the early persistent-AKI in patients with sepsis.

CONCLUSION

Four AKI subphenotypes were identified based on the timing onset and progression of AKI. Early persistent-AKI showed higher risk of major adverse kidney events and in-hospital mortality.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trials Registry (www.chictr.org/cn) under registration number ChiCTR-ECH-13003934.

Predicting Risk Factors of Acute Kidney Injury in the First 7 Days after Admission: Analysis of a Group of Critically Ill Patients

Background

Acute kidney injury (AKI) is a common complication in critically ill patients. Some predictive models have been reported, but the conclusions are controversial. The aim of this study was the formation of nomograms to predict risk factors for AKI in critically ill patients within the first 7 days after admission to the intensive care unit (ICU).

Methods

Data were extracted from the Medical Information Mart for Intensive Care- (MIMIC-) III database. The random forest method was used to fill in the missing values, and least absolute shrinkage and selection operator (Lasso) regression analysis was performed to screen for possible risk factors.

Results

A total of 561 patients were enrolled. Complication with AKI is significantly associated with a longer length of stay (LOS). For all patients, the predictors contained in the prediction nomogram included hypertension, coronary artery disease (CAD), cardiopulmonary bypass (CPB), coronary artery bypass grafting (CABG), Simplified Acute Physiology Score II (SAPS II), central venous pressure (CVP) measured for the first time after admission, and maximum and minimum mean artery pressure (MAP). The model showed good discrimination (C - index = 0.818, 95% CI: 0.779-0.857). In the subgroup of patients with well-controlled blood glucose levels, the significant predictors included hypertension, CABG, CPB, SAPS II, and maximum and minimum MAP. Good discrimination was also present before (C - index = 0.785, 95% CI: 0.736-0.834) and after adjustment (adjusted C - index = 0.770).

Conclusion

Hypertension, CAD, CPB, CABG, SAPS II, CVP measured for the first time after admission, and maximum and minimum MAP were independent risk factors for AKI in critically ill patients.

Platelet Function in Acute Kidney Injury: A Systematic Review and a Cohort Study

Acute kidney injury (AKI) patients have increased bleeding risk, which could be partially due to acquired platelet dysfunction. We conducted a systematic review and a cohort study to investigate platelet function and count in AKI and their association with AKI-related bleeding and mortality. Through a systematic literature search in PubMed and Embase, we identified 9 studies reporting platelet function and 56 studies reporting platelet count or platelet indices in AKI patients. Overall, platelet aggregation was reduced in AKI patients in nonintensive care unit (ICU) settings but not in ICU settings, except that reduced aggregation was associated with renal replacement therapy. Thrombocytopenia in AKI was frequent and often predictive of mortality. In our cohort study, we prospectively included 54 adult ICU patients who developed AKI within 24 hours of ICU admission and 33 non-AKI ICU controls. Platelet function was measured with light transmission aggregometry and flow cytometry. AKI patients bled more frequently than non-AKI patients (p = 0.04), and bleeding was associated with increased 30-day mortality in AKI (p = 0.02). However, platelet function was not different between AKI and non-AKI patients (aggregation: all p > 0.52; flow cytometry: all p > 0.07) and platelet function was not associated with bleeding in AKI. In conclusion, a reduced platelet count is frequent in AKI, but the literature on platelet function in AKI is sparse. In a cohort study, we demonstrated that patients with AKI within 24 hours of ICU admission exhibited increased bleeding tendency but this was not associated with reduced platelet function.

Clinical characteristics of new-onset acute kidney injury in patients with established acute respiratory distress syndrome: A prospective single-center post hoc observational study

Background

We assessed the incidence and clinical characteristics of acute kidney injury (AKI) in acute respiratory distress syndrome (ARDS) patients and its effect on clinical outcomes.

Methods

We conducted a single-center prospective longitudinal study. Patients who met the Berlin definition of ARDS in the medical ICU in China-Japan Friendship Hospital from March 1, 2016, to September 30, 2020, were included. AKI was defined according to the KDIGO clinical practice guidelines. Early and late AKI were defined as AKI occurring within 48 h after ARDS was diagnosed or after 48 h, respectively.

Results

Of the 311 ARDS patients, 161 (51.8%) developed AKI after ICU admission. Independent risk factors for AKI in ARDS patients were age (OR 1.027, 95% CI 1.009–1.045), a history of diabetes mellitus (OR 2.110, 95%CI 1.100–4.046) and chronic kidney disease (CKD) (OR 9.328, 95%CI 2.393–36.363), APACHE II score (OR 1.049, 95%CI 1.008–1.092), average lactate level in the first 3 days (OR 1.965, 95%CI 1.287–3.020) and using ECMO support (OR 2.359, 95%CI 1.154–4.824). Early AKI was found in 91 (56.5%) patients and late AKI was found in 70 (43.5%). Early AKI was related to the patient’s underlying disease and the severity of hospital admission, while late AKI was related to the application of nephrotoxic drugs. The mortality rate of ARDS combined with AKI was 57.1%, which was independently associated with shock (OR 54.943, 95%CI 9.751–309.573).

Conclusion

A significant number of patients with ARDS developed AKI, and the mortality rate for ARDS patients was significantly higher when combined with AKI. Therapeutic drug monitoring should be routinely used to avoid drug toxicity during treatment.

Development and validation of the MMCD score to predict kidney replacement therapy in COVID-19 patients

BACKGROUND

Acute kidney injury (AKI) is frequently associated with COVID-19, and the need for kidney replacement therapy (KRT) is considered an indicator of disease severity. This study aimed to develop a prognostic score for predicting the need for KRT in hospitalised COVID-19 patients, and to assess the incidence of AKI and KRT requirement.

METHODS

This study is part of a multicentre cohort, the Brazilian COVID-19 Registry. A total of 5212 adult COVID-19 patients were included between March/2020 and September/2020. Variable selection was performed using generalised additive models (GAM), and least absolute shrinkage and selection operator (LASSO) regression was used for score derivation. Accuracy was assessed using the area under the receiver operating characteristic curve (AUC-ROC).

RESULTS

The median age of the model-derivation cohort was 59 (IQR 47-70) years, 54.5% were men, 34.3% required ICU admission, 20.9% evolved with AKI, 9.3% required KRT, and 15.1% died during hospitalisation. The temporal validation cohort had similar age, sex, ICU admission, AKI, required KRT distribution and in-hospital mortality. The geographic validation cohort had similar age and sex; however, this cohort had higher rates of ICU admission, AKI, need for KRT and in-hospital mortality. Four predictors of the need for KRT were identified using GAM: need for mechanical ventilation, male sex, higher creatinine at hospital presentation and diabetes. The MMCD score had excellent discrimination in derivation (AUROC 0.929, 95% CI 0.918-0.939) and validation (temporal AUROC 0.927, 95% CI 0.911-0.941; geographic AUROC 0.819, 95% CI 0.792-0.845) cohorts and good overall performance (Brier score: 0.057, 0.056 and 0.122, respectively). The score is implemented in a freely available online risk calculator ( https://www.mmcdscore.com/ ).

CONCLUSIONS

The use of the MMCD score to predict the need for KRT may assist healthcare workers in identifying hospitalised COVID-19 patients who may require more intensive monitoring, and can be useful for resource allocation.

Missed diagnosis of acute kidney injury in older patients with invasive mechanical ventilation: a multicenter retrospective study

OBJECTIVES

Patients who undergo mechanical ventilation (MV) are at higher risk of suffering from acute kidney injury (AKI). However, whether AKI is diagnosed in all patients and the association between AKI and mortality are unclear.

METHODS

This was a retrospective, observational, multicenter cohort study conducted from January 2008 to December 2020 that included 3271 consecutive older patients (≥ 75 years) who received invasive MV from four medical centers in Chinese PLA General Hospital. AKI was diagnosed according to the serum creatinine (Scr)-based Kidney Disease: Improving Global Outcomes guidelines by an absolute increase in Scr of ≥ 26.5 µmol/L within the first 48 h of MV. The outcomes of patients with and without AKI and whether AKI was recognized were compared.

RESULTS

A total of 1292 patients were included in the final evaluation. Three hundred seventy-six patients (29.1%) fulfilled the diagnostic criteria. Among the 376 AKI patients, the recognition rate and nonrecognition rate were 62.8% (236/376) and 37.2% (140/376), respectively. The overall 90-day mortality rate was 45.2% (584/1,292), which was dramatically increased in unrecognized AKI patients and recognized AKI compared to non-AKI patients (70.7% vs. 54.7% vs. 38.9%, respectively, P < 0.001). The survival of patients with recognized AKI was better than that of patients with unrecognized AKI. Multivariate logistic regression analysis revealed that recognized AKI was significantly associated with mean arterial pressure, positive end-expiratory pressure, uric acid, baseline Scr, and peak Scr. AKI was identified as an independent predictor of all-cause 90-day mortality (recognized AKI vs. non-AKI: HR = 1.722; 95% CI = 1.399-2.119; P < 0.001 and unrecognized AKI vs. non-AKI: HR = 2.632; 95% CI = 2.081-3.329; P < 0.001).

CONCLUSIONS

AKI is a common complication in older patients undergoing MV, with substantial underdiagnosis and undertreatment. Interventions for improving the diagnosis of AKI are urgently needed.

Internal and external validation of machine learning-assisted prediction models for mechanical ventilation-associated severe acute kidney injury

BACKGROUND

Currently, very few preventive or therapeutic strategies are used for mechanical ventilation (MV)-associated severe acute kidney injury (AKI).

OBJECTIVES

We developed clinical prediction models to detect the onset of severe AKI in the first week of intensive care unit (ICU) stay during the initiation of MV.

METHODS

A large ICU database Medical Information Mart for Intensive Care IV (MIMIC-IV) was analysed retrospectively. Data were collected from the clinical information recorded at the time of ICU admission and during the initial 12 h of MV. Using univariate and multivariate analyses, the predictors were selected successively. For model development, two machine learning algorithms were compared. The primary goal was to predict the development of AKI stage 2 or 3 (AKI-23) and AKI stage 3 (AKI-3) in the first week of patients' ICU stay after initial 12 h of MV. The developed models were externally validated using another multicentre ICU database (eICU Collaborative Research Database, eICU) and evaluated in various patient subpopulations.

RESULTS

Models were developed using data from the development cohort (MIMIC-IV: 2008-2016; n = 3986); the random forest algorithm outperformed the logistic regression algorithm. In the internal (MIMIC-IV: 2017-2019; n = 1210) and external (eICU; n = 1494) validation cohorts, the incidences of AKI-23 were 154 (12.7%) and 119 (8.0%), respectively, with areas under the receiver operator characteristic curve of 0.78 (95% confidence interval [CI]: 0.74-0.82) and 0.80 (95% CI: 0.76-0.84); the incidences of AKI-3 were 81 (6.7%) and 67 (4.5%), with areas under the receiver operator characteristic curve of 0.81 (95% CI: 0.76-0.87) and 0.80 (95% CI: 0.73-0.86), respectively.

CONCLUSIONS

Models driven by machine learning and based on routine clinical data may facilitate the early prediction of MV-associated severe AKI. The validated models can be found at: https://apoet.shinyapps.io/mv_aki_2021_v2/.

Association Between the Severity of Early Acute Kidney Injury and Subsequent in-Hospital Complications and 90-Day Mortality in Geriatric Patients Receiving Invasive Mechanical Ventilation

Purpose

Acute kidney injury (AKI) in elderly patients is associated with higher hospital mortality. However, the relationship between AKI and peri-intubation complications is unclear.

Methods

This retrospective, observational, multicenter cohort study enrolled 3271 consecutive elderly patients (≥75 years) who received invasive mechanical ventilation (MV) in four medical centers of Chinese PLA General Hospital from 2008 to 2020. AKI was diagnosed according to the 2012 KDIGO criteria by an absolute increase in serum creatinine of ≥26.5 µmol/L within the first 48 hours of MV. We recorded subsequent in-hospital complications, including incident gastrointestinal bleeding, new-onset electrolyte imbalances, severe hypoxemia, hypoalbuminemia, cardiovascular instability and all-cause 90-day mortality.

Results

A total of 1292 patients were included in the final evaluation, with 29.1% presenting AKI (stage 1: 31.4%, stage 2: 35.1%, stage 3: 33.5%). Multiple regression analyses show that more advanced AKI increased the risk of MAP <65 mmHg (stage 1: OR=1.833, P=0.002; stage 2: OR= 4.653, P<0.001; stage 3: OR=4.834, P<0.001) and SBP <90 mmHg (stage 1: OR=1.644, P=0.014; stage 2: OR=3.701, P<0.001; stage 3: OR=5.750, P<0.001), a new need for or requiring an increased dose of vasopressors (stage 1: OR=1.623, P=0.014; stage 2: OR=3.250, P<0.001; stage 3: OR=12.132, P<0.001), gastrointestinal bleeding (stage 1: OR=1.102, P=0.669; stage 2: OR=1.471, P=0.060; stage 3: OR=2.377, P<0.001), severe hypoxia (stage 1: OR=1.213, P=0.399; stage 2: OR=1.449, P=0.077; stage 3: OR=2.214, P<0.001) and all-cause 90-day mortality (stage 1: OR =0.935; P=0.741; stage 2: OR=1.888; P=0.001; stage 3: OR=12.584; P<0.001).

Conclusion

Our study suggests that the presence of AKI within the first 48 hours of MV in geriatric patients is associated with a higher risk for postintubation complications and 90-day mortality. Moreover, the risk of complications was greater for patients with more severe AKI.

Predictors for mortality and recovery in patients with acute renal injury receiving continuous renal replacement therapy

OBJECTIVE

Despite continuous renal replacement therapy (CRRT) has been widely used in critically ill patients with acute kidney injury (AKI), the prognosis and recovery of renal function in these patients are still poor. Therefore, we aimed to identify the prognostic factors for the mortality and recovery of renal function in patients with AKI receiving CRRT.

METHODS

A total of 125 patients with AKI, treated with CRRT in the emergency intensive care unit (EICU) in an academic teaching hospital from January 2014 to December 2018 were enrolled in this retrospective study. The clinical data of these patients were collected. Univariate regression analysis and multivariate regression analysis were conducted to identify the predictors for the mortality and recovery of renal function.

RESULTS

The median age was 68.0 (56.5-79.0) years old, and from which 69.6% were males. Sixty-four patients (51.2%) survived and 50 patients (40%) recovered their renal function. Multivariate regression analysis showed that the independent risk factors for mortality were male (odds ratio [OR]:3.771, 95% confidence interval [CI]:1.063-13.372, p = 0.04), Acute Physiology and Chronic Health Evaluation (APACHE) II score (OR: 1.187, 95% CI: 1.050-1.341, p = 0.006), mechanical ventilation (OR: 6.266, 95% CI: 1.771-22.167, p = 0.004) and vasopressor use (OR: 5.224, 95% CI: 1.546-17.657, p = 0.008). Moreover, the independent predictors for not recovering of renal function were male (OR: 3.440, 95% CI: 1.271-9.311, p = 0.015), pre-existing comorbidity of hypertension (OR: 4.207, 95% CI: 1.609-11.000, p = 0.003) and vasopressor use (OR: 5.280, 95% CI: 2.018-13.811, p = 0.001).

CONCLUSIONS

Male, high APACHE II score, mechanical ventilation and vasopressor use were closely associated with the increased mortality, while male, pre-existing history of hypertension, and vasopressor use were the independent predictors for non-recovery of renal function.

COVID-19-induced acute kidney injury in critically ill patients: epidemiology, risk factors, and outcome

Background

The kidney represents a potential target for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Clinical data about acute kidney injury (AKI) during SARS-CoV-2 infection are lacking. We aimed to investigate the proportion, risk factors, and prognosis of AKI in critical patients affected with SARS-CoV-2.

Methods

A case/control study was conducted in two intensive care units of a tertiary teaching hospital.

Results

Among 109 patients, 75 were male (69%) with median age at 64 years and 48 (44%) developed AKI within 4 days (interquartile range [IQR], 1–9). Of them, 11 (23%), 9 (19%), and 28 (58%) were classified as stage 1, 2, and 3, respectively. AKI patients were older and presented more sepsis, acute respiratory distress syndrome, and rhabdomyolysis; higher initial urea and creatinine; more marked inflammatory syndrome and hematological disorders; and required more mechanical ventilation and vasopressors. An elevated D-dimers level (odds ratio [OR], 12.83; 95% confidence interval [CI], 1.9–85) was an independent factor of AKI. Sepsis was near to significance (OR, 5.22; 95% CI, 0.94–28; P=0.058). AKI was independently related to mortality (OR, 6.8; 95% CI, 1.49–105) and significantly reduced the survival (14.7 days; IQR, 12-17 vs. 19.9 days; IQR, 17-22.7; P=0.011) in AKI and no AKI group respectively. Hypoxemia with the ratio of the arterial partial pressure of oxygen and the inspiratory concentration of oxygen <70, and vasopressors were identified as mortality factors.

Conclusions

AKI occurred in almost half the studied patients and significantly worsened their prognosis. A high D-dimers level and sepsis contributed significantly to its development.

Assessing the association between mean systemic filling pressure and acute kidney injury after cardiac surgery

With a great interest we read the recent article by Neuman et al¹ assessing the association between mean systemic filling pressure analogue (P_msa ) and acute kidney injury (AKI) following cardiac surgery. They showed that Pmsa as a surrogate for renal venous pressure was more closely associated with AKI than central venous pressure. As AKI has been significantly associated with morbidity and mortality in after cardiac surgery,² their findings have potential implication. Other than the limitations described by authors in discussion, however, we noted several issues in their article on which we invited the authors to comment.

COVID-19 and the kidney: A retrospective analysis of 37 critically ill patients using machine learning

INTRODUCTION

There is evidence that SARS-CoV2 has a particular affinity for kidney tissue and is often associated with kidney failure.

METHODS

We assessed whether proteinuria can be predictive of kidney failure, the development of chronic kidney disease, and mortality in 37 critically ill COVID-19 patients. We used machine learning (ML) methods as decision trees and cut-off points created by the OneR package to add new aspects, even in smaller cohorts.

RESULTS

Among a total of 37 patients, 24 suffered higher-grade renal failure, 20 of whom required kidney replacement therapy. More than 40% of patients remained on hemodialysis after intensive care unit discharge or died (27%). Due to frequent anuria proteinuria measured in two-thirds of the patients, it was not predictive for the investigated endpoints; albuminuria was higher in patients with AKI 3, but the difference was not significant. ML found cut-off points of >31.4 kg/m2 for BMI and >69 years for age, constructed decision trees with great accuracy, and identified highly predictive variables for outcome and remaining chronic kidney disease.

CONCLUSIONS

Different ML methods and their clinical application, especially decision trees, can provide valuable support for clinical decisions. Presence of proteinuria was not predictive of CKD or AKI and should be confirmed in a larger cohort.

Fluid management in patients with acute kidney injury - A post-hoc analysis of the FINNAKI study

PURPOSE

Whether positive fluid balance among patients with acute kidney injury (AKI) stems from decreased urine output, overzealous fluid administration, or both is poorly characterized.

MATERIALS AND METHODS

This was a post hoc analysis of the prospective multicenter observational Finnish Acute Kidney Injury study including 824 AKI and 1162 non-AKI critically ill patients.

RESULTS

We matched 616 AKI (diagnosed during the three first intensive care unit (ICU) days) and non-AKI patients using propensity score. During the three first ICU days, AKI patients received median [IQR] of 11.4 L [8.0-15.2]L fluids and non-AKI patients 10.2 L [7.5-13.7]L, p < 0.001 while the fluid output among AKI patients was 4.7 L [3.0-7.2]L and among non-AKI patients 5.8 L [4.1-8.0]L, p < 0.001. In AKI patients, the median [IQR] cumulative fluid balance was 2.5 L [-0.2-6.0]L compared to 0.9 L [-1.4-3.6]L among non-AKI patients, p < 0.001. Among the 824 AKI patients, smaller volumes of fluid input with a multivariable OR of 0.90 (0.88-0.93) and better fluid output (multivariable OR 1.12 (1.07-1.18)) associated with enhanced change of resolution of AKI.

CONCLUSIONS

AKI patients received more fluids albeit having lower fluid output compared to matched critically ill non-AKI patients. Smaller volumes of fluid input and higher fluid output were associated with better AKI recovery.

Risk Factors, Clinical Characteristics, and Prognosis of Acute Kidney Injury in Hospitalized COVID-19 Patients: A Retrospective Cohort Study

Background: Acute kidney injury (AKI) is a serious complication of COVID-19. Methods: Records of hospitalized adult patients with confirmed SARS-CoV-2 infection from 1 March to 31 May 2020 were retrospectively reviewed. Results: Of 283 patients, AKI occurred in 40.6%. From multivariate analyses, the risk factors of AKI in COVID-19 can be divided into: (1) demographics/co-morbidities (male, increasing age, diabetes, chronic kidney disease); (2) other organ involvements (transaminitis, elevated troponin I, ST segment/T wave change on electrocardiography); (3) elevated biomarkers (ferritin, lactate dehydrogenase); (4) possible bacterial co-infection (leukocytosis, elevated procalcitonin); (5) need for advanced oxygen delivery (non-invasive positive pressure ventilation, mechanical ventilation); and (6) other critical features (ICU admission, need for vasopressors, acute respiratory distress syndrome). Most AKIs were due to pre-renal (70.4%) and intrinsic (34.8%) causes. Renal replacement therapy was more common in intrinsic AKI. Both pre-renal (HR 3.2; 95% CI 1.7–5.9) and intrinsic AKI (HR 7.7; 95% CI 3.6–16.3) were associated with higher mortality. Male, stage 3 AKI, higher baseline and peak serum creatinine and blood urea nitrogen were prevalent in intrinsic AKI. Urine analysis and the fractional excretion of sodium and urea were not helpful in distinguishing intrinsic AKI from other causes. Conclusions: AKI is very common in COVID-19 and is associated with higher mortality. Characterization of AKI is warranted due to its diverse nature and clinical outcome.

The incidence, risk factors and prognosis of acute kidney injury in severe and critically ill patients with COVID-19 in mainland China: a retrospective study

BACKGROUND

The clinical correlates, prognosis and determinants of acute kidney injury (AKI) in patients with coronavirus disease 2019 (Covid-19) remain largely unclear.

METHODS

We retrospectively reviewed medical records of all adult patients with laboratory-confirmed Covid-19 who were admitted to the intensive care unit (ICU) between January 23rd 2020 and April 6th 2020 at Wuhan JinYinTan Hospital and The First Affiliated Hospital of Guangzhou Medical University.

RESULTS

Among 210 patients, 131 were males (62.4%). The median Age was 64 years (IQR: 56-71). Of 92 (43.8%) patients who developed AKI during hospitalization, 13 (14.1%), 15 (16.3%) and 64 (69.6%) were classified as being at stage 1, 2 and 3, respectively. 54 patients (58.7%) received continuous renal replacement therapy. Age, sepsis, nephrotoxic drug, invasive mechanical ventilation and elevated baseline serum creatinine levels were associated with the occurrence of AKI. Renal recovery during hospitalization was identified among 16 patients with AKI (17.4%), who had a significantly shorter time from admission to AKI diagnosis, lower incidence of right heart failure and higher ratio of partial pressure of oxygen to the fraction of inspired oxygen. Of 210 patients, 93 deceased within 28 days of ICU admission. AKI stage 3, critical disease, greater Age and the lowest ratio of partial pressure of oxygen to the fraction of inspired oxygen being < 150 mmHg were independently associated with death.

CONCLUSIONS

Among patients with Covid-19, the incidence of AKI was high. Our findings of the risk factors of the development of AKI and factors associated with renal function recovery may inform clinical management of patients with critical illness of Covid-19.

Incidence of acute kidney injury and its association with mortality in patients with COVID-19: a meta-analysis

Acute kidney injury (AKI) is a complication of COVID-19. However, the incidence of AKI in COVID-19 varies among studies. Thus, we aimed to evaluate the pooled incidence of AKI and its association with mortality in patients with COVID-19 using a meta-analysis. We search Ovid MEDLINE, EMBASE, and the Cochrane Library for eligible publications reporting the clinical characteristics of patients with COVID-19 without language restriction. Incidence of AKI and mortality were reported. Meta-regression was used to describe the association between outcomes. From 26 studies (n=5497), the pooled incidence of AKI in patients with COVID-19 was 8.4% (95% CI 6.0% to 11.7%) with a pooled incidence of renal replacement therapy of 3.6% (95% CI 1.8% to 7.1%). The incidence of AKI was higher in critically ill patients (19.9%) compared with hospitalized patients (7.3%). The pooled estimated odds ratio for mortality from AKI was 13.33 (95% CI 4.05 to 43.91). No potential publication bias was detected. By using meta-regression analyses, the incidence of AKI was positively associated with mortality after adjusted for age and sex (Q=26.18; p=0.02). Moreover, age (p<0.01), diabetes (p=0.02), hypertension (p<0.01) and baseline serum creatinine levels (p=0.04) were positively associated with AKI incidence in adjusted models. In conclusion, AKI is present in 8.3% of overall patients with COVID-19 and in 19.9% of critically ill patients with COVID-19. Presence of AKI is associated with 13-fold increased risk of mortality. Age, diabetes, hypertension, and baseline serum creatinine levels are associated with increased AKI incidence.

Acute Kidney Injury in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To describe the incidence of and risk factors for acute kidney injury (AKI) in children with acute respiratory distress syndrome (ARDS) and study the effect of AKI on patient outcomes.

DESIGN

A single-center retrospective study.

SETTING

A tertiary care children's hospital.

PATIENTS

All patients less than 18 years of age who received invasive mechanical ventilation (MV) and developed ARDS between July 2010 and July 2013 were included. Acute kidney injury was defined using p-RIFLE (risk, injury, failure, loss, and end-stage renal disease) criteria.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred fifteen children met the criteria and were included in the study. Seventy-four children (74/115, 64%) developed AKI. The severity of AKI was risk in 34 (46%) of 74, injury in 19 (26%) of 74, and failure in 21 (28%) of 74. The presence of AKI was associated with lower Pao ₂ to Fio ₂ (P/F) ratio (P = .007), need for inotropes (P = .003), need for diuretics (P = .004), higher oxygenation index (P = .03), higher positive end-expiratory pressure (PEEP; P = .01), higher mean airway pressure (P = .008), and higher Fio ₂ requirement (P = .03). Only PEEP and P/F ratios were significantly associated with AKI in the unadjusted logistic regression model. Patients with AKI had a significantly longer duration of hospital stay, although there was no significant difference in the intensive care unit stay, duration of MV, and mortality. Recovery of AKI occurred in 68% of the patients. A multivariable model including PEEP, P/F ratio, weight, need for inotropes, and need for diuretics had a better receiver operating characteristic (ROC) curve with an AUC of 0.75 compared to the ROC curves for PEEP only and P/F ratio only for the prediction of AKI.

CONCLUSIONS

Patients with ARDS have high rates of AKI, and its presence is associated with increased morbidity and mortality.

Lung-kidney interactions in critically ill patients: consensus report of the Acute Disease Quality Initiative (ADQI) 21 Workgroup

BACKGROUND

Multi-organ dysfunction in critical illness is common and frequently involves the lungs and kidneys, often requiring organ support such as invasive mechanical ventilation (IMV), renal replacement therapy (RRT) and/or extracorporeal membrane oxygenation (ECMO).

METHODS

A consensus conference on the spectrum of lung-kidney interactions in critical illness was held under the auspices of the Acute Disease Quality Initiative (ADQI) in Innsbruck, Austria, in June 2018. Through review and critical appraisal of the available evidence, the current state of research, and both clinical and research recommendations were described on the following topics: epidemiology, pathophysiology and strategies to mitigate pulmonary dysfunction among patients with acute kidney injury and/or kidney dysfunction among patients with acute respiratory failure/acute respiratory distress syndrome. Furthermore, emphasis was put on patients receiving organ support (RRT, IMV and/or ECMO) and its impact on lung and kidney function.

CONCLUSION

The ADQI 21 conference found significant knowledge gaps about organ crosstalk between lung and kidney and its relevance for critically ill patients. Lung protective ventilation, conservative fluid management and early recognition and treatment of pulmonary infections were the only clinical recommendations with higher quality of evidence. Recommendations for research were formulated, targeting lung-kidney interactions to improve care processes and outcomes in critical illness.

Respiratory parameters and acute kidney injury in acute respiratory distress syndrome: a causal inference study

Background

Assess the respiratory-related parameters associated with subsequent severe acute kidney injury in mechanically ventilated patients with acute respiratory distress syndrome (ARDS).

Methods

Retrospective cohort, analyzing a large public database-Multiparameter Intelligent Monitoring in Intensive Care-III. Adult patients with at least 48 h of mechanical ventilation (MV), under volume controlled ventilation and an oxygenation index less than 300 mmHg were included.

Results

A total of 1,142 patients had complete data and were included in the final analyses. According to a causal directed acyclic graph (DAG) that included respiratory system compliance (C_rs), tidal volume (Vt), driving pressure (ΔP), plateau pressure (P_Plat), PEEP, PaO₂ and PaCO₂ as possible exposures related to severe AKI, only C_rs and PEEP levels had significant causal association with severe acute kidney injury (AKI) (OR 0.90, 95% CI: 0.84-0.94 for each 5-mL/cmH₂O reduction in C_rs; OR, 1.05 95% CI: 1.03-1.10 for each 1-cmH₂O increase of PEEP). Using mediation analysis, we examined whether any mechanical ventilation, blood gas or hemodynamic parameters could explain the effects of C_sr on AKI. Only PEEP mediated the significant but small effect (less than 5%) of C_sr on severe AKI. The effects of PEEP, in turn, were not mediated by any other evaluated parameter. Several sensitivity analyses with (I) need of renal replacement therapy (RRT) as an alternative outcome and (II) only patients with Vt <8 mL/kg, confirmed our main findings. In trying to validate our DAG assumptions, we confirmed that only ΔP was associated with mortality but not with severe AKI.

Conclusions

C_rs and PEEP are the only respiratory-related variables with a direct causal association in severe AKI. No mechanical ventilator or blood gas parameter mediated the effects of C_rs. Approaches reducing Vt and/or ΔP in ARDS can have limited effect on renal protection.

Effect of Dexmedetomidine on Lactate Clearance in Patients With Septic Shock: A Subanalysis of a Multicenter Randomized Controlled Trial

Lactate clearance is useful to guide initial resuscitation of patients with septic shock. We conducted this study to evaluate whether dexmedetomidine increases lactate clearance in patients with septic shock. This was a randomized controlled trial that involved a post hoc subgroup analysis. Adult patients with septic shock under ventilation were randomized to receive sedation strategy with or without dexmedetomidine (60 in the dexmedetomidine and 51 in the nondexmedetomidine groups). The primary outcome was the lactate clearance at 6 h, defined as the percent decrease in lactate from randomization to 6 h after. The median Acute Physiology and Chronic Health Evaluation II score was 25 (interquartile range 19-31). The median serum lactate value at randomization was lower in the dexmedetomidine group than in the nondexmedetomidine group (4.0 mmol/L vs. 4.8 mmol/L; P = 0.053). The lactate clearance at 6 h was higher in the dexmedetomidine group, although this was not statistically significant (23.3 ± 29.8 vs. 11.1 ± 54.4, mean difference 12.2, 95% confidence interval (CI), -4.4 to 28.8). After adjusting for the lactate level at randomization, lactate clearance at 6 h was significantly higher in the dexmedetomidine group (adjusted mean difference 18.5, 95% CI, 2.2-34.9). There was no statistically significant difference in the 28-day mortality between the dexmedetomidine and the nondexmedetomidine groups (13 [22%] vs. 18 [35%] patients, P = 0.11). In conclusion, among mechanically ventilated patients with septic shock, sedation with dexmedetomidine resulted in increased lactate clearance compared with sedation without dexmedetomidine.

Clinical predictors of renal non-recovery in acute respiratory distress syndrome

Background

Acute kidney injury (AKI) is the most common extra-pulmonary organ failure in acute respiratory distress syndrome (ARDS). Renal recovery after AKI is determined by several factors. The objective of this study was to determine the predictors of renal non-recovery in ARDS patients.

Methods

A single center retrospective cohort study of patients with AKI after onset of ARDS. Patients with preexisting chronic kidney disease or intensive care unit stay < 24 h were excluded. AKI staging was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) 2012 guidelines. Renal non-recovery was defined as death, dialysis dependence, serum creatinine ≥1.5 times the baseline, or urine output < 0.5 mL/kg/h more than 6 h.

Results

Of the 244 patients that met study criteria, 60 (24.6%) had stage I AKI, 66 (27%) had stage II AKI, and 118 (48.4%) had stage III AKI. Of those, 148 (60.7%) patients had renal non-recovery. On multivariable analysis, factors associated with renal non-recovery were a higher stage of AKI (odds ratio [OR] stage II 5.71, 95% confidence interval [CI] 2.17–14.98; OR stage III 45.85, 95% CI 16.27–129.2), delay in the onset of AKI (OR 1.12, 95% CI 1.03–1.21), history of malignancy (OR 4.02, 95% CI 1.59–10.15), septic shock (OR 3.2, 95% CI 1.52–6.76), and a higher tidal volume on day 1–3 of ARDS (OR 1.41, 95% CI 1.05–1.90). Subgroup analysis of survival at day 28 of ARDS also found that higher severity of AKI (OR stage II 8.17, 95% CI 0.84–79.91; OR stage III 111.67, 95% CI 12.69–982.91), delayed onset of AKI (OR 1.12, 95% CI 1.02–1.23), and active malignancy (OR 6.55, 95% CI 1.34–32.04) were significant predictors of renal non-recovery.

Conclusions

A higher stage of AKI, delayed onset of AKI, a history of malignancy, septic shock, and a higher tidal volume on day 1–3 of ARDS predicted renal non-recovery in ARDS patients. Among survivors, a higher stage of AKI, delayed onset of AKI, and a history of malignancy were associated with renal non-recovery.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1439-2) contains supplementary material, which is available to authorized users.

Factors associated with acute kidney injury in acute respiratory distress syndrome

Background

Acute kidney injury (AKI) is the most frequent extra-pulmonary organ failure in acute respiratory distress syndrome (ARDS). The objective of this study was to assess the factors associated with the development and severity of AKI in patients with ARDS.

Methods

This is a retrospective cohort study of ARDS patients without acute or chronic kidney disease prior to the onset of ARDS over a 7-year period (2010–2017). AKI and severity of AKI were defined according to the Kidney Disease Improving Global Outcomes 2012 guidelines.

Results

Of the 634 ARDS patients, 357 patients met study criteria. A total of 244 (68.3%) patients developed AKI after ARDS onset: 60 (24.6%) had stage I AKI, 66 (27%) had stage II AKI, and 118 (48.4%) had stage III AKI. The median time of AKI onset for stage I AKI was 2 days (interquartile range, 1.5–5.5) while stage II and III AKI was 4 days. On multivariable analysis, factors associated with development of AKI were age [subdistribution hazard ratio (SHR) 1.01, 95% confidence interval (CI) 1.00–1.02], SOFA score (SHR 1.16, 95%CI 1.12–1.21), a history of diabetes mellitus (DM) (SHR 1.42, 95%CI 1.07–1.89), and arterial pH on day 1 of ARDS (SHR per 0.1 units decrease was 1.18, 95%CI 1.05–1.32). In severity of AKI, stage I AKI was associated with age (SHR 1.03, 95%CI 1.01–1.05) and serum bicarbonate on day 1 of ARDS (SHR 1.07, 95%CI 1.02–1.13). Stage II AKI was associated with age (SHR 1.03, 95%CI 1.01–1.05), serum bicarbonate on day 1 (SHR 1.12, 95%CI 1.06–1.18), SOFA score (SHR 1.19, 95%CI 1.10–1.30), history of heart failure (SHR 3.71, 95%CI 1.63–8.46), and peak airway pressure (SHR 1.04, 95%CI 1.00–1.07). Stage III AKI was associated with a higher BMI (SHR 1.02, 95%CI 1.00–1.03), a history of DM (SHR 1.79, 95%CI 1.18–2.72), SOFA score (SHR 1.29, 95%CI 1.22–1.36), and arterial pH on day 1 (SHR per 0.1 units decrease was 1.25, 95%CI 1.05–1.49).

Conclusions

Age, a higher severity of illness, a history of diabetes, and acidosis were associated with development of AKI in ARDS patients. Severity of AKI was further associated with BMI, history of heart failure, and peak airway pressure.

Electronic supplementary material

The online version of this article (10.1186/s13613-019-0552-5) contains supplementary material, which is available to authorized users.

Associations between tricuspid annular plane systolic excursion to reflect right ventricular function and acute kidney injury in critically ill patients: a SICS-I sub-study

BACKGROUND

Acute kidney injury (AKI) occurs in up to 50% of all critically ill patients and hemodynamic abnormalities are assumed to contribute, but their nature and share is still unclear. We explored the associations between hemodynamic variables, including cardiac index and right ventricular function, and the occurrence of AKI in critically ill patients.

METHODS

In this prospective cohort study, we included all patients acutely admitted to an intensive care unit (ICU). Within 24 h after ICU admission clinical and hemodynamic variables were registered including ultrasonographic measurements of cardiac index and right ventricular function, assessed using tricuspid annular plane systolic excursion (TAPSE) and right ventricular systolic excursion (RV S'). Maximum AKI stage was assessed according to the KDIGO criteria during the first 72 h after admission. Multivariable logistic regression modeling was used including both known predictors and univariable significant predictors of AKI. Secondary outcomes were days alive outside ICU and 90-day mortality.

RESULTS

A total of 622 patients were included, of which 338 patients (54%) had at least AKI stage 1 within 72 h after ICU admission. In the final multivariate model higher age (OR 1.01, 95% CI 1.00-1.03, for each year), higher weight (OR 1.03 CI 1.02-1.04, for each kg), higher APACHE IV score (OR 1.02, CI 1.01-1.03, per point), lower mean arterial pressure (OR 1.02, CI 1.01-1.03, for each mmHg decrease) and lower TAPSE (OR 1.05, CI 1.02-1.09 per millimeter decrease) were all independent predictors for AKI in the final multivariate logistic regression model. Sepsis, cardiac index, RV S' and use of vasopressors were not significantly associated with AKI in our data. AKI patients had fewer days alive outside of ICU, and their mortality rate was significantly higher than those without AKI.

CONCLUSIONS

In our cohort of acutely admitted ICU patients, the incidence of AKI was 54%. Hemodynamic variables were significantly different between patients with and without AKI. A worse right ventricle function was associated with AKI in the final model, whereas cardiac index was not.

Identification of novel metabolomic biomarkers in an experimental model of septic acute kidney injury

The aim of this study is the identification of metabolomic biomarkers of sepsis and sepsis-induced acute kidney injury (AKI) in an experimental model. Pigs were anesthetized and monitored to measure mean arterial pressure (MAP), systemic blood flow (Q_T), mean pulmonary arterial pressure, renal artery blood flow (Q_RA), renal cortical blood flow (Q_RC), and urine output (UO). Sepsis was induced at t = 0 min by the administration of live Escherichia coli ( n = 6) or saline ( n = 8). At t = 300 min, animals were killed. Renal tissue, urine, and serum samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy. Principal component analyses were performed on the processed NMR spectra to highlight kidney injury biomarkers. Sepsis was associated with decreased Q_T and MAP and decreased Q_RA, Q_RC, and UO. Creatinine serum concentration and neutrophil gelatinase-associated lipocalin (NGAL) serum and urine concentrations increased. NMR-based metabolomics analysis found metabolic differences between control and septic animals: 1) in kidney tissue, increased lactate and nicotinuric acid and decreased valine, aspartate, glucose, and threonine; 2) in urine, increased isovaleroglycine, aminoadipic acid, N-acetylglutamine, N-acetylaspartate, and ascorbic acid and decreased myoinositol and phenylacetylglycine; and 3) in serum, increased lactate, alanine, pyruvate, and glutamine and decreased valine, glucose, and betaine concentrations. The concentration of several metabolites altered in renal tissue and urine samples from septic animals showed a significant correlation with markers of AKI (i.e., creatinine and NGAL serum concentrations). NMR-based metabolomics is a potentially useful tool for biomarker identification of sepsis-induced AKI.