In critically ill patients requiring CRRT, AKI is associated with increased respiratory failure and death versus ESRD

Interorgan communication networks in the kidney-lung axis

The homeostasis and health of an organism depend on the coordinated interaction of specialized organs, which is regulated by interorgan communication networks of circulating soluble molecules and neuronal connections. Many diseases that seemingly affect one primary organ are really multiorgan diseases, with substantial secondary remote organ complications that underlie a large part of their morbidity and mortality. Acute kidney injury (AKI) frequently occurs in critically ill patients with multiorgan failure and is associated with high mortality, particularly when it occurs together with respiratory failure. Inflammatory lung lesions in patients with kidney failure that could be distinguished from pulmonary oedema due to volume overload were first reported in the 1930s, but have been largely overlooked in clinical settings. A series of studies over the past two decades have elucidated acute and chronic kidney-lung and lung-kidney interorgan communication networks involving various circulating inflammatory cytokines and chemokines, metabolites, uraemic toxins, immune cells and neuro-immune pathways. Further investigations are warranted to understand these clinical entities of high morbidity and mortality, and to develop effective treatments.

Incidence and Outcomes of Patients Receiving Chronic Kidney Replacement Therapy Admitted to Scottish ICUs Between 2009 and 2019-A National Observational Cohort Study

OBJECTIVES

To determine the incidence and characteristics of ICU admissions in the Scottish population of patients treated with chronic kidney replacement therapy (KRT) over an 11-year period and determine factors associated with post-ICU admission mortality.

DESIGN

Retrospective observational cohort study.

SETTING

We analyzed admissions to Scottish intensive care environments between January 1, 2009, and December 31, 2019.

PATIENTS

All patients receiving chronic KRT-including maintenance dialysis and kidney transplant-in Scotland.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Descriptive statistics and factors associated with mortality using logistic regression and Cox proportional hazard models. From 10,657 unique individuals registered in the Scottish Renal Registry over the 11-year study period and alive as of January 1, 2009, 1,402 adult patients were identified as being admitted to a Scottish critical care setting. Between 2009 and 2019, admissions to ICU increased in a nonlinear manner driven by increases in admissions for renal causes and elective cardiac surgery. The ICU admission rate was higher among patients on chronic dialysis than in kidney transplant recipients (59.1 vs 19.9 per 1,000 person-years), but post-ICU mortality was similar (about 24% at 30 d and 40% at 1 year). Admissions for renal reasons were most common (20.9%) in patients undergoing chronic dialysis, whereas kidney transplant recipients were most frequently admitted for pneumonia (19.3%) or sepsis (12.8%). Adjusted Cox PH models showed that receiving invasive ventilation and vasoactive drugs was associated with an increased risk of death at 30 days post-ICU admission (HR, 1.75; 95% CI, 1.28-2.39 and 1.72; 95% CI, 1.28-2.31, respectively).

CONCLUSIONS

With a growing population of kidney transplant recipients and the improved survival of patients on chronic dialysis, the number of ICU admissions is rising in the chronic KRT population. Mortality post-ICU admission is high for these patients.

A nomogram for reduced cardiac function in postoperative acute type A aortic dissection patients with acute kidney injury undergoing continuous renal replacement therapy

Background

This study aimed to develop a nomogram to predict reduced cardiac function for acute kidney injury (AKI) patients who received continuous renal replacement therapy (CRRT) after acute type A aortic dissection (ATAAD) surgery.

Methods

This study was a retrospective analysis. ATAAD patients with preoperative normal ejection fraction (EF) and postoperative AKI with CRRT admitted between January 2014 and November 2021 were included. The reduced cardiac function was defined as EF <50%. The data were analyzed by the univariate and multivariate logistic regression analyses. A diagnostic model was established by a nomogram, and its discriminative performance was validated by the received operating characteristic (ROC) curve and concordance (C) statistic. The calibration of the diagnostic model was tested by calibration curves and the HosmerLemeshow test. The clinical utility was evaluated by the decision curve analysis (DCA).

Result

In total, 208 patients were eligible for analysis, of which 98 patients with reduced cardiac function. The logistic regression analyses showed age ≥60 years old, history of coronary atherosclerotic disease, preoperative pericardial tamponade, and cardiopulmonary bypass time were risk factors for reduced cardiac function, which were further employed in the nomogram. As results, nomogram revealed a high predictive power (C statistic = 0.723, 0.654–0.792; the bootstrap-corrected concordance C statistic = 0.711, the area under the ROC curve = 0.723). The calibration curves showed good consistency between the predicted and the actual probabilities (calibration curve: Brier points = 0.208, Emax = 0.103, Eavg = 0.021; Hosmer-Lemeshow test, P = 0.476). DCA showed that the nomogram could augment net benefits and exhibited a wide range of threshold probabilities in the prediction of EF reduction.

Conclusion

This nomogram is an effective diagnostic model for predicting the reduced cardiac function in postoperative ATAAD patients with AKI undergoing CRRT and can be used to protect postoperative renal functions and facilitate patient-specific care after ATAAD surgery.

An analysis of non-nutritive calories from propofol, dextrose, and citrate among critically ill patients receiving continuous renal replacement therapy

BACKGROUND

Propofol, dextrose, and citrate infusions are necessary treatment modalities in the intensive care units (ICUs). They are, however, a potential source of non-nutritive calories (NNCs) which may cause over-feeding and adverse complications. The literature surrounding the role of NNCs is limited. We aimed to examine the energy contribution of NNCs. Our secondary aim is to assess the nutritional impact of NNCs, especially among patients receiving continuous renal replacement therapy (CRRT).

MATERIALS /METHODS

We enrolled 177 mechanically ventilated patients admitted to medical-surgical ICUs from August to December 2019. Patients were monitored over the first 7 days of admission. Infusion rates of EN/PN and NNCs, as well as clinical characteristics, were examined. Patients receiving CRRT were compared to those without.

RESULTS

In total, 24% received additional energy from citrate. Patients received a maximum of 331kcal from citrate, 492kcal from propofol, and 992kcal from dextrose per ICU day. CRRT-group achieved higher total energy on the first two days (Day 1 - 55.1% vs. 46.4%; p=0.008, Day 2 - 73.2% vs. 55.4%, p=0.025). They also received higher mean NNCs on all days, except for Day 1 (p=0.068).

CONCLUSION

NNCs, especially citrate, are significant sources of energy. Patients receiving CRRT may have greater nutritional risk. There should be close monitoring and adaption of energy prescription accordingly to prevent over-feeding. This article is protected by copyright. All rights reserved.

Development and Validation of a Prognostic Model to Predict the Risk of In-hospital Death in Patients With Acute Kidney Injury Undergoing Continuous Renal Replacement Therapy After Acute Type a Aortic Dissection

Background

This study aimed to construct a model to predict the risk of in-hospital death in patients with acute renal injury (AKI) receiving continuous renal replacement therapy (CRRT) after acute type A aortic dissection (ATAAD) surgery.

Methods

We reviewed the data of patients with AKI undergoing CRRT after ATAAD surgery. The patients were divided into survival and nonsurvival groups based on their vital status at hospital discharge. The data were analyzed using univariate and multivariate logistic regression analyses. Establish a risk prediction model using a nomogram and its discriminative ability was validated using C statistic and the receiver operating characteristic (ROC) curve. Its calibration ability was tested using a calibration curve, 10-fold cross-validation and Hosmer–Lemeshow test.

Results

Among 175 patients, in-hospital death occurred in 61 (34.9%) patients. The following variables were incorporated in predicting in-hospital death: age > 65 years, lactic acid 12 h after CRRT, liver dysfunction, and permanent neurological dysfunction. The risk model revealed good discrimination (C statistic = 0.868, 95% CI: 0.806–0.930; a bootstrap-corrected C statistic of 0.859, the area under the ROC = 0.868). The calibration curve showed good consistency between predicted and actual probabilities (via 1,000 bootstrap samples, mean absolute error = 2.2%; Hosmer–Lemeshow test, P = 0.846). The 10-fold cross validation of the nomogram showed that the average misdiagnosis rate was 16.64%.

Conclusion

The proposed model could be used to predict the probability of in-hospital death in patients undergoing CRRT for AKI after ATAAD surgery. It had the potential to assist doctors to identify the gravity of the situation and make the targeted therapeutic measures.

Hyperoxia and Acute Kidney Injury: A Tale of Oxygen and the Kidney

Although oxygen supplementation is beneficial to support life in the clinic, excessive oxygen therapy also has been linked to damage to organs such as the lung or the eye. However, there is a lack of understanding of whether high oxygen therapy directly affects the kidney, leading to acute kidney injury, and what molecular mechanisms may be involved in this process. In this review, we revise our current understanding of the mechanisms by which hyperoxia leads to organ damage and highlight possible areas of investigation for the scientific community interested in novel mechanisms of kidney disease. Overall, we found a significant need for both animal and clinical studies evaluating the role of hyperoxia in inducing kidney damage. Thus, we urge the research community to further investigate oxygen therapy and its impact on kidney health with the goal of optimizing oxygen therapy guidelines and improving patient care.

Physiological and Pathophysiological Consequences of Mechanical Ventilation

Mechanical ventilation is a life-support system used to ensure blood gas exchange and to assist the respiratory muscles in ventilating the lung during the acute phase of lung disease or following surgery. Positive-pressure mechanical ventilation differs considerably from normal physiologic breathing. This may lead to several negative physiological consequences, both on the lungs and on peripheral organs. First, hemodynamic changes can affect cardiovascular performance, cerebral perfusion pressure (CPP), and drainage of renal veins. Second, the negative effect of mechanical ventilation (compression stress) on the alveolar-capillary membrane and extracellular matrix may cause local and systemic inflammation, promoting lung and peripheral-organ injury. Third, intra-abdominal hypertension may further impair lung and peripheral-organ function during controlled and assisted ventilation. Mechanical ventilation should be optimized and personalized in each patient according to individual clinical needs. Multiple parameters must be adjusted appropriately to minimize ventilator-induced lung injury (VILI), including: inspiratory stress (the respiratory system inspiratory plateau pressure); dynamic strain (the ratio between tidal volume and the end-expiratory lung volume, or inspiratory capacity); static strain (the end-expiratory lung volume determined by positive end-expiratory pressure [PEEP]); driving pressure (the difference between the respiratory system inspiratory plateau pressure and PEEP); and mechanical power (the amount of mechanical energy imparted as a function of respiratory rate). More recently, patient self-inflicted lung injury (P-SILI) has been proposed as a potential mechanism promoting VILI. In the present chapter, we will discuss the physiological and pathophysiological consequences of mechanical ventilation and how to personalize mechanical ventilation parameters.

Experimental models of acute kidney injury for translational research

Preclinical models of human disease provide powerful tools for therapeutic discovery but have limitations. This problem is especially apparent in the field of acute kidney injury (AKI), in which clinical trial failures have been attributed to inaccurate modelling performed largely in rodents. Multidisciplinary efforts such as the Kidney Precision Medicine Project are now starting to identify molecular subtypes of human AKI. In addition, over the past decade, there have been developments in human pluripotent stem cell-derived kidney organoids as well as zebrafish, rodent and large animal models of AKI. These organoid and AKI models are being deployed at different stages of preclinical therapeutic development. However, the traditionally siloed, preclinical investigator-driven approaches that have been used to evaluate AKI therapeutics to date rarely account for the limitations of the model systems used and have given rise to false expectations of clinical efficacy in patients with different AKI pathophysiologies. To address this problem, there is a need to develop more flexible and integrated approaches, involving teams of investigators with expertise in a range of different model systems, working closely with clinical investigators, to develop robust preclinical evidence to support more focused interventions in patients with AKI.

Interorgan crosstalk mechanisms in disease: the case of acute kidney injury-induced remote lung injury

Homeostasis and health of multicellular organisms with multiple organs depends on interorgan communication. Tissue injury in one organ disturbs this homeostasis and can lead to disease in multiple organs, or multiorgan failure. Many routes of interorgan crosstalk during homeostasis are relatively well known, but interorgan crosstalk in disease still lacks understanding. In particular, how tissue injury in one organ can drive injury at remote sites and trigger multiorgan failure with high mortality is poorly understood. As examples, acute kidney injury can trigger acute lung injury and cardiovascular dysfunction; pneumonia, sepsis or liver failure conversely can cause kidney failure; lung transplantation very frequently triggers acute kidney injury. Mechanistically, interorgan crosstalk after tissue injury could involve soluble mediators and their target receptors, cellular mediators, in particular immune cells, as well as newly identified neuro-immune connections. In this review, I will focus the discussion of deleterious interorgan crosstalk and its mechanistic concepts on one example, acute kidney injury-induced remote lung injury.

Outcomes of critically ill patients with acute kidney injury in COVID-19 infection: an observational study

BACKGROUND

Early reports indicate that AKI is common during COVID-19 infection. Different mortality rates of AKI due to SARS-CoV-2 have been reported, based on the degree of organic dysfunction and varying from public to private hospitals. However, there is a lack of data about AKI among critically ill patients with COVID-19.

METHODS

We conducted a multicenter cohort study of 424 critically ill adults with severe acute respiratory syndrome (SARS) and AKI, both associated with SARS-CoV-2, admitted to six public ICUs in Brazil. We used multivariable logistic regression to identify risk factors for AKI severity and in-hospital mortality.

RESULTS

The average age was 66.42 ± 13.79 years, 90.3% were on mechanical ventilation (MV), 76.6% were at KDIGO stage 3, and 79% underwent hemodialysis. The overall mortality was 90.1%. We found a higher frequency of dialysis (82.7% versus 45.2%), MV (95% versus 47.6%), vasopressors (81.2% versus 35.7%) (p < 0.001) and severe AKI (79.3% versus 52.4%; p = 0.002) in nonsurvivors. MV, vasopressors, dialysis, sepsis-associated AKI, and death (p < 0.001) were more frequent in KDIGO 3. Logistic regression for death demonstrated an association with MV (OR = 8.44; CI 3.43-20.74) and vasopressors (OR = 2.93; CI 1.28-6.71; p < 0.001). Severe AKI and dialysis need were not independent risk factors for death. MV (OR = 2.60; CI 1.23-5.45) and vasopressors (OR = 1.95; CI 1.12-3.99) were also independent risk factors for KDIGO 3 (p < 0.001).

CONCLUSION

Critically ill patients with SARS and AKI due to COVID-19 had high mortality in this cohort. Mortality was largely determined by the need for mechanical ventilation and vasopressors rather than AKI severity.

GDF-15 Predicts In-Hospital Mortality of Critically Ill Patients with Acute Kidney Injury Requiring Continuous Renal Replacement Therapy: A Multicenter Prospective Study

Growth differentiation factor-15 (GDF-15) is a stress-responsive cytokine. This study evaluated the association between GDF-15 and in-hospital mortality among patients with severe acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT). Among the multicenter prospective CRRT cohort between 2017 and 2019, 66 patients whose blood sample was available were analyzed. Patients were divided into three groups according to the GDF-15 concentrations. The median GDF-15 level was 7865.5 pg/mL (496.9 pg/mL in the healthy control patients). Baseline characteristics were not different among tertile groups except the severity scores and serum lactate level, which were higher in the third tertile. After adjusting for confounding factors, the patients with higher GDF-15 had significantly increased risk of mortality (second tertile: adjusted hazards ratio [aHR], 3.67; 95% confidence interval [CI], 1.05-12.76; p = 0.041; third tertile: aHR, 6.81; 95% CI, 1.98-23.44; p = 0.002). Furthermore, GDF-15 predicted in-hospital mortality (area under the curve, 0.710; 95% CI, 0.585-0.815) better than APACHE II and SOFA scores. Serum GDF-15 concentration was elevated in AKI patients requiring CRRT, higher in more severe patients. GDF-15 is a better independent predictor for in-hospital mortality of critically ill AKI patients than the traditional risk scoring system such as APACHE II and SOFA scores.

Lung metabolomics after ischemic acute kidney injury reveals increased oxidative stress, altered energy production, and ATP depletion

Acute kidney injury (AKI) is a complex disease associated with increased mortality that may be due to deleterious distant organ effects. AKI associated with respiratory complications, in particular, has a poor outcome. In murine models, AKI is characterized by increased circulating cytokines, lung chemokine upregulation, and neutrophilic infiltration, similar to other causes of indirect acute lung injury (ALI; e.g., sepsis). Many causes of lung inflammation are associated with a lung metabolic profile characterized by increased oxidative stress, a shift toward the use of other forms of energy production, and/or a depleted energy state. To our knowledge, there are no studies that have evaluated pulmonary energy production and metabolism after AKI. We hypothesized that based on the parallels between inflammatory acute lung injury and AKI-mediated lung injury, a similar metabolic profile would be observed. Lung metabolomics and ATP levels were assessed 4 h, 24 h, and 7 days after ischemic AKI in mice. Numerous novel findings regarding the effect of AKI on the lung were observed including 1) increased oxidative stress, 2) a shift toward alternate methods of energy production, and 3) depleted levels of ATP. The findings in this report bring to light novel characteristics of AKI-mediated lung injury and provide new leads into the mechanisms by which AKI in patients predisposes to pulmonary complications.

Development of a new mortality scoring system for acute kidney injury with continuous renal replacement therapy

AIM

On the basis of the worst outcomes of patients undergoing continuous renal replacement therapy (CRRT) in intensive care unit, previously developed mortality prediction model, Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) needs to be modified.

METHODS

A total of 828 patients who underwent CRRT were recruited. Mortality prediction model was developed for the prediction of death within 7 days after starting the CRRT. Based on regression analysis, modified scores were assigned to each variable which were originally used in the APACHE II and SOFA scoring models. Additionally, a new abbreviated Mortality Scoring system for AKI with CRRT (MOSAIC) was developed after stepwise selection analysis.

RESULTS

We used all the variables included in the APACHE II and SOFA scoring models. The prediction powers indicated by C-statistics were 0.686 and 0.683 for 7-day mortality by the APACHE II and SOFA systems, respectively. After modification of these models, the prediction powers increased up to 0.752 for the APACHE II and 0.724 for the SOFA systems. Using multivariate analysis, seven significant variables were selected in the MOSAIC model wherein its C-statistic value was 0.772. These models also showed good performance with 0.720, 0.734 and 0.773 of C-statistics in the modified APACHE II, modified SOFA and MOSAIC scoring models in the external validation cohort (n = 497).

CONCLUSION

The modified APACHE II/SOFA and newly developed MOSAIC models could be more useful tool for predicting mortality for patients receiving CRRT.

Lower short-term mortality in ICU patients on chronic dialysis than in those requiring acute dialysis

BACKGROUND

In ICU patients, we aimed to describe the outcomes of those with end-stage renal disease (ESRD) as compared to those requiring acute renal replacement therapy (RRT).

METHODS

Retrospective analysis of all adult patients admitted to a general, university hospital ICU from 2005 to 2012. ESRD was defined as use of chronic RRT >90 days prior to admission.

RESULTS

We included 5927 patients of whom 1004 (17%) received acute RRT and 161 (3%) had pre-existing ESRD requiring RRT. Thirty-day mortality was 42% vs 28% for acute RRT vs ESRD patients (adjusted hazard ratio (aHR) 0.90 (0.61-1.34)), and 16% for those not requiring RRT (aHR 0.91 (0.60-1.38) compared to ESRD patients). Ninety-day mortality was 55% vs 45% for acute RRT vs ESRD patients (aHR 0.96 (0.70-1.31)), and 22% for those not requiring RRT (aHR 1.19 (0.84-1.67) compared to ESRD patients). Ninety-day ESRD survivors were younger, less severely ill and needed less vasopressor treatment than 90-day ESRD non-survivors. Five-year mortality was 68% vs 69% for acute RRT vs ESRD patients (aHR 1.06 (0.81-1.39)), and 38% for those not requiring RRT (aHR 1.31 (0.99-1.74) compared to ESRD patients).

CONCLUSIONS

The crude mortality for patients with pre-existing ESRD was high. Short-term mortality was within range of those not receiving RRT when adjusted for confounders. The severity of acute illness and the burden of comorbidities may be more important than the lack of kidney function per se for the short-term prognosis of RRT patients in the ICU.

[Interactions between lung and kidney in the critically ill]

Interactions between lung and kidney can significantly affect the course of acute diseases, a phenomenon that was first observed in the 1950s by describing pulmonary dysfunction in uremic patients. From animal experiments there is ample evidence for remote lung injury following acute kidney injury (AKI), with an increased risk for the development of pulmonary edema and acute respiratory distress syndrome (ARDS). Coincident ARDS and AKI are associated with higher rates of intubation and mechanical ventilation, significantly prolonged weaning from mechanical ventilation and increased mortality. On the other hand, acute lung diseases and mechanical ventilation can promote the development of AKI and are associated with increased mortality when AKI is also present. These bidirectional interactions may include hemodynamic adverse effects during mechanical ventilation or volume overload as well as the release or decreased clearance and metabolism of proinflammatory mediators (e.g., interleukin-6 and tumor necrosis factor-α), which may induce and aggravate distant organ injury. The aim of this work is to examine the interactions between lung and the kidney in critically ill patients, as well as discuss potential preventive approaches.

Acute Kidney Injury in Burn Patients: Clinically Significant Over the Initial Hospitalization and 1 Year After Injury: An Original Retrospective Cohort Study

OBJECTIVE

To examine the development of acute kidney injury (AKI) after burn injury as an independent risk factor for increased morbidity and mortality over initial hospitalization and 1-year follow-up.

BACKGROUND

Variability in fluid resuscitation and difficulty recognizing early sepsis are major barriers to preventing AKI after burn injury. Expanding our understanding of the burden AKI has on the clinical course of burn patients would highlight the need for standardized protocols.

METHODS

We queried the Healthcare Cost and Utilization Project State Inpatient Databases in the states of Florida and New York during the years 2009 to 2013 for patients over age 18 hospitalized with a primary diagnosis of burn injury using ICD-9 codes. We identified and grouped 18,155 patients, including 1476 with burns >20% total body surface area, by presence of AKI. Outcomes were compared in these cohorts via univariate analysis and multivariate logistic regression models.

RESULTS

During initial hospitalization, AKI was associated with increased pulmonary failure, mechanical ventilation, pneumonia, myocardial infarction, length of stay, cost, and mortality, and also a lower likelihood of being discharged home. One year after injury, AKI was associated with development of chronic kidney disease, conversion to chronic dialysis, hospital readmission, and long-term mortality.

CONCLUSIONS

AKI is associated with a profound and severe increase in morbidity and mortality in burn patients during initial hospitalization and up to 1 year after injury. Consensus protocols for initial burn resuscitation and early sepsis recognition and treatment are crucial to avoid the consequences of AKI after burn injury.

D-dimer Is a Predictor of 28-Day Mortality in Critically Ill Patients Receiving Continuous Renal Replacement Therapy

BACKGROUND AND AIMS

Continuous renal replacement therapy (CRRT) is an important treatment in the intensive care unit (ICU). Nevertheless, the outcome of CRRT remains unclear. It is important to find a useful and easy indicator to predict the prognosis in patients on CRRT treatment. We undertook this study to observe the association between serum D-dimer level and mortality of ICU patients in the treatment of CRRT.

METHODS

A total of 149 patients who received CRRT were enrolled in our study. We observed the correlation of D-dimer with the information of biochemical parameters, acute physiology and chronic health evaluation II (APACHE II) score. We analyzed the association between serum D-dimer level before CRRT and 28-d mortality retrospectively. Furthermore, we used Cox regression analysis to assess whether D-dimer could be the independent risk factor for mortality.

RESULTS

There were significant correlations between D-dimer and C-reaction protein (r² = 0.033, p = 0.026), creatinine (r² = 0.066, p = 0.002) and APACHE II (r² = 0.036, p = 0.021). The difference in 28-d mortality risk between elevated D-dimer group and normal D-dimer group was significant (HR 2.872, 95% CI 1.563-5.278, p = 0.001), and the elevated D-dimer level was an independent risk factor for 28-d mortality (HR 2.067, 95% CI 1.104-3.872, p = 0.023). The difference in 28-d mortality was significant between groups (p <0.001). ROC curves showed that the area under the curve (AUC) of D-dimer was 0.763.

CONCLUSION

The present study demonstrates that serum D-dimer could be a useful and easy prognostic variable of 28-d mortality in critically ill patients who received CRRT.

Factors associated with poor outcomes of continuous renal replacement therapy

Continuous renal replacement therapy (CRRT) is one of the dialysis modalities for critically ill patients. Despite intensive dialysis care, a high mortality rate is found in these patients. Our objective was to investigate the factors associated with poor outcomes in these patients. We conducted a retrospective cohort study using the National Health Insurance Research Database. Records of critically ill patients who received CRRT between 2007 and 2011 were retrieved, and the patients were categorized into two groups: those with acute kidney injury (AKI) and those with history of end-stage renal disease (ESRD). Our primary and secondary outcomes were in-hospital mortality and long-term survival and non-renal recovery (long-term dialysis dependence), respectively, in the AKI group. We enrolled 15,453 patients, with 13,204 and 2249 in the AKI and ESRD groups, respectively. Overall, 66.5% patients died during hospitalization. In-hospital mortality did not differ significantly between groups (adjusted odds ratio, 0.93; 95% CI, 0.84–1.02). Age, chronic liver disease, and cancer history were identified as independent risk factors for in-hospital mortality in both groups. Hypertension was associated with higher risk of in-hospital mortality in patients with AKI. Age, coronary artery disease, and admission to the medical intensive care unit (MICU) were risk factors for long-term dialysis dependence in patients with AKI. Patients with AKI and ESRD have similarly poor outcomes after CRRT. Older age and presence of chronic liver disease and cancer were associated with higher mortality. Older age, presence of coronary artery disease, and admission to MICU were associated with lower renal recovery rate in patients with AKI.

Effect of continuous renal replacement therapy on kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin in patients with septic acute kidney injury

Kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL) have been investigated as biomarkers for acute kidney injury (AKI). However, they are seldom investigated in patients with septic AKI treated with continuous renal replacement therapy (CRRT). The aim of the present study was to investigate the therapeutic effectiveness and possible mechanisms of CRRT in septic AKI by observing the changes in Kim-1 and NGAL levels. A group of 38 patients with septic AKI was randomly divided into the conventional drug treatment group (group A) and the CRRT group (group B). All patients were treated with standard antisepsis agents, and group B was additionally submitted to CRRT for 24 h. The levels of Kim-1 and NGAL in serum, urine and the ultrafiltrate of CRRT were measured prior to and at 12, 24, and 48 h after treatment. In group A, urinary Kim-1 (uKim-1) levels at 12, 24 and 48 h were lower than prior to treatment (P<0.05), whereas urinary NGAL (uNGAL) showed no difference among the various time points (P>0.05). In group B, uKim-1 was decreased at 24 and 48 h compared with before treatment (all P<0.05), whereas uNGAL was decreased at 48 h (P<0.05). Serum Kim-1 did not change with time in groups A and B (P>0.05), whereas serum NGAL was increased after treatment in group A (P<0.05) but did not change in group B (P>0.05). Kim-1 and NGAL were not detected in the ultrafiltrate of CRRT. uKim-1 and uNGAL decreased significantly after CRRT, and therefore may be used to reflect the change of renal function during CRRT and to evaluate the therapeutic effectiveness of the method.

Effects of continuous renal replacement therapy on serum cytokines, neutrophil gelatinase-associated lipocalin, and prognosis in patients with severe acute kidney injury after cardiac surgery

The aim of our study was to evaluate the effect of continuous renal replacement therapy (CRRT) on serum cytokines, neutrophil gelatinase-associated lipocalin (NGAL), and prognosis in patients with severe acute kidney injury (AKI) following cardiac surgery. A total number of 153 patients with severe AKI following cardiac surgery were treated with CRRT. They were divided into the survival and non-survival groups. Clinical data from these two groups before and after CRRT were recorded and analyzed. It was found that the number of impaired organs, MODS and APACHE II scores were significantly higher in the non-survival group than those in the survival group before CRRT. After CRRT, MODS and APACHE II scores decreased significantly. The post-CRRT levels of serum TNF-a and IL-6 were significantly decreased. After CRRT, serum NGAL decreased in the two groups, but the levels were higher in the non-survival group than those in the survival group. MODS and APACHE II scores could be used to evaluate the severity of AKI in patients after cardiac surgery. CRRT is an effective treatment for these patients and high levels of TNF-a, IL-6, and NGAL are associated with a poor prognosis in these patients.

Renal replacement therapy in the ICU: comparison of clinical features and outcomes of patients with acute kidney injury and dialysis-dependent end-stage renal disease

BACKGROUND

The goal of this study is to study clinical features and outcomes of the patients who had renal replacement therapy (RRT) in the intensive care unit (ICU) between 2000 and 2007.

METHODS

We retrospectively studied 222 patients.

RESULTS

Overall ICU mortality and invasive mechanical ventilation (IMV) rates were 58.1 and 61.3 %. The mean APACHE II score was 27.6 ± 8.3. Chronic dialysis (CD) patients formed 45.5 % of the study population. Acute kidney injury (AKI) patients had higher rates of IMV (73 vs. 51.5 %, p = 0.002), cancer (27.8 vs. 7.9 %, p ≤ 0.001) and mortality (67.8 vs. 50.5 %, p = 0.010) than CD patients. AKI patients with normal kidney function (NKF) before ICU admission had poorer prognosis than acute-on-chronic kidney disease (CKD) and CD patients (78.6, 51 and 50.5 %, respectively, p ≤ 0.001). Multivariate analysis showed that IMV (OR, 14.8; 95 % CI, 5.47-40.05; p ≤ 0.001) and having NKF before hospitalization (OR, 2.8; 95 % CI, 1.04-7.37; p = 0.041) were predictors of overall ICU mortality. Additionally, IMV is found as a prognostic factor for both AKI (OR, 18.7; 95 % CI, 4.48-77.72; p ≤ 0.001) and CD patients (OR, 8.14; 95 % CI, 2.01-33.04; p = 0.003), but APACHE II score is meaningful only for CD patients (OR, 1.13; 95 % CI, 1.02-1.26; p = 0.024). The areas under the ROC curves for APACHE II score were 0.52 (95 % CI, 0.39-0.66) for AKI and 0.78 (95 % CI, 0.55-0.89) for CD patients.

CONCLUSION

The observed ICU mortality among patients requiring RRT is high and IMV is associated with mortality. AKI patients have increased mortality compared to CD patients. AKI patients with past NKF have poorer prognosis than acute-on-CKD and CD patients.

Prolonged acute kidney injury exacerbates lung inflammation at 7 days post-acute kidney injury

Patients with acute kidney injury (AKI) have increased mortality; data suggest that the duration, not just severity, of AKI predicts increased mortality. Animal models suggest that AKI is a multisystem disease that deleteriously affects the lungs, heart, brain, intestine, and liver; notably, these effects have only been examined within 48 h, and longer term effects are unknown. In this study, we examined the longer term systemic effects of AKI, with a focus on lung injury. Mice were studied 7 days after an episode of ischemic AKI (22 min of renal pedicle clamping and then reperfusion) and numerous derangements were present including (1) lung inflammation; (2) increased serum proinflammatory cytokines; (3) liver injury; and (4) increased muscle catabolism. Since fluid overload may cause respiratory complications post‐AKI and fluid management is a critical component of post‐AKI care, we investigated various fluid administration strategies in the development of lung inflammation post‐AKI. Four different fluid strategies were tested – 100, 500, 1000, or 2000 μL of saline administered subcutaneously daily for 7 days. Interestingly, at 7 days post‐AKI, the 1000 and 2000 μL fluid groups had less severe AKI and less severe lung inflammation versus the 100 and 500 μL groups. In summary, our data demonstrate that appropriate fluid management after an episode of ischemic AKI led to both (1) faster recovery of kidney function and (2) significantly reduced lung inflammation, consistent with the notion that interventions to shorten AKI duration have the potential to reduce complications and improve patient outcomes.

e12084

Our data demonstrate that prolonged AKI is associated with lung inflammation up to 7 days post‐AKI consistent with the notion that duration of AKI is important in the adverse outcomes associated with AKI.

Outcomes of chronic hemodialysis patients in the intensive care unit

Patients with end-stage renal disease (ESRD) experience higher rates of hospitalisation, cardiovascular events, and all-cause mortality and are more likely to require admission to the intensive care unit (ICU) than patients with normal renal function. Sepsis and cardiovascular diseases are the most common reasons for ICU admission. ICU mortality rates in patients requiring chronic hemodialysis are significantly higher than for patients without ESRD; however, dialysis patients have a better ICU outcome than those with acute kidney injury (AKI) requiring renal replacement therapy suggesting that factors other than loss of renal function contribute to their prognosis. Current evidence suggests, the longer-term outcomes after discharge from ICU may be favourable and that long-term dependence on dialysis should not prejudice against prompt referral or admission to ICU.

Intratracheal IL-6 protects against lung inflammation in direct, but not indirect, causes of acute lung injury in mice

Introduction

Serum and bronchoalveolar fluid IL-6 are increased in patients with acute respiratory distress syndrome (ARDS) and predict prolonged mechanical ventilation and poor outcomes, although the role of intra-alveolar IL-6 in indirect lung injury is unknown. We investigated the role of endogenous and exogenous intra-alveolar IL-6 in AKI-mediated lung injury (indirect lung injury), intraperitoneal (IP) endotoxin administration (indirect lung injury) and, for comparison, intratracheal (IT) endotoxin administration (direct lung injury) with the hypothesis that IL-6 would exert a pro-inflammatory effect in these causes of acute lung inflammation.

Methods

Bronchoalveolar cytokines (IL-6, CXCL1, TNF-α, IL-1β, and IL-10), BAL fluid neutrophils, lung inflammation (lung cytokines, MPO activity [a biochemical marker of neutrophil infiltration]), and serum cytokines were determined in adult male C57Bl/6 mice with no intervention or 4 hours after ischemic AKI (22 minutes of renal pedicle clamping), IP endotoxin (10 µg), or IT endotoxin (80 µg) with and without intratracheal (IT) IL-6 (25 ng or 200 ng) treatment.

Results

Lung inflammation was similar after AKI, IP endotoxin, and IT endotoxin. BAL fluid IL-6 was markedly increased after IT endotoxin, and not increased after AKI or IP endotoxin. Unexpectedly, IT IL-6 exerted an anti-inflammatory effect in healthy mice characterized by reduced BAL fluid cytokines. IT IL-6 also exerted an anti-inflammatory effect in IT endotoxin characterized by reduced BAL fluid cytokines and lung inflammation; IT IL-6 had no effect on lung inflammation in AKI or IP endotoxin.

Conclusion

IL-6 exerts an anti-inflammatory effect in direct lung injury from IT endotoxin, yet has no role in the pathogenesis or treatment of indirect lung injury from AKI or IP endotoxin. Since intra-alveolar inflammation is important in the pathogenesis of direct, but not indirect, causes of lung inflammation, IT anti-inflammatory treatments may have a role in direct, but not indirect, causes of ARDS.

Patients with end-stage renal disease admitted to the intensive care unit: systematic review

The number of patients with end-stage renal disease (ESRD) is increasing worldwide, with a growing demand on healthcare services. A systematic review of the literature was performed to determine the requirement for intensive care unit (ICU) services, reasons for admission, predictors of mortality, and short- and long-term outcomes of ESRD patients admitted to ICU. Sixteen studies were identified, comprising 6591 ICU admissions. Cardiovascular disease and sepsis accounted for the majority of admissions. Acute illness severity scores tend to overestimate mortality among ESRD patients. Critical illness associated with acute kidney injury (AKI) requiring renal replacement therapy (RRT) is associated with significantly higher hospital mortality compared with ESRD patients admitted to the ICU [odds ratio (OR) 3.9; 3.5-4.4; P<0.0001]. However, hospital mortality of ESRD patients is less favourable compared with matched patients with mild AKI (OR 1.5; 1.4-1.6; P<0.0001). Although the mortality rate remains high shortly after hospital discharge, the duration of increased mortality risk is unclear. Patients with ESRD frequently benefit from ICU admission, despite chronic co-morbidity. Further studies are required to modify and validate existing illness severity scores for ESRD patients admitted to the ICU, and to establish the duration of increased mortality risk after discharge from ICU.