Pulmonary complications after acute kidney injury

Association of point-of-care lung ultrasound findings with 30-day pulmonary complications after cardiac surgery: A prospective cohort study

Background

Several studies have shown that bedside lung ultrasound findings in postanaesthesia care units (PACUs) and intensive care units (ICUs) correlate with postoperative pulmonary complications(PPCs) after noncardiac major surgery. However, it remains unclear whether lung ultrasound findings can be used as early predictors of PPCs in patients undergoing cardiac surgery. The main aim of our study was to evaluate the relationship between early postoperative point-of-care lung ultrasound findings and PPCs after cardiac surgery.

Methods

Two board-certified physicians performed a point-of-care pulmonary ultrasound on cardiac surgery patients approximately 2 h after the patient was admitted to the ICU. Pulmonary complications occurring within 30 days postoperatively were recorded. Logistic regression modeling was used to analyze the relationship between lung ultrasound findings and PPCs.

Results

PPCs occurred in 61 (30.9 %) of the 197 patients. Lung ultrasound scores(LUS), number of lung consolidation(NLC), and depth of pleural effusion(DPE) were more significant in patients who developed PPCs (P < 0.001). According to the multivariate analysis, NLC≥3(aOR 2.71,95%CI 1.14-6.44; p = 0.024)and DPE >0.95(aOR 3.79,95%CI 1.60-8.99; p = 0.002) were found to be independently associated with PPCs during this study.

Conclusions

Our study demonstrated that DPE >0.95 and NLC ≥3 were associated with PPCs after cardiac surgery based on bedside lung ultrasound findings in the ICU. When these signs manifest perioperatively, the surgeon should be alerted and the necessary steps should be taken, especially if they present simultaneously.

In vivo hepatoprotective and nephroprotective effects of Stenocarpus sinuatus leaf extract against ifosfamide-induced toxicity in rats

Ifosfamide (IFOS) is a broad-spectrum chemotherapeutic agent that has been extensively used for breast cancer and other solid tumors. Unfortunately, its use is associated with toxicities of several organs. Stenocarpus sinuatus is an Australian tree belonging to the Proteaceae family. In the current study, the phytochemical constituents of S. sinuatus methanol leaf extract (SSLE) were assessed. In addition, the protective effect of SSLE against IFOS-induced nephrotoxicity and hepatotoxicity was evaluated. Rats were randomly divided into six groups: control, IFOS (50 mg/kg), IFOS + SSLE (100 mg/kg), IFOS + SSLE (200 mg/kg), IFOS + SSLE (400 mg/kg), and SSLE (400 mg/kg). Hepatoprotective and nephroprotective potency of SSLE was assessed using different biochemical parameters. The phytochemical investigation resulted in the isolation of four flavonoid glycosides (kaempferol 3-O-β- d-glucopyranosyl-(1→2)-α- l-rhamnopyranoside, kaempferol 3-O-α-rhamnopyranoside, isorhamnetin 3-O-β- d-glucopyranosyl-(1→2)-α- l-rhamnopyranoside, and quercetin 3-O-β- d-glucopyranosyl-(1→2)-α- l-rhamnopyranoside) and a coumarin (scopoletin). This is the first report on the isolated compounds from the genus Stenocarpus. SSLE showed enhancement of kidney and liver functions and reduction of oxidative stress and inflammation. The histopathology of the investigated organs confirmed the protective effect of SSLE. In conclusion, SSLE is considered as a promising candidate that can be used in defense against the toxic effects of IFOS after further clinical trials.

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.

Development and validation of risk prediction nomograms for acute respiratory failure in elderly patients with hip fracture

BACKGROUND

Hip fractures in the elderly often lead to acute respiratory failure, but there is currently no tool to assess the prognosis of such patients. This study aims to develop a risk prediction model for respiratory failure in these patients.

METHODS

A retrospective cross-sectional study was conducted using the Medical Information Mart for Intensive Care (MIMIC)-IV database, incorporating data from 3,266 patients with hip fractures aged over 55 years from 2008 to 2019. Data included demographic information, laboratory indicators, comorbidities, and treatment methods. Patients were divided into a training group (70%) and a validation group (30%). Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to select prognostic predictors, and a visualized nomogram model was constructed using multivariate logistic regression analysis. Model performance and clinical applicability were assessed. Statistical analyses were done using R4.2.2, with P < 0.05 deemed significant.

RESULTS

Seven key factors, including age, height, albumin, chloride, pneumonia, acute kidney injury (AKI), and heparin use, were associated with respiratory failure risk. The model demonstrated good performance with area under the curve (AUC) values of 0.77 and 0.73 in the training and validation sets, respectively. The calibration curve showed good agreement, and decision curve analysis (DCA) indicated the model's clinical benefit.

CONCLUSIONS

This risk prediction model can effectively predict respiratory failure in hip fracture patients, assisting clinicians in identifying high-risk individuals and providing evidence-based references for treatment strategies.

Association of preoperative frailty with pulmonary complications after cardiac surgery in elderly individuals: a prospective cohort study

BACKGROUND

The relationship between preoperative frailty and pulmonary complications after cardiac surgery in elderly patients is unclear. This study was designed to evaluate the relationship between frailty and postoperative pulmonary complications (PPCs) in elderly patients undergoing cardiac surgery and to provide a basis for their prevention and treatment.

AIMS

This study aimed to investigate the predictive value of preoperative frailty on pulmonary complications after cardiac surgery in elderly patients.

METHODS

Frailty was assessed using the CAF. The diagnosis of PPCs was based on the criteria defined by Hulzebos et al., and patients were classified into a PPCs group and a non-PPCs group. Factors with clinical significance and P < 0.05 in univariate regression analysis were included in multivariate logistic regression analysis to determine the relationship between preoperative frailty and PPCs. The area under the receiver operating characteristic (ROC) curve (AUC) was used to compare the predictive effects of the CAF, EuroSCORE II, and ASA + age on the occurrence of PPCs.

RESULTS

A total of 205 patients were enrolled in this study, 31.7% of whom developed PPCs. Univariate logistic regression analysis showed that frailty, ASA grade, EuroSCORE II, hemoglobin concentration, FVC, time of operation, and postoperative AKI were associated with the development of PPCs. However, after adjustments for all possible confounding factors, multivariate logistic regression results showed that frailty, prolonged operation time, and postoperative AKI were risk factors for PPCs, and the risk of postoperative PPCs in frail patients was approximately 4.37 times that in nonfrail patients (OR = 4.37, 95%CI: 1.6-11.94, P < 0.05). The predictive efficacy of the traditional perioperative risk assessment tools EuroSCORE II and ASA + age was lower than that of CAF.

CONCLUSIONS

Frailty before surgery, prolonged operation time, and postoperative AKI were independent risk factors for pulmonary complications after heart surgery in elderly individuals, and CAF was more effective than the traditional risk predictors EuroSCORE II and ASA + age.

Acute kidney injury decreases pulmonary vascular growth and alveolarization in neonatal rat pups

BACKGROUND

Acute kidney injury (AKI) is common in sick neonates and associated with poor pulmonary outcomes, however, the mechanisms responsible remain unknown. We present two novel neonatal rodent models of AKI to investigate the pulmonary effects of AKI.

METHODS

In rat pups, AKI was induced surgically via bilateral ischemia-reperfusion injury (bIRI) or pharmacologically using aristolochic acid (AA). AKI was confirmed with plasma blood urea nitrogen and creatinine measurements and kidney injury molecule-1 staining on renal immunohistochemistry. Lung morphometrics were quantified with radial alveolar count and mean linear intercept, and angiogenesis investigated by pulmonary vessel density (PVD) and vascular endothelial growth factor (VEGF) protein expression. For the surgical model, bIRI, sham, and non-surgical pups were compared. For the pharmacologic model, AA pups were compared to vehicle controls.

RESULTS

AKI occurred in bIRI and AA pups, and they demonstrated decreased alveolarization, PVD, and VEGF protein expression compared controls. Sham pups did not experience AKI, however, demonstrated decreased alveolarization, PVD, and VEGF protein expression compared to controls.

CONCLUSION

Pharmacologic AKI and surgery in neonatal rat pups, with or without AKI, decreased alveolarization and angiogenesis, producing a bronchopulmonary dysplasia phenotype. These models provide a framework for elucidating the relationship between AKI and adverse pulmonary outcomes.

IMPACT

There are no published neonatal rodent models investigating the pulmonary effects after neonatal acute kidney injury, despite known clinical associations. We present two novel neonatal rodent models of acute kidney injury to study the impact of acute kidney injury on the developing lung. We demonstrate the pulmonary effects of both ischemia-reperfusion injury and nephrotoxin-induced AKI on the developing lung, with decreased alveolarization and angiogenesis, mimicking the lung phenotype of bronchopulmonary dysplasia. Neonatal rodent models of acute kidney injury provide opportunities to study mechanisms of kidney-lung crosstalk and novel therapeutics in the context of acute kidney injury in a premature infant.

Harnessing Machine Learning for Prediction of Postoperative Pulmonary Complications: Retrospective Cohort Design

Postoperative pulmonary complications (PPCs) are significant causes of postoperative morbidity and mortality. This study presents the utilization of machine learning for predicting PPCs and aims to identify the important features of the prediction models. This study used a retrospective cohort design and collected data from two hospitals. The dataset included perioperative variables such as patient characteristics, preexisting diseases, and intraoperative factors. Various algorithms, including logistic regression, random forest, light-gradient boosting machines, extreme-gradient boosting machines, and multilayer perceptrons, have been employed for model development and evaluation. This study enrolled 111,212 adult patients, with an overall incidence rate of 8.6% for developing PPCs. The area under the receiver-operating characteristic curve (AUROC) of the models was 0.699-0.767, and the f1 score was 0.446-0.526. In the prediction models, except for multilayer perceptron, the 10 most important features were obtained. In feature-reduced models, including 10 important features, the AUROC was 0.627-0.749, and the f1 score was 0.365-0.485. The number of packed red cells, urine, and rocuronium doses were similar in the three models. In conclusion, machine learning provides valuable insights into PPC prediction, significant features for prediction, and the feasibility of models that reduce the number of features.

Determination of Risk Factors for Postoperative Acute Kidney Injury in Patients With Gynecologic Malignancies

Background Postoperative acute kidney injury (AKI) is an important cause of mortality and morbidity among surgical patients. There is little information on the occurrence of AKI after operations for gynecologic malignancies. This study aimed to determine the incidence of AKI in patients who underwent surgery for gynecological malignancies and determine the risk factors in those who developed postoperative AKI. Methodology A total of 1,000 patients were enrolled retrospectively from January 2007 to March 2013. AKI was defined according to the Kidney Disease Improving Global Outcomes 2012 Clinical Practice Guideline for Acute Kidney Injury. Perioperative variables of patients were collected from medical charts. Results The incidence of postoperative AKI was 8.8%, with stage 1 occurring in 5.9%, stage 2 in 2.4%, and stage 3 in 0.5% of the patients. Patients who had AKI were significantly older, had higher body mass index (BMI) higher preoperative C-reactive protein (CRP) levels, and more frequently had a history of distant organ metastasis when compared with those who did not have AKI. When compared with patients who did not develop AKI postoperatively, longer operation times and intraoperative usage of higher amounts of erythrocyte suspension and fresh frozen plasma were seen in those who developed AKI. Conclusions Patients who had AKI were older, had higher BMI with higher preoperative CRP levels, more frequent distant organ metastasis, longer operation times, and higher amounts of blood transfused intraoperatively. Defining preoperative, intraoperative, and postoperative risk factors for postoperative AKI and taking necessary precautions are important for the early detection and intervention of AKI.

Where are the medical countermeasures against the ARS and DEARE? A current topic relative to an animal model research platform, radiation exposure context, the acute and delayed effects of acute exposure, and the FDA animal rule

PURPOSE

A question echoed by the National Biodefense Science Board (NBSB) in 2010, remains a reasonable question in 2023; 'Where are the Countermeasures?'. A critical path for development of medical countermeasures (MCM) against acute, radiation-induced organ-specific injury within the acute radiation syndrome (ARS) and the delayed effects of acute radiation exposure (DEARE) requires the recognition of problems and solutions inherent in the path to FDA approval under the Animal Rule. Keep Rule number one in mind, It's not easy.

CONSIDERATIONS

The current topic herein is focused on defining the nonhuman primate model(s) for efficient MCM development relative to consideration of prompt and delayed exposure in the context of the nuclear scenario. The rhesus macaque is a predictive model for human exposure of partial-body irradiation with marginal bone marrow sparing that allows definition of the multiple organ injury in the acute radiation syndrome (ARS) and the delayed effects of acute radiation exposure (DEARE). The continued definition of natural history is required to delineate an associative or causal interaction within the concurrent multi-organ injury characteristic of the ARS and DEARE. A more efficient development of organ specific MCM for both pre-exposure and post-exposure prophylaxis to include acute radiation-induced combined injury requires closing critical gaps in knowledge and urgent support to rectify the national shortage of nonhuman primates. The rhesus macaque is a validated, predictive model of the human response to prompt and delayed radiation exposure, medical management and MCM treatment. A rational approach to further development of the cynomolgus macaque as a comparable model is urgently required for continued development of MCM for FDA approval.

CONCLUSION

It is imperative to examine the key variables relative to animal model development and validation, The pharmacokinetics, pharmacodynamics and exposure profiles, of candidate MCM relative to route, administration schedule and optimal efficacy define the fully effective dose. The conduct of adequate and well-controlled pivotal efficacy studies as well as safety and toxicity studies support approval under the FDA Animal Rule and label definition for human use.

IPW-5371 mitigates the delayed effects of acute radiation exposure in WAG/RijCmcr rats when started 15 days after PBI with bone marrow sparing

PURPOSE

To test IPW-5371 for the mitigation of the delayed effects of acute radiation exposure (DEARE). Survivors of acute radiation exposure are at risk for developing delayed multi-organ toxicities; however, there are no FDA-approved medical countermeasures (MCM) to mitigate DEARE.

METHODS

WAG/RijCmcr female rat model of partial-body irradiation (PBI), by shielding part of one hind leg, was used to test IPW-5371 (7 and 20 mg kg-1 d-1) for mitigation of lung and kidney DEARE when started 15 d after PBI. Rats were fed known amounts of IPW-5371 using a syringe, instead of delivery by daily oral gavage, sparing exacerbation of esophageal injury by radiation. The primary endpoint, all-cause morbidity was assessed over 215 d. Secondary endpoints: body weight, breathing rate and blood urea nitrogen were also assessed.

RESULTS

IPW-5371 enhanced survival (primary endpoint) as well as attenuated secondary endpoints of lung and kidney injuries by radiation.

CONCLUSION

To provide a window for dosimetry and triage, as well as avoid oral delivery during the acute radiation syndrome (ARS), the drug regimen was started at 15 d after 13.5 Gy PBI. The experimental design to test mitigation of DEARE was customized for translation in humans, using an animal model of radiation that was designed to simulate a radiologic attack or accident. The results support advanced development of IPW-5371 to mitigate lethal lung and kidney injuries after irradiation of multiple organs.

Effect of Renal Ischemia Reperfusion on Brain Neuroinflammation

Acute kidney injury (AKI) is an inflammatory sequence. It can lead to distant organ injury, including damage to the central nervous system (CNS), mediated by increased circulating cytokines and other inflammatory mediators. It can also lead to increased blood-brain barrier (BBB) permeability. However, the effect of AKI on the inflammatory response of the brain has not yet been investigated. Therefore, we observed the effect of AKI on BBB permeability, microglia and astrocyte activation, and neuronal toxicity in the brain. The striatum and ventral midbrain, known to control overall movement, secrete the neurotransmitter dopamine. The activation of microglia and astrocytes present in this area causes neuro-degenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). The activation of astrocytes and microglia in the hippocampus and cerebral cortex, which are responsible for important functions, including memory, learning, concentration, and language, can trigger nerve cell apoptosis. The activation of astrocytes and microglia at this site is also involved in the inflammatory response associated with the accumulation of beta-amyloid. In the situation of kidney ischemia reperfusion (IR)-induced AKI, activation of microglia and astrocytes were observed in the striatum, ventral midbrain, hippocampus, and cortex. However, neuronal cell death was not observed until 48 h.

Characteristics and predictors of ICU-mortality in critically ill patients with hyperlactatemia requiring CRRT: A retrospective cohort study

BACKGROUND

Hyperlactatemia is a common complication in critically ill patients with high morbidity and mortality. Hyperlactatemia patients who require continuous renal replacement therapy (CRRT) constitute a subgroup with increased mortality risk. The clinical significance of serum lactate in these patients was not well understood and clearance of lactate using CRRT shown no survival benefits. The aim of this study is to investigate the incidence and non-lactate risk factors for ICU mortality in hyperlactatemia patients who underwent CRRT.

METHOD

Hyperlactatemia patients with a serum lactate level >2 μmol/L who underwent CRRT between January, 2014 and May, 2021 were retrospectively investigated. Demographic characteristics and clinical data were collected from the electronic medical record system. The primary endpoint was predictors for ICU mortality which were identified by using multivariate logistic regression analysis.

RESULTS

A total of 178 eligible patients were finally included with a mean age of 56.6 ± 17.9 years and a median APACHE II score of 18 (IQR (14-22)). The multivariate regression results showed that male gender (OR 0.55 (95%CI 0.27-1.12), p = 0.1), mechanical ventilation (OR 2.60 (95%CI 1.27-5.34), p = 0.008), history of hypertension (OR 2.40 (95%CI 1.12-5.14), p = 0.02), SOFA score (OR 1.16 (95%CI 1.05-1.28), p = 0.002), AST (OR 1.0005 (95%CI 0.99-1.001), p = 0.08), and PT (OR 1.08 (95%CI 0.99-1.17), p = 0.06) were independently associated with ICU mortality. After adjusting for age, illness severity (APACHE II score), and serum lactate level, the statistical significances of SOFA score (OR 1.16 (95%CI 1.04-1.29), p = 0.005), hypertension (OR 2.25 (95%CI 1.02-4.95), p = 0.04), and mechanical ventilation (OR 2.54 (95%CI 1.22-5.25), p = 0.01) were not affected. The overall ICU mortality was 58.4% (104/178).

CONCLUSION

The hyperlactatemia patients who underwent CRRT were at increased ICU mortality. Gender, AST, PT, SOFA score, history of hypertension, and mechanical ventilation were independent predictors for ICU mortality. Future studies with prospectively design, large sample size, and subgroup analyses are warranted to validate these findings.

Protective effect of empagliflozin on gentamicin-induced acute renal injury via regulation of SIRT1/NF-κB signaling pathway

Gentamicin is a highly effective antibiotic. However, its major complication is nephrotoxicity. This study investigated the beneficial effects of empagliflozin against gentamicin-induced nephropathy. Kidney damage was induced in male Wistar rats by administration of gentamicin (100 mg/kg/day, i.p.) for 8 days. Two doses of empagliflozin (10 and 20 mg/kg, p.o.) were concomitantly given with gentamicin for 8 days. Gentamicin administration increased serum creatinine, urea, and cystatin C concentrations. Empagliflozin in both doses ameliorated these changes via mitigation of gentamicin-induced increase in renal oxidative stress, inflammation, and apoptosis. Empagliflozin added to GM treatment led to lower measured levels of TGF-B, NF-κB and caspase 3, and only the higher dose increased PAX2 levels indicating an improvement in tubular regeneration. Additionally, empagliflozin (20 mg/kg/day) markedly prevented gentamicin-induced histopathological changes. The protective effects of empagliflozin may be mediated by decreasing gentamicin concentration in renal tissue and possibly other effects like antioxidant and antiapoptotic effects.

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.

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.

Utility of bedside ultrasound derived hepatic and renal parenchymal flow patterns to guide management of acute kidney injury

PURPOSE OF REVIEW

Ideal fluid management of critically ill patients is maintaining an adequate perfusion pressure but avoiding venous congestion. Venous excess ultrasound score (VExUS) quantifies venous congestion to guide the management of fluid balance.

RECENT FINDINGS

VExUS of abdominal veins measures fluid tolerance and helps clinicians avoid congestion. VExUS scoring predicts the development of acute kidney injury (AKI) that is a common hospital problem resulting in higher mortality and morbidity. VExUS can predict patients at risk of developing AKI post cardiac surgery. VExUS has been associated with an increase in adverse outcomes in a general intensive care population. Hepatic vein ultrasound can manifest as a sequela of right heart failure and pulmonary hypertension. Intrarenal congestion suggests poorer prognosis in heart failure patients. VExUS score has been used in decision-making to remove fluid in patients with cardiorenal syndrome. VExUS scoring may help curtail overly aggressive fluid resuscitation for patients with septic shock and help avoid iatrogenic 'salt water drowning'.

SUMMARY

We summarize the technique and clinical practice of VExUS to help guide fluid balance across different populations of critically ill patients.

Effects of Mean Artery Pressure and Blood pH on Survival Rate of Patients with Acute Kidney Injury Combined with Acute Hypoxic Respiratory Failure: A Retrospective Study

Background and Objectives: In the intensive care unit (ICU), renal failure and respiratory failure are two of the most common organ failures in patients with systemic inflammatory response syndrome (SIRS). These clinical symptoms usually result from sepsis, trauma, hypermetabolism or shock. If this syndrome is caused by septic shock, the Surviving Sepsis Campaign Bundle suggests that vasopressin be given to maintain mean arterial pressure (MAP) > 65 mmHg if the patient is hypotensive after fluid resuscitation. Nevertheless, it is important to note that some studies found an effect of various mean arterial pressures on organ function; for example, a MAP of less than 75 mmHg was associated with the risk of acute kidney injury (AKI). However, no published study has evaluated the risk factors of mortality in the subgroup of acute kidney injury with respiratory failure, and little is known of the impact of general risk factors that may increase the mortality rate. Materials and Methods: The objective of this study was to determine the risk factors that might directly affect survival in critically ill patients with multiple organ failure in this subgroup. We retrospectively constructed a cohort study of patients who were admitted to the ICUs, including medical, surgical, and neurological, over 24 months (2015.1 to 2016.12) at Chiayi Chang Gung Memorial Hospital. We only considered patients who met the criteria of acute renal injury according to the Acute Kidney Injury Network (AKIN) and were undergoing mechanical ventilator support due to acute respiratory failure at admission. Results: Data showed that the overall ICU and hospital mortality rate was 63.5%. The most common cause of ICU admission in this cohort study was cardiovascular disease (31.7%) followed by respiratory disease (28.6%). Most patients (73%) suffered sepsis during their ICU admission and the mean length of hospital stay was 24.32 ± 25.73 days. In general, the factors independently associated with in-hospital mortality were lactate > 51.8 mg/dL, MAP ≤ 77.16 mmHg, and pH ≤ 7.22. The risk of in-patient mortality was analyzed using a multivariable Cox regression survival model. Adjusting for other covariates, MAP ≤ 77.16 mmHg was associated with higher probability of in-hospital death [OR = 3.06 (1.374–6.853), p = 0.006]. The other independent outcome predictor of mortality was pH ≤ 7.22 [OR = 2.40 (1.122–5.147), p = 0.024]. Kaplan-Meier survival curves were calculated and the log rank statistic was highly significant. Conclusions: Acute kidney injury combined with respiratory failure is associated with high mortality. High mean arterial pressure and normal blood pH might improve these outcomes. Therefore, the acid–base status and MAP should be considered when attempting to predict outcome. Moreover, the blood pressure targets for acute kidney injury in critical care should not be similar to those recommended for the general population and might prevent mortality.

Penehyclidine hydrochloride ameliorates renal ischemia reperfusion-stimulated lung injury in mice by activating Nrf2 signaling

Introduction: Penehyclidine hydrochloride (PHC) is an anticholinergic with anti-inflammatory and anti-oxidation activities. PHC displayed protectivity against renal ischemia reperfusion (RIR) injury. Nevertheless, the precise protectivity of PHC on RIR-induced lung injury remains unknown. Methods: We examined the effects of PHC on RIR-induced lung injury and investigated the underlying mechanism. We induced RIR in mice and administrated PHC to RIR mice. Kidney function was monitored by measuring the blood urea nitrogen (BUN) and creatinine level in serum. We evaluated the lung injury, myeloperoxidase (MPO) activity in lung, pro-inflammatory cytokine level, and oxidative markers in serum and lung tissues. We tested the expression level of nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase 1 (HO-1) in lung of RIR mice after PHC treatment. Finally, we evaluated the effects of PHC in RIR Nrf2^-/- mice. Results: PHC greatly downregulated the serum levels of BUN, creatinine, IL-6, NO, malondialdehyde (MDA), and matrix metalloproteinase-2. PHC also ameliorated the lung injury, decreased the MPO activity, and suppressed production of IL-6, TNF-α, IFN-γ, MDA, and O2-, while it promoted production of superoxide dismutase (SOD) and catalase (CAT) in lung. PHC improved the production of Nrf2 and HO-1. Conclusion: The protectivity of PHC was absent in Nrf2^-/- mice. PHC ameliorated RIR-induced lung injury through Nrf2 pathway.

Effect of Intra- and Post-Operative Fluid and Blood Volume on Postoperative Pulmonary Edema in Patients with Intraoperative Massive Bleeding

In patients with intraoperative massive bleeding, the effects of fluid and blood volume on postoperative pulmonary edema are uncertain. Patients with intraoperative massive bleeding who had undergone a non-cardiac surgery in five hospitals were enrolled in this study. We evaluated the association of postoperative pulmonary edema risk and intra- and post-operatively administered fluid and blood volumes in patients with intraoperative massive bleeding. In total, 2090 patients were included in the postoperative pulmonary edema analysis, and 300 patients developed pulmonary edema within 72 h of the surgery. The postoperative pulmonary edema with hypoxemia analysis included 1660 patients, and the condition occurred in 161 patients. An increase in the amount of red blood cells transfused per hour after surgery increased the risk of pulmonary edema (hazard ratio: 1.03; 95% confidence interval: 1.01–1.05; p = 0.013) and the risk of pulmonary edema with hypoxemia (hazard ratio: 1.04; 95% confidence interval: 1.01–1.07; p = 0.024). An increase in the red blood cells transfused per hour after surgery increased the risk of developing pulmonary edema. This increase can be considered as a risk factor for pulmonary edema.

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.

Cardiorespiratory and skeletal muscle damage due to COVID-19: making the urgent case for rehabilitation

INTRODUCTION

It has become increasingly evident that COVID-19 contributes to multiorgan pathophysiology. The systemic inflammatory response increases both pro-inflammatory cytokine and chemokine levels, leading to immune dysregulation and increasing the likelihood of incurring cardiac and pulmonary injuries.

AREAS COVERED

Longer periods of hospitalization (~20 days) increase susceptibility to ICU-acquired muscle weakness and deconditioning, which decreases muscle function and functional capacity. These conditions affect the quality of life in the post-COVID-19 period and require multi-disciplinary approaches to rehabilitate the cardiopulmonary and musculoskeletal systems of these patients. In this context, this narrative review, which included articles published in the Embase, PEDro and PubMed databases up to December 2020, is focused on discussing the essential role of exercise and rehabilitation health professionals in the COVID-19 recovery process, from hospitalization to hospital discharge, addressing strategies for professionals to mitigate the cardiac and pulmonary impairments associated with hospitalization to home or ambulatory rehabilitation, purposing ways to conduct rehabilitation programs to restore their functional status and quality of life after the infection.

EXPERT OPINION

In the current environment, these findings further point to the vital role of rehabilitation health professionals in the coming years and the urgent need to develop strategies to assist COVID-19 survivors.

Renohepatic crosstalk: a review of the effects of acute kidney injury on the liver

Several theories regarding acute kidney injury (AKI)-related mortality have been entertained, although mounting evidence supports the paradigm that impaired kidney function directly and adversely affects the function of several remote organs. The kidneys and liver are fundamental to human metabolism and detoxification, and it is therefore hardly surprising that critical illness complicated by hepatorenal dysfunction portends a poor prognosis. Several diseases can simultaneously impact the proper functioning of the liver and kidneys, although this review will address the impact of AKI on liver function. While evidence for this relationship in humans remains sparse, we present supportive studies and then discuss the most likely mechanisms by which AKI can cause liver dysfunction. These include 'traditional' complications of AKI (uremia, volume overload and acute metabolic acidosis, among others) as well as systemic inflammation, hepatic leukocyte infiltration, cytokine-mediated liver injury and hepatic oxidative stress. We conclude by addressing the therapeutic implications of these findings to clinical medicine.

Factors Impacting Survival in Patients With Major Burn-Induced Acute Kidney Injury Postrenal Replacement Therapy: A Nationwide Study With 15 Years Follow-Up in Taiwan

BACKGROUND

Major burn-induced acute kidney injury (AKI) causes extremely high mortality, even though renal replacement therapy (RRT) was thought of as the most efficient treatment. There was scanty research for investigating the characteristic of burn-AKI-RRT patients during intensive care. This study aims to investigate the factors impacting the survival outcomes in those burn-AKI-RRT cases.

METHODS

Using the Taiwan National Health Insurance Research Database and its affiliated database, the Registry for Catastrophic Illness Patients, we defined a cohort composed of 171 patients encountering major burn-induced AKI and receiving RRT during burn care for a 15-year observation period. Demographic characteristic, comorbidities, total body surface area (TBSA), major procedures, and complications were analyzed to explore the factors affecting the survival outcomes during acute burn care and 1 year after discharge.

RESULTS

Patients who underwent tracheostomy and skin grafting had higher survival rates during acute burn care (tracheostomy: mortality vs survival, 15.7% vs 30.2%; P = 0.0257; skin grafting: mortality vs survival, 57.4% vs 76.2%; P = 0.0134). Multivariate regression analysis showed that tracheostomy group significantly presented with lower mortality risk by 65% (odds ratio [OR], 0.35; P = 0.0372), and subgroup analysis of delaminating follow-up duration showed that patients with tracheostomy had higher overall survival by 22% (90-day postburn mortality: nontracheostomy vs tracheostomy, 58.3% vs 36.3%; adjusted hazards ratio, 0.39; 95% confidence interval, 0.22-0.69; P = 0.0011), especially during postburn first 30 days (adjusted hazards ratio, 0.15; 95% confidence interval, 0.05-0.49; P = 0.0016). Total body surface area did not significantly affect survival; however, mortality risk was significantly higher in those with a larger TBSA (TBSA, ≥80%; OR, 6.48; P = 0.0022; TBSA, 60-79%; OR, 3.12; P = 0.0518; TBSA, 40-59%; OR, 1.88; P = 0.2402; TBSA, 30-39% as reference).

CONCLUSIONS

For patients with major burn-induced AKI receiving RRT, tracheostomy and skin grafting may improve survival in the cases living through acute burn stage.

Acute Radiation-induced Lung Injury in the Non-human Primate: A Review and Comparison of Mortality and Co-morbidities Using Models of Partial-body Irradiation with Marginal Bone Marrow Sparing and Whole Thorax Lung Irradiation

The nonhuman primate, rhesus macaque, is a relevant animal model that has been used to determine the efficacy of medical countermeasures to mitigate major signs of morbidity and mortality of radiation-induced lung injury. Herein, a literature review of published studies showing the evolution of lethal lung injury characteristic of the delayed effects of acute radiation exposure between the two significantly different exposure protocols, whole thorax lung irradiation and partial-body irradiation with bone marrow sparing in the nonhuman primate, is provided. The selection of published data was made from the open literature. The primary studies conducted at two research sites benefitted from the similarity of major variables; namely, both sites used rhesus macaques of approximate age and body weight and radiation exposure by LINAC-derived 6 MV photons at dose rates of 0.80 Gy min and 1.00 Gy min delivered to the midline tissue via bilateral, anterior/posterior, posterior/anterior geometry. An advantage relative to sex difference resulted from the use of male and female macaques by the Maryland and the Washington sites, respectively. Subject-based medical management was used for all macaques. The primary studies (6) provided adequate data to establish dose response relationships within 180 d for the radiation-induced lung injury consequent to whole thorax lung irradiation (male vs. female) and partial-body irradiation with bone marrow sparing exposure protocols (male). The dose response relationships established by probit analyses vs. linear dose relationships were characterized by two main parameters or dependent variables, a slope and LD50/180. Respective LD50/180 values for the primary studies that used whole thorax lung irradiation for respective male and female nonhuman primates were 10.24 Gy [9.87, 10.52] (n = 76, male) and 10.28 Gy [9.68, 10.92] (n = 40, female) at two different research sites. The respective slopes were steep at 1.73 [0.841, 2.604] and 1.15 [0.65, 1.65] probits per linear dose. The LD50/180 value and slope derived from the dose response relationships for the partial-body irradiation with bone marrow sparing exposure was 9.94 Gy [9.35, 10.29] (n = 87) and 1.21 [0.70, 1.73] probits per linear dose. A secondary study (1) provided data on limited control cohort of nonhuman primates exposed to whole thorax lung irradiation. The data supported the incidence of clinical, radiographic, and histological indices of the dose-dependent lung injury in the nonhuman primates. Tertiary studies (6) provided data derived from collaboration with the noted primary and secondary studies on control cohorts of nonhuman primates exposed to whole thorax lung irradiation and partial-body irradiation with bone marrow sparing exposure. These studies provided a summary of histological evidence of fibrosis, inflammation and reactive/proliferative changes in pneumonocytes characteristic of lung injury and data on biomarkers for radiation-induced lung injury based on matrix-assisted laser desorption ionization-mass spectrometry imaging and gene expression approaches. The available database in young rhesus macaques exposed to whole thorax lung irradiation or partial-body irradiation with bone marrow sparing using 6 MV LINAC-derived radiation with medical management showed that the dose response relationships were equivalent relative to the primary endpoint all-cause mortality. Additionally, the latency, incidence, severity, and progression of the clinical, radiographic, and histological indices of lung injury were comparable. However, the differences between the exposure protocols are remarkable relative to the demonstrated time course between the multiple organ injury of the acute radiation syndrome and that of the delayed effects of acute radiation exposure, respectively.

Intravenous Immunoglobulin Attenuates Cecum Ligation and Puncture-Induced Acute Lung Injury by Inhibiting Apoptosis of Alveolar Epithelial Cells

PURPOSE

Intravenous immunoglobulin (IVIG) therapy has been used to treat sepsis, but its mechanisms of action remain unclear. Sepsis causes multiple organ failure, such as acute lung injury (ALI), which involves apoptosis of alveolar epithelial cells. In this study, we hypothesized that IVIG suppresses apoptosis in alveolar epithelial cells and evaluated mortality, cytokine levels, histological changes in the lung, and alveolar epithelial cell apoptosis after IVIG administration, in mice with experimentally induced sepsis.

METHODS

Mice received an injection of vehicle (saline) or immunoglobulin (100 mg/kg or 400 mg/kg) into the tail vein, after which they underwent cecal ligation and puncture. A sham-operated group was used as the normal control. Survival was assessed in all groups after 72 hours. Plasma levels of TNF-α and IL-6, histopathological changes and wet-to-dry ratio in lung, and alveolar epithelial cell apoptosis were evaluated in all groups at 4 hours after surgery.

RESULTS

In the vehicle group, histopathological injury of the lung was severe, and apoptosis of alveolar epithelial cells was significant. Survival and plasma cytokine levels were better in the IVIG treatment groups than in the vehicle group. IVIG 400 mg/kg suppressed apoptosis of alveolar epithelial cells and reduced ALI.

CONCLUSION

IVIG suppressed inflammatory cytokine levels and improved survival. Lung histopathology and alveolar epithelial cell apoptosis were improved by IVIG treatment, in a dose-dependent manner. Suppressing apoptosis in alveolar epithelial cells appears to be a mechanism by which IVIG improves survival.

Acute Kidney Injury in the Context of Acute Respiratory Distress Syndrome

Acute kidney injury is a heterogeneous syndrome defined by rapid (hours to days) decline in the glomerular filtration rate leading to retention of metabolic waste products including creatinine and urea, resulting in declination of the body's ability to manage fluid status and acid-base regulation. Acute kidney injury is seen commonly in acute respiratory distress syndrome and this article will explore the relationship between the 2 entities.

Lung ultrasound to detect and monitor pulmonary congestion in patients with acute kidney injury in nephrology wards: a pilot study

INTRODUCTION

Lung congestion and frank pulmonary edema are established complications of acute kidney injury (AKI) and early detection and monitoring of lung congestion may be useful for the clinical management of AKI patients.

METHODS

We compared standardized clinical criteria (including lung crackles and peripheral edema grading) and simultaneous chest ultrasound (US) to detect lung congestion in a series of 39 inpatients with AKI.

RESULTS

At baseline, twelve patients (31%) were clinically euvolemic and twelve presented clear-cur cardiovascular congestion (31%) by clinical criteria. Fifteen patients (38%) were hypovolemic. The median number of US-B lines in patients with cardiovascular congestion was much higher (50, inter-quartile range 27-99) than in euvolemic (14, IQR 11-37) and hypovolemic patients (7, IQR 3-16, P < 0.001). Remarkably, a substantial proportion of asymptomatic euvolemic (66%) and hypovolemic (46%) patients had lung congestion of moderate to severe degree (> 15 US-B lines) by lung US. Crackles severity and the number of US-B lines over time were inter-related (Spearman's ρ = 0.38, P < 0.01) but the agreement (Cohen k statistics) between the two metrics was unsatisfactory. Forty-eight percent of patients had lung congestion of moderate to severe degree by lung US and this estimate by far exceeded that by clinical criteria (32%).

CONCLUSIONS

This pilot study shows that chest US has potential for the detection of lung congestion at a pre-clinical stage in AKI. The results of this pilot study form the basis for a clinical trial testing the usefulness of this technique for guiding lung congestion treatment in patients with AKI.

Renal ischemia/reperfusion induced learning and memory deficit in the rat: Insights into underlying molecular and cellular mechanisms

Distance organ dysfunction is the major cause of death in the patients with acute kidney injury (AKI). However, the neurobiological basis of AKI-induced brain disorders and their mediators are poorly understood. This study was aimed to find out the links between AKI and brain injury and also the underlying cellular and electrophysiological mechanisms of memory deficit following induction of AKI via different experimental models of renal ischemia with or without uremia and uremia without renal ischemia. Fifty four male Sprague-Dawley rats were divided into 4 groups that underwent 1-h bilateral or 2-h unilateral renal ischemia followed by 1-day reperfusion (BIR and UIR, respectively), and 1-day following bilateral nephrectomy (BNX) or sham-operation. There were 2 subgroups in each group, which blood-brain barrier (BBB) integrity was evaluated in one subgroup. The other subgroup was used for recordings electrophysiological activities of the hippocampus; and after blood sampling and sacrificing animal, the cerebral hemispheres were removed and preserved for performing stereological study and Western-blotting of caspase-3 in the left and right hippocampus, respectively. Plasma urea and creatinine and CA1 neuronal loss were largely increased by BNX and BIR, but slightly by UIR. Apoptosis was stimulated in the hippocampus intensively by BIR but moderately by UIR and BNX. However, BIR and UIR were associated with profoundly disturbed BBB, increased CA1 neuronal excitability, impaired LTP induction and memory deficit. Therefore, AKI most likely through inflammatory mediators leads to hippocampal apoptosis and electrophysiological impairments, BBB disruption and memory loss, whereas uremia may contribute to necrotic neuronal death.

The Time Course of Radiation-induced Lung Injury in a Nonhuman Primate Model of Partial-body Irradiation With Minimal Bone Marrow Sparing: Clinical and Radiographic Evidence and the Effect of Neupogen Administration

The primary objectives of two companion manuscripts were to assess the natural history of delayed radiation-induced lung injury in a nonhuman primate model of acute high-dose, partial-body irradiation with 5% bone marrow sparing, to include the clinical, radiographic, and histopathological evidence and the effect of Neupogen administration on the morbidity and mortality. Nonhuman primates were exposed to 10.0 or 11.0 Gy with 6 MV linac-derived photons at approximately 0.80 Gy min. All nonhuman primates received subject-based, medical management. Subsets of nonhuman primates were administered Neupogen (10 μg kg) starting on day 1, day 3, or day 5 until recovery (absolute neutrophil count ≥ 1,000 cells μL for three consecutive days). Mortality due to multiple organ injury at 180 d study duration: Mortality at 180 d post either 10.0 Gy or 11.0 Gy was the consequence of concurrent injury due to the acute radiation syndrome (gastrointestinal and hematological) and delayed radiation-induced lung injury. The 180-d all-cause mortality observed in the control cohorts at 10.0 Gy (53%) or 11.0 Gy (86%) did not vary from cohorts that received Neupogen at any administration schedule. Mortality ranged from 43-50% (10 Gy) to 75-100% (11.0 Gy) in the Neupogen-treated cohorts. The study, however, was not powered to detect statistical significant differences between mortality in the control and Neupogen-treated cohorts. Clinical and radiographic evidence of radiation-induced lung injury: The mean nonsedated respiratory rate in the control cohorts exposed to 10 or 11 Gy increased from a baseline value of 37 breaths min to >60 breaths min within 103 d and 94 d postexposure, and the incidence of nonsedated respiratory rate > 80 breaths min was 50% and 70%, respectively. The mean duration of latency to development of clinical pneumonitis and/or fibrosis (nonsedated respiratory rate > 80 breaths min) was not significantly different between the 10.0-Gy or 11.0 Gy-cohorts (range 100-107 d). Neupogen (granulocyte colony-stimulating factor) administration had no apparent effect of the latency, incidence, or severity of nonsedated respiratory rate within either radiation dose or administration schedule. Computed tomography scans were obtained and images were analyzed for evidence of lung injury, e.g., pneumonitis and/or fibrosis, pleural and pericardial effusion. A quantitative, semiautomated method was developed based on differences in radiodensity (Hounsfield units) and lung morphology to extract the volume of pneumonitis/fibrosis and pleural effusion as indexed against total lung at each time point obtained. At both irradiation doses, 100% of the nonhuman primates surviving acute radiation syndrome manifested radiographic evidence of radiation-induced lung injury as pneumonitis and/or fibrosis. There was no apparent effect of Neupogen administration on the latency, incidence, severity, or progression of pneumonitis/fibrosis:total lung volume or pleural effusion:total lung volume at either exposure. A comparative review of the data illustrated the concomitant time course of increased mortality, nonsedated respiratory rate, and pneumonitis/fibrosis:total lung volume and pleural effusion:total lung volume consequent to 10.0-Gy or 11.0-Gy partial-body irradiation with 5% bone marrow sparing. All key parameters proceeded from a latent period of approximately 60 d followed by an increase in all three indices of clinical and radiographic evidence of radiation-induced lung injury within the next 60 d to 120 d postexposure. The subsequent time course and longitudinal analysis was influenced by the persistent progression of radiation-induced lung injury, administration of dexamethasone, and loss of nonhuman primates due to lethality. Companion paper: Lung and Heart Injury in a Nonhuman Primate Model of Partial-body Irradiation With Minimal Bone Marrow Sparing: Histopathological Evidence of Lung and Heart Injury (Parker et al. 2019): Note that the computed tomography-based radiodensity data do not permit differentiation of pneumonitis and fibrosis. The companion paper employed Masson's trichrome, collagen 1, and selected staining to identify the key time and incidence parameters relative to excessive collagen deposition indicative of fibrosis and associated histopathology in the lung. This histological database provided valuable longitudinal analysis in support of the clinical and radiographic evidence associated with the time course of radiation-induced lung injury.

Effect of hemodialysis on respiratory mechanics in acute kidney injury patients

INTRODUCTION

Hemodialysis (HD) is one treatment for acute kidney injury (AKI) patients. Studies have shown that this dialysis modality may lead to changes in pulmonary function with an impact on prognosis. The aim of our study was to evaluate changes in respiratory mechanics and oxygenation of AKI patients admitted to an intensive care unit who were undergoing intermittent mechanical ventilation (IMV) and daily HD.

METHODS

This prospective cohort study evaluated 94 AKI patients and 234 HD sessions. Pulmonary static compliance (Pcs), resistance (Rsr), and arterial partial pressure of oxygen and the fraction of inspired oxygen (PaO₂ /FiO₂ ) ratio were assessed during the initial three-day period of daily HD therapy.

FINDINGS

Psc increased progressively during HD sessions, from 39.4 ± 21.4 mL/cm H₂ O prior to the initial dialysis to 55.5 ± 25.2 at the end of the last dialysis during the study period (P = 0.04). Similarly, Rsr and PaO₂ /FiO₂ ratio also improved, from 11.1 ± 6.3 cm H₂ O/L/s prior to the initial dialysis to 8.8 ± 4.2 at the end of the last dialysis (P =0.0027) and from 228 ± 85 prior to the initial dialysis to 312.1 ± 111.5, P < 0.001, to the end of the last dialysis, respectively.

CONCLUSION

This study showed that AKI patients undergoing IMV and daily HD improve their respiratory mechanics and oxygenation.

Th17 cells contribute to pulmonary fibrosis and inflammation during chronic kidney disease progression after acute ischemia

Acute kidney injury (AKI) is associated with high mortality rates and predisposes development of chronic kidney disease (CKD). Distant organ damage, particularly in the lung, may contribute to mortality in AKI patients. Animal models of AKI demonstrate an increase in pulmonary infiltration of lymphocytes and reveal an acute compromise of lung function, but the chronic effects of AKI on pulmonary inflammation are unknown. We hypothesized that in response to renal ischemia/reperfusion (I/R), there is a persistent systemic increase in Th17 cells with potential effects on pulmonary structure and function. Renal I/R injury was performed on rats, and CKD progression was hastened by unilateral nephrectomy and exposure to 4.0% sodium diet between 35 and 63 days post-I/R. Th17 cells in peripheral blood showed a progressive increase up to 63 days after recovery from I/R injury. Infiltration of leukocytes including Th17 cells was also elevated in bronchiolar lavage (BAL) fluid 7 days after I/R and remained elevated for up to 63 days. Lung histology demonstrated an increase in alveolar cellularity and a significant increase in picrosirius red staining. Suppression of lymphocytes with mycophenolate mofetil (MMF) or an IL-17 antagonist significantly reduced Th17 cell infiltration and fibrosis in lung. In addition, tracheal smooth muscle contraction to acetylcholine was significantly enhanced 63-days after I/R relative to sham-operated controls. These data suggest that AKI is associated with a persistent increase in circulating and lung Th17 cells which may promote pulmonary fibrosis and the potential alteration in airway contractility.

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.

Acute lung injury complicating acute kidney injury: A model of endogenous αKlotho deficiency and distant organ dysfunction

The lung interfaces with atmospheric oxygen via a large surface area and is perfused by the entire venous return bearing waste products collected from the whole body. It is logical that the lung is endowed with generous anti-oxidative capacity derived both locally and from the circulation. The single-pass pleiotropic alpha-Klotho (αKlotho) protein was discovered when its genetic disruption led to premature multi-organ degeneration and early death. The extracellular domain of αKlotho is cleaved by secretases and released into circulation as endocrine soluble αKlotho protein, exerting wide-ranging cytoprotective effects including anti-oxidation on distant organs including the lung, which exhibits high sensitivity to circulating αKlotho insufficiency. Because circulating αKlotho is derived mainly from the kidney, acute kidney injury (AKI) leads to systemic αKlotho deficiency that in turn increases the risks of pulmonary complications, i.e., edema and inflammation, culminating in the acute respiratory distress syndrome. Exogenous αKlotho increases endogenous anti-oxidative capacity partly via activation of the Nrf2 pathway to protect lungs against injury caused by direct hyperoxia exposure or AKI. This article reviews the current knowledge of αKlotho antioxidation in the lung in the setting of AKI as a model of circulating αKlotho deficiency, an under-recognized condition that weakens innate cytoprotective defenses and contributes to the dysfunction in distant organs.

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.

Drug-associated acute kidney injury: who's at risk?

The contribution of nephrotoxic medications to the development of acute kidney injury (AKI) is becoming better understood concomitant with the increased incidence of AKI in children. Treatment of AKI is not yet available, so prevention continues to be the most effective approach. There is an opportunity to mitigate severity and prevent the occurrence of AKI if children at increased risk are identified early and nephrotoxins are used judiciously. Early detection of AKI is limited by the dependence of nephrologists on serum creatinine as an indicator. Promising new biomarkers may offer early detection of AKI prior to the rise in serum creatinine. Early detection of evolving AKI is improving and offers opportunities for better management of nephrotoxins. However, the identification of patients at increased risk will remain an important first step, with a focus on the use of biomarker testing and interpretation of the results.

Renal ischemia/reperfusion against nephrectomy for induction of acute lung injury in rats

PURPOSE

Acute kidney injury (AKI) induces acute lung injury (ALI) through releasing injurious mediators or impairing clearance of systemic factors. To determine the links between AKI and ALI, pulmonary and blood variables were evaluated following induction of AKI via different experimental models of bilateral renal ischemia/reperfusion (BIR: renal ischemia with uremia), unilateral renal ischemia/reperfusion (UIR: renal ischemia without uremia), bilateral nephrectomy (BNX: uremia without renal ischemia), and unilateral nephrectomy (UNX: without uremia and renal ischemia).

METHODS

Ninety male Sprague-Dawley rats were divided into six groups. Animals had 1-h bilateral or 2-h unilateral renal ischemia followed by 24-h reperfusion in the BIR and UIR groups, respectively, and 24-h period following bilateral or unilateral nephrectomy in the BNX and UNX groups, respectively. There were also sham and control groups with and without sham-operation, respectively.

RESULTS

Plasma malondialdehyde and nitric oxide were elevated by BIR more than UIR, but not changed by UNX and BNX. UIR slightly increased plasma creatinine, whereas BIR and BNX largely increased plasma creatinine, urea, K⁺and osmolality and decreased arterial HCO₃^-, pH, and CO₂. UNX and UIR did not affect lung, but BIR and BNX induced ALI with equal capillary leak and macrophages infiltration. However, there were more prominent lung edema and vascular congestion following BNX and more severe neutrophils infiltration and P_aO₂/F_iO₂ reduction following BIR.

CONCLUSION

Acutely accumulated systemic mediators following renal failure in the absence of kidneys vary from those due to combined renal failure with ischemic-reperfused kidneys and consequently they induce ALI with distinct characteristics.

Hospital Mortality in the United States following Acute Kidney Injury

Acute kidney injury (AKI) is a common reason for hospital admission and complication of many inpatient procedures. The temporal incidence of AKI and the association of AKI admissions with in-hospital mortality are a growing problem in the world today. In this review, we discuss the epidemiology of AKI and its association with in-hospital mortality in the United States. AKI has been growing at a rate of 14% per year since 2001. However, the in-hospital mortality associated with AKI has been on the decline starting with 21.9% in 2001 to 9.1 in 2011, even though the number of AKI-related in-hospital deaths increased almost twofold from 147,943 to 285,768 deaths. We discuss the importance of the 71% reduction in AKI-related mortality among hospitalized patients in the United States and draw on the discussion of whether or not this is a phenomenon of hospital billing (coding) or improvements to the management of AKI.

Reduced Mortality Associated with Acute Kidney Injury Requiring Dialysis in the United States

BACKGROUND

Dialysis-requiring acute kidney injury (AKI-D) is a documented complication of hospitalization and procedures. Temporal incidence of AKI-D and related hospital mortality in the US population has not been recently characterized. We describe the epidemiology of AKI-D as well as associated in-hospital mortality in the US.

METHODS

Retrospective cohort of a national discharge data (n = 86,949,550) from the Healthcare Cost and Utilization Project's National Inpatient Sample, 2001-2011 of patients' hospitalization with AKI-D. Primary outcomes were AKI-D and in-hospital mortality. We determined the annual incidence rate of AKI-D in the US from 2001 to 2011. We estimated ORs for AKI-D and in-hospital mortality for each successive year compared to 2001 using multiple logistic regression models, adjusted for patient and hospital characteristics, and stratified the analyses by sex and age. We also calculated population-attributable risk of in-hospital mortality associated with AKI-D.

RESULTS

The adjusted odds of AKI-D increased by a factor of 1.03 (95% CI 1.02-1.04) each year. The number of AKI-D-related (19,886-34,195) in-hospital deaths increased almost 2-fold, although in-hospital mortality associated with AKI-D (28.0-19.7%) declined significantly from 2001 to 2011. Over the same period, the adjusted odds of mortality for AKI-D patients were 0.60 (95% CI 0.56-0.67). Population-attributable risk of mortality associated with AKI-D increased (2.1-4.2%) over the study period.

CONCLUSIONS

The incidence rate of AKI-D has increased considerably in the US since 2001. However, in-hospital mortality associated with AKI-D hospital admissions has decreased significantly.

The effect of insulin-loaded linear poly(ethylene glycol)-brush-like poly(l-lysine) block copolymer on renal ischemia/reperfusion-induced lung injury through downregulating hypoxia-inducible factor

The aim of this study was to observe the therapeutic effect of insulin-loaded linear poly(ethylene glycol)-brush-like poly(l-lysine) block copolymer poly(ethylene glycol)-b-(poly(ethylenediamine l-glutamate)-g-poly(l-lysine)) (PEG-b-(PELG-g-PLL) on renal ischemia/reperfusion-induced lung injury through downregulating hypoxia-inducible factor (HIF) as compared to free insulin. Sprague Dawley rats were pretreated with 30 U/kg insulin or insulin/PEG-b-(PELG-g-PLL) complex, and then subjected to 45 minutes of ischemia and 24 hours of reperfusion. The blood and lungs were collected, the level of serum creatinine and blood urea nitrogen were measured, and the dry/wet lung ratios, the activity of superoxide dismutase and myeloperoxidase, the content of methane dicarboxylic aldehyde and tumor necrosis factor-α, and the expression of HIF-1α and vascular endothelial growth factor (VEGF) were measured in pulmonary tissues. Both insulin and insulin/PEG-b-(PELG-g-PLL) preconditioning improved the recovery of renal function, reduced pulmonary oxidative stress injury, restrained inflammatory damage, and downregulated the expression of HIF-1α and VEGF as compared to ischemia/reperfusion group, while insulin/PEG-b-(PELG-g-PLL) significantly improved this effect.

Associations of pulmonary function with serum biomarkers and dialysis adequacy in patients undergoing peritoneal dialysis

BACKGROUND

As lung impairment is an indicator of increased morbidity and mortality in patients receiving continuous ambulatory peritoneal dialysis (CAPD), the risk factors associated with impaired lung function are of great significance. The aim of this study is to elucidate the effects of inflammatory biomarkers and dialysis adequacy on pulmonary function, in CAPD patients.

METHODS

101 patients undergoing CAPD, 30 CKD5 patients and 30 healthy subjects were enrolled. Spirometry and serum biomarkers were evaluated in each subject. Pulmonary function was compared among patients and control groups. Pearson analysis was used to analyze the correlation between serum biomarkers, dialysis adequacy and pulmonary function.

RESULTS

Lower vital capacity, maximal voluntary ventilation (MVV), forced vital capacity (FVC), peak expiratory flow (PEF), maximal mid-expiratory flow rate (MMEF), and diffusing capacity of the lung for carbon monoxide (DLCO) were observed in the CAPD group (all P < 0.05) when compared with control subjects. DLCO % was negatively correlated with CRP (r = -0.349, P = 0.007) and positively correlated with albumin (r = 0.401, P = 0.002). Total Kt/V was associated positively with MMEF % (r = 0.316, P = 0.019), and MVV % (r = 0.362, P = 0.007). nPNA was positively correlated with FVC % (r = 0.295, P = 0.049) and MMEF % (r = 0.381, P = 0.010).

CONCLUSION

The results suggest that lung function decline was directly related to higher CRP level, hypoalbuminemia, and dialysis inadequacy. These findings provide the evidence that inflammation and dialysis adequacy play a role in predicting outcomes of CAPD patients with pulmonary impairment.

αKlotho deficiency in acute kidney injury contributes to lung damage

αKlotho is a circulating protein that originates predominantly from the kidney and exerts cytoprotective effects in distant sites. We previously showed in rodents that the lung is particularly vulnerable to αKlotho deficiency. Because acute lung injury is a common and serious complication of acute kidney injury (AKI), we hypothesized that αKlotho deficiency in AKI contributes to lung injury. To test the hypothesis, we created AKI by renal artery ischemia-reperfusion in rats and observed the development of alveolar interstitial edema and increased pulmonary oxidative damage to DNA, protein, and lipids. Administration of αKlotho-containing conditioned media 6 h post-AKI did not alter plasma creatinine but improved recovery of endogenous αKlotho production 3 days post-AKI, reduced lung edema and oxidative damage, and increased endogenous antioxidative capacity in the lung. Intravenously injected αKlotho rapidly exits alveolar capillaries as a macromolecule, suggesting transcytosis and direct access to the epithelium. To explore the epithelial action of αKlotho, we simulated oxidative stress in vitro by adding hydrogen peroxide to cultured A549 lung epithelial cells. Purified recombinant αKlotho directly protected cells at 20 pM with half-maximal effects at 40-50 pM, which is compatible with circulating αKlotho levels. Addition of recombinant αKlotho activated an antioxidant response element reporter and increased the levels of target proteins of the nuclear factor erythroid-derived 2 related factor system. In summary, αKlotho deficiency in AKI contributes to acute lung injury by reducing endogenous antioxidative capacity and increasing oxidative damage in the lung. αKlotho replacement partially reversed these abnormalities and mitigated pulmonary complications in AKI.

Remote effects of acute kidney injury in a porcine model

Acute kidney injury (AKI) is a common and serious condition with no specific treatment. An episode of AKI may affect organs distant from the kidney, further increasing the morbidity associated with AKI. The mechanism of organ cross talk after AKI is unclear. The renal and immune systems of pigs and humans are alike. Using a preclinical animal (porcine) model, we tested the hypothesis that early effects of AKI on distant organs is by immune cell infiltration, leading to inflammatory cytokine production, extravasation, and edema. In 29 pigs exposed to either sham surgery or renal ischemia-reperfusion (control, n = 12; AKI, n = 17), we assessed remote organ (liver, lung, brain) effects in the short (from 2- to 48-h reperfusion) and longer term (5 wk later) using immunofluorescence (for leukocyte infiltration, apoptosis), a cytokine array, tissue elemental analysis (e.g., electrolytes), blood hematology and chemistry (e.g., liver enzymes), and PCR (for inflammatory markers). AKI elicited significant, short-term (∼24 h) increments in enzymes indicative of acute liver damage (e.g. , AST: ALT ratio; P = 0.02) and influenced tissue biochemistry in some remote organs (e.g., lung tissue [Ca(2+)] increased; P = 0.04). These effects largely resolved after 48 h, and no further histopathology, edema, apoptosis, or immune cell infiltration was noted in the liver, lung, or hippocampus in the short and longer term. AKI has subtle biochemical effects on remote organs in the short term, including a transient increment in markers of acute liver damage. These effects resolved by 48 h, and no further remote organ histopathology, apoptosis, edema, or immune cell infiltration was noted.

Distant effects of unilateral renal ischemia/reperfusion on contralateral kidney but not lung in rats: the roles of ROS and iNOS

Acute kidney injury is usually associated with distant organ dysfunction. The roles of inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS) in this phenomenon were investigated following 2 h unilateral renal ischemia and 24 h reperfusion. There were 3 groups of rats subjected to either unilateral ischemia/reperfusion (UIR group), unilateral nephrectomy (UNX group), or sham operation. Two further groups were given α-tocopherol and aminoguanidine with UIR (treated-UIR group) and UNX (treated-UNX group). Plasma nitrite/nitrate and malondialdehyde were elevated only in the UIR group. Creatinine clearance and blood flow increased in non-ischemic kidney of the UIR, but not to the same extent as remnant kidney of the UNX group, while they had equal compensatory rises in absolute Na(+) and K(+) excretion and urine flow. Non-ischemic kidney of the treated-UIR group, but not remnant kidney of the treated-UNX group, showed more elevation in blood flow, whereas both kidneys had reductions in absolute Na(+) excretion and urine flow. Respiratory functional variable were not different between all groups. Therefore, 2 h unilateral renal ischemia and 24 h reperfusion did not affect lung but had distant effects on contralateral kidney partly mediated by ROS and NO-derived from iNOS to dampen compensatory increases in renal hemodynamics and to decrease tubular reabsorption.

[Pulmonary-renal crosstalk in the critically ill patient]

Despite advances in the development of renal replacement therapy, mortality of acute renal failure remains high, especially when occurring simultaneously with distant organic failure as it is in the case of the acute respiratory distress syndrome. In this update, birideccional deleterious relationship between lung and kidney on the setting of organ dysfunction is reviewed, which presents important clinical aspects of knowing. Specifically, the renal effects of acute respiratory distress syndrome and the use of positive-pressure mechanical ventilation are discussed, being ventilator induced lung injury one of the most common models for studying the lung-kidney crosstalk. The role of renal failure induced by mechanical ventilation (ventilator-induced kidney injury) in the pathogenesis of acute renal failure is emphasized. We also analyze the impact of the acute renal failure in the lung, recognizing an increase in pulmonary vascular permeability, inflammation, and alteration of sodium and water channels in the alveolar epithelial. This conceptual model can be the basis for the development of new therapeutic strategies to use in patients with multiple organ dysfunction syndrome.

Growth arrest-specific protein 6 protects against renal ischemia-reperfusion injury

BACKGROUND

Renal injury caused by ischemia-reperfusion (I/R) often occurs after shock or transplantation. Growth arrest-specific protein 6 (Gas6) is a secreted protein that binds to the TAM-Tyro3, Axl, Mer-family tyrosine kinase receptors, which modulate the inflammatory response and activate cell survival pathways. We hypothesized that Gas6 could have a protective role in attenuating the severity of renal injury after I/R.

MATERIALS AND METHODS

Adult mice were subjected to 45 min of bilateral renal ischemia. Recombinant mouse Gas6 (rmGas6, 5 μg per mouse) or normal saline (vehicle) was administered intraperitoneally 1 h before ischemia and all subjects were sacrificed at 23 h after I/R for blood and tissue analysis. The expression of protein and messenger RNA (mRNA) was assessed by Western blotting and quantitative polymerase chain reaction, respectively.

RESULTS

Treatment with rmGas6 significantly decreased serum levels of creatinine and blood urea nitrogen by 29% and 27%, respectively, improved the renal histologic injury index, and reduced the apoptosis in the kidneys, compared with the vehicle. Renal mRNA levels of interleukin 1β, interleukin 6, tumor necrosis factor α, keratinocyte-derived chemokine and macrophage inflammatory protein 2 were decreased significantly by 99%, 60%, 53%, 58%, and 43%, with rmGas6 treatment, respectively. After I/R, renal I-kappa-B α levels were reduced by 40%, whereas they returned to sham levels with rmGas6 treatment. The mRNA levels of inducible nitric oxide synthase and cyclooxygenase 2 were reduced by 79% and 70%, respectively, whereas the expression of cyclin D1 was increased by 2.1-fold in the rmGas6-treated group, compared with the vehicle.

CONCLUSIONS

Gas6 suppresses the nuclear factor κB pathway and promotes cell proliferation, leading to the reduction of inflammation and protection of renal injury induced by I/R.

The protective effects of prostaglandin E1 on lung injury following renal ischemia-reperfusion in rats

For the purposes of the present study, the protective effect of prostaglandin E1 (PGE1) on lung injury following renal ischemia-reperfusion (RIR) was investigated. Adult male rats were divided into four groups, namely, (I) control rats given physiological saline; (II) rats given PGE1 (20 μg/kg, intravenously); (III) rats subjected to RIR; and (IV) rats subjected to RIR given PGE1 30 min prior to ischemia and just before reperfusion. The right nephrectomy was performed in the RIR model. The left renal pedicle was occluded for 60 min to induce ischemia and then the left kidney was subjected to reperfusion for 60 min. The lungs of rats were used for microscopic and biochemical analyses. Although rats subjected to RIR did not exhibit heavy degenerative alterations in the lung structure, they possessed pulmonary interstitial edema. Lung glutathione levels and catalase, superoxide dismutase, glutathione peroxidase, and tissue factor (TF) activities were decreased in rats subjected to RIR, while lung lipid peroxidation, myeloperoxidase (MPO), xanthine oxidase and serum lactate dehydrogenase (LDH) activities, and blood urea and serum creatinine levels were increased in these rats when compared with the control group. PGE1 treatments resulted in the regression of oxidative stress via induction of antioxidant system, the decreased MPO and LDH activities, the reduced urea and creatinine levels, and the induced TF activity in rats subjected to RIR, while edema still remained permanent. We conclude that PGE1 may be useful in preventing lung injury with the exception of edema that occurred as a result of RIR in rats.