Early peritoneal dialysis reduces lung inflammation in mice with ischemic acute kidney injury

Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute kidney injury (AKI) complicates approximately a third of all acute respiratory distress syndrome (ARDS) cases, and the combination of the two drastically worsens prognosis. Recent advances in ARDS supportive care have led to improved outcomes; however, much less is known on how to prevent and support patients with AKI and ARDS together. Understanding the dynamic relationship between the kidneys and lungs is crucial for the practicing intensivist to prevent injury. This article summarizes key concepts for the critical care physician managing a patient with ARDS complicated by AKI. Also provided is a discussion of AKI in the COVID-19 era.

Acute Kidney Injury in Hospitalized Children with COVID19

BACKGROUND

Acute kidney injury (AKI) has been recognized as a significant risk factor for mortality among adults with severe acute respiratory syndrome coronavirus infection.

AIM

The aim of this study is to assess the prevalence and risk factors for AKI and mortality in children with coronavirus disease 2019 (COVID19) from a resource-limited setting.

METHODS

Cross-sectional analysis of laboratory confirmed COVID19 children admitted from 1 March to 30 November 2020 in a tertiary care hospital in New Delhi, India was done. Clinical features and associated comorbidities of COVID19 were noted. Baseline serum creatinine (height-independent Hoste's equation) and peak serum creatinine were used for staging of AKI by the 2012 Kidney Disease Improving Global Outcomes serum creatinine criteria. Univariate analysis and Kaplan-Meier survival analysis were used to compare the overall outcome in the AKI vs. the non-AKI group.

RESULTS

A total of 64 810 children between 1 month and 18 years visited the hospital; 3412 were tested for suspected COVID19, 295 tested positive and 105 (54% boys) were hospitalized. Twenty-four hospitalized children (22.8%) developed AKI; 8 in Stage 1 (33.3%), 7 in Stage 2 (29.2%) and 9 in Stage 3 (37.5%) respectively. Overall, three patients received KRT. Highest reported mortality was (66.6%) in AKI Stage 3. Risk factors for AKI included associated sepsis (OR 95% CI, 1.22-9.43, p < 0.01), nephrotic syndrome (OR 95% CI, 1.13-115.5, p < 0.01), vasopressor support (OR 3.59, 95% CI, 1.37-9.40, p value< 0.007), shock at presentation (OR 2.98, 95% CI, 1.16-7.60, p value 0.01) and mechanical ventilation (OR 2.64, 95% CI, 1.04-6.71, p value< 0.03). Mortality (25.71%) was higher in the AKI group (OR 95% CI, 1.14-8.35, p < 0.023) with shock (OR 45.92; 95% CI, 3.44-612.0, p value <0.004) and ventilation (OR 46.24; 95% CI, 1.6-1333.0 p value< 0.02) as significant risk factors for mortality.

CONCLUSION

AKI is an important modifiable risk factor for mortality in children with COVID19 in a resource-limited setting. Our study supports the strengthening of kidney replacement therapy and its timely initiation to reduce the progression of AKI and thus mortality in children.

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.

Peritoneal dialysis in children with sepsis-associated AKI (SA-AKI): an experience in a low- to middle-income country

Background: In critically ill children, sepsis-associated acute kidney injury (SA-AKI) has significant morbidity and mortality.Aim: To estimate whether early initiation of peritoneal dialysis (PD) has a better short-term outcome than standard PD.Methods: Early PD (n = 25) was defined as a need for PD in Kidney Disease: Improving Global Outcomes (KDIGO) stage 2 AKI, while those fulfilling the criteria for stage 3 KDIGO were categorised as a standard PD group (n = 25). The primary outcome measure was the estimated glomerular filtration rate (eGFR) at discharge or at 4 weeks after initiation of PD, whichever occurred earlier.Results: A prospective cohort of 50 children (32 boys) aged 2 months to 16 years with SA-AKI who underwent PD were recruited. The most frequent indication for PD was fluid overload (40%), followed by persistent metabolic acidosis (36%). Children in the early PD group had lower creatinine and higher eGFR at discharge/4-week follow-up (p < 0.001). The duration of PD was less if it was commenced early (p < 0.04); 24 of 25 (96%) children in the early PD group were off PD within 6 days of initiation compared with 13 of 25 (52%) in the standard PD group (p < 0.001).Conclusions: Compared with standard PD, early PD in SA-AKI resulted in a favourable renal outcome, decreased duration of PD and early discontinuation of dialysis.Abbreviations : AKI: acute kidney injury; CRRT: continuous renal replacement therapy; CS-AKI: cardiac surgery-associated acute kidney injury; eGFR: estimated glomerular filtration rate; ELAIN: early versus late initiation of renal replacement therapy in critically ill patients with acute kidney injury; ESCAPE: effect of strict blood pressure control and ACE inhibition on the progression of chronic kidney disease in paediatric patients; HIC: high-income countries; ISN: international society of nephrology; KDIGO: Kidney Disease: Improving Global Outcomes; LMIC: low- to middle-income countries; PD: peritoneal dialysis; PICU: paediatric intensive care unit; RRT: renal replacement therapy; SA-AKI: sepsis-associated acute kidney injury; SYL: Saving Young Lives; SOFA: sequential (sepsis-related) organ failure assessment score; STARRT-AKI: standard versus accelerated initiation of renal replacement therapy in acute kidney injury.

Early Peritoneal Dialysis Ameliorates Blast Lung Injury by Alleviating Pulmonary Edema and Inflammation

BACKGROUND

Blast lung injury is a high-energy trauma with high mortality for explosion victims. A treatment for blast lung injury is still lacking. The aim of this study was to observe the efficacy and mechanism of peritoneal dialysis combined with glucocorticoids (GC) in the treatment of blast lung injury in rats.

METHODS

Rats were randomly divided into five groups: control, sham, GC, peritoneal dialysis (dialysis for short), and dialysis + GC groups. All rats were injured by a biological shock tube-I.

RESULTS

The lung water levels in the dialysis group and dialysis + GC group were significantly lower than that in the control group at 6 and 24 h after blast injury. The oxygenation index, forced vital capacity, maximum midexpiratory flow, and functional residual capacity of rats in the dialysis and dialysis + GC groups were significantly higher than those in the control group. The serum levels of interleukin (IL)-1β, IL-6, tumor necrosis factor- α, monocyte chemoattractant protein-1, C-reactive protein, and IL-10 in the dialysis and dialysis + GC groups were significantly lower than those in the control group. Genome-wide mRNA microarray results showed that the aquaporin 1 level in the lung tissue of the dialysis group was 6.67 times higher than that in the control group.

CONCLUSION

Early peritoneal dialysis can attenuate pulmonary edema and inflammation, and protect acute lung injury after blast injury.

Peritoneal dialysis in critically ill children in resource-limited setting: A prospective cohort study

BACKGROUND

Peritoneal dialysis (PD) is easily available and simple lifesaving procedure in children with renal impairment. There is paucity of reports on efficacy of PD in critically ill children in presence of shock and those requiring mechanical ventilation.

METHODS

In this prospective observational study, efficacy and outcome of PD were evaluated in 50 critically ill children aged 1 month to 14 years admitted in pediatric intensive care unit of a tertiary care teaching hospital in India.

RESULTS

Indication of PD was acute kidney injury (AKI) in 66% of patients followed by chronic kidney disease with acute deterioration due to infectious complications in 34%. Bacterial sepsis was the most common cause of AKI (22%), others being malaria (14%) and severe dengue (12%). At initiation of PD, 26% of patients were in shock and 46% were mechanically ventilated. PD was effective and improvement in pH, bicarbonate, and lactate started within hours, with consistent improvement in estimated glomerular filtration rate by 24 h, which continued till the end of procedure, including the subgroup of patients with shock and mechanical ventilation. Total complications were seen in 14% and of which peritonitis was present in 4.0% of patients. Mortality was seen in 14% (7/50) of patients. Shock at initiation of PD (odds ratio (OR), 5.03; 95% confidence interval (CI), 0.95-26.69; p < 0.04) and requirement of mechanical ventilation (OR, 9.17; 95% CI, 1.01-83.10; p < 0.02) were associated with mortality.

CONCLUSIONS

Acute PD in critically ill children with renal impairment is a lifesaving procedure. Treatment of shock with resuscitative measures and respiratory failure with mechanical ventilation, along with PD, resulted in favorable renal outcome.

Peritoneal Dialysis Is an Option for Acute Kidney Injury Management in Patients with COVID-19

In December 2019, cases of acute respiratory illness of unknown origin were reported in Wuhan, China. The disease is caused by "severe acute respiratory syndrome coronavirus 2". After identifying severe lung damage, injury to other organs, such as the kidney, has been identified. Peritoneal dialysis is a renal replacement therapy (RRT) and is at least as effective as other extracorporeal therapy options, with significant cost-effective advantages. However, this strategy is rarely used for the management of acute kidney injury in severe lung disease. In this review, we explore PD as an RRT strategy that may be a key instrument in countries and hospitals with limited access to all RRTs.

Prophylactic Peritoneal Drainage is Associated with Improved Fluid Output after Congenital Heart Surgery

Infants undergoing congenital heart surgery (CHS) with cardiopulmonary bypass (CPB) are at risk of acute kidney injury (AKI) and fluid overload. We hypothesized that placement of a passive peritoneal drain (PPD) can improve postoperative fluid output in such infants. We analyzed 115 consecutive patients, age birth to 60 days, admitted to the PICU after CHS with CPB between 2012 and 2018. Patients who needed postoperative ECMO were excluded. Linear and logistic regression models compared postoperative fluid balances, diuretics administration, AKI, vasoactive-inotropic scores (VIS), time intubated, and length of stay after adjusting for pre/operative predictors including STAT category, bypass time, age, weight, and open chest status. PPD patients had higher STAT category (p = 0.001), longer CPB times (p = 0.001), and higher VIS on POD 1-3 (p ≤ 0.005 daily). PPD patients also had higher AKI rates (p = 0.01) that did not reach significance in multivariable modeling. There were no postoperative deaths. Postoperative hours of intubation, hospital length of stay, and POD 1-5 fluid intake did not differ between groups. Over POD 1-5, PPD use accounted for 48.8 mL/kg increased fluid output (95% CI [2.2, 95.4], p = 0.043) and 3.41 mg/kg less furosemide administered (95% CI [1.69, 5.14], p < 0.001). No PPD complications were observed. Although PPD placement did not affect end-outcomes, it was used in higher acuity patients. PPD placement is associated with improved fluid output despite lower diuretic administration and may be a useful postoperative fluid management adjunct in some complex CHS patients.

Change of surfactant protein D and A after renal ischemia reperfusion injury

Acute kidney injury (AKI) is associated with widespread effects on distant organs, including the lungs. Surfactant protein (SP)-A and SP-D are members of the C-type lectin family, which plays a critical role in host defense and regulation of inflammation in a variety of infections. Serum levels of SP-A and SP-D are markers to reflect lung injury in acute respiratory distress syndrome, idiopathic pulmonary fibrosis, and sarcoidosis. We investigated the change of lung-specific markers, including SP-A and SP-D in an AKI mice model. We studied C57BL/6J mice 4 and 24 hours after an episode of ischemic AKI (23 min of renal pedicle clamping and then reperfusion); numerous derangements were present, including SP-A, SP-D, and lung tight-junction protein. Neutrophil infiltration and apoptosis in the lungs increased in ischemic AKI. Receptor for advanced glycation end products (RAGE) in the lungs, a marker of pneumocyte I, was not changed. Lung tight-junction proteins, particularly claudin-4, claudin-18, and anti-junctional adhesion molecule 1 (JAMA-1), were reduced in 24 hours after AKI. Serum SP-A and SP-D significantly increased in ischemic AKI. SP-A and SP-D in the lungs did not increase in ischemic AKI. The immunohistochemistry showed that the expression of SP-A and SP-D was intact in ischemic AKI. SP-A and SP-D in the kidneys were significantly higher in AKI than in the sham. These patterns of SP-A and SP-D in the kidneys were similar to those of serum. AKI induces apoptosis and inflammation in the lungs. Serum SP-A and SP-D increased in ischemic AKI, but these could have originated from the kidneys. So serum SP-A and SP-D could not reflect lung injury in AKI. Further study is needed to reveal how a change in lung tight-junction protein could influence the prognosis in patients with AKI.

IL-6-mediated hepatocyte production is the primary source of plasma and urine neutrophil gelatinase-associated lipocalin during acute kidney injury

Neutrophil gelatinase associated lipocalin (NGAL, Lcn2) is the most widely studied biomarker of acute kidney injury (AKI). Previous studies have demonstrated that NGAL is produced by the kidney and released into the urine and plasma. Consequently, NGAL is currently considered a tubule specific injury marker of AKI. However, the utility of NGAL to predict AKI has been variable suggesting that other mechanisms of production are present. IL-6 is a proinflammatory cytokine increased in plasma by two hours of AKI and mediates distant organ effects. Herein, we investigated the role of IL-6 in renal and extra-renal NGAL production. Wild type mice with ischemic AKI had increased plasma IL-6, increased hepatic NGAL mRNA, increased plasma NGAL, and increased urine NGAL; all reduced in IL-6 knockout mice. Intravenous IL-6 in normal mice increased hepatic NGAL mRNA, plasma NGAL and urine NGAL. In mice with hepatocyte specific NGAL deletion (Lcn2hep-/-) and ischemic AKI, hepatic NGAL mRNA was absent, and plasma and urine NGAL were reduced. Since urine NGAL levels appear to be dependent on plasma levels, the renal handling of circulating NGAL was examined using recombinant human NGAL. After intravenous recombinant human NGAL administration to mice, human NGAL in mouse urine was detected by ELISA during proximal tubular dysfunction, but not in pre-renal azotemia. Thus, during AKI, IL-6 mediates hepatic NGAL production, hepatocytes are the primary source of plasma and urine NGAL, and plasma NGAL appears in the urine during proximal tubule dysfunction. Hence, our data change the paradigm by which NGAL should be interpreted as a biomarker of AKI.

Fluid Management With Peritoneal Dialysis After Pediatric Cardiac Surgery

Children who undergo cardiac surgery with cardiopulmonary bypass are a unique population at high risk for postoperative acute kidney injury (AKI) and fluid overload. Fluid management is important in the postoperative care of these children as fluid overload is associated with increased morbidity and mortality. Peritoneal dialysis catheters are an important tool in the armamentarium of a cardiac intensivist and are used for passive drainage for fluid removal or dialysis for electrolyte and uremia control in AKI. Prophylactic placement of a peritoneal catheter is a safe method of fluid removal that is associated with few major complications. Early initiation of peritoneal dialysis has been associated with improved clinical markers and outcomes such as early achievement of a negative fluid balance, lower vasoactive medication needs, shorter duration of mechanical ventilation, and decreased mortality. In this review, we discuss the safety and potential benefits of peritoneal catheters for dialysis or passive drainage in children following cardiopulmonary bypass.

Surgical Techniques for Catheter Placement and 5/6 Nephrectomy in Murine Models of Peritoneal Dialysis

Peritoneal dialysis (PD) is a renal replacement therapy consistent on the administration and posterior recovery of a hyperosmotic fluid in the peritoneal cavity to drain water and toxic metabolites that functionally-insufficient kidneys are not able to eliminate. Unfortunately, this procedure deteriorates the peritoneum. Tissue damage triggers the onset of inflammation to heal the injury. If the injury persists and inflammation becomes chronic, it may lead to fibrosis, which is a common occurrence in many diseases. In PD, chronic inflammation and fibrosis, along with other specific processes related to these ones, lead to ultrafiltration capacity deterioration, which means the failure and subsequent cessation of the technique. Working with human samples provides information about this deterioration but presents technical and ethical limitations to obtain biopsies. Animal models are essential to study this deterioration since they overcome these shortcomings. A chronic mouse infusion model was developed in 2008, which benefits from the wide range of genetically modified mice, opening up the possibility of studying the mechanisms involved. This model employs a customized device designed for mice, consisting of a catheter attached to an access port that is placed subcutaneously at the back of the animal. This procedure avoids continuous puncture of the peritoneum during long-term experiments, reducing infections and inflammation due to injections. Thanks to this model, peritoneal damage induced by chronic PD fluid exposure has been characterized and modulated. This technique allows the infusion of large volumes of fluids and could be used for the study of other diseases in which inoculation of drugs or other substances over extended periods of time is necessary. This article shows the method for the surgical placement of the catheter in mice. Moreover, it explains the procedure for a 5/6 nephrectomy to mimic the state of renal insufficiency present in PD patients.

Distant Organ Dysfunction in Acute Kidney Injury: A Review

Acute kidney injury (AKI) is common in critically ill patients and is associated with increased morbidity and mortality. Dysfunction of other organs is an important cause of poor outcomes from AKI. Ample clinical and epidemiologic data show that AKI is associated with distant organ dysfunction in lung, heart, brain, and liver. Recent advancements in basic and clinical research have demonstrated physiologic and molecular mechanisms of distant organ interactions in AKI, including leukocyte activation and infiltration, generation of soluble factors such as inflammatory cytokines/chemokines, and endothelial injury. Oxidative stress and production of reactive oxygen species, as well as dysregulation of cell death in distant organs, are also important mechanism of AKI-induced distant organ dysfunction. This review updates recent clinical and experimental findings on organ crosstalk in AKI and highlights potential molecular mechanisms and therapeutic targets to improve clinical outcomes during AKI.