Acute kidney injury in critically ill burn patients. Risk factors, progression and impact on mortality

Undetectable haptoglobin is associated with major adverse kidney events in critically ill burn patients

BACKGROUND

Intravascular haemolysis has been associated with acute kidney injury (AKI) in different clinical settings (cardiac surgery, sickle cell disease). Haemolysis occurs frequently in critically ill burn patients. The aim of this study was to assess the predictive value of haptoglobin at admission to predict major adverse kidney events (MAKE) and AKI in critically ill burn patients.

METHODS

We conducted a retrospective, single-centre cohort study in a burn critical care unit in a tertiary centre, including all consecutive severely burned patients (total burned body surface > 20% and/or shock and/or mechanical ventilation at admission) from January 2012 to April 2017 with a plasmatic haptoglobin dosage at admission.

RESULTS

A total of 130 patients were included in the analysis. Their mean age was 49 (34-62) years, their median total body surface area burned was 29% (15-51%) and the intensive care unit (ICU) mortality was 25%. Early haemolysis was defined as an undetectable plasmatic haptoglobin at admission. We used logistic regression to identify MAKE and AKI risk factors. In multivariate analysis, undetectable haptoglobin was associated with MAKE and AKI (respectively, OR 6.33, 95% CI 2.34-16.45, p < 0.001; OR 8.32, 95% CI 2.86-26.40, p < 0.001).

CONCLUSIONS

Undetectable plasmatic haptoglobin at ICU admission is an independent risk factor for MAKE and AKI in critically ill burn patients. This study provides a rationale for biomarker-guided therapy using haptoglobin in critically ill burn patients.

Presenting hypertension, burn injury, and mortality in combat casualties

INTRODUCTION

The effect of presenting hypertension is poorly studied in combat casualties. We hypothesized that elevated mean arterial pressure (MAP) on presentation to combat hospitals would be associated with poor outcomes.

METHODS

Data was obtained from the Department of Defense Trauma Registry and the Armed Forces Medical Examiner System. Variables analyzed included presenting vital signs to Role II-III military theater hospital, demographic variables, injury severity score (ISS), location and mechanism of injury, presence of traumatic brain injury (TBI), acute kidney injury (AKI), and mortality. Patients were stratified by decile of MAP and logistic regression analysis was employed to adjust for confounders.

RESULTS

A total of 4072 subjects injured from February 2002 to February 2011 were identified. Compared to patients in the middle deciles of presenting MAP, patients in the highest and lowest MAP deciles were the only groups that demonstrated a higher mortality on univariate analysis (OR 2.06, 95% CI 1.16-2.31 and OR 2.86, 95% CI 1.76-4.67, respectively), and this relationship persisted after adjustment for ISS, HR, temperature, presence of burn injury, TBI, and AKI. Burn injury was associated with mortality in the full multivariate analysis. However, further analysis limited to patients without burn injury did not demonstrate an association between high MAP and mortality (OR 0.84, 95% CI 0.36-1.99; p=0.70). Conversely, when limited to patients with burn injury, high MAP was associated with mortality (OR 3.78, 95% CI 1.74-8.20; p=0.001).

CONCLUSION

The relationship between mortality and presenting MAP appears to be U-shaped, demonstrating increased mortality in the lowest and highest deciles. However, mortality in the highest MAP decile appears to be limited to casualties with associated burn injury, even after adjustment for TBI, AKI, and ISS, which takes into account the severity of the burn injury. Physicians should recognize that burn patients presenting with an elevated MAP are at an increased risk for poor outcomes.

LEVEL OF EVIDENCE

III.

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.

Hold the Pendulum: Rates of Acute Kidney Injury are Increased in Patients Who Receive Resuscitation Volumes Less than Predicted by the Parkland Equation

OBJECTIVE

To determine whether restrictive fluid resuscitation results in increased rates of acute kidney injury (AKI) or infectious complications.

BACKGROUND

Studies demonstrate that patients often receive volumes in excess of those predicted by the Parkland equation, with potentially detrimental sequelae. However, the consequences of under-resuscitation are not well-studied.

METHODS

Data were collected from a multicenter prospective cohort study. Adults with greater than 20% total burned surface area injury were divided into 3 groups on the basis of the pattern of resuscitation in the first 24 hours: volumes less than (restrictive), equal to, or greater than (excessive) standard resuscitation (4 to 6 cc/kg/% total burned surface area). Multivariable regression analysis was employed to determine the effect of fluid group on AKI, burn wound infections (BWIs), and pneumonia.

RESULTS

Among 330 patients, 33% received restrictive volumes, 39% received standard resuscitation volumes, and 28% received excessive volumes. The standard and excessive groups had higher mean baseline APACHE scores (24.2 vs 16, P < 0.05 and 22.3 vs 16, P < 0.05) than the restrictive group, but were similar in other characteristics. After adjustment for confounders, restrictive resuscitation was associated with greater probability of AKI [odds ratio (OR) 3.25, 95% confidence interval (95% CI) 1.18-8.94]. No difference in the probability of BWI or pneumonia among groups was found (BWI: restrictive vs standard OR 0.74, 95% CI 0.39-1.40, excessive vs standard OR 1.40, 95% CI 0.75-2.60, pneumonia: restrictive vs standard, OR 0.52, 95% CI 0.26-1.05; excessive vs standard, OR 1.12, 95% CI 0.58-2.14).

CONCLUSIONS

Restrictive resuscitation is associated with increased AKI, without changes in infectious complications.

Analysis of prognostic factors for acute kidney injury with continuous renal replacement therapy in severely burned patients

BACKGROUND

Acute kidney injury (AKI) is a critical complications in severely burned patients associated with high morbidity and mortality. The purpose of this study was to investigate the impact of severity of AKI at the time of continuous renal replacement therapy (CRRT) start on patient outcome and to identify the prognostic factors in severely burned patients with CRRT application.

METHODS

From January 2007 to June 2010, 84 burn patients with more than 40% of total body surface area (TBSA) burned who treated with continuous renal replacement therapy for acute kidney injury were analyzed retrospectively.

RESULTS

There was no significant difference of mortality by the severity of AKI at the time of CRRT start. However, the mean TBSA burned, abbreviated burn severity index, arterial pH, partial pressure of carbon dioxide (PaCO₂) and blood urea nitrogen (BUN)/creatinine (Cr) ratio had a statistical significance to predict mortality in receiver operation characteristic curve. In a multivariate logistic regression analysis, only sepsis had an independent association with mortality.

CONCLUSIONS

The severity of the AKI at the time of CRRT start did not have significant relationship with patient outcome. CRRT can be applied to minimize the complication of AKI including electrolyte imbalance and volume overload. Because only the presence of sepsis was independently associated with mortality, treatment for sepsis should be focused to improve the survival of the severely burned patients with CRRT.

The Clinical Epidemiology and 30-Day Outcomes of Emergency Department Patients With Acute Kidney Injury

BACKGROUND

Acute kidney injury (AKI) is associated with increased mortality and dialysis in hospitalized patients but has been little explored in the emergency department (ED) setting.

OBJECTIVE

The objective of this study was to describe the risk factors, prevalence, management, and outcomes in the ED population, and to identify the proportion of AKI patients who were discharged home with no renal-specific follow-up.

DESIGN

This is a retrospective cohort study using administrative and laboratory databases.

SETTING

Two urban EDs in Vancouver, British Columbia, Canada.

PATIENTS

We included all unique ED patients over a 1-week period.

METHODS

All patients had their described demographics, comorbidities, medications, laboratory values, and ED treatments collected. AKI was defined pragmatically, based upon accepted guidelines. The cohort was then probabilistically linked to the provincial renal database to ascertain renal replacement (transplant or dialysis) and the provincial vital statistics database to obtain mortality. The primary outcome was the prevalence of AKI; secondary outcomes included (1) the proportion of AKI patients who were discharged home with no renal-specific follow-up and (2) the combined 30-day rate of death or renal replacement among AKI patients.

RESULTS

There were 1651 ED unique patients, and 840 had at least one serum creatinine (SCr) obtained. Overall, 90 patients had AKI (10.7% of ED patients with at least one SCr, 95% confidence interval [CI], 8.7%-13.1%; 5.5% of all ED patients, 95% CI, 4.4%-6.7%) with a median age of 74 and 70% male. Of the 31 (34.4%) AKI patients discharged home, 4 (12.9%) had renal-specific follow-up arranged in the ED. Among the 90 AKI patients, 11 died and none required renal replacement at 30 days, for a combined outcome of 12.2% (95% CI, 6.5%-21.2%).

LIMITATIONS

Sample sizes may be small. Nearly half of ED patients did not obtain an SCr. Many patients did not have sequential SCr testing, and a modified definition of AKI was used.

Fluid resuscitation mediates the association between inhalational burn injury and acute kidney injury in the major burn population

BACKGROUND

It is known that acute respiratory distress syndrome and acute lung injury are independent risk factors for developing acute kidney injury (AKI) through complex pathophysiologic mechanisms. Our specific aim is to evaluate the risk factors for AKI postburn injury and whether inhalation thermal injury is an independent risk factor for developing AKI in the major burn population.

METHODS

This is an institutional review board-approved, retrospective cohort study of patients admitted to a tertiary burn intensive care unit between 2011 and 2013. We included adults (age 18 years or older) with major burn injury greater than or equal to 20% total burn surface area (TBSA) and patients with confirmed inhalation injury (±major burn). Acute kidney injury was defined using the acute kidney injury network serum creatinine criteria up to 5 days after admission. Patient demographics and clinical data were compared across cohorts using the Wilcoxon rank sum test or Pearson χ² test, as appropriate. Multiple logistic regression was used to assess the effect of inhalation injury and major burn on the incidence of AKI, adjusting for clinical and demographic confounders.

RESULTS

Two hundred fifty-four patient records (90 with inhalation injury and 164 with major burn only) were evaluated. The mean age on admission was 47±19 years and 72% of the cohort were men. There were more men in the major burn group (78% vs 62%; P=.007). No other significant differences were observed in the baseline demographics. The overall incidence of AKI was 28% (95% confidence interval, 22, 33). The unadjusted odds of AKI were nearly double (odds ratio, 1.99; 95% confidence interval, 1.13, 3.49) among those with inhalation injury relative to those with major burn only. However, there was no evidence of an independent inhalational injury effect after adjusting for potential confounders. In particular, TBSA (P=.051), daily 24-hour fluid balance (P<.001), and most recent 24-hour albumin transfusion status (P=.002) were all significantly associated with AKI in the adjusted analysis. Age and packed red blood cell transfusion status were not significant.

CONCLUSION

Inhalation thermal injury is not an independent risk factor for AKI after adjusting for TBSA and surrogates for fluid resuscitation. In patients with major burns, intensity of fluid resuscitation may mediate the development of AKI.

Early and Late Acute Kidney Injury in Severely Burned Patients

Background

This study evaluated factors influencing early and late occurrence of AKI in severely burned patients and assessed the relationship between time of occurrence of AKI and mortality of AKI patients.

Material/Methods

Renal function was evaluated at 3 time points: at admission, at the critical point or middle point of hospitalization, and at the endpoint for which death or a discharge from the center was considered. AKI criteria were: decrease in GFR of less than 60 ml/min at admission, decrease in GFR of more than 75% compared to baseline, and decrease in the daily diuresis of less than 500 ml/24 h.

Results

At admission, 15.1% of the patients had eGFR <60 ml/min. AKI occurred in 38.5% of cases. The occurrence of AKI was associated with: elderly age (p<0.001), female sex (p=0.017), overweight and obesity (p=0.055); extent and depth of burns, respiratory failure, low protein concentration (for all p<0.001), low blood pressure (p=0.014), and high WBC (p=0.010). Early AKI was detected in 28% of patients. Mortality was 100% with the initial GFR ≥60, 100% with the initial GFR <60 and early deterioration of renal function, 80% with the initial GFR <60 and late worsening, and 60% with the initial GFR <60 and no worsening. Late AKI was observed in 10% of patients and mortality in this group was 79.2%. Mortality in the entire group with AKI was 88.0% versus 24.5%.

Conclusions

The frequent occurrence of AKI, especially early, worsens the prognosis for survival. Assessment of renal function should be included in the prognostic scales for burned patients.

Melatonin prevents acute kidney injury in severely burned rats via the activation of SIRT1

Acute kidney injury (AKI) is a common complication after severe burns. Melatonin has been reported to protect against multiple organ injuries by increasing the expression of SIRT1, a silent information regulator that regulates stress responses, inflammation, cellular senescence and apoptosis. This study aimed to investigate the protective effects of melatonin on renal tissues of burned rats and the role of SIRT1 involving the effects. Rat severely burned model was established, with or without the administration of melatonin and SIRT1 inhibitor. The renal function and histological manifestations were determined to evaluate the severity of kidney injury. The levels of acetylated-p53 (Ac-p53), acetylated-p65 (Ac-p65), NF-κB, acetylated-forkhead box O1 (Ac-FoxO1), Bcl-2 and Bax were analyzed to study the underlying mechanisms. Our results suggested that severe burns could induce acute kidney injury, which could be partially reversed by melatonin. Melatonin attenuated oxidative stress, inflammation and apoptosis accompanied by the increased expression of SIRT1. The protective effects of melatonin were abrogated by the inhibition of SIRT1. In conclusion, we demonstrate that melatonin improves severe burn-induced AKI via the activation of SIRT1 signaling.

Kidney and Liver Injuries After Major Burns in Rats Are Prevented by Resolvin D2

OBJECTIVES

Innate immune dysfunction after major burn injuries increases the susceptibility to organ failure. Lipid mediators of inflammation resolution, e.g., resolvin D2, have been shown recently to restore neutrophil functionality and reduce mortality rate in a rat model of major burn injury. However, the physiological mechanisms responsible for the benefic activity of resolvin D2 are not well understood.

DESIGN

Prospective randomized animal investigation.

SETTING

Academic research setting.

SUBJECTS

Wistar male rats.

INTERVENTIONS

Animals were subjected to a full-thickness burn of 30% total body surface area. Two hours after burn, 25 ng/kg resolvin D2 was administered IV and repeated every day, for 8 days. At day 10 post burn, 2 mg/kg of lipopolysaccharide was administered IV, and the presence of renal and hepatic injuries was evaluated at day 11 post burn by histology, immunohistochemistry, and relevant blood chemistry.

MEASUREMENTS AND MAIN RESULTS

In untreated animals, we found significant tissue damage in the kidneys and liver, consistent with acute tubular necrosis and multifocal necrosis, and changes in blood chemistry, reflecting the deterioration of renal and hepatic functions. We detected less tissue damage and significantly lower values of blood urea nitrogen (26.4 ± 2.1 vs 36.0 ± 9.3 mg/dL; p ≤ 0.001), alanine aminotransferase (266.5 ± 295.2 vs 861.8 ± 813.7 U/L; p ≤ 0.01), and total bilirubin (0.13 ± 0.05 vs 0.30 ± 0.14 mg/dL; p ≤ 0.01) in resolvin D2-treated rats than in untreated animals. The mean blood pressure of all animals was above 65 mm Hg, indicating adequate tissue perfusion throughout the experiments. We measured significantly larger amounts of chromatin in the circulation of untreated than of resolvin D2-treated rats (575.1 ± 331.0 vs 264.1 ± 122.4 ng/mL; p ≤ 0.05) and identified neutrophil extracellular traps in kidney and liver tissues from untreated rats, consistent with the tissue damage.

CONCLUSIONS

Pathologic changes in kidney and liver tissues in a rat model of major burn and endotoxin insults are ameliorated by resolvin D2.

A novel mathematical model to predict prognosis of burnt patients based on logistic regression and support vector machine

OBJECTIVE

To develop a mathematical model of predicting mortality based on the admission characteristics of 6220 burn cases.

METHODS

Data on all the burn patients presenting to Institute of Burn Research, Southwest Hospital, Third Military Medical University from January of 1999 to December of 2008 were extracted from the departmental registry. The distributions of burn cases were scattered by principal component analysis. Univariate associations with mortality were identified and independent associations were derived from multivariate logistic regression analysis. Using variables independently and significantly associated with mortality, a mathematical model to predict mortality was developed using the support vector machine (SVM) model. The predicting ability of this model was evaluated and verified.

RESULTS

The overall mortality in this study was 1.8%. Univariate associations with mortality were identified and independent associations were derived from multivariate logistic regression analysis. Variables at admission independently associated with mortality were gender, age, total burn area, full thickness burn area, inhalation injury, shock, period before admission and others. The sensitivity and specificity of logistic model were 99.75% and 85.84% respectively, with an area under the receiver operating curve of 0.989 (95% CI: 0.979-1.000; p<0.01). The model correctly classified 99.50% of cases. The subsequently developed support vector machine (SVM) model correctly classified nearly 100% of test cases, which could not only predict adult group but also pediatric group, with pretty high robustness (92%-100%).

CONCLUSION

A mathematical model based on logistic regression and SVM could be used to predict the survival prognosis according to the admission characteristics.

Pediatric Acute Respiratory Distress Syndrome: Fluid Management in the PICU

The administration of an appropriate volume of intravenous fluids, while avoiding fluid overload, is a major challenge in the pediatric intensive care unit. Despite our efforts, fluid overload is a very common clinical observation in critically ill children, in particular in those with pediatric acute respiratory distress syndrome (PARDS). Patients with ARDS have widespread damage of the alveolar-capillary barrier, potentially making them vulnerable to fluid overload with the development of pulmonary edema leading to prolonged course of disease. Indeed, studies in adults with ARDS have shown that an increased cumulative fluid balance is associated with adverse outcome. However, age-related differences in the development and consequences of fluid overload in ARDS may exist due to disparities in immunologic response and body water distribution. This systematic review summarizes the current literature on fluid imbalance and management in PARDS, with special emphasis on potential differences with adult patients. It discusses the adverse effects associated with fluid overload and the corresponding possible pathophysiological mechanisms of its development. Our intent is to provide an incentive to develop age-specific fluid management protocols to improve PARDS outcomes.

Point-of-care B-type natriuretic peptide and neutrophil gelatinase-associated lipocalin measurements for acute resuscitation: a pilot study

Adequate resuscitation is paramount to burn patient survival and recovery. Novel biomarkers of intravascular volume and renal perfusion may augment resuscitation strategies. The purpose of this study is to characterize serum B-type natriuretic peptide (BNP) and neutrophil gelatinase-associated lipocalin (NGAL) during burn resuscitation and correlate to clinical assessments of volume status. We hypothesize that BNP and NGAL will help predict inadequate resuscitation during the first 48 hours following burn injury. We conducted a pilot observational study recruiting 15 adult (age ≥18 years) patients with ≥20% TBSA burns. Paired serial BNP, NGAL, and creatinine measurements were performed using point-of-care testing. Samples were tested every 4 hours for the first 48 hours following admission. Acute kidney injury (AKI) was defined by the RIFLE criteria. Over-resuscitation was defined as developing compartment syndrome. Demographics and TBSA were similar between AKI (n = 7) vs non-AKI (n = 8), and over-resuscitated (n = 5) vs adequately resuscitated groups (n = 10). NGAL (184.9 ± 72.2 vs 110.8 ± 35.8 ng/ml, P = .004) and BNP (25.3 ± 17.3 vs 8.8 ± 5.2 pg/ml, P = .033) values were significantly higher in AKI patients. Creatinine values were similar between AKI and non-AKI patients. NGAL levels suggested presence of AKI 12 hours earlier than creatinine levels. BNP values (23.1 ± 21.9 vs 13.9 ± 13.4 pg/ml, P < .001) were significantly higher in over-resuscitated patients. Point-of-care BNP, NGAL, and creatinine measurements aid in the assessment of vascular volume and renal function during acute burn resuscitation. Further studies are warranted to determine BNP and NGAL cut-offs for guiding burn resuscitation.

Factors associated with vancomycin nephrotoxicity in the critically ill

Vancomycin is a glycopeptide antibiotic commonly used in the management of methicillin-resistant Staphylococcus aureus infection. The recent increase in prevalence of methicillin-resistant Staphylococcus aureus with reduced susceptibility to vancomycin has prompted experts to advocate for higher target trough serum concentrations. This study aimed to evaluate the potential consequences of more aggressive vancomycin therapy, by examining the association between higher serum concentrations and acute kidney injury (AKI) in a population of critically ill patients. We collected data for all patients who received vancomycin over a five-year period and evaluated the prevalence of new-onset AKI using the Risk, Injury, Failure, Loss and End-stage (RIFLE) kidney disease criteria. One-hundred and fifty-nine patients provided complete data, with 8.8% manifesting new onset AKI while receiving vancomycin. The median age was 57 (44 to 68) years, while the median trough serum concentration was 16 (10 to 19) mg/l. Multivariate logistic regression analysis identified mean trough concentration (OR=1.174, P=0.024), APACHE II score (OR=1.141, P=0.012) and simultaneous aminoglycoside prescription (OR=18.896, P=0.002) as significant predictors of AKI. These data suggest higher trough vancomycin serum concentrations are associated with greater odds of AKI in the critically ill.

Elevated serum uric acid after injury correlates with the early acute kidney in severe burns

OBJECTIVE

Early acute kidney injury (AKI) is one of the most serious and common complications in the early stage of severe burns, but the pathological mechanisms still need to be elucidated. High uric acid (UA) has been found to be correlated with renal dysfunction in some experimental and clinical studies; however, the study of the dynamic correlation between AKI and UA in severe burns is still lacking.

METHODS

The diagnosis and classification of AKI were performed according to RIFLE criteria, UA, serum creatinine (Scr), estimated glomerular filtration rate (eGFR), C-reactive protein (CRP) and lactic acid (LA) were dynamically monitored within 2 days after injury in 59 severely burned patients.

RESULTS

Within 2 days after injury, AKI occurred in 23 of 59 patients (risk in 12 cases, injury in seven cases and failure in four cases), UA level in AKI patients was significantly higher than that in No-AKI patients, and referring to the cutoff level of UA (375.5 μmol/l) from ROC curve for predicting AKI, the abnormal increase of UA levels was earlier than acute deterioration of renal function in most of the AKI patients after injury. Among AKI patients, the Scr/eGFR levels were closely related to UA levels for 2 days after injury. Moreover, UA level in cases with severe grade of AKI was significantly higher than that in those with less severe grade of AKI. Furthermore, there was a positive correlation between UA and CRP for 2 days after injury in AKI patients, and a significant correlation between CRP and Scr/eGFR was found 1 day after injury. The positive correlation was also found between LA and UA after injury in AKI patients.

CONCLUSION

The results suggest that elevated serum UA after injury due to hypoxia is closely correlated with early AKI after severe burns, and UA-related aberrant inflammation also appears to be one of the pathogenic factors, providing the useful information for potential therapy.

Effects of hydrogen-rich saline on early acute kidney injury in severely burned rats by suppressing oxidative stress induced apoptosis and inflammation

Background

Early acute kidney injury (AKI) in severely burned patients predicts a high mortality that is multi-factorial. Hydrogen has been reported to alleviate organ injury via selective quenching of reactive oxygen species. This study investigated the potential protective effects of hydrogen against severe burn-induced early AKI in rats.

Methods

Severe burn were induced via immersing the shaved back of rats into a 100°C bath for 15 s. Fifty-six Sprague–Dawley rats were randomly divided into Sham, Burn + saline, and Burn + hydrogen-rich saline (HS) groups, and renal function and the apoptotic index were measured. Kidney histopathology and immunofluorescence staining, quantitative real-time PCR, ELISA and western blotting were performed on the sera or renal tissues of burned rats to explore the underlying effects and mechanisms at varying time points post burn.

Results

Renal function and tubular apoptosis were improved by HS treatment. In addition, the oxidation–reduction potential and malondialdehyde levels were markedly reduced with HS treatment, whereas endogenous antioxidant enzyme activities were significantly increased. HS also decreased the myeloperoxidase levels and influenced the release of inflammatory mediators in the sera and renal tissues of the burned rats. The regulatory effects of HS included the inhibition of p38, JNK, ERK and NF-κB activation, and an increase in Akt phosphorylation.

Conclusion

Hydrogen can attenuate severe burn-induced early AKI; the mechanisms of protection include the inhibition of oxidative stress induced apoptosis and inflammation, which may be mediated by regulation of the MAPKs, Akt and NF-κB signalling pathways.

Astaxanthin attenuates early acute kidney injury following severe burns in rats by ameliorating oxidative stress and mitochondrial-related apoptosis

Early acute kidney injury (AKI) is a devastating complication in critical burn patients, and it is associated with severe morbidity and mortality. The mechanism of AKI is multifactorial. Astaxanthin (ATX) is a natural compound that is widely distributed in marine organisms; it is a strong antioxidant and exhibits other biological effects that have been well studied in various traumatic injuries and diseases. Hence, we attempted to explore the potential protection of ATX against early post burn AKI and its possible mechanisms of action. The classic severe burn rat model was utilized for the histological and biochemical assessments of the therapeutic value and mechanisms of action of ATX. Upon ATX treatment, renal tubular injury and the levels of serum creatinine and neutrophil gelatinase-associated lipocalin were improved. Furthermore, relief of oxidative stress and tubular apoptosis in rat kidneys post burn was also observed. Additionally, ATX administration increased Akt and Bad phosphorylation and further down-regulated the expression of other downstream pro-apoptotic proteins (cytochrome c and caspase-3/9); these effects were reversed by the PI3K inhibitor LY294002. Moreover, the protective effect of ATX presents a dose-dependent enhancement. The data above suggested that ATX protects against early AKI following severe burns in rats, which was attributed to its ability to ameliorate oxidative stress and inhibit apoptosis by modulating the mitochondrial-apoptotic pathway, regarded as the Akt/Bad/Caspases signalling cascade.

Whole blood neutrophil gelatinase-associated lipocalin predicts acute kidney injury in burn patients

BACKGROUND

Early detection of acute kidney injury (AKI) in severely burn-injured patients can help alter treatment to prevent progression to acute failure and reduce the need for renal replacement therapy. We hypothesized that whole blood neutrophil gelatinase-associated lipocalin (NGAL) will be increased in severely burn-injured patients who develop AKI during acute resuscitation.

MATERIALS AND METHODS

We performed a prospective observation study of adult burn patients with a 20% total body surface area (TBSA) burned or greater burn injury. Two-hour serial measurements of NGAL, serum creatinine (Cr), and hourly urine output (UO) were collected for 48 h after admission. Our primary goal was to correlate the risk of AKI in the first week after burn injury with serial NGAL levels in the first 48 h after admission. Our secondary goal was to determine if NGAL was an earlier independent predictor of AKI compared with Cr and UO.

RESULTS

We enrolled 30 adult (age ≥ 18 y) burn patients with the mean ± standard deviation age of 40.9 ± 15.4 and mean TBSA of 46.4 ± 22.4. Fourteen patients developed AKI within the first 7 d after burn injury. There were no differences in age, TBSA, fluid administration, mean arterial pressure, UO, and Cr between AKI and no-AKI patients. NGAL was significantly increased as early as 4 h after injury (182.67 ± 83.3 versus 107.37 ± 46.15) in the AKI group. Controlling for age, TBSA, and inhalation injury, NGAL was a predictor of AKI at 4 h after injury (odds ratio, 1.02) and remained predictive of AKI for the period of more than the first 24 h after admission. UO and Cr were not predictive of AKI in the first 24 h after admission.

CONCLUSIONS

Whole blood NGAL is markedly increased in burn patients who develop AKI in the first week after injury. In addition, NGAL is an early independent predictor of AKI during acute resuscitation for severe burn injury. UO and Cr are not predictive of AKI during this time period.

Plasma neutrophil gelatinase-associated lipocalin as early biomarker for acute kidney injury in burn patients

This study evaluated whether measurements of plasma neutrophil gelatinase-associated lipocalin (NGAL) can predict acute kidney injury (AKI) in adult burn patients, and assessed the use of this biomarker in risk stratification. We performed a prospective observational study of consecutive patients with major burns admitted to the burn center within 12 hours of injury. Samples for plasma NGAL assay were obtained three times (at admission, day 3, and day 7). The main outcome measures were occurrence of AKI based on Risk-Injury-Failure classification and mortality. A total 45 patients with burns injury were enrolled. There was a high prevalence (11 of 45, 24.4%) of AKI in burn patients. All patients with AKI developed AKI after hospital day 8. Multivariate logistic regression analysis demonstrated that burn size and abbreviated burn severity index were independent risk factors of AKI. Patients who developed AKI had significantly higher admission plasma NGAL levels, hospital day 3 NGAL levels, and hospital day 7 NGAL levels. Especially, hospital day 7 NGAL levels strongly correlated with AKI. For concentration in plasma NGAL at hospital day 7, the area under the receiver operating characteristic curve was 0.903, sensitivity was 87%, and specificity was 91% for a cutoff value of 125 ng/ml. The mean plasma NGAL at hospital day 7 of patients who died was significantly higher than that of patients who did not (485 ng/ml vs 111 ng/ml, P = .001). Plasma NGAL levels are early predictive biomarkers for AKI and its clinical outcomes after burn injury.

Burn intensive care

As a result of continuous development in the treatment of burns, the LD50 (the burn size lethal to 50% of the population) for thermal injuries has risen from 42% total body surface area (TBSA) during the 1940s and 1950s to more than 90% TBSA for young thermally injured patients. This vast improvement in survival is due to simultaneous developments in critical care, advancements in resuscitation, control of infection through early excision, and pharmacologic support of the hypermetabolic response to burns. This article reviews these recent advances and how they influence modern intensive care of burns.

Neutrophil gelatinase associated lipocalin as an indicator of acute kidney injury and inflammation in burned children

INTRODUCTION

Neutrophil gelatinase associated lipocalin (NGAL) is a novel predictor of acute kidney injury (AKI), which increases with inflammation. We aimed to assess whether serum NGAL (SNGAL) and urine NGAL (UNGAL) can predict AKI in burned children.

METHODS

Patients were referred within the 12 h of burn to our center. Serum samples for SNGAL, C-reactive protein (CRP), procalcitonin (PCT) and urine for UNGAL, microalbumine (Umalb), creatinine (Ucr) were obtained at both admission and the 5th day after burn. Blood urea nitrogen (BUN) and serum creatinine (Scr) were examined daily.

RESULTS

Twenty-two subjects were enrolled and six (27.2%) of them developed AKI within the 48 h of injury. Burn size and abbreviated burn severity index (ABSI) were significantly increased in patients with AKI. CRP, PCT, SNGAL and UNGAL levels at admission and day 5 were significantly higher in patients with AKI than in those without AKI and controls. Scr was not significant between AKI and non-AKI groups at hospital days 1 and 5. A SNGAL level of 315 ng/ml and a UNGAL level of 100 ng/ml were determined as predictive cut-off values of AKI at admission (sensitivity and specificity: 71.4%, 83.3% and 93.3%, 93.7%, respectively). SNGAL and UNGAL were positively correlated with CRP, PCT, ABSI and Umalb/Ucr.

CONCLUSION

SNGAL and UNGAL are good early predictors of AKI in children with severe burn. NGAL might reflect the severity of burn insult and also could be used as an indicator of inflammation in burn children.

Umbilical Cord Mesenchymal Stem Cell Transplantation Ameliorates Burn-Induced Acute Kidney Injury in Rats

Excessive systemic inflammation following burns could lead to acute kidney injury (AKI). Mesenchymal stromal cells (MSCs) suppress immune cell responses and have beneficial effects in various inflammatory-related immune disorders. However, autologous MSCs are not vital enough for the treatment because of the severely burned patients’ deleterious condition. Umbilical cord–derived mesenchymal stem cells (UC-MSCs) could be a suitable substitute cell candidate but no data are available on the therapeutic effectiveness of UC-MSCs transplantation for burn injury and its consequences. In this study, UC-MSCs or ulinastatin was administered intravenously in the rats with burn trauma, and the therapeutic effects of UC-MSCs on the survival of severe burn-induced AKI rats and functional protection of kidney were analyzed. Results showed that UC-MSCs promoted the survival and prevented commitment to apoptosis of resident kidney cells and reduced organ microscopic damage in kidneys after thermal trauma. Thus, our study demonstrates that intravenously delivered UC-MSCs protected the host from death caused by kidney injury subsequent to severe burn, identifying UC-MSCs transplantation may be an attractive candidate for cell-based treatments for burns and induced organ damage.

Epidemiology of acute kidney injury in the intensive care unit

The incidence of acute kidney injury (AKI) in the intensive care unit (ICU) has increased during the past decade due to increased acuity as well as increased recognition. Early epidemiology studies were confounded by erratic definitions of AKI until recent consensus guidelines (RIFLE and AKIN) standardized its definition. This paper discusses the incidence of AKI in the ICU with focuses on specific patient populations. The overall incidence of AKI in ICU patients ranges from 20% to 50% with lower incidence seen in elective surgical patients and higher incidence in sepsis patients. The incidence of contrast-induced AKI is less (11.5%–19% of all admissions) than seen in the ICU population at large. AKI represents a significant risk factor for mortality and can be associated with mortality greater than 50%.

Incidence and relevance of acute kidney injury in patients hospitalized with acute coronary syndromes

Acute kidney injury (AKI) occurs frequently in patients with acute coronary syndromes (ACS) and is associated with adverse short- and long-term outcomes. To date, however, no standardized definition of AKI has been used for patients with ACS. As a result, information on its true incidence and the clinical and prognostic relevance according to the severity of renal function deterioration are still lacking. We retrospectively studied 3,210 patients with ACS. AKI was identified on the basis of the changes in serum creatinine during hospitalization according to the AKI Network criteria. Overall, 409 patients (13%) developed AKI: 262 (64%) had stage 1, 25 (6%) stage 2, and 122 (30%) stage 3 AKI. In-hospital mortality was greater in patients with AKI than in those without AKI (21% vs 1%; p <0.001). The adjusted risk of death increased with increasing AKI severity. Compared to no AKI, the adjusted odds ratio for death was 3.5 (95% confidence interval 1.79 to 6.83) with stage 1 AKI and 31.2 (95% confidence interval 16.96 to 57.45) with stage 2 to 3 AKI. A significant parallel increase in major adverse cardiac events was also observed comparing patients without AKI and those with stage 2 to 3 AKI. In conclusion, in patients with ACS, AKI is a frequent complication, and the graded increase of its severity, as assessed using the AKI Network classification, is associated with a progressive increased risk of in-hospital morbidity and mortality.

Selenium inhibits renal oxidation and inflammation but not acute kidney injury in an animal model of rhabdomyolysis

Acute kidney injury (AKI) is a manifestation of rhabdomyolysis (RM). Extracellular myoglobin accumulating in the kidney after RM promotes oxidative damage, which is implicated in AKI.

AIM

To test whether selenium (Se) supplementation diminishes AKI and improves renal function.

RESULTS

Dietary selenite increased Se in the renal cortex, as demonstrated by X-ray fluorescence microscopy. Experimental RM-stimulated AKI as judged by increased urinary protein/creatinine, clusterin, and kidney injury molecule-1 (KIM-1), decreased creatinine clearance (CCr), increased plasma urea, and damage to renal tubules. Concentrations of cholesterylester (hydro)peroxides and F₂-isoprostanes increased in plasma and renal tissues after RM, while aortic and renal cyclic guanidine monophosphate (cGMP; marker of nitric oxide (NO) bioavailability) decreased. Renal superoxide dismutase-1, phospho-P65, TNFα gene, MCP-1 protein, and the 3-chloro-tyrosine/tyrosine ratio (Cl-Tyr/Tyr; marker of neutrophil activation) all increased after RM. Dietary Se significantly decreased renal lipid oxidation, phospho-P65, TNFα gene expression, MCP-1 and Cl-Tyr/Tyr, improved NO bioavailability in aorta but not in the renal microvasculature, and inhibited proteinuria. However, CCr, plasma urea and creatinine, urinary clusterin, and histopathological assessment of AKI remained unchanged. Except for the Se++ group, renal angiotensin-receptor-1/2 gene/protein expression increased after RM with parallel increases in MEK1/2 inhibitor-sensitive MAPkinase (ERK) activity.

INNOVATION

We employed synchrotron radiation to identify Se distribution in kidneys, in addition to assessing reno-protection after RM.

CONCLUSION

Se treatment has some potential as a therapeutic for AKI as it inhibits oxidative damage and inflammation and decreases proteinuria, albeit histopathological changes to the kidney and some plasma and urinary markers of AKI remain unaffected after RM.

Review of burn research for the year 2010

Like the previous year, 2010 was another active year for research in burn care. For this year, more than 1200 burn-related articles were published on a diverse array of topics. In this review, we focus on innovative and impactful burn injury-related research. As in the previous review, we group articles according to the following categories: critical care, infection, inhalation injury, epidemiology, psychology, wound characterization and treatment, nutrition and metabolism, pain and itch management, burn reconstruction, and rehabilitation. We have found that burn research continues to be prolific throughout the world and reflects the wide-ranging and complex care requirements of burn survivors.

Relation between proteinuria and acute kidney injury in patients with severe burns

Introduction

Proteinuria in burn patients is common, and may be associated with acute kidney injury (AKI) and adverse outcomes. We evaluated the incidences, outcomes, characteristics and determinants of proteinuria and its influence on AKI and outcomes in burn patients.

Methods

This retrospective study was carried out in a hospital's burn department. The study population consisted of patients with burn injuries admitted during a five-year period. Positive urine dipstick readings were defined as mild (± or 1+) or heavy (≥ 2+) proteinuria, and AKI was diagnosed and staged according to the Risk, Injury, Failure, Loss, End Stage (RIFLE) classification system. Patient characteristics, management and outcomes were evaluated for associations with proteinuria using nonparametric tests, chi-square (χ²) tests and binary logistic regression.

Results

Of the patients admitted to the burn unit during the study period (n = 2,497), 865 (34.64%) were classified as having proteinuria. In the patients whose total burn surface areas (TBSA) were > 30% (n = 396), 271 patients (68.43%) had proteinuria and 152 of these patients (56.09%) met AKI criteria. No patients without proteinuria developed AKI. Intensive care unit (ICU) mortality rates were 0.8%, 16.67% and 30.77% (P < 0.001) in the groups with no, mild and heavy proteinuria, respectively. Logistic regression analysis identified proteinuria (OR 4.48; 95% CI, 2.824 to 7.108; P < 0.001) and sequential organ failure assessment (OR 1.383; 95% CI, 1.267 to 1.509; P < 0.001) as risk factors for AKI.

Conclusions

We observed a high prevalence of proteinuria in patients with severe burns (> 30% TBSA). Severely burned patients with proteinuria had a high risk of developing AKI and a poor prognosis for survival. This suggests that proteinuria should be used for identifying burn patients at risk of developing AKI.

The year in burns 2010

For 2010, roughly 1446 original burn research articles were published in scientific journals using the English language. This article reviews those with the most impact on burn treatment according to the Editor of one of the major journals (Burns) and his colleagues. As in previous reviews, articles were divided into the following topic areas: epidemiology, demographics of injury, wound characterisation and treatment, critical care, inhalation injury, infection, metabolism and nutrition, psychological considerations, pain and itching management, rehabilitation and long-term outcomes, and burn reconstruction. Each paper is considered very briefly, and the reader is referred to full manuscripts for details.

Outcome of acute kidney injury in severe burns: a systematic review and meta-analysis

PURPOSE

The main objective of this review was to analyse the prevalence and outcome of acute kidney injury (AKI) in patients with severe burn injury. AKI is a common complication in patients with severe burn injury and one of the major causes of death (often combined with other organ dysfunctions). Several definitions of AKI have been used, but the RIFLE 'consensus' classification is nowadays considered the gold standard, enabling a more objective comparison of populations.

METHODS

We performed a systematic literature search (1960-2009), involving PubMed, the Web of Science, the search engine Google and textbooks. Reference lists and the Science Citation Index search were also consulted. Attributable mortality was assessed by performing a meta-analysis.

RESULTS

This search yielded 57 articles and abstracts with relevant epidemiologic data of AKI in the burn population. Of these, 30 contained complete mortality data of the burn and control population, which revealed a 3- to 6-fold higher mortality for AKI patients in univariate analysis, depending on the applied definition. When defined by the RIFLE consensus classification, AKI occurred in one quarter of patients with severe burn injury (median mortality of 34.9%), and when defined by the need for renal replacement therapy (RRT), AKI occurred in 3% (median mortality of 80%). The prevalence of AKI slightly increased, but AKI-RRT decreased. However, the outcome in both groups improved.

CONCLUSION

Despite the wide variation of the analysed burn populations and definitions of AKI, this review clearly showed that AKI remains prevalent and is associated with increased mortality in patients with severe burn injury.