Can we prevent acute kidney injury?

Efficacy and safety of an algorithm using C-reactive protein to guide antibiotic therapy applied through a digital clinical decision support system: a study protocol for a randomised controlled clinical trial

INTRODUCTION

The escalating resistance of microorganisms to antimicrobials poses a significant public health threat. Strategies that use biomarkers to guide antimicrobial therapy-most notably Procalcitonin (PCT) and C-reactive protein (CRP)-show promise in safely reducing patient antibiotic exposure. While CRP is less studied, it offers advantages such as lower cost and broader availability compared with PCT.

METHODS AND ANALYSIS

This randomised clinical trial aims to evaluate a novel algorithm for non-critically ill adult patients. The algorithm incorporates key clinical variables and CRP behaviour. It will be applied through a mobile application as a digital clinical decision support system. The primary goal will be to assess the algorithm's effectiveness in reducing treatment duration compared with standard care based on current guidelines, while ensuring patient safety by monitoring the occurrence of adverse events.

ETHICS AND DISSEMINATION

Only patients who agree to participate in the study after reading the informed consent form will be included. This project was submitted for consideration to the Research Ethics Committee of the Federal University of Minas Gerais (COEP-UFMG) and received approval (Approval Number: 5.905.290). Collection of clinical and laboratory data from 200 patients is expected, extracted from electronic medical records and laboratory systems, along with serum samples stored for potential future analyses. Data will be preserved using the Research Electronic Data Capture platform, and serum samples will be stored in a regulated biorepository at UFMG. Access will be controlled via credentials, with privacy protections and anonymisation prior to sharing, which will occur during scientific publications.

TRIAL REGISTRATION NUMBER

This trial was registered on ClinicalTrials.gov (NCT05841875) and was last updated on 5 December 2024 at 12:49.

Pathophysiology of Red Blood Cell Trapping in Ischemic Acute Kidney Injury

Red blood cell (RBC) trapping describes the accumulation of RBCs in the microvasculature of the kidney outer medulla that occurs following ischemic acute kidney injury (AKI). Despite its prominence in human kidneys following AKI, as well as evidence from experimental models demonstrating that the severity of RBC trapping is directly correlated with renal recovery, to date, RBC trapping has not been a primary focus in understanding the pathogenesis of ischemic kidney injury. New evidence from rodent models suggests that RBC trapping is responsible for much of the tubular injury occurring in the initial hours after kidney reperfusion from ischemia. This early injury appears to result from RBC cytotoxicity and closely reflects the injury profile observed in human kidneys, including sloughing of the medullary tubules and the formation of heme casts in the distal tubules. In this review, we discuss what is currently known about RBC trapping. We conclude that RBC trapping is likely avoidable. The primary causes of RBC trapping are thought to include rheologic alterations, blood coagulation, tubular cell swelling, and increased vascular permeability; however, new data indicate that a mismatch in blood flow between the cortex and medulla where medullary perfusion is maintained during cortical ischemia is also likely critical. The mechanism(s) by which RBC trapping contributes to renal functional decline require more investigation. We propose a renewed focus on the mechanisms mediating RBC trapping, and RBC trapping-associated injury is likely to provide important knowledge for improving AKI outcomes. © 2024 American Physiological Society. Compr Physiol 14:5325-5343, 2024.

Analysis of the Association Between the Number of Intensivists and the Use of Cardiovascular Agonists: An Ecological Study Using Data From National Databases of Japan

Background Previous studies have demonstrated a correlation between management by intensivists and a decrease in hospital stay and mortality, yet the underlying reason remains unknown. Using open data from the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) and other databses, the present study aimed to explore the relationship between inotrope and vasoconstrictor use and the number of intensivists. Materials and methods Cardiovascular agonists listed in the 2020 NDB for which the total dose was known were included for analysis. Trends in cardiovascular agonist use over six years were then graphically assessed, and a linear regression model with the use of each target drug per prefecture as the objective variable in the 2020 data was created to analyze the impact of intensivists on drug use. Results A total of 61 drugs were classified into eight groups based on their composition, and drug use in each of the 47 prefectures was tabulated. Both the rate of use and cost showed a yearly decrease for dopamine but a yearly increase for norepinephrine. Multivariable analysis indicated that the number of intensivists was only significant for dopamine, which had a coefficient of -310 (95% CI: -548 to -72, p = 0.01) but that no such trend was evident for the other drugs. Conclusions The results demonstrated that an increasing number of intensivists in each prefecture correlated with decreasing use of dopamine, possibly explaining the improved outcomes observed in closed ICUs led by intensivists. Further research is warranted to establish causality.

Contrast removal from coronary sinus for prevention of contrast-induced nephropathy: a review

The occurrence of contrast-induced-nephropathy (CIN) is related to the amount of contrast administration. Any removal of contrast from systemic circulation before reaching the kidneys might be beneficial using a device that removes contrast from a coronary sinus (CS). This manuscript aims to review the available literature regarding contrast removal from CS during coronary angiography or intervention for the prevention of CIN.

Dopamine use and its consequences in the intensive care unit: a cohort study utilizing the Japanese Intensive care PAtient Database

Background

Dopamine is used to treat patients with shock in intensive care units (ICU) throughout the world, despite recent evidence against its use. The aim of this study was to identify the latest practice of dopamine use in Japan and also to explore the consequences of dopamine use in a large Asian population.

Methods

The Japanese Intensive Care PAtient Database (JIPAD), the largest intensive care database in Japan, was utilized. Inclusion criteria included: 1) age 18 years or older, 2) admitted to the ICU for reasons other than procedures, 3) ICU length of stay of 24 h or more, and 4) treatment with either dopamine or noradrenaline within 24 h of admission. The primary outcome was in-hospital mortality. Multivariable regression analysis was performed, followed by a propensity score-matched analysis.

Results

Of the 132,354 case records, 14,594 records from 56 facilities were included in this analysis. Dopamine was administered to 4,653 patients and noradrenaline to 11,844. There was no statistically significant difference in facility characteristics between frequent dopamine users (N = 28) and infrequent users (N = 28). Patients receiving dopamine had more cardiovascular diagnosis codes (70% vs. 42%; p < 0.01), more post-elective surgery status (60% vs. 31%), and lower APACHE III scores compared to patients given noradrenaline alone (70.7 vs. 83.0; p < 0.01). Multivariable analysis showed an odds ratio for in-hospital mortality of 0.86 [95% CI: 0.71–1.04] in the dopamine ≤ 5 μg/kg/min group, 1.46 [95% CI: 1.18–1.82] in the 5–15 μg/kg/min group, and 3.30 [95% CI: 1.19–9.19] in the > 15 μg/kg/min group. In a 1:1 propensity score matching for dopamine use as a vasopressor (570 pairs), both in-hospital mortality and ICU mortality were significantly higher in the dopamine group compared to no dopamine group (22.5% vs. 17.4%, p = 0.038; 13.3% vs. 8.8%, p = 0.018), as well as ICU length of stay (mean 9.3 days vs. 7.4 days, p = 0.004).

Conclusion

Dopamine is still widely used in Japan. The results of this study suggest detrimental effects of dopamine use specifically at a high dose.

Trial registration Retrospectively registered upon approval of the Institutional Review Board and the administration office of JIPAD.

Prediction of ventilator-associated pneumonia outcomes according to the early microbiological response: a retrospective observational study

Ventilator-associated pneumonia is a leading infectious cause of morbidity in critically ill patients; yet current guidelines offer no indications for follow-up cultures.We aimed to evaluate the role of follow-up cultures and microbiological response 3 days after diagnosing ventilator-associated pneumonia as predictors of short- and long-term outcomes.We performed a retrospective analysis of a cohort prospectively collected from 2004 to 2017. Ventilator-associated pneumonia was diagnosed based on clinical, radiographic, and microbiological criteria. For microbiological identification, a tracheobronchial aspirate was performed at diagnosis and repeated after 72 h. We defined three groups when comparing the two tracheobronchial aspirate results: persistence, superinfection, and eradication of causative pathogens.One-hundred-fifty-seven patients were enrolled in the study, among whom microbiological persistence, superinfection, and eradication was present in 67 (48%), 25 (16%), and 65 (41%), respectively, after 72hs. Those with superinfection had the highest mortalities in the intensive care unit (p=0.015) and at 90 days (p=0.036), while also having the fewest ventilation-free days (p=0.024). Multivariable analysis revealed shock at VAP diagnosis (odds ratios [OR] 3.43; 95% confidence interval [CI] 1.25 to 9.40), Staphylococcus aureus isolation at VAP diagnosis (OR 2.87; 95%CI 1.06 to 7.75), and hypothermia at VAP diagnosis (OR 0.67; 95%CI 0.48 to 0.95, per +1°C) to be associated with superinfection.Our retrospective analysis suggests that ventilator-associated pneumonia short-term and long-term outcomes may be associated with superinfection in follow-up cultures. Follow-up cultures may help guiding antibiotic therapy and its duration. Further prospective studies are necessary to verify our findings.

Ischemic Renal Injury: Can Renal Anatomy and Associated Vascular Congestion Explain Why the Medulla and Not the Cortex Is Where the Trouble Starts?

The kidneys receive approximately 20% of cardiac output and have a low fractional oxygen extraction. Quite paradoxically, however, the kidneys are highly susceptible to ischemic injury (injury associated with inadequate blood supply), which is most evident in the renal medulla. The predominant proposal to explain this susceptibility has been a mismatch between oxygen supply and metabolic demand. It has been proposed that unlike the well-perfused renal cortex, the renal medulla normally operates just above the threshold for hypoxia and that further reductions in renal perfusion cause hypoxic injury in this metabolically active region. An alternative proposal is that the true cause of ischemic injury is not a simple mismatch between medullary metabolic demand and oxygen supply, but rather the susceptibility of the outer medulla to vascular congestion. The capillary plexus of the renal outer medullary region is especially prone to vascular congestion during periods of ischemia. It is the failure to restore the circulation to the outer medulla that mediates complete and prolonged ischemia to much of this region, leading to injury and tubular cell death. We suggest that greater emphasis on developing clinically useful methods to help prevent or reverse the congestion of the renal medullary vasculature may provide a means to reduce the incidence and cost of acute kidney injury.

Physical Exercise Exacerbates Acute Kidney Injury Induced by LPS via Toll-Like Receptor 4

Introduction: Lipopolysaccharide (LPS) is a systemic response-triggering endotoxin, which has the kidney as one of its first targets, thus causing acute injuries to this organ. Physical exercise is capable of promoting physiological alterations and modulating inflammatory responses in the infectious process through multiple parameters, including the toll-like receptor (TLR)-4 pathway, which is the main LPS signaling in sepsis. Additionally, previous studies have shown that physical exercise can be both a protector factor and an aggravating factor for some kidney diseases. This study aims at analyzing whether physical exercise before the induction of LPS endotoxemia can protect kidneys from acute kidney injury.

Methods: C57BL/6J male mice, 12 weeks old, were distributed into four groups: (1) sedentary (control, N = 7); (2) sedentary + LPS (N = 7); (3) trained (N = 7); and (4) trained + LPS (N = 7). In the training groups, the animals exercised 5×/week in a treadmill, 60 min/day, for 4 weeks (60% of max. velocity). Sepsis was induced in the training group by the application of a single dose of LPS (5 mg/kg i.p.). Sedentary animals received LPS on the same day, and the non-LPS groups received a saline solution instead. All animals were euthanized 24 h after the administration of LPS or saline.

Results: The groups receiving LPS presented a significant increase in serum urea (p < 0.0001) and creatinine (p < 0.001) concentration and renal gene expression of inflammatory markers, such as tumor necrosis factor alpha and interleukin-6, as well as TLRs. In addition, LPS promoted a decrease in reduced glutathione. Compared to the sedentary + LPS group, trained + LPS showed overexpression of a gene related to kidney injury (NGAL, p < 0.01) and the protein levels of LPS receptor TLR-4 (p < 0.01). Trained + LPS animals showed an expansion of the tubulointerstitial space in the kidney (p < 0.05) and a decrease in the gene expression of hepatic AOAH (p < 0.01), an enzyme involved in LPS clearance.

Conclusion: In contrast to our hypothesis, training was unable to mitigate the renal inflammatory response caused by LPS. On the contrary, it seems to enhance injury by accentuating endotoxin-induced TLR-4 signaling. This effect could be partly due to the modulation of a hepatic enzyme that detoxifies LPS.

Renal replacement therapy: a practical update

Acute kidney injury (AKI) is defined as an abrupt decrease in kidney function, with the most severe form requiring some method of renal replacement therapy (RRT). The use of RRT is required in 5-10% of critically ill patients who develop severe AKI. Renal replacement therapy can be provided as either intermittent hemodialysis or one of the various modes of continuous renal replacement therapy (CRRT), with CRRT potentially conferring an advantage with respect to renal recovery and dialysis independence. There is no difference in mortality when comparing low (< 25 mL·kg^-1·hr^-1) vs high (> 40 mL·kg^-1·hr^-1) RRT dosing. Continuous renal replacement therapy may be run in different modes of increasing complexity depending on a given patient's clinical needs. Regional citrate anticoagulation is recommended as the therapy of choice for the majority of critically ill patients requiring CRRT.

Effects of fenoldopam on kidney function parameters and its therapeutic efficacy in the management of acute kidney injury in dogs with heatstroke

Background

Acute kidney injury (AKI) is common in dogs, but evidence of efficacy of its treatment is lacking.

Objective

To evaluate the efficacy of fenoldopam in the management of AKI.

Animals

Forty dogs with naturally occurring heatstroke.

Methods

Dogs were prospectively enrolled and divided into treatment and the placebo groups (fenoldopam, constant rate infusion [CRI] of 0.1 µg/kg/min or saline, respectively). Urine production (UP) was measured using a closed system. Urinary clearances were performed at 4, 12, and 24 hours after presentation to estimate the effect of fenoldopam on UP, glomerular filtration rate (GFR) and sodium fractional excretion (NaFE).

Results

At presentation, severity of heatstroke, based on a previously developed scoring system, was similar between the study groups, but was significantly worse in nonsurvivors compared with survivors. Fenoldopam administration was not associated with hypotension. Overt AKI was diagnosed, based on the International Renal Interest Society guidelines in 22/40 (55%) of the dogs. Overall, 14/40 dogs (35%) died, with no significant (P = .507) mortality rate difference between the fenoldopam (6/20 dogs; 30%) and placebo (8/20; 40%) groups. The proportion of dogs with AKI did not differ between the fenoldopam and the placebo groups (9/20; 45% versus 13/20; 65%, respectively; P = .204). There were no differences in UP, GFR, and NaFE between the fenoldopam and the placebo groups.

Conclusion and Clinical Importance

Fenoldopam CRI at 0.1 µg/kg/min did not have a clinically relevant effect on kidney function parameters in dogs with severe heatstroke‐associated AKI.

Preoperative hydration with 0.9% normal saline to prevent acute kidney injury after major elective open abdominal surgery: A randomised controlled trial

BACKGROUND

Postoperative acute kidney injury (AKI) is the second leading cause of hospital-acquired AKI. Although many preventive strategies have been tested, none of them has been totally effective.

OBJECTIVE

We investigated whether preoperative intravenous hydration with 0.9% normal saline could prevent postoperative AKI.

DESIGN

Randomised controlled trial.

SETTING

University Ramón y Cajal Hospital, Spain, from June 2006 to February 2011.

PATIENTS

Total 328 inpatients scheduled for major elective open abdominal surgery.

INTERVENTION

0.9% normal saline at a dose of 1.5 ml kg h for 12 h before surgery.

MAIN OUTCOME MEASURES

The primary outcome was the overall postoperative AKI incidence during the first week after surgery defined by risk, injury, failure, loss, end-stage kidney disease (RIFLE) and AKI network (AKIN) creatinine criteria. Secondary endpoints were the need for ICU admission, renal replacement therapy during the study period and adverse events and hospital mortality during hospital admission.

RESULTS

There was no difference in the incidence of AKI between groups: 4.7% in the normal saline group versus 5.0% in the control group and 11.4% in the 0.9% normal saline group versus 7.9% in the control group as assessed by the RIFLE and AKIN creatinine criteria, respectively. Absolute risk reductions (95% confidence interval) were -0.3% (-5.3 to 4.7%) for RIFLE and 3.5% (-10.2 to 3.6%) for AKIN. ICU admission after surgery was required in 44.5% of all participants. Only 2 (0.7%) patients required renal replacement therapy during the first week after surgery. The analysis of adverse events did not show statistically significant differences between the groups except for pain. In our population, 8 (2.4%) patients died during their hospital admission.

CONCLUSION

Intravenous hydration with 0.9% normal saline before major open abdominal surgery was not effective in preventing postoperative AKI. No safety concerns were identified during the trial.

TRIAL REGISTRATIONS

Clinical trials.gov: NCT00953940 and EUDRA CT: 2005-004755-35.

Infectious Etiologies and Patient Outcomes in Pediatric Septic Shock

BACKGROUND

Septic shock remains an important cause of death and disability in children. Optimal care requires early recognition and treatment.

METHODS

We evaluated a retrospective cohort of children (age <19) treated in our emergency department (ED) for septic shock during 2008-2012 to investigate the association between timing of antibiotic therapy and outcomes. The exposures were (1) receipt of empiric antibiotics in ≤1 hour and (2) receipt of appropriate antibiotics in ≤1 hour. The primary outcome was development of new or progressive multiple system organ dysfunction syndrome (NP-MODS). The secondary outcome was mortality.

RESULTS

Among 321 patients admitted to intensive care, 48% (n = 153) received empiric antibiotics in ≤1 hour. These patients were more ill at presentation with significantly greater median pediatric index of mortality 2 (PIM2) scores and were more likely to receive recommended resuscitation in the ED (61% vs 14%); however, rates of NP-MODS (9% vs 12%) and hospital mortality (7% vs 4%) were similar to those treated later. Early, appropriate antibiotics were administered to 33% (n = 67) of patients with identified or suspected bacterial infection. These patients had significantly greater PIM2 scores but similar rates of NP-MODS (15% vs 15%) and hospital mortality (10% vs 6%) to those treated later.

CONCLUSIONS

Critically ill children with septic shock treated in a children's hospital ED who received antibiotics in ≤1 hour were significantly more severely ill than those treated later, but they did not have increased risk of NP-MODS or death.

Protection of nitro-fatty acid against kidney diseases

Nitrated derivatives of unsaturated fatty acids are endogenously formed under oxidative and nitrative stress condition and are defined as electrophilic fatty acids containing a nitro group to a carbon-carbon double bond. Among the most studied nitro derivatives of unsaturated fatty acids are nitro-oleic acid (OA-NO₂) and nitro-linoleic acid (LNO₂). These products exhibit novel protective actions in a variety of rodent disease models. Diverse signaling events are responsible for effects of nitrated fatty acid, including activating peroxisome proliferator-activated receptor-dependent gene expression, suppressing NF-κB-induced inflammation, inhibiting oxidative stress, and increasing both endothelial nitric oxide synthase- and Nrf2-dependent gene regulation. Nitrated fatty acids have been emerging not only as a unique class of signaling molecules produced endogenously and but also as multipotent modulators of cell signaling pathways in cardiovascular and renal diseases. In this review, we discuss biochemical properties of nitrated fatty acid and its signaling pathways in the modulation of cellular events. A major focus is to review recent knowledge of nitrated fatty acid on the treatment of kidney diseases and its therapeutic potential for inflammation and metabolic disorders, with special emphasis on acute kidney injury and diabetic kidney disease.

Kidney donation after circulatory death (DCD): state of the art

Ischemia–reperfusion (IR) injury to the kidney occurs in a range of clinically important scenarios including hypotension, sepsis and in surgical procedures such as cardiac bypass surgery and kidney transplantation, leading to acute kidney injury (AKI). Mitochondrial oxidative damage is a significant contributor to the early phases of IR injury and may initiate a damaging inflammatory response. Here we assessed whether the mitochondria targeted antioxidant MitoQ could decrease oxidative damage during IR injury and thereby protect kidney function. To do this we exposed kidneys in mice to in vivo ischemia by bilaterally occluding the renal vessels followed by reperfusion for up to 24 h. This caused renal dysfunction, measured by decreased creatinine clearance, and increased markers of oxidative damage. Administering MitoQ to the mice intravenously 15 min prior to ischemia protected the kidney from damage and dysfunction. These data indicate that mitochondrial oxidative damage contributes to kidney IR injury and that mitochondria targeted antioxidants such as MitoQ are potential therapies for renal dysfunction due to IR injury.

Importance of neutrophil gelatinase-associated lipocalin in differential diagnosis of acute and chronic renal failure

Background:

Neutrophil Gelatinase-associated Lipocalin (NGAL) protein is easily detected in the blood and urine soon after acute renal injury. NGAL gains features of an early, sensitive and noninvasive biomarker for acute renal injury. Recent evidences suggest that its expression is also increased in CRF reflecting the severity of disease.

Objectives:

In the present study, we aimed to investigate whether blood NGAL level plays a role in the differential diagnosis of acute and chronic renal failure.

Patients and Methods:

This was a prospective case-control study. Fifty patients presented to emergency department with acute renal failure (ARF), 30 with chronic renal failure (CRF) and 20 healthy individuals as control group were included in this study. Blood pH, HCO3^-, BUN, creatinine and potassium values were evaluated in all patients. Blood NGAL values were evaluated in all groups. BUN, serum creatinine and NGAL values were statistically compared between patients and controls.

Results:

Median NGAL levels in patients was 304.50 (29), and 60 (0) in control, which was statistically significant between the two groups (Z = -6.477, P < 0.001). The median NGAL values were 261.50 ± 291 in ARF group and 428.50 ± 294 in CRF group. There was a significant difference in NGAL level between ARF and CRF groups (Z = -2.52, P = 0.012). Median BUN values were 153.46 ± 82.47 in ARF group and 169.40 ± 93.94 in CRF group. There was no significant difference in BUN value between ARF and CRF groups (P > 0.05). Median creatinine values were 2.84 ± 2.95 in ARF group and 4.78 ± 4.32 in CRF group. In serum creatinine values, a significant difference was found between ARF and CRF groups (P < 0.05).

Conclusions:

Serum NGAL levels of ARF and CRF patients were significantly higher than healthy individuals. In addition, NGAL values of patients with CRF were significantly higher than those of ARF. Serum NGAL values can be used to detect renal injury and differentiate ARF and CRF.

Acute kidney injury

Acute kidney injury is a frequent and serious complication in hospitalized patients. Mortality rates have not substantially been decreased during the last 20 years. In most patients AKI results from transient renal hypoperfusion or ischemia. The consequences include tubular cell dysfunction/damage, inflammation of the organ, and post-ischemic microvasculopathy. The two latter events perpetuate kidney damage in AKI. Clinical manifestations result from diminished excretion of water, electrolytes, and endogenous / exogenous waste products. Patients are endangered by cardiovascular complications such as hypertension, heart failure, and arrhythmia. In addition, the whole organism may be affected by systemic toxification (uremia). The diagnostic approach in AKI involves several steps with renal biopsy inevitable in some patients. The current therapy focuses on preventing further kidney damage and on treatment of complications. Different pharmacological strategies have failed to significantly improve prognosis in AKI. If dialysis treatment becomes mandatory, intermittent and continuous renal replacement therapies are equally effective. Thus, new therapies are urgently needed in order to reduce short- and long-term outcome in AKI. In this respect, stem cell-based regimens may offer promising perspectives.

The attributable mortality of acute kidney injury: a sequentially matched analysis*

OBJECTIVE

Acute kidney injury in the critically ill is an independent risk factor for adverse outcome. The magnitude of the impact of acute kidney injury on outcome, however, is still unclear. This study aimed to estimate the excess mortality attributable to acute kidney injury.

DESIGN

We performed a sequentially matched analysis according to the day of acute kidney injury diagnosis after ICU admission. Patients with acute kidney injury and those without acute kidney injury were matched according to age, sex, ICU admission diagnosis, Simplified Acute Physiology Score II without renal and age components, and the propensity to develop acute kidney injury at each of the four matching time points.

SETTING

Cohort of 16 participating ICUs from the prospective Finnish Acute Kidney Injury study.

PATIENTS

Cohort of 2,719 consecutive patients with either emergency admission or elective postsurgical patients with an expected ICU stay greater than 24 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 2,719 patients included in the study, acute kidney injury developed in 1,081 patients (39.8%) according to the Kidney Disease: Improving Global Outcomes-definition during ICU treatment on days 1-5. Of these, 477 patients were successfully matched to 477 patients who did not develop acute kidney injury. The 90-day mortality of the matched patients with acute kidney injury was 125 of 477 (26.2%) compared with 84 of 477 (17.6%) for their matched controls without acute kidney injury. Thus, the absolute excess 90-day mortality attributable to acute kidney injury was estimated at 8.6 percentage points (95% CI, 2.6-17.6 percentage points). The population attributable risk (95% CI) of 90-day mortality associated with acute kidney injury was 19.6% (10.3-34.1%).

CONCLUSIONS

In general ICU patients, the absolute excess 90-day mortality statistically attributable to acute kidney injury is substantial (8.6%), and the population attributable risk was nearly 20%. Our findings are useful in planning suitably powered future clinical trials to prevent and treat acute kidney injury in critically ill patients.

Intravascular administration of mannitol for acute kidney injury prevention: a systematic review and meta-analysis

BACKGROUND

The effects of mannitol administration on acute kidney injury (AKI) prevention remain uncertain, as the results from clinical studies were conflicting. Due to the lack of strong evidence, the KDIGO Guideline for AKI did not propose completely evidence-based recommendations on this issue.

METHODS

We searched PubMed, EMBASE, clinicaltrials.gov and Cochrane Controlled Trials Register. Randomized controlled trials on adult patients at increased risk of AKI were considered on the condition that they compared the effects of intravascular administration of mannitol plus expansion of intravascular volume with expansion of intravascular volume alone. We calculated pooled risk ratios, numbers needed to treat and mean differences with 95% confidence intervals for dichotomous data and continuous data, respectively.

RESULTS

Nine trials involving 626 patients were identified. Compared with expansion of intravascular volume alone, mannitol infusion for AKI prevention in high-risk patients can not reduce the serum creatinine level (MD 1.63, 95% CI -6.02 to 9.28). Subgroup analyses demonstrated that serum creatinine level is negatively affected by the use of mannitol in patients undergoing an injection of radiocontrast agents (MD 17.90, 95% CI 8.56 to 27.24). Mannitol administration may reduce the incidence of acute renal failure or the need of dialysis in recipients of renal transplantation (RR 0.34, 95% CI 0.21 to 0.57, NNT 3.03, 95% CI 2.17 to 5.00). But similar effects were not found in patients at high AKI risk, without receiving renal transplantation (RR 0.29, 95% CI 0.01 to 6.60).

CONCLUSIONS

Intravascular administration of mannitol does not convey additional beneficial effects beyond adequate hydration in the patients at increased risk of AKI. For contrast-induced nephropathy, the use of mannitol is even detrimental. Further research evaluating the efficiency of mannitol infusions in the recipients of renal allograft should be undertaken.

The significance of antiretroviral-associated acute kidney injury in a cohort of ambulatory human immunodeficiency virus-infected patients

BACKGROUND

To determine the incidence and significance of acute kidney injury (AKI) after initiating highly active antiretroviral therapy (HAART).

METHODS

A prospective cohort study of 271 consecutively treated HIV-infected patients, initiating first (75) or sequential HAART (196) from January 2008 to June 2011. AKI was diagnosed according to the Risk, Injury, Failure, Loss of kidney function, End-stage renal disease (RIFLE)/Acute Kidney Injury Network (AKIN) criteria, and the risk of progression to chronic kidney disease (CKD) was evaluated.

RESULTS

A greater estimated glomerular filtration rate (eGFR) decrease after 1 year was observed for patients initiating a tenofovir disoproxil fumarate (TDF)-based regimen (-6.45 versus +0.98 mL/min/1.73 m(2) when compared with patients without TDF; P < 0.01), both in the case of the first (-8.5 versus -2.27; P = 0.04) or successive regimens (-5.3 versus + 1.18 mL/min/1.73 m(2); P < 0.01). AKI, as defined, was observed in 10% (28 cases, 6.98 episodes/100 patients-year), mostly stage I (27 cases), in a median time of 6 (3-16.5) months. Four cases (14%), having a worse baseline renal function progressed to CKD, whereas four recovered completely. In the multivariate analysis, AKI was associated with the concomitant use of cotrimoxazole prophylaxis and to low CD4+ count. CKD was diagnosed in 2% (six cases) of patients. Therefore, the overall rate of HAART-associated renal disorders was 11% (30 cases, 7.46 episodes/100 patients-year (95% confidence interval, 6.09-8.83).

CONCLUSIONS

The initiation of a tenofovir-based regimen is followed by a significant decline in eGFR, although it could be misinterpreted by the concomitant use of cotrimoxazole. A substantial proportion of patients develop AKI, but only a minority progress to CKD. Patients initiating HAART and developing AKI should be carefully monitored for progression of renal disease.

Sepsis: update in the management

Sepsis and septic shock are syndromes that overlap between several disciplines and subspecialties. Emerging evidence suggests that sepsis may be associated with short- and long-term adverse outcomes, even when the syndrome does not appear to be severe and is not managed in the intensive care unit. Hence, all practicing clinicians need to be familiar with the fundamental principles of diagnosis and management of sepsis. In this review, we have summarized the key components in the management of sepsis/septic shock, including early recognition, early resuscitation, principles of antibiotic therapy, organ support, and role of adjunctive therapies.

Contrast-induced kidney injury: mechanisms, risk factors, and prevention

In general, iodinated contrast media (CM) are tolerated well, and CM use is steadily increasing. Acute kidney injury is the leading life-threatening side effect of CM. Here, we highlight endpoints used to assess CM-induced acute kidney injury (CIAKI), CM types, risk factors, and CIAKI prevention. Moreover, we put forward a unifying theory as to how CIAKI comes about; the kidney medulla's unique hyperosmolar environment concentrates CM in the tubules and vasculature. Highly concentrated CM in the tubules and vessels increases fluid viscosity. Thus, flow through medullary tubules and vessels decreases. Reducing the flow rate will increase the contact time of cytotoxic CM with the tubular epithelial cells and vascular endothelium, and thereby damage cells and generate oxygen radicals. As a result, medullary vasoconstriction takes place, causing hypoxia. Moreover, the glomerular filtration rate declines due to congestion of highly viscous tubular fluid. Effective prevention aims at reducing the medullary concentration of CM, thereby diminishing fluid viscosity. This is achieved by generous hydration using isotonic electrolyte solutions. Even forced diuresis may prove efficient if accompanied by adequate volume supplementation. Limiting the CM dose is the most effective measure to diminish fluid viscosity and to reduce cytotoxic effects.

N-acetylcysteine is effective for prevention but not for treatment of folic acid-induced acute kidney injury in mice

OBJECTIVES

There is controversy regarding the benefits of N-acetylcysteine in acute kidney injury. This study was to compare three commonly used regimens and explore which regimen is best for the protection of acute kidney injury.

DESIGN

Prospective experimental study.

SETTING

University research laboratory.

INTERVENTIONS

Acute kidney injury was induced with folic acid intraperitoneal injection in mice. Mice in pretreatment were treated with a subcutaneous injection of N-acetylcysteine before the folic acid injection. Mice in posttreatment were treated with N-acetylcysteine after folic acid. Mice in pre- + posttreatment were treated with N-acetylcysteine before folic acid and after folic acid. Placebo mice received vehicle only using the pre- + posttreatment protocol. Fourteen healthy animals were given N-acetylcysteine to evaluate for toxicity and the other 24 mice subjected to folic acid were killed for kidney histology and analysis for oxidative injury. The same studies were also carried out in milder acute kidney injury (lower folic acid) model.

MEASUREMENTS AND MAIN RESULTS

Plasma concentrations of creatinine, cystatin C, and reduced glutathione were measured. Survival time was assessed up to 7 days. The survival rates in N-acetylcysteine pretreatment mice were significantly better (73.33% vs. 46.67%, p < .04) and acute kidney injury was significantly less compared with placebo. However, mice with posttreatment exhibited significantly worse survival and more severe acute kidney injury. Histologic findings were consistent with functional parameters. Glutathione levels decreased less in N-acetylcysteine pretreatment but also increased beginning on day 2 compared with placebo (11.5 vs. 8.1 μg/mL, p < .05). Glutathione levels did not increase in N-acetylcysteine posttreatment. However, three different N-acetylcysteine interventions neither significantly improved nor worsened renal function in the milder acute kidney injury model.

CONCLUSION

N-acetylcysteine pretreatment was effective in reducing the incidence and severity of acute kidney injury as well as in increasing survival. However, N-acetylcysteine posttreatment worsened folic acid toxicity. Only pretreatment was effective in increasing glutathione. These data may help explain the variation from clinical studies of N-acetylcysteine use.

Identification of candidate serum biomarkers for severe septic shock-associated kidney injury via microarray

Introduction

Septic-shock-associated acute kidney injury (SSAKI) carries high morbidity in the pediatric population. Effective treatment strategies are lacking, in part due to poor detection and prediction. There is a need to identify novel candidate biomarkers of SSAKI. The objective of our study was to determine whether microarray data from children with septic shock could be used to derive a panel of candidate biomarkers for predicting SSAKI.

Methods

A retrospective cohort study compared microarray data representing the first 24 hours of admission for 179 children with septic shock with those of 53 age-matched normal controls. SSAKI was defined as a >200% increase of baseline serum creatinine, persistent to 7 days after admission.

Results

Patients with SSAKI (n = 31) and patients without SSAKI (n = 148) were clinically similar, but SSAKI carried a higher mortality (45% vs. 10%). Twenty-one unique gene probes were upregulated in SSAKI patients versus patients without SSAKI. Using leave-one-out cross-validation and class prediction modeling, these probes predicted SSAKI with a sensitivity of 98% (95% confidence interval (CI) = 81 to 100) and a specificity of 80% (95% CI = 72 to 86). Serum protein levels of two specific genes showed high sensitivity for predicting SSAKI: matrix metalloproteinase-8 (89%, 95% CI = 64 to 98) and elastase-2 (83%, 95% CI = 58 to 96). Both biomarkers carried a negative predictive value of 95%. When applied to a validation cohort, although both biomarkers carried low specificity (matrix metalloproteinase-8: 41%, 95% CI = 28 to 50; and elastase-2: 49%, 95% CI = 36 to 62), they carried high sensitivity (100%, 95% CI = 68 to 100 for both).

Conclusions

Gene probes upregulated in critically ill pediatric patients with septic shock may allow for the identification of novel candidate serum biomarkers for SSAKI prediction.

Goal-directed therapy in small animal critical illness

Monitoring critically ill patients can be a daunting task even for experienced clinicians. Goal-directed therapy is a technique involving intensive monitoring and aggressive management of hemodynamics in patients with high risk of morbidity and mortality. The aim of goal-directed therapy is to ensure adequate tissue oxygenation and survival. This article reviews commonly used diagnostics in critical care medicine and what the information gathered signifies and discusses clinical decision making on the basis of diagnostic test results. One example is early goal-directed therapy for severe sepsis and septic shock. The components and application of goals in early goal-directed therapy are discussed.

[Acute kidney injury]

Acute kidney injury (AKI) is defined as an abrupt decline in the glomerular filtration rate with accumulation of nitrogenous waste products and the inability to maintain fluid and electrolyte homeostasis. Occurring in 7% of all hospitalized patients and 28% to 35% of those in intensive care units, AKI increases hospital mortality. Early evaluation should include differentiating prerenal and postrenal components from intrinsic renal disease. Biological markers can give early warning of AKI and assist with differential diagnosis and assessment of prognosis. The most effective preventive measure is to maintain adequate circulation and cardiac output, avoiding ischemia- or nephrotoxin-induced injury. To that end, patients and situations of risk must be identified, hemodynamics and diuresis monitored, hypovolemia reversed, and nephrotoxins avoided. Protective agents such as sodium bicarbonate, mannitol, prostagiandins, calcium channel blockers, N-acetyl-L-cysteine, sodium deoxycholate, allopurinol, and pentoxifylline should be used. Treatment includes the elimination of prerenal and postrenal causes of AKI; adjustment of doses according to renal function; avoidance of both overhydration and low arterial pressure; maintenance of electrolytic balance, avoiding hyperkalemia and correcting hyperglycemia; and nutritional support, assuring adequate protein intake. For severe AKI, several modalities of renal replacement therapy, differentiated by mechanism and duration, are available. Timing--neither the best moment to start dialysis nor the optimal duration--has been not established. Early detection of AKI is necessary for preventing progression and starting renal replacement therapy at adjusted doses that reflect metabolic requirements.

Acute kidney injury: not just acute renal failure anymore?

Until recently, no uniform standard existed for diagnosing and classifying acute renal failure. To clarify diagnosis, the Acute Dialysis Quality Initiative group stated its consensus on the need for a clear definition and classification system of renal dysfunction with measurable criteria. Today the term acute kidney injury has replaced the term acute renal failure, with an understanding that such injury is a common clinical problem in critically ill patients and typically is predictive of an increase in morbidity and mortality. A classification system, known as RIFLE (risk of injury, injury, failure, loss of function, and end-stage renal failure), includes specific goals for preventing acute kidney injury: adequate hydration, maintenance of renal perfusion, limiting exposure to nephrotoxins, drug protective strategies, and the use of renal replacement therapies that reduce renal injury.

Contrast-induced nephropathy in patients undergoing elective and urgent procedures

Contrast-induced nephropathy (CIN) is an acute and severe complication after contrast media administration. The most important step in preventing CIN is identifying high-risk patients. In this review, we evaluate and summarize the evidence regarding the CIN prophylaxis, including the withdrawal of the potentially nephrotoxic drugs, hydration by isotonic solution or NaHCO(3), pharmaceutical treatment with N-acetylcysteine (N-AC), adenosine antagonists, ascorbic acid, renal procedures including hemofiltration or dialysis, and to the optimal use of the contrast. We suggest it is possible to reduce the burden of CIN by carefully incorporating these recommendations. After review of published literature in this field, we conclude that the cornerstone of the CIN prevention should be combination of hydration (normal saline or NaHCO(3)) and the use of N-AC.

Acute kidney injury in hospitalized HIV-infected patients: a cohort analysis

BACKGROUND

Acute kidney injury (AKI) in hospitalized human immunodeficiency virus (HIV)-infected patients in the highly active antiretroviral therapy (HAART) era has not been extensively addressed. The aim of the present study was to analyze the incidence, etiology, risk factors and the impact of AKI on in-hospital mortality in this population.

METHODS

A total of 489 HIV-infected patients hospitalized in the Department of Infectious Diseases of the Hospital de Santa Maria (Lisbon, Portugal) between January 2005 and December 2007 were retrospectively studied. AKI was defined by 'Risk Injury Failure Loss of kidney function End-stage kidney disease'(RIFLE) criteria based on serum creatinine. Comparisons between patients with and without AKI were performed using the Student's t-test or the χ2 test. Logistic regression method was used to determine predictors of AKI and in-hospital mortality. A two-tailed P-value <0.05 was considered significant.

RESULTS

Eighty-eight patients (18%) had AKI within the hospitalization period. The most common etiologies of AKI were sepsis (59%), nephrotoxic drug administration (37.5%), volume depletion (21.6%) and radiocontrast use (20.5%). Preexisting hypertension [adjusted odds ratio (OR) 2.4, 95% confidence interval (CI) 1.04-5.6, P = 0.04], acquired immunodeficiency syndrome (adjusted OR 2.7, 95% CI 1.2-6, P = 0.02), sepsis (adjusted OR 23, 95% CI 11-45.3, P < 0.001) and nephrotoxic drug administration (adjusted OR 2.8, 95% CI 1.4-5.8, P = 0.004) were risk factors of AKI. Patients with AKI had higher in-hospital mortality than patients without AKI (27.3 versus 8%, P < 0.001). In multivariate analysis, AKI was a risk factor of in-hospital mortality (adjusted OR 2.7, 95% CI 1.3-5.6, P = 0.008).

CONCLUSION

AKI occurred in 18% of hospitalized HIV-infected patients and it was independently associated with increased in-hospital mortality.

An update and review of acute kidney injury in pediatrics

OBJECTIVES

To inform the pediatric intensivist of recent advancements in acute kidney injury diagnosis and management.

DATA SOURCES

Studies were identified from MEDLINE (OVID), PubMed, and the Cochrane Library for topics relevant to acute kidney injury. We also reviewed bibliographies of relevant studies. DATA EXTRACTION, SYNTHESIS, AND OUTLINE REVIEW: Because of the lack of prospective trials, a majority of information is extracted from observational and retrospective data. The pathophysiology section reviews acute kidney injury mechanisms and highlights data regarding distal injury from experimental acute kidney injury. The epidemiology section focuses on incidence and outcomes of acute kidney injury, highlighting new strategies for diagnosis. The management section cites studies investigating hemodynamic optimization, nutrition, and fluid management, including the indications and impact of continuous renal replacement therapy in fluid overload.

CONCLUSIONS

There is limited data-driven evidence in pediatrics regarding effective therapy for acute kidney injury, a significant problem in the pediatric intensive care unit extending length of stay, ventilator days, and overall mortality. Sublethal kidney injury may be contributing to overall morbidity. We conclude that prospective clinical trials are needed to evaluate specific diagnostic aids, such as biomarkers, and therapeutic strategies, such as early initiation of continuous renal replacement therapy in children with fluid overload.

Novel aspects of pharmacological therapies for acute renal failure

Acute renal failure (ARF) comprises several syndromes that are associated with a sudden decrease in renal function. ARF is common among critically ill patients, is typically multifactorial and is of great prognostic significance. Indeed, even moderate changes in renal function significantly add to the morbidity and worsen mortality associated with ARF. Recent definitions, namely the renal Risk, Injury, Failure, Loss of renal function and End-stage kidney disease (RIFLE) classification or Acute Kidney Injury Network (AKIN) criteria, which incorporate the levels of oliguria in addition to fractional serum creatinine elevation, are important because the magnitude of kidney injury according to those definitions correlates very well with both short- and long-term patient survival. However, preventive strategies are most effective when started before oliguria or elevated serum creatinine is detectable, as those criteria already reflect established renal tubular cell injury. New biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) or kidney injury molecule-1 (KIM-1) that increase prior to the serum creatinine elevation are promising and have been proven to be useful in this regard in a few clinical trials. In addition, genetic profiling may define patients at risk earlier and help to individualize preventive strategies. Well established strategies include limiting dehydration and hypotension by the use of intravenous isotonic fluids at an optimal and individualized rate, as well as avoiding exposure to nephrotoxins, which include aminoglycosides, amphotericin or non-ionic contrast. Generally accepted and evidence-based pharmacological preventive or therapeutic options have not yet been established, although many drugs (e.g. renal vasodilators, diuretics and HMG-CoA reductase inhibitors [statins]) have been tested. New promising agents interfere with the apoptotic signalling that can occur in the setting of toxin exposure or ischaemia-reperfusion injury, limit inflammatory responses or modulate endothelial cell activation. In the future, these new approaches will enable us to extend our therapeutic repertoire.

Contrast-induced nephropathy in elderly trauma patients

BACKGROUND

Computed tomography (CT) is the gold standard for the identification of occult injuries, but the intravenous (IV) contrast used in CT scans is potentially nephrotoxic. Because elderly patients have decreased renal function secondary to aging and chronic disease, we sought to determine the rate of acute kidney injury (AKI) in elderly trauma patients exposed to IV contrast.

METHODS

Medical records of patients older than 55 years evaluated at a level-one trauma center between January 2003 and July 2008 were reviewed. Contrast was nonionic, isosmolar, and administered in standard volumes. Groups were based on administration of contrast. AKI was defined as a 25% relative or 0.5 mg/dL absolute increase in serum creatinine within 72 hours of presentation [corrected].

RESULTS

During the study period 1,371 patients older than 55 years were evaluated, and 1,152 met the inclusion criteria. CT was performed on 1,071 patients (96%); 71% of this group received IV contrast. There was no significant difference between the contrast and noncontrast groups in terms of baseline characteristics. Criteria for AKI were satisfied in 2.1% of all patients, including 1.9% the contrast group versus 2.4% in the noncontrast group. AKI diagnosed within 72 hours of patient presentation was an independent risk factor for in-hospital mortality and prolonged length of stay.

CONCLUSIONS

IV contrast media in elderly trauma patients is not associated with an increased risk of AKI. Development of AKI within 72 hours of admission is associated with mortality and increased length of stay.

Comparative protective effect of N-acetyl cysteine and tetramethylpyrazine in rats with gentamicin nephrotoxicity

Gentamicin (GM) is used against serious and life-threatening infections, but its use is limited by the occurrence of nephrotoxicity, which involves the generation of free radicals. In this work we tested the effect of a compound with antioxidant properties, tertamethylpyrazine (TMP), a major constituent of the Chinese medicinal plant Lingusticum wallichi, on GM-induced nephrotoxicity, and compared it with an established anti-oxidant compound N-acetyl cysteine (NAC). Six groups of rats were studied: (1) control, treated orally (p.o.) and intraperitoneally (i.p.) with saline; (2) treated i.p. with GM (80 mg kg(-1) per day for 6 days); (3) TMP, given p.o. (100 mg kg(-1) per day for 10 days) + GM (same dose as above during the last 6 days); (4) NAC, given i.p. (500 mg kg(-1) per day for 10 days) + GM as above; (5) TMP (100 mg kg(-1) per day for 10 days) + saline; (6) NAC (500 mg kg(-1) per day for 10 days) + saline. GM nephrotoxicity was characterized by reduced creatinine clearance, increased creatinine and urea concentrations in plasma, increased urinary excretion of N-acetyl-beta-d-glucosaminidase (NAG) and total protein. These functional and structural alterations were prevented or ameliorated by NAC treatment, while TMP had only a slight mitigating effect that was less marked than that produced by NAC. The concentration of GM in the renal cortex of the rats given GM + NAC (but not TMP) was lower than that found in rats treated with GM alone by about 25%. The mechanism by which NAC and, to a lesser extent TMP, protected against GM-induced nephrotoxicity may be related, at least in part, to the decrease in oxidative stress in renal cortex.

In emergency situations, should serum creatinine be checked in all patients before performing second contrast CT examinations within 24 hours?

OBJECTIVE

The aim of this study was to determine the frequency of contrast-induced nephropathy (CIN) in patients undergoing repeat contrast-enhanced computed tomographic (CT) examinations within 24 hours, as well as associated risk factors.

MATERIALS AND METHODS

Through a search of medical and radiologic records, patients who underwent 2 contrast-enhanced CT examinations within 24 hours during a 4-year period (2003-2006), with available serum creatinine measurements before and after CT imaging were included. Medical records were reviewed for demographic data, risk factors, renal status, and CT contrast volume. The frequency of CIN was calculated, and odds ratios of risk factors were determined.

RESULTS

There were 164 patients (90 men, 74 women; mean age, 56.3 years), with an average baseline serum creatinine level of 1.02 +/- 0.73 mg/dL (range, 0.3-6.6 mg/dL). Three hundred twenty-eight CT examinations were performed: 2 in each patient, at an average interval of 11.4 hours. The mean doses of contrast medium used for the first and second CT examinations were 126.2 and 123.4 mL, respectively. Twenty-one patients (12.8%) developed CIN. Comparing patients with and without CIN, the only statistically significant risk factor for CIN was an increase in serum creatinine between the first and second CT examinations, with an odds ratio of 18 (P < .005).

CONCLUSION

The incidence of CIN in patients who underwent repeat contrast-enhanced CT examinations was 12.8%. An increase in serum creatinine between the first and second CT examinations was highly associated with CIN and may serve as a risk factor for developing CIN.

Prevention of acute kidney injury

Acute kidney injury is common and carries a high mortality. Many drugs have been evaluated for their role in preventing acute kidney injury, of which some are of no benefit and others may be harmful. This review discusses current interventions to prevent acute kidney injury and reviews the evidence base for each.