Prevention of acute kidney injury and protection of renal function in the intensive care unit. Expert opinion of the Working Group for Nephrology, ESICM

Geriatric patients with known acute kidney injury and normal renal function at the time of admittance to the intensive care unit/assessment of RRT requirement and mortality: retrospective case-control study

BACKGROUND

The objective of our study was to investigate the renal functions on admittance, chronic disease status, the diagnosis on admittance to the intensive care unit (ICU), need for mechanical ventilation and medication groups and their impact over mortality and renal replacement treatment (RRT) requirement in geriatric patients with and without known acute kidney injury (AKI) at the time of admittance.

METHODS

A total of 168 patients over 65 years of age having been monitored for more than 24 h in our Respiratory ICU and were assessed retrospectively. Factors influencing the RRT requirement and the mortality rates of patients with known AKI and normal renal function at the time of admittance were reviewed.

RESULTS

Of 80 patients, 8 (10 %) without AKI at the time of admittance to the ICU required RRT during the follow-up, however, 72 of those (90 %) completed the follow-up without developing AKI. Of 88 patients, 29 (33 %) with AKI at the time of admittance to the ICU required RRT, however, 59 of those (67 %) completed the follow-up without any need for RRT.

CONCLUSIONS

Presence of known AKI in the geriatric population at the time of their admittance to the respiratory ICU remarkably increased both the need for RRT and the mortality with respect to the geriatric population with normal renal functions. After having assessed the reasons justifying RRT and increasing the mortality during the intensive care, gastrointestinal bleeding and hypotension which necessitate the combined use of dopamine and noradrenaline were concluded to be prominent.

N-acyl dopamine derivates as lead compound for implementation in transplantation medicine

Conjugates of fatty acids with ethanolamine, amino acids or monoamine neurotransmitters occur widely in nature giving rise to so-called endocannabinoids. Anandamide and 2-arachidonoyl glycerol are the best characterized endocannabinoids activating both cannabinoid receptors (CB1 and CB2) and transient receptor potential vanilloid type 1 (TRPV1) channels (anandamide) or activating cannabinoid receptors only (2-arachidonoyl glycerol). TRPV1 is also activated by vanilloids, such as capsaicin, and endogenous neurolipins, e.g. N-arachidonoyl dopamine (NADA) and N-oleoyl dopamine (OLDA). Because donor dopamine treatment has shown to improve transplantation outcome in renal and heart recipients, this review will mainly focus on the biological activities of N-acyl dopamine derivates (NADD) as potential non-hemodynamic alternative for implementation in transplantation medicine. Hence the influence of NADD on transplantation relevant entities, i.e. cold inflicted injury, cytoprotection, I/R-injury, immune-modulation and inflammation will be summarized. The cytoprotective properties of endogenous endocannabinoids in this context will be briefly touched upon.

Intensive care unit management of patients with liver failure

Acute liver failure (ALF) and acute-on-chronic liver failure (ACLF) usually mandate management within an intensive care unit (ICU). Even though the conditions bear some similarities, precipitating causes, and systemic complications management practices differ. Although early identification of ALF and ACLF, improvements in ICU management, and the widespread availability of liver transplantation have improved mortality, optimal management practices have not been defined. This article summarizes current ICU management practices and identifies areas of management that require further study.

Effect of aging on renal function plus monitoring and support

Several anatomic changes and physiologic alterations occur in the aging kidney, awareness of which is essential for the early recognition of acute kidney injury (AKI) to improve outcomes in hospitalized geriatric patients. There are no unique diagnostic methods or treatment modalities in the care of the geriatric patient with AKI. Therapy is mainly supportive, and the full spectrum of treatment options, including renal replacement therapy (RRT), should not be withheld from a patient based on age. More studies need to be performed to determine the optimal timing, intensity, and modality of RRT in the geriatric population.

Are diuretics harmful in the management of acute kidney injury?

PURPOSE OF REVIEW

To assess the role of diuretics in acute kidney injury (AKI) and their effectiveness in preventing AKI, achieving fluid balance, and decreasing progression to chronic kidney disease (CKD).

RECENT FINDINGS

Diuretics are associated with increased risk for AKI. The theoretical advantage of diuretic-induced preservation of renal medullary oxygenation to prevent AKI has not been proven. A higher cumulative diuretic dose during the dialysis period can cause hypotension and increase mortality in a dose-dependent manner. Data on the use of forced euvolemic diuresis to prevent AKI remains controversial. Positive fluid balance has emerged as an independent predictor of adverse outcomes. Post-AKI furosemide dose had a favorable effect on mortality due in part to the reduction of positive fluid balance. There are exciting experimental data suggesting that spironolactone may prevent AKI once an ischemic insult has occurred and thus prevent the progression to CKD.

SUMMARY

Diuretics are ineffective and even detrimental in the prevention and treatment of AKI, and neither shorten the duration of AKI, nor reduce the need for renal replacement therapy. Diuretics have an important role in volume management in AKI, but they are not recommended for the prevention of AKI. There is increased emphasis on the prevention of progression of AKI to CKD.

Does diabetic status in the ICU predict haemofiltration requirement? The haemofiltration in the ICU and diabetic status (HIDS) study

Diabetes is already a major health burden and prevalence is expected to double by 2025. The impact of diabetes and clinical outcomes in the intensive care unit is an evolving area of research. This study seeks to identify whether diabetic status is an independent risk factor for haemofiltration. This is a retrospective cohort study. All unique patients from a seven-year period from 2004 to 2010 at a major intensive care unit in Melbourne, Australia were analysed using multivariate regression to look for an association between diabetic status and haemofiltration. After exclusion criteria there were 7262 patients, 1674 with a history of diabetes (median age of 69, 66.72% male) and 5588 without a history of diabetes (median age 64, 64.13% male). Diabetic status was an independent risk factor (odds ratio 1.401, 95% confidence interval 1.079 to 1.820, P=0.011) for haemofiltration. Further research may identify intensive care unit-based renoprotective measures specifically for patients with diabetes.

Usefulness of stroke volume index obtained with the FloTrac/ Vigileo system for the prediction of acute kidney injury after radical esophagectomy

PURPOSE

To assess the impact of stroke volume index (SVI) at the end of esophagectomy upon postoperative renal function.

METHODS

We reviewed medical records of 128 patients undergoing esophagectomy. Intraoperative hemodynamics were monitored with the FloTrac sensor/Vigileo monitor system in addition to standard monitors. Patients were divided into two groups according to SVI at the end of surgery: the normal SVI group (n = 76), with SVI ≥ 35 ml/m2, and the low SVI group (n = 52), with SVI<35 ml/m2. We compared postoperative renal function, indicated by serum creatinine and estimated glomerular filtration rate, on post-operative days 0 through 3. We also compared numbers of patients who developed postoperative acute kidney injury (AKI).

RESULTS

Although there were no intergroup differences in preoperative renal function or other intraoperative hemodynamic variables, including arterial pressure, central venous pressure, stroke volume variation, a volume of infusion, urine output, and the total intraoperative in-out balance, estimated glomerular filtration rate was significantly lower and serum creatinine was significantly higher in the low SVI group than in the normal SVI group on postoperative days 1 and 2 (P<0.05). In addition, more patients developed postoperative AKI in the low SVI group than in the normal SVI group (12 of 52 vs. 5 of 76, P = 0.015).

CONCLUSIONS

Low SVI at the end of esophagectomy may represent a risk factor for AKI in the early postoperative period. Further studies are required to examine whether maintaining SVI above 35 ml/m2 reduces the incidence of AKI after esophagectomy.

Diuretic response to colloid and crystalloid fluid loading in critically ill patients

AIMS

In the critically ill patient, fluid loading is commonly done to stabilise hemodynamics and increase diuresis, whereas the absence of diuresis may predispose to harmful overloading. The goal of the current study was to evaluate the diuretic response and determinants thereof upon crystalloid and colloid fluid loading.

SUBJECTS AND METHODS

This is a substudy on 42 clinically hypovolemic, septic or non-septic patients without acute kidney injury, who were randomly assigned, after stratification for sepsis, to a 90-min fluid loading protocol with either 0.9% saline or a colloid solution (gelatin, hydroxyethyl starch 200/0.5 or albumin). Hemodynamics, biochemical parameters and diuresis were recorded. A response was defined by an increase in diuresis of >10% during fluid loading.

RESULTS

Diuresis increased more during saline than colloid infusion, together with a decline in colloid osmotic pressure (COP) of plasma and less increase in plasma volume and global hemodynamics with saline, at similar fluid balance. Nine patients (82%) receiving saline had a diuretic response, compared to 13 patients (42%) receiving colloids (P = 0.04), and the response was not predicted by underlying condition, global hemodynamics, volume of fluid infused and COP.

CONCLUSION

In critically ill patients with clinical hypovolemia, diuresis increases more during saline than colloid fluid loading, only partly dependent of a fall in plasma COP.

Alkaline phosphatase: a possible treatment for sepsis-associated acute kidney injury in critically ill patients

Acute kidney injury (AKI) is a common disease in the intensive care unit and accounts for high morbidity and mortality. Sepsis, the predominant cause of AKI in this setting, involves a complex pathogenesis in which renal inflammation and hypoxia are believed to play an important role. A new therapy should be aimed at targeting both these processes, and the enzyme alkaline phosphatase, with its dual mode of action, might be a promising candidate. First, alkaline phosphatase is able to reduce inflammation through dephosphorylation and thereby detoxification of endotoxin (lipopolysaccharide), which is an important mediator of sepsis. Second, adenosine triphosphate, released during cellular stress caused by inflammation and hypoxia, has detrimental effects but can be converted by alkaline phosphatase into adenosine with anti-inflammatory and tissue-protective effects. These postulated beneficial effects of alkaline phosphatase have been confirmed in animal experiments and two phase 2a clinical trials showing that kidney function improved in critically ill patients with sepsis-associated AKI. Because renal inflammation and hypoxia also are observed commonly in AKI induced by other causes, it would be of interest to investigate the therapeutic effect of alkaline phosphatase in these nephropathies as well.

Hemodynamic variables and progression of acute kidney injury in critically ill patients with severe sepsis: data from the prospective observational FINNAKI study

Introduction

Knowledge of the association of hemodynamics with progression of septic acute kidney injury (AKI) is limited. However, some recent data suggest that mean arterial pressure (MAP) exceeding current guidelines (60–65 mmHg) may be needed to prevent AKI. We hypothesized that higher MAP during the first 24 hours in the intensive care unit (ICU), would be associated with a lower risk of progression of AKI in patients with severe sepsis.

Methods

We identified 423 patients with severe sepsis and electronically recorded continuous hemodynamic data in the prospective observational FINNAKI study. The primary endpoint was progression of AKI within the first 5 days of ICU admission defined as new onset or worsening of AKI by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We evaluated the association of hemodynamic variables with this endpoint. We included 53724 10-minute medians of MAP in the analysis. We analysed the ability of time-adjusted MAP to predict progression of AKI by receiver operating characteristic (ROC) analysis.

Results

Of 423 patients, 153 (36.2%) had progression of AKI. Patients with progression of AKI had significantly lower time-adjusted MAP, 74.4 mmHg [68.3-80.8], than those without progression, 78.6 mmHg [72.9-85.4], P < 0.001. A cut-off value of 73 mmHg for time-adjusted MAP best predicted the progression of AKI. Chronic kidney disease, higher lactate, higher dose of furosemide, use of dobutamine and time-adjusted MAP below 73 mmHg were independent predictors of progression of AKI.

Conclusions

The findings of this large prospective multicenter observational study suggest that hypotensive episodes (MAP under 73 mmHg) are associated with progression of AKI in critically ill patients with severe sepsis.

Protocoled resuscitation and the prevention of acute kidney injury

PURPOSE OF REVIEW

Acute kidney injury (AKI) occurrence in critically ill patients is common and is associated with a substantial increase in morbidity and mortality. The scope of this review is to summarize the most recent evidence-based knowledge for prevention of AKI.

RECENT FINDINGS

Recent recommendations for prevention of AKI in ICU patients are all 'negative' and, similarly, the most recent and updated guidelines about major topic areas of interest for AKI, including definition and classification, prevention, and pharmacologic treatment, have failed to identify single evidence-based recommendations for prevention and treatment of AKI. Therefore, the evaluation and management of AKI should be guided by clinical algorithms aiming to protocolized hemodynamic optimization, metabolic control, monitoring of intra-abdominal hypertension, use of diuretics to control fluid overload, and careful management of nephrotoxic factors.

SUMMARY

Key components of optimal AKI prevention include maintenance of renal perfusion and avoidance of precipitating factors. Adequate renal blood flow maintenance is the first strategy to employ not only to assure renal oxygenation, but also to prevent nephrotoxic drugs-associated AKI. Many potential therapies and interventions are on the horizon, but most of the future research will need to focus more on a step-wise, protocoled, kidney-oriented approach, than on single treatments.

Advances in critical care for the older patient

As the proportion of elderly people in the general population increases, so does the number admitted to critical care. In caring for an older patient, the intensivist has to balance the complexities of an acute illness, pre-existing co-morbidities and patient preference for life-sustaining treatment with the chances of survival, quality of life after critical illness and rationing of expensive, limited resources. This remains one of the most challenging areas of critical care practice.

Update on clinical trials for the prevention of acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

Effective therapeutic agents for the prevention and treatment of acute kidney injury (AKI) after cardiac surgery remain elusive despite the tremendous advances in surgical techniques, technology, and understanding of disease processes. Recent developments and their effect on the incidence of AKI after cardiac surgery are discussed.

DATA SOURCES

Published clinical trials in PubMed, strength of evidence assessed by the guidelines of the American Family Physicians.

CONCLUSIONS

The definition of AKI has changed, and the focus of interventions has shifted from treatment to prevention to recovery from AKI. Antioxidants and biological agents have been added to classic armaments of hydration and diuretics in addition to tighter metabolic control to prevent AKI. Although the treatment options remain unsatisfactory, a lot of progress nevertheless continues to be made in the prevention and treatment of AKI.

In-line filtration minimizes organ dysfunction: new aspects from a prospective, randomized, controlled trial

BACKGROUND

Infused particles induce thrombogenesis, impair microcirculation and modulate immune response. We have previously shown in critically ill children, that particle-retentive in-line filtration reduced the overall complication rate of severe events, length of stay and duration of mechanical ventilation. We now evaluated the influence of in-line filtration on different organ function and thereby elucidated the potential underlying pathophysiological effects of particle infusion.

METHODS

In this single-centre, prospective, randomized controlled trial 807 critically ill children were assigned to either control (n = 406) or filter group (n = 401), the latter receiving in-line filtration for complete infusion therapy. Both groups were compared regarding the differences of incidence rates and its 95% confidence interval (CI) of different organ dysfunction as defined by the International Pediatric Sepsis Consensus Conference 2005.

RESULTS

The incidence rates of respiratory (-5.06%; 95% CI, -9.52 to -0.59%), renal (-3.87%; 95% CI, -7.58 to -0.15%) and hematologic (-3.89%; 95% CI, -7.26 to -0.51%) dysfunction were decreased in the filter group. No difference was demonstrated for the occurrence rates of cardiovascular, hepatic, or neurologic dysfunction between both groups.

CONCLUSIONS

In-line filtration has beneficial effects on the preservation of hematologic, renal and respiratory function in critically ill patients. The presented clinical data further support our hypothesis regarding potential harmful effects of particles. In critically ill patients infused particles may lead to further deterioration of the microcirculation, induce a systemic hypercoagulability and inflammation with consecutive negative effects on organ function.

TRIAL REGISTRATION

ClinicalTrials.gov number; NCT00209768.

Cardiorenal syndrome in critical care: the acute cardiorenal and renocardiac syndromes

Heart and kidney disease often coexist in the same patient, and observational studies have shown that cardiac disease can directly contribute to worsening kidney function and vice versa. Cardiorenal syndrome (CRS) is defined as a complex pathophysiological disorder of the heart and the kidneys in which acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other organ. This has been recently classified into five subtypes on the basis of the primary organ dysfunction (heart or kidney) and on whether the organ dysfunction is acute or chronic. Of particular interest to the critical care specialist are CRS type 1 (acute cardiorenal syndrome) and type 3 (acute renocardiac syndrome). CRS type 1 is characterized by an acute deterioration in cardiac function that leads to acute kidney injury (AKI); in CRS type 3, AKI leads to acute cardiac injury and/or dysfunction, such as cardiac ischemic syndromes, congestive heart failure, or arrhythmia. Both subtypes are encountered in high-acuity medical units; in particular, CRS type 1 is commonly seen in the coronary care unit and cardiothoracic intensive care unit. This paper will provide a concise review of the epidemiology, pathophysiology, prevention strategies, and selected kidney management aspects for these two acute CRS subtypes.

Renal replacement therapy in ICU

Diagnosing and managing critically ill patients with renal dysfunction is a part of the daily routine of an intensivist. Acute kidney insufficiency substantially contributes to the morbidity and mortality of critically ill patients. Renal replacement therapy (RRT) not only does play a significant role in the treatment of patients with renal failure, acute as well as chronic, but also has spread its domains to the treatment of many other disease conditions such as myaesthenia gravis, septic shock and acute on chronic liver failure. This article briefly outlines the role of renal replacement therapy in ICU.

Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury

INTRODUCTION

Renal resistive index (RI), determined by Doppler ultrasonography, directly reveals and quantifies modifications in renal vascular resistance. The aim of this study was to evaluate if mean arterial pressure (MAP) is determinant of renal RI in septic, critically ill patients suffering or not from acute kidney injury (AKI).

METHODS

This prospective observational study included 96 patients. AKI was defined according to RIFLE criteria and transient or persistent AKI according to renal recovery within 3 days.

RESULTS

Median renal RIs were 0.72 (0.68-0.75) in patients without AKI and 0.76 (0.72-0.80) in patients with AKI (P = 0.001). RIs were 0.75 (0.72-0.79) in transient AKI and 0.77 (0.70-0.80) in persistent AKI (P = 0.84). RI did not differ in patients given norepinephrine infusion and was not correlated with norepinephrine dose. RI was correlated with MAP (ρ = -0.47; P = 0.002), PaO2/FiO2 ratio (ρ = -0.33; P = 0.04) and age (ρ = 0.35; P = 0.015) only in patients without AKI.

CONCLUSIONS

A poor correlation between renal RI and MAP, age, or PaO2/FiO2 ratio was found in septic and critically ill patients without AKI compared to patients with AKI. These findings suggest that determinants of RI are multiple. Renal circulatory response to sepsis estimated by Doppler ultrasonography cannot reliably be predicted simply from changes in systemic hemodynamics. As many factors influence its value, the interest in a single RI measurement at ICU admission to determine optimal MAP remains uncertain.

N-octanoyl-dopamine is an agonist at the capsaicin receptor TRPV1 and mitigates ischemia-induced [corrected] acute kidney injury in rat

Since stimulation of transient receptor potential channels of the vanilloid receptor subtype 1 (TRPV1) mitigates acute kidney injury (AKI) and endogenous N-acyl dopamine derivatives are able to activate TRPV1, we tested if synthetic N-octanoyl-dopamine (NOD) activates TRPV1 and if it improves AKI. These properties of NOD and its intrinsic anti-inflammatory character were compared with those of dopamine (DA). TRPV1 activation and anti-inflammatory properties of NOD and DA were tested using primary cell cultures in vitro. The influence of NOD and DA on AKI was tested in a prospective, randomized, controlled animal study with 42 inbred male Lewis rats (LEW, RT1), treated intravenously with equimolar concentrations of DA or NOD one hour before the onset of warm ischemia and immediately before clamp release. NOD, but not DA, activates TRPV1 channels in isolated dorsal root ganglion neurons (DRG) that innervate several tissues including kidney. In TNFα stimulated proximal tubular epithelial cells, inhibition of NFκB and subsequent inhibition of VCAM1 expression by NOD was significantly stronger than by DA. NOD improved renal function compared to DA and saline controls. Histology revealed protective effects of NOD on tubular epithelium at day 5 and a reduced number of monocytes in renal tissue of DA and NOD treated rats. Our data demonstrate that NOD but not DA activates TRPV1 and that NOD has superior anti-inflammatory properties in vitro. Although NOD mitigates deterioration in renal function after AKI, further studies are required to assess to what extend this is causally related to TRPV1 activation and/or desensitization.

Systematic analysis of hydroxyethyl starch (HES) reviews: proliferation of low-quality reviews overwhelms the results of well-performed meta-analyses

PURPOSE

Hydroxyethyl starch (HES) is a synthetic colloid used widely for resuscitation despite the availability of safer, less costly fluids. Numerous HES reviews have been published that may have influenced clinicians' practice. We have therefore examined the relationship between the methodological quality of published HES reviews, authors' potential conflicts of interest (pCOI) and the recommendations made.

METHODS

Systematic analysis of reviews on HES use.

RESULTS

Between 1975 and 2010, 165 reviews were published containing recommendations for or against HES use. From the 1990s onwards, favorable reviews increased from two to eight per year and HES's share of the artificial colloid market tripled from 20 to 60 %. Only 7 % (12/165) of these reviews of HES use contained meta-analyses; these 7 % had higher Overview Quality Assessment Questionnaire (OQAQ) scores [median (range) 6.5 (3-7)] than reviews without meta-analysis [2 (1-4); p < 0.001]. The rates of recommending against HES use are 83 % (10/12) in meta-analyses and 20 % (31/153) in reviews without meta-analysis (p < 0.0001). Fourteen authors published the majority (70/124) of positive reviews, and ten of these 14 had or have since developed a pCOI with various manufacturers of HES.

CONCLUSIONS

Low-quality HES reviews reached different conclusions than high-quality meta-analyses from independent entities, such as Cochrane Reviews. The majority of these low-quality positive HES reviews were written by a small group of authors, most of whom had or have since established ties to industry. The proliferation of positive HES reviews has been associated with increased utilization of an expensive therapy despite the lack of evidence for meaningful clinical benefit and increased risks. Clinicians need to be more informed that marketing efforts are potentially influencing scientific literature.

Perioperative acute kidney injury

Acute kidney injury (AKI) is a serious complication in the perioperative period, and is consistently associated with increased rates of mortality and morbidity. Two major consensus definitions have been developed in the last decade that allow for easier comparison of trial evidence. Risk factors have been identified in both cardiac and general surgery and there is an evolving role for novel biomarkers. Despite this, there has been no real change in outcomes and the mainstay of treatment remains preventive with no clear evidence supporting any therapeutic intervention as yet. This review focuses on definition, risk factors, the emerging role of biomarkers and subsequent management of AKI in the perioperative period, taking into account new and emerging strategies.

Adverse effects of α-ketoglutarate/malate in a rat model of acute kidney injury

Acute kidney injury (AKI) is the most common kidney disease in hospitalized patients with high mortality. Ischemia and reperfusion (I/R) is one of the major causes of AKI. The combination of α-ketoglutarate+malate (αKG/MAL) showed the ability to reduce hypoxia-induced damage to isolated proximal tubules. The present study utilizes a rat model of I/R-induced AKI accompanied by intensive biomonitoring to examine whether αKG/MAL provides protection in vivo. AKI was induced in male Sprague-Dawley rats by bilateral renal clamping (40 min) followed by reperfusion (240 min). αKG/MAL was infused continuously for 60 min before and 45 min after ischemia. Normoxic and I/R control groups received 0.9% NaCl solution. The effect of αKG/MAL was evaluated by biomonitoring, blood and plasma parameters, histopathology, and immunohistochemical staining for kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL), as well as by determination of tissue ATP and nonesterified fatty acid concentrations. Intravenous infusion of αKG/MAL at a cumulative dose of 1 mmol/kg each (146 mg/kg αKG and 134 mg/kg MAL) did not prevent I/R-induced increases in plasma creatinine, histopathological alterations, or cortical ATP depletion. On the contrary, the most notable adverse affect in animals receiving αKG/MAL was the decrease in mean arterial blood pressure, which was also accompanied by a reduction in heart rate. Supplementation with αKG/MAL, which is very protective against hypoxia-induced injury in isolated proximal tubules, does not protect against I/R-induced renal injury in vivo, possibly due to cardiovascular depressive effects.

Management of critically-ill cirrhotic patients

Cirrhotic patients are prone to develop life-threatening complications that require emergency care and ICU admission. They can present specific decompensations related to cirrhosis such as variceal bleeding and hepatorenal syndrome (HRS) or other critical events also observed in the general population such as severe sepsis or septic shock. Clinical management of all these entities requires a specific approach in cirrhosis. Cirrhotic patients have a hyperdynamic circulation with high cardiac output and low systemic vascular resistance in the absence of infection. Circulatory dysfunction increases the susceptibility of critically-ill cirrhotic patients to develop multiple organ failure and attenuates vascular reactivity to vasopressor drugs. HRS, a severe functional renal failure occurring in patients with advanced cirrhosis and ascites, is also secondary to this circulatory dysfunction that leads to an extreme renal vasoconstriction. Moreover, hypotensive cirrhotic patients require a carefully balanced replacement of volemia, since overtransfusion increases portal hypertension and the risk of variceal bleeding and undertransfusion causes tissue hypoperfusion which increases the risk of multiple organ failure. Cirrhotic patients are also at a high risk for development of other bleeding complications and are more susceptible to nosocomial infections. This extreme complexity of critically-ill cirrhotic patients requires a specific medical approach that should be known by general intensivists since it has a negative impact on patient prognosis. This review will focus on the diagnostic approach and treatment strategies currently recommended in the critical care management of patients with cirrhosis.

Rhabdomyolysis

Rhabdomyolysis is the destruction of a significant amount of striated muscle, leading to disruptions in fluid balance, electrolytes and renal function. It may have either traumatic (such as crush injury) or non-traumatic causes. Diagnosis is typically made through the timely determination of the serum creatine kinase activity in a patient with a suggestive history or clinical features. Treatment is supportive, with generous intravenous hydration and correction of electrolyte abnormalities. Sometimes haemofiltration or dialysis is required, but the renal prognosis is generally good.

Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients

PURPOSE

Acute kidney injury (AKI) is a dynamic process that evolves from an early reversible condition to an established disease. Value of urine indices in the event of AKI is uncertain in critically ill patients. The aim of this study was to evaluate the performance of fractional excretion of urea (FeU) for differentiating persistent from transient AKI in patients admitted to the intensive care unit.

METHODS

This was an observational study. Forty-seven patients with AKI according to the RIFLE classification were included. Transient AKI was defined as AKI resolved within 3 days after inclusion. Persistent AKI was defined as persistent serum creatinine elevation or oliguria.

RESULTS

Fractional excretion of urea was lower in case of transient, 33% (25-39), than persistent AKI, 47% (36-61) (P = .001). Areas under the receiver operating characteristic curve for FeU in case of transient AKI were better than those for other urinary indexes, 0.78 (95% confidence interval, 0.63-0.92). Optimal cutoff point according to the receiver operating characteristic curve was 40%. In patients treated with diuretics, FeU was the only predictive index of transient AKI. Fractional excretion of urea gradually increased from days 1 to 7 in transient AKI, whereas plasma creatinine decreased.

CONCLUSIONS

Fractional excretion of urea less than 40% was found to be a sensitive and specific index in differentiating transient from persistent AKI in intensive care unit patients especially if diuretics had been administered.

[Acute kidney injury]

Acute kidney injury plays a pivotal role in intensive care medicine and exerts crucial adverse effects on the course of the disease and overall prognosis of the critically ill patient. Intensive renal support, including initiation of earlier dialysis or maximal uremic toxin removal by higher dosage and frequency of renal replacement therapy, and individualized selection of modality were not able to decrease excessive mortality in this population. Systemic acute inflammation, mediated, at least in part, by cytokines, and not secondary uremic side effects, seems to have a major impact on nonrenal organ damage. Assessment of short-term outcome in critically ill patients who develop acute kidney injury may underestimate the true burden of disease. The overall survival at 5 years in patients discharged alive after severe acute kidney injury necessitating renal replacement therapy is only 20-30%, comparable to cancer patients. In addition, acute renal damage was identified as an independent risk factor for progression of chronic renal insufficiency. Current research focuses on strategies for the prevention of acute kidney injury and on the establishment of effective biomarkers for the early recognition and accurate diagnosis of subclinical renal damage.

Intra- and postoperative adverse events in children with nephrotic syndrome requiring surgery under general anesthesia

BACKGROUND

There are few data regarding perioperative adverse events in children with nephrotic syndrome.

OBJECTIVES

The aim of this study was to describe the nature and frequency of perioperative adverse events in children with nephrotic syndrome.

MATERIALS AND METHODS

This is a retrospective study from a large university pediatric hospital. All procedures under general anesthesia in children with nephrotic syndrome between January 1995 and May 2007 were included, with the exception of renal transplantation. Data were collected on demographics, etiology of nephrotic syndrome and related treatments, surgical procedures and anesthetic techniques, and pre- and postoperative treatments. Adverse events occurring during the intraoperative period and up to the fifth postoperative day were recorded.

RESULTS

Data on eight patients who underwent 24 surgical or interventional procedures under general anesthesia over the study period were reviewed. Three patients had steroid-resistant nephrotic syndrome and five patients had congenital or infantile nephrotic syndrome. Five patients had progressed to end-stage renal failure requiring dialysis. General anesthesia was performed for: nephrectomy (n = 9), central venous catheter insertion (n = 8), peritoneal dialysis catheter insertion (n = 5), and emergency surgery in two cases (acute intestinal intussusception and hemodialysis catheter insertion). Three patients were receiving aspirin and one anticoagulant therapy. No postoperative thrombosis or infections, bleeding, peripheral edema or ascites, and increase in kalemia were noted. There was no significant postoperative increase in median serum creatinine level.

CONCLUSIONS

Surgical procedures were seldom associated with the occurrence of perioperative adverse events. However, larger studies are needed to confirm these results.

Consensus statement of the ESICM task force on colloid volume therapy in critically ill patients

PURPOSE

Colloids are administered to more patients than crystalloids, although recent evidence suggests that colloids may possibly be harmful in some patients. The European Society of Intensive Care Medicine therefore assembled a task force to compile consensus recommendations based on the current best evidence for the safety and efficacy of the currently most frequently used colloids--hydroxyethyl starches (HES), gelatins and human albumin.

METHODS

Meta-analyses, systematic reviews and clinical studies of colloid use were evaluated for the treatment of volume depletion in mixed intensive care unit (ICU), cardiac surgery, head injury, sepsis and organ donor patients. Clinical endpoints included mortality, kidney function and bleeding. The relevance of concentration and dosage was also assessed. Publications from 1960 until May 2011 were included. The quality of available evidence and strength of recommendations were based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RECOMMENDATIONS AND CONCLUSIONS

We recommend not to use HES with molecular weight ≥ 200 kDa and/or degree of substitution >0.4 in patients with severe sepsis or risk of acute kidney injury and suggest not to use 6% HES 130/0.4 or gelatin in these populations. We recommend not to use colloids in patients with head injury and not to administer gelatins and HES in organ donors. We suggest not to use hyperoncotic solutions for fluid resuscitation. We conclude and recommend that any new colloid should be introduced into clinical practice only after its patient-important safety parameters are established.

Insights on urinary NGAL obtained in a primary care setting

BACKGROUND

A majority of patients developing acute kidney injury (AKI) receive medical care from their primary care physicians prior to the occurrence of conditions that predispose them to this complication.

METHODS

To characterize the uNGAL concentrations in primary care patients and to assess these concentrations with regard to different reference intervals, we conducted a multicenter, cross-sectional study with random selection of general practitioners (GP) from all GP offices in seven Swiss cantons. 1000 adults (566 females; mean age 57±17 years) were included.

RESULTS

The median absolute uNGAL was 21 ng/L. Elevated uNGAL (>100 ng/L) together with normal kidney test results (eGFR and albuminuria) were found in 6.5% of all patients. Females had a significantly higher uNGAL than did males. Among a multitude of different clinical and laboratory variables, only age, gender, liver function parameters, WBC and CRP were significantly associated with uNGAL levels in a multivariate analysis. When examining the proposed KDIGO classification of chronic kidney disease, the uNGAL levels at the given eGFR stages changed with increasing albuminuria stages and vice versa.

CONCLUSIONS

Age, gender, markers of inflammation and liver function, exert influences on uNGAL concentrations. A substantial proportion of patients exhibited normal kidney testing together with elevated uNGAL, potentially identifying patients with increased renal stress and at increased risk for the development of AKI.

Timing of initiation of renal replacement therapy for acute kidney injury: a survey of nephrologists and intensivists in Canada

BACKGROUND

Little is known about factors that influence the timing of initiation of renal replacement therapy (RRT) for acute kidney injury (AKI). We sought to better describe these factors for Canadian physicians that prescribe RRT for AKI.

METHODS

A web-based survey was conducted of physicians involved in the decision to initiate RRT for critically ill patients in Canada. Participants were asked about the factors that prompt them to initiate RRT for AKI both directly and using scenario-based questions.

RESULTS

Surveys completed by 180 physicians at 32 different sites were included for analysis. Serum potassium level and severity of pulmonary edema were the most commonly utilized factors for deciding when RRT should be started. For all clinical and laboratory factors inquired about, there was wide variation in the minimum severity that prompted respondents to indicate that they would initiate RRT. Additional factors that influenced the timing of initiation were the time-of-day that laboratory and clinical results became available, patient age and co-morbidity, responsiveness to a diuretic challenge and the specialty of the prescribing physician. Over 90% of respondents indicated that a randomized controlled trial to assess the optimal timing of initiation of RRT for AKI is ethically justified.

CONCLUSIONS

These results provide insight into clinical and laboratory factors that influence the timing of initiation of RRT for AKI and may aid in the design of future trials. While most clinicians consider the degree of hyperkalemia and pulmonary edema in deciding when to initiate RRT for AKI, there is a wide range of clinical practice, uncertainty regarding the optimal timing of initiation and enthusiasm for prospective interventional studies to address this topic.

Care of the critically ill emergency department patient with acute kidney injury

Introduction. Acute Kidney Injury (AKI) is common and associated with significant mortality and complications. Exact data on the epidemiology of AKI in the Emergency Department (ED) are sparse. This review aims to summarise the key principles for managing AKI patients in the ED. Principal Findings. Timely resuscitation, goal-directed correction of fluid depletion and hypotension, and appropriate management of the underlying illness are essential in preventing or limiting AKI. There is no specific curative therapy for AKI. Key principles of secondary prevention are identification of patients with early AKI, discontinuation of nephrotoxic medication where possible, attention to fluid resuscitation, and awareness of the risks of contrast-induced nephropathy. In patients with advanced AKI, arrangements for renal replacement therapy need to be made before the onset of life-threatening uraemic complications. Conclusions. Research and guidelines regarding AKI in the ED are lacking and AKI practice from critical care departments should be adopted.

Renal dysfunction and fluid and electrolyte disturbances

PURPOSE OF REVIEW

To examine recent developments in preventing and treating postoperative acute renal dysfunction. To review contemporary issues concerning perioperative fluid and electrolyte management.

RECENT FINDINGS

Renal dysfunction remains a major postoperative morbidity despite the advent of intermittent and continuous renal replacement therapies. It is also associated with increased mortality. Newer techniques, such as off-pump coronary artery bypass surgery, which promised to reduce the incidence of postoperative renal injury, have failed to do so. In addition, newer techniques such as endovascular repair of aortic disorder and the transcutaneous insertion of aortic valves are associated with substantial degrees of kidney injury partially due to the use of much intravenous contrast material. Therefore, the present-day approach to preventing contrast-induced nephropathy is reviewed. Electrolyte disturbances are especially problematic after certain types of surgery, such as trans-sphenoidal adenomectomy and surgeries requiring the use of large volumes of irrigating solutions.

SUMMARY

Renal dysfunction, along with fluid and electrolyte disturbances, is a major issue that needs to be considered as part of perioperative management. Moreover, it is the prevention of clinically significant renal injury and electrolyte disturbances that is the cornerstone of contemporary anesthetic and surgical care.

Different patterns in a cohort of patients with severe leptospirosis (Weil syndrome): effects of an educational program in an endemic area

The aim of this study is to investigate the changes in clinical pattern and therapeutic measures in leptospirosis-associated acute kidney injury; a retrospective study with 318 patients in Brazil. Patients were divided according to the time of admission: 1985-1996 (group I) and 1997-2010 (group II). Patients were younger in group I (36 ± 13 versus 41 ± 16 years, P = 0.005) and the numbers of oliguria increased (21% versus 41% in group II, P = 0.014). Higher frequency of lung manifestations was observed in group II (P < 0.0001). Although increased severity, there was a significant reduction in mortality (20% in group I versus 12% in group II, P = 0.03). Mortality was associated with advanced age, low diastolic blood pressure, oliguria, arrhythmia, and peritoneal dialysis, besides a trend to better mortality with penicillin administration. Leptospirosis is occurring in an older population, with a higher number of oliguria and lung manifestations. However, mortality is decreasing and can be the result of changes in treatment.

Incidence, morbidity, and mortality of contrast-induced acute kidney injury in a surgical intensive care unit: a prospective cohort study

PURPOSE

Data on contrast-induced acute kidney injury (CI-AKI) in intensive care unit (ICU) are scarce and controversial. The objectives of the study were to evaluate the incidence and characteristics of CI-AKI in a surgical ICU.

MATERIALS AND METHODS

We conducted a 13-month prospective observational study. Three definitions were compared to characterize CI-AKI: Barrett and Parfrey criteria; Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function and End stage renal disease (RIFLE) classification; and Acute Kidney Injury Network (AKIN) criteria. Patients hospitalized in surgical ICU who had received an injection of contrast medium, who were not on renal replacement therapy, who had stable serum creatinine before injection, and no other etiology for new acute kidney injury were included.

RESULTS

One hundred one patients were included. The frequency of CI-AKI was 17%, 19%, and 19% according to Barrett and Parfrey criteria; RIFLE classification; and AKIN criteria, respectively. Diabetes mellitus, creatinine clearance less than 60 mL/min, and concomitant aminoglycoside administration were associated with CI-AKI. Statistically significant associations were found between CI-AKI and renal replacement therapy with all 3 definitions and between CI-AKI and mortality when AKIN criteria were used.

CONCLUSIONS

These results show that CI-AKI is not inconsequential in critically ill patients. In the present study, AKIN criteria appear to be most relevant to define CI-AKI. Further studies are required to explore CI-AKI prevention in ICU.

[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.

Clinical review: timing of renal replacement therapy

Acute kidney injury is common in intensive care patients and continuous renal replacement therapy is the preferred treatment for this in most centres. Although these techniques have been adopted internationally, there remains significant variation with regard to their clinical application. This is particularly pertinent when one considers that the fundamental questions regarding any treatment, such as initiation, dose and length of treatment, remain a source of debate and have not as yet all been fully answered. In this narrative review we consider the timing of renal replacement therapy, highlighting the relative paucity of high quality data regarding this fundamental question. We examine the role of the usual biochemical criteria as well as conventional clinical indications for commencing renal replacement therapy together with the application of recent classification systems, namely RIFLE and AKIN. We discuss the potential role of biomarkers for acute kidney injury as predictors for the need for renal support and discuss commencing therapy for indications other than acute kidney injury.

Relation between mean arterial pressure and renal function in the early phase of shock: a prospective, explorative cohort study

INTRODUCTION

Because of disturbed renal autoregulation, patients experiencing hypotension-induced renal insult might need higher levels of mean arterial pressure (MAP) than the 65 mmHg recommended level in order to avoid the progression of acute kidney insufficiency (AKI).

METHODS

In 217 patients with sustained hypotension, enrolled and followed prospectively, we compared the evolution of the mean arterial pressure (MAP) during the first 24 hours between patients who will show AKI 72 hours after inclusion (AKIh72) and patients who will not. AKIh72 was defined as the need of renal replacement therapy or "Injury" or "Failure" classes of the 5-stage RIFLE classification (Risk, Injury, Failure, Loss of kidney function, End-stage renal disease) for acute kidney insufficiency using the creatinine and urine output criteria. This comparison was performed in four different subgroups of patients according to the presence or not of AKI at the sixth hour after inclusion (AKIh6 as defined as a serum creatinine level above 1.5 times baseline value within the first six hours) and the presence or not of septic shock at inclusion.The ability of MAP averaged over H6 to H24 to predict AKIh72 was assessed by the area under the receiver operating characteristic curve (AUC) and compared between groups.

RESULTS

The MAP averaged over H6 to H24 or over H12 to H24 was significantly lower in patients who showed AKIh72 than in those who did not, only in septic shock patients with AKIh6, whereas no link was found between MAP and AKIh72 in the three others subgroups of patients. In patients with septic shock plus AKIh6, MAP averaged over H6 to H24 or over H12 to H24 had an AUC of 0.83 (0.72 to 0.92) or 0.84 (0.72 to 0.92), respectively, to predict AKIh72 . In these patients, the best level of MAP to prevent AKIh72 was between 72 and 82 mmHg.

CONCLUSIONS

MAP about 72 to 82 mmHg could be necessary to avoid acute kidney insufficiency in patients with septic shock and initial renal function impairment.

Management of acute renal failure in the pediatric intensive care unit

Pediatric acute renal failure (ARF) is a dynamic entity that has many causes. ARF is frequently seen in the pediatric population and is associated with increased mortality and long-term morbidity rates. Of importance is its early detection so as to allow interventions to either prevent or treat the disease timely during its course. Recent developments in the definitions and classification schemes and the identification of new biomarkers shall allow better predictive interventions for childhood ARF. ARF management in children requires special considerations. Optimal care for the pediatric patient requiring renal replacement therapy requires an understanding of the causes and patterns of pediatric ARF and recognition of the local expertise with respect to the personnel and equipment resources. The aim of this article is to review pediatric ARF management with an emphasis on emerging practice patterns and the modalities for renal replacement therapy.

Renal and neurological side effects of colistin in critically ill patients

Colistin is a complex polypeptide antibiotic composed mainly of colistin A and B. It was abandoned from clinical use in the 1970s because of significant renal and, to a lesser extent, neurological toxicity. Actually, colistin is increasingly put forward as salvage or even first-line treatment for severe multidrug-resistant, Gram-negative bacterial infections, particularly in the intensive care setting. We reviewed the most recent literature on colistin treatment, focusing on efficacy and toxicity issues. The method used for literature search was based on a PubMed retrieval using very precise criteria.

Despite large variations in dose and duration, colistin treatment produces relatively high clinical cure rates. Colistin is potentially nephrotoxic but currently used criteria tend to overestimate the incidence of kidney injury. Nephrotoxicity independently predicts fewer cures of infection and increased mortality. Total cumulative colistin dose is associated with kidney damage, suggesting that shortening of treatment duration could decrease the incidence of nephrotoxicity. Factors that may enhance colistin nephrotoxicity (i.e., shock, hypoalbuminemia, concomitant use of potentially nephrotoxic drugs) must be combated or controlled. Neurotoxicity does not seem to be a major issue during colistin treatment. A better knowledge of colistin pharmacokinetics in critically ill patients is imperative for obtaining colistin dosing regimens that ensure maximal antibacterial activity at minimal toxicity.