Fluid overload at initiation of renal replacement therapy is associated with lack of renal recovery in patients with acute kidney injury

The Role of Point-of-Care Ultrasound Monitoring in Cardiac Surgical Patients With Acute Kidney Injury

The approach to the patient with acute kidney injury (AKI) after cardiac surgery involves multiple aspects. These include the rapid recognition of reversible causes, the accurate identification of patients who will progress to severe stages of AKI, and the subsequent management of complications resulting from severe renal dysfunction. Unfortunately, the inherent limitations of physical examination and laboratory parameter results are often responsible for suboptimal clinical management. In this review article, the authors explore how point-of-care ultrasound, including renal and extrarenal ultrasound, can be used to complement all aspects of the care of cardiac surgery patients with AKI, from the initial approach of early AKI to fluid balance management during renal replacement therapy. The current evidence is reviewed, including knowledge gaps and future areas of research.

Fluid accumulation during acute kidney injury in the intensive care unit

INTRODUCTION

Fluid therapy is a ubiquitous intervention in patients admitted to the intensive care unit, but positive fluid balance may be associated with poor outcomes and particular in patients with acute kidney injury. Studies describing this have defined fluid overload either at specific time points or considered patients with a positive mean daily fluid balance as fluid overloaded. We wished to detail this further and performed joint model analyses of the association between daily fluid balance and outcome represented by mortality and renal recovery in patients admitted with acute kidney injury.

METHOD

We did a retrospective cohort study of patients admitted to the intensive care unit with acute kidney injury during a 2-year observation period. We used serum creatinine measurements to identify patients with acute kidney injury and collected sequential daily fluid balance during the first 5 days of admission to the intensive care unit. We used joint modelling techniques to correlate the development of fluid overload with survival and renal recovery adjusted for age, gender and disease severity.

RESULTS

The cohort contained 863 patients with acute kidney injury of whom 460 (53%) and 254 (29%) developed 5% and 10% fluid overload, respectively. We found that both 5% and 10% fluid overload was correlated with reduced survival and renal recovery.

CONCLUSION

Joint model analyses of fluid accumulation in patients admitted to the intensive care unit with acute kidney injury confirm that even a modest degree of fluid overload (5%) may be negatively associated with both survival and renal recovery.

Biomarkers of renal recovery after acute kidney injury

Novel biomarkers can be suitable for early acute kidney injury diagnosis and the prediction of the need for dialysis. It remains unclear whether such biomarkers may also play a role in the prediction of recovery after established acute kidney injury or in aiding the decision of when to stop renal support therapy. PubMed, Web of Science and Google Scholar were searched for studies that reported on the epidemiology of renal recovery after acute kidney injury, the risk factors of recovery versus non-recovery after acute kidney injury, and potential biomarkers of acute kidney injury recovery. The reference lists of these articles and relevant review articles were also reviewed. Final references were selected for inclusion in the review based on their relevance. New biomarkers exhibited a potential role in the early diagnosis of acute kidney injury recovery. Urine HGF, IGFBP-7, TIMP-2 and NGAL may improve our ability to predict the odds and timing of recovery and eventually renal support withdrawal. Acute kidney injury recovery requires more study, and its definition needs to be standardized to allow for better and more powerful research on biomarkers because some of them show potential for the prediction of acute kidney injury recovery.

Assessment of adequacy of volume resuscitation

PURPOSE OF REVIEW

It has recently become evident that administration of intravenous fluids following initial resuscitation has a greater probability of producing tissue edema and hypoxemia than of increasing oxygen delivery. Therefore, it is essential to have a rational approach to assess the adequacy of volume resuscitation. Here we review passive leg raising (PLR) and respiratory variation in hemodynamics to assess fluid responsiveness.

RECENT FINDINGS

The use of ultrasound enhances the clinician's ability to detect and predict fluid responsiveness, whereas enthusiasm for this modality must be tempered by recent evidence that it is only reliable in apneic patients.

SUMMARY

The best predictor of fluid response for hypotensive patients not on vasopressors is a properly conducted passive leg raise maneuver. For more severely ill patients who are apneic, mechanically ventilated and on vasopressors, point of care echocardiography is the best choice. Increases in vena caval diameter induced by controlled positive pressure breaths are insensitive to arrhythmias and can be performed with relatively brief training. Most challenging are patients who are awake and on vasopressors; we suggest that the best method to discriminate fluid responders is PLR measuring changes in cardiac output.

Clarifications on Continuous Renal Replacement Therapy and Hemodynamics

Objective:

Continuous renal replacement therapy (CRRT) is a continuous process of bedside blood purification which is widely used in the treatment of acute kidney injury (AKI) and for fluid management. However, since AKI and fluid overload are often found to be associated with hemodynamic abnormalities, determining the relationship between CRRT and hemodynamics remains a challenge in the treatment of critically ill patients. The aim of this review was to summarize key points in the relationship between CRRT and hemodynamics and to understand and monitor renal hemodynamics in critically ill patients, especially those with AKI.

Data Sources:

This review was based on data in articles published in the PubMed databases up to January 30, 2017, with the following keywords: “continuous renal replacement therapy,” “Hemodynamics,” and “Acute kidney injury.”

Study Selection:

Original articles and critical reviews on CRRT were selected for this review.

Results:

CRRT might treat AKI by hemodynamic therapy, and it was an important form of hemodynamic therapy. The targets of hemodynamic therapy should be established when using CRRT. Therefore, hemodynamic management and stability were very important during CRRT. Most studies suggested that renal hemodynamics should be clearly identified.

Conclusions:

CRRT is not only a replacement for organ function, but an important form of hemodynamic therapy. Improved hemodynamic management of critically ill patients can be achieved by establishing specific therapeutic hemodynamic targets and maintaining circulatory stability during CRRT. Over the long term, observation of renal hemodynamics will provide greater opportunities for the progression of CRRT hemodynamic therapy.

Interventions to prevent hemodynamic instability during renal replacement therapy in critically ill patients: a systematic review

Background

Hemodynamic instability related to renal replacement therapy (HIRRT) may increase the risk of death and limit renal recovery. Studies in end-stage renal disease populations on maintenance hemodialysis suggest that some renal replacement therapy (RRT)-related interventions (e.g., cool dialysate) may reduce the occurrence of HIRRT, but less is known about interventions to prevent HIRRT in critically ill patients receiving RRT for acute kidney injury (AKI). We sought to evaluate the effectiveness of RRT-related interventions for reducing HIRRT in such patients across RRT modalities.

Methods

A systematic review of publications was undertaken using MEDLINE, MEDLINE in Process, EMBASE, and Cochrane’s Central Registry for Randomized Controlled Trials (RCTs). Studies that assessed any intervention’s effect on HIRRT (the primary outcome) in critically ill patients with AKI were included. HIRRT was variably defined according to each study’s definition. Two reviewers independently screened abstracts, identified articles for inclusion, extracted data, and evaluated study quality using validated assessment tools.

Results

Five RCTs and four observational studies were included (n = 9; 623 patients in total). Studies were small, and the quality was mostly low. Interventions included dialysate sodium modeling (n = 3), ultrafiltration profiling (n = 2), blood volume (n = 2) and temperature control (n = 3), duration of RRT (n = 1), and slow blood flow rate at initiation (n = 1). Some studies applied more than one strategy simultaneously (n = 5). Interventions shown to reduce HIRRT from three studies (two RCTs and one observational study) included higher dialysate sodium concentration, lower dialysate temperature, variable ultrafiltration rates, or a combination of strategies. Interventions not found to have an effect included blood volume and temperature control, extended duration of intermittent RRT, and slower blood flow rates during continuous RRT initiation. How HIRRT was defined and its frequency of occurrence varied widely across studies, including those involving the same RRT modality. Pooled analysis was not possible due to study heterogeneity.

Conclusions

Small clinical studies suggest that higher dialysate sodium, lower temperature, individualized ultrafiltration rates, or a combination of these strategies may reduce the risk of HIRRT. Overall, for all RRT modalities, there is a paucity of high-quality data regarding interventions to reduce the occurrence of HIRRT in critically ill patients.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-1965-5) contains supplementary material, which is available to authorized users.

Pre-admission proteinuria impacts risk of non-recovery after dialysis-requiring acute kidney injury

Renal recovery after dialysis-requiring acute kidney injury (AKI-D) is an important clinical and patient-centered outcome. Here we examined whether the pre-admission proteinuria level independently influences risk for non-recovery after AKI-D in a community-based population. All adult members of Kaiser Permanente Northern California who experienced AKI-D between January 1, 2009 and September 30, 2015 were included. Pre-admission proteinuria levels were determined by dipstick up to four years before the AKI-D hospitalization and the outcome was renal recovery (survival and dialysis-independence four weeks and more) at 90 days after initiation of renal replacement therapy. We used multivariable logistic regression to adjust for baseline estimated glomerular filtration rate (eGFR), age, sex, ethnicity, short-term predicted risk of death, comorbidities, and medication use. Among 5,347 adults with AKI-D, the mean age was 66 years, 59% were men, and 50% were white. Compared with negative/trace proteinuria, the adjusted odds ratios for non-recovery (continued dialysis-dependence or death) were 1.47 (95% confidence interval 1.19-1.82) for 1+ proteinuria and 1.92 (1.54-2.38) for 2+ or more proteinuria. Among survivors, the crude probability of recovery ranged from 83% for negative/trace proteinuria with baseline eGFR over 60 mL/min/1.73m² to 25% for 2+ or more proteinuria with eGFR 15-29 mL/min/1.73m². Thus, the pre-AKI-D level of proteinuria is a graded, independent risk factor for non-recovery and helps to improve short-term risk stratification for patients with AKI-D.

Fluid Overload and Renal Angina Index at Admission Are Associated With Worse Outcomes in Critically Ill Children

Objectives: We investigated the association of fluid overload and oxygenation in critically sick children, and their correlation with various outcomes (duration of ventilation, ICU stay, and mortality). We also assessed whether renal angina index (RAI) at admission can predict mortality or acute kidney injury (AKI) on day 3 after admission. Design and setting: Prospective study, pediatric intensive care in a tertiary hospital. Duration: June 2013-June 2014. Patients: Patients were included if they needed invasive mechanical ventilation for >24 h and had an indwelling arterial catheter. Patients with congenital heart disease or those who received renal replacement therapy (RRT) were excluded. Methods: Oxygenation index, fluid overload percent (daily, cumulative), RAI at admission and pediatric logistic organ dysfunction (PELOD) score were obtained in all critically ill children. KDIGO classification was used to define AKI, using both creatinine and urine output criteria. Admission data for determination of RAI included the use of vasopressors, invasive mechanical ventilation, percent fluid overload, and change in kidney function (estimated creatinine clearance). Univariable and multivariable approaches were used to assess the relations between fluid overload, oxygenation index and clinical outcomes. An RAI cutoff >8 was used to predict AKI on day 3 of admission and mortality. Results: One hundred and two patients were recruited. Fluid overload predicted oxygenation index in all patients, independent of age, gender and PELOD score (p < 0.05). Fluid overload was associated with longer duration of ventilation (p < 0.05), controlled for age, gender, and PELOD score. Day-3 AKI rates were higher in patients with a RAI of 8 or more, and higher areas under the RAI curve had better prediction rates for Day-3 AKI. An RAI <8 had high negative predictive values (80-95%) for Day-3 AKI. RAI was better than traditional markers of pediatric severity of illness (PELOD) score for prediction of AKI on day 3. Conclusions: This study emphasizes that positive fluid balance adversely affects intensive care in critically ill children. Further, the RAI prediction model may help optimize treatment and improve clinical prediction of AKI.

The role of fluid overload in the prediction of outcome in acute kidney injury

Our understanding of the epidemiology and the impact of acute kidney injury (AKI) and fluid overload on outcomes has improved significantly over the past several decades. Fluid overload occurs commonly in critically ill children with and without associated AKI. Researchers in pediatric AKI have been at the forefront of describing the impact of fluid overload on outcomes in a variety of populations. A full understanding of this topic is important as fluid overload represents a potentially modifiable risk factor and a target for intervention. In this state-of-the-art review, we comprehensively describe the definition of fluid overload, the impact of fluid overload on kidney function, the impact of fluid overload on the diagnosis of AKI, the association of fluid overload with outcomes, the targeted therapy of fluid overload, and the impact of the timing of renal replacement therapy on outcomes.

3-month prognostic impact of severe acute renal failure under veno-venous ECMO support: Importance of time of onset

PURPOSE

Veno-venous ECMO is increasingly used for the management of refractory ARDS. In this context, acute kidney injury (AKI) is a major and frequent complication, often associated with poor outcome. We aimed to identify characteristics associated with severe renal failure (Kidney Disease Improving Global Outcome (KDIGO) 3) and its impact on 3-month outcome.

METHODS

Between May 2009 and April 2016, 60 adult patients requiring VV-ECMO in our University Hospital were prospectively included.

RESULTS

AKI occurrence was frequent (75%; n=45), 51% of patients (n=31) developed KDIGO 3 - predominantly prior to ECMO insertion - and renal replacement therapy was required in 43% (n=26) of cases. KDIGO 3 was associated with a lower mechanical ventilation weaning rate (24% vs 68% for patients with no AKI or other stages of AKI; p<0.001) and a higher 90-day mortality rate (72% vs 32%, p=0.002). Multivariate logistic regression suggested that KDIGO 3 occurrence prior to ECMO insertion, as well as PaCO2>57mmHg and mSOFA>12 were independent risks factors for 90-day mortality.

CONCLUSION

KDIGO 3 AKI occurrence is correlated with the severity of patients' clinical condition prior to ECMO insertion and is negatively associated with 90-day survival.

Both Positive and Negative Fluid Balance May Be Associated With Reduced Long-Term Survival in the Critically Ill

OBJECTIVES

Among critically ill patients with acute kidney injury, exposure to positive fluid balance, compared with negative fluid balance, has been associated with mortality and impaired renal recovery. However, it is unclear whether positive and negative fluid balances are associated with poor outcome compared to patients with even fluid balance (euvolemia). In this study, we examined the association between exposure to positive or negative fluid balance, compared with even fluid balance, on 1-year mortality and renal recovery.

DESIGN

Retrospective cohort study.

SETTING

Eight medical-surgical ICUs at the University of Pittsburgh Medical Center, Pittsburgh, PA.

PATIENTS

Critically ill patients admitted between July 2000 and October 2008.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among 18,084 patients, fluid balance was categorized as negative (< 0%), even (0% to < 5%), or positive (≥ 5%). Following propensity matching, positive fluid balance, compared with even or negative fluid balance, was associated with increased mortality (30.3% vs 21.1% vs 22%, respectively; p < 0.001). Using Gray's model, negative fluid balance, compared with even fluid balance, was associated with lower short-term mortality (adjusted hazard ratio range, 0.81; 95% CI, 0.68-0.96) but higher long-term mortality (adjusted hazard ratio range, 1.16-1.22; p = 0.004). Conversely, positive fluid balance was associated with higher mortality throughout 1-year (adjusted hazard ratio range, 1.30-1.92; p < 0.001), which was attenuated in those who received renal replacement therapy (positive fluid balance × renal replacement therapy interaction (adjusted hazard ratio range, 0.43-0.89; p < 0.001). Of patients receiving renal replacement therapy, neither positive (adjusted odds ratio, 0.98; 95% CI, 0.68-1.4) nor negative (adjusted odds ratio, 0.81; 95% CI, 0.43-1.55) fluid balance was associated with renal recovery.

CONCLUSIONS

Among critically ill patients, exposure to positive or negative fluid balance, compared with even fluid balance, was associated with higher 1-year mortality. This mortality risk associated with positive fluid balance, however, was attenuated by use of renal replacement therapy. We found no association between fluid balance and renal recovery.

CRRTnet: a prospective, multi-national, observational study of continuous renal replacement therapy practices

Background

Continuous renal replacement therapy (CRRT) is the recommended modality of dialysis for critically ill patients with hemodynamic instability. Yet there remains significant variability in how CRRT is prescribed and delivered, and limited evidence-basis to guide practice.

Methods

This is a prospective, multi-center observational study of patients undergoing CRRT. Initial enrollment phase will occur at 4 academic medical centers in North America over 5 years, with a target enrollment of 2000 patients. All adult patients (18–89 years of age) receiving CRRT will be eligible for inclusion; patients who undergo CRRT for less than 24 h will be excluded from analysis. Data collection will include patient characteristics at baseline and at time of CRRT initiation; details of CRRT prescription and delivery, including machine-generated treatment data; and patient outcomes.

Discussion

The goal of this study is to establish a large comprehensive registry of critically ill adults receiving CRRT. Specific aims include describing variations in CRRT prescription and delivery across quality domains; validating quality measures for CRRT care by correlating processes and outcomes; and establishing a large registry for use in quality improvement and benchmarking efforts. For initial analyses, some particular areas of interest are anticoagulation protocols; approach to fluid overload; CRRT-related workload; and patient safety.

Trial registration

Registered on ClinicalTrials.gov 1/10/2014: NCT02034448.

Intradialytic hypotension in acute kidney injury requiring renal replacement therapy

The treatment of severe acute kidney injury (AKI) with dialytic support for renal replacement therapy can be life sustaining and permit recovery from critical illness. Like any interventional therapy, however, renal replacement therapy with intermittent hemodialysis or continuous therapy can cause complications. Intradialytic hypotension is a common complication and can cause further ischemic injury to the recovering kidneys, thereby reducing the probability of renal recovery. The optimal dialytic technique-continuous or intermittent-has not been conclusively demonstrated in randomized controlled trials. In general, treatment or prophylactic strategies for intradialytic hypotension in AKI have not been comprehensively tested. Given the frequency of intradialytic hypotension in dialytic treatment of AKI and its adverse clinical consequences, future research should rigorously compare dialytic techniques and other prevention strategies in adequately powered, randomized controlled trials.

Issues of Acute Kidney Injury Staging and Management in Sepsis and Critical Illness: A Narrative Review

Acute kidney injury (AKI) has a high incidence on intensive care units around the world and is a major complication in critically ill patients suffering from sepsis or septic shock. The short- and long-term complications are thereby devastating and impair the quality of life. Especially in terms of AKI staging, the determination of kidney function and the timing of dialytic AKI management outside of life-threatening indications are ongoing matters of debate. Despite several studies, a major problem remains in distinguishing between beneficial and unnecessary "early" or even harmful renal replacement therapy (RRT). The latter might prolong disease course and renal recovery. AKI scores, however, provide an insufficient outcome-predicting ability and the related estimation of kidney function via serum creatinine or blood urea nitrogen (BUN)/urea is not reliable in AKI and critical illness. Kidney independent alterations of creatinine- and BUN/urea-levels further complicate the situation. This review critically assesses the current AKI staging, issues and pitfalls of the determination of kidney function and RRT timing, as well as the potential harm reflected by unnecessary RRT. A better understanding is mandatory to improve future study designs and avoid unnecessary RRT for higher patient safety and lower health care costs.

Effect of high-dose furosemide on the prognosis of critically ill patients

PURPOSE

Diuretics are used frequently in critically ill patients. We investigated the effects of furosemide on the prognosis.

MATERIALS AND METHODS

Following a retrospective review of patients admitted to the medical intensive care unit (ICU), we analyzed risk factors with variables including initial furosemide dose for ICU mortality.

RESULTS

A total of 448 patients were included. Total furosemide dose during the first three days of the ICU stay (odds ratio (OR) 2.35, 95% confidence interval (CI) 1.01-5.02) and fluid balance during the same period (OR 3.04, 95% CI 1.46-6.31) were associated with ICU mortality, as were malignancy, chronic furosemide use, and APACHE II score. However, in oliguric patients, positive fluid balance was associated with ICU mortality (OR 22.33, 95% CI 1.82-273.72) but the high-dose furosemide was not. In contrast, in non-oliguric patients, high-dose furosemide was associated with ICU mortality (OR 2.47, 95% CI 1.01-5.68); however, the positive fluid balance showed only a trend for high ICU mortality.

CONCLUSION

Early high-dose furosemide use is associated with ICU mortality, particularly in non-oliguric patients. We suggest that furosemide should be used with caution even in non-oliguric critically ill patients until the safety is confirmed in powered study.

Assessment of hydration status using bioelectrical impedance vector analysis in critical patients with acute kidney injury

BACKGROUND & AIMS

The state of hyperhydration in critically ill patients with acute kidney injury (AKI) is associated with increased mortality. Bioelectrical impedance vector analysis (BIVA) appears to be a viable method to access the fluid status of critical patients but has never been evaluated in critical patients with AKI. The objective of this study is to evaluate the hydration status measured using BIVA in critical patients under intensive care at the time of AKI diagnosis and to correlate this measurement with mortality.

METHODS

We assessed the fluid status measured using BIVA in 224 critical patients at the time of AKI diagnosis and correlated it with mortality. To interpret the results, BIVA Software 2002 was used to plot the data from the patients studied on the 95% confidence ellipses of the RX_c plane for comparisons between groups (non-survivors, survivors). Variables such as mechanical ventilation, vasoactive drug, and sepsis, among others, were collected.

RESULTS

The impedance vector analysis conducted using BIVA Software 2002 indicated changes in the body compositions of patients according to the 95% confidence ellipse between the vectors R/H and X_c/H of the group of survivors and the group of deceased patients. Hotelling's test (T² = 21.2) and the F test (F = 10.6) revealed significant differences (p < 0.001) between the two groups. These results demonstrate that patients who died presented with a greater hydration volume at the time of AKI diagnosis compared with those who survived. In addition to the hydration status measured using BIVA, the following were also correlated with death: diagnosis at hospitalization, APACHE II score, length of hospital stay, RIFLE score, maximum organ failure, sepsis type, hemoglobin, and AF.

CONCLUSIONS

The fluid status assessment measured using BIVA significantly demonstrated the difference in hydration between survivors and non-survivors among critically ill patients with AKI.

Fluid overload is an independent risk factor for acute kidney injury in critically Ill patients: results of a cohort study

BACKGROUND

Acute Kidney injury (AKI) is common and increases mortality in the intensive care unit (ICU). We carried out this study to explore whether fluid overload is an independent risk factor for AKI.

METHODS

Single-center prospective, observational study. Consecutively admitted, ICU patients were followed for development of AKI. Intravenous fluid volumes, daily fluid balances were measured, hourly urine volumes, daily creatinine levels were recorded.

RESULTS

Three hundred thirty nine patients were included; AKI developed in 141 (41.6%) patients; RISK in 27 (8%) patients; INJURY in 25 (7%); FAILURE in 89 (26%) by the RIFLE criteria. Fluid balance was significantly higher in patients with AKI; 1755 ± 2189 v/s 924 ± 1846 ml, p < 0.001 on ICU day 1. On multivariate regression analysis, a net fluid balance in first 24 h of ICU admission, OR 1.02 (95% CI 1.01,1.03 p = 0.003), percentage of fluid accumulation adjusted for body weight OR1.009 (95% CI 1.001,1.017, p = 0.02), fluid balance in first 24 h of ICU admission with serum creatinine adjusted for fluid balance, OR 1.024 (95% CI 1.012,1,035, p = 0.005), Age, OR 1.02 95% CI 1.01,1.03, p < 0.001, CHF, OR 3.1 (95% CI 1.16,8.32, p = 0.023), vasopressor requirement on ICU day one, OR 1.9 (95% CI 1.13,3.19, p = 0.014) and Colistin OR 2.3 (95% CI 1.3, 4.02, p < 0.001) were significant predictors of AKI. There was no significant association between fluid type; Chloride-liberal, Chloride-restrictive, and AKI.

CONCLUSIONS

Fluid overload is an independent risk factor for AKI.

Volume-related weight gain as an independent indication for renal replacement therapy in the intensive care units

Attempts to identify specific therapies to reverse acute kidney injury (AKI) have been unsuccessful in the past; only modifying risk profile or addressing the underlying disease processes leading to AKI proved efficacious. The current thinking on recognizing AKI is compromised by a "kidney function percent-centered" viewpoint, a paradigm further reinforced by the emergence of serum creatinine-based automated glomerular filtration reporting over the last two decades. Such thinking is, however, grossly corrupted for AKI and poorly applicable in critically ill patients in general. Conventional indications for renal replacement therapy (RRT) may have limited applicability in critically ill patients and there has been a relative lack of progress on RRT modalities in these patients. AKI in critically ill patients is a highly complex syndrome and it may be counterproductive to produce complex clinical practice guidelines, which are labor and resource-intensive to maintain, difficult to memorize or may not be immediately available in all settings all over the world. Additionally, despite attempts to develop reliable and reproducible biomarkers to replace serum creatinine as a guide to therapy such biomarkers failed to materialize. Under such circumstances, there is an ongoing need to reassess the practical value of simple measures, such as volume-related weight gain (VRWG) and urine output, both for prognostic markers and clinical indicators for the need for RRT. This current paper reviews the practical utility of VRWG as an independent indication for RRT in face of reduced urine output and hemodynamic instability.

Acute kidney injury adjusted to volume status in critically ill patients: recognition of delayed diagnosis, restaging, and associated outcomes

Critically ill patients receive a significant amount of fluids leading to a positive fluid balance; this dilutes serum creatinine resulting in an overestimated glomerular filtration rate. The goal of our study is to identify undiagnosed or underestimated acute kidney injury (AKI) in the intensive care unit (ICU). It will also identify the morbidity and mortality associated with an underestimated AKI. We reviewed records of patients admitted to our institution (Staten Island University Hospital) between 2012 and 2013 for more than 2 days. Patients with end stage renal disease were excluded. AKI was defined using the Acute Kidney Injury Network criteria. The following formula was used to identify and restage patients with AKI: adjusted creatinine = serum creatinine × [(hospital admission weight (kg) 0.6 + Σ (daily cumulative fluid balance (L))/hospital admission weight × 0.6]. The primary outcome identified newly diagnosed AKI and those who were restaged. The secondary outcome identified associated morbidities. Seven-hundred and thirty-three out of 1,982 ICU records reviewed, were used. Two-hundred and fifty-seven (mean age 69.8±14.9) had AKI, out of which 15.9% were restaged using the equation. Comparison of mean by Student's t-test showed no difference between patients who were restaged. Similarly, chi-square revealed no differences between both arms, except mean admission weight (lower in patients who were restaged), fluid balance on days 1, 2, and 3 (higher in the restaged arm), and the presence of congestive heart failure (more prevalent in the restaged arm). Of note, the mean cost of stay was US$150,562.82 vs $197,174.63 for same stage vs restaged, respectively, however, without statistical significance (P=0.74). Applying the adjustment equation showed a modest (15.9%) increase in the AKI staging slightly impacting outcomes (mortality, length, and cost of stay) without statistical significance.

Cumulative Fluid Balance and Mortality in Septic Patients With or Without Acute Kidney Injury and Chronic Kidney Disease

OBJECTIVE

Incident acute kidney injury and prevalent chronic kidney disease are commonly encountered in septic patients. We examined the differential effect of acute kidney injury and chronic kidney disease on the association between cumulative fluid balance and hospital mortality in critically ill septic patients.

DESIGN

Retrospective cohort study.

SETTING

Urban academic medical center ICU.

PATIENTS

ICU adult patients with severe sepsis or septic shock and serum creatinine measured within 3 months prior to and 72 hours of ICU admission. Patients with estimated glomerular filtration rate less than 15 mL/min/1.73 m or receiving chronic dialysis were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 2,632 patients, 1,211 with chronic kidney disease, were followed up until hospital death or discharge. Acute kidney injury occurred in 1,525 patients (57.9%), of whom 679 (44.5%) had chronic kidney disease. Hospital mortality occurred in 603 patients (22.9%). Every 1-L increase in cumulative fluid balance at 72 hours of ICU admission was independently associated with hospital mortality in all patients (adjusted odds ratio, 1.06 [95% CI] 1.04-1.08; p < 0.001), and in each acute kidney injury/chronic kidney disease subgroup (adjusted odds ratio, 1.06 [1.03-1.09] for acute kidney injury+/chronic kidney disease+; 1.09 [1.05-1.13] for acute kidney injury-/chronic kidney disease+; 1.05 [1.03-1.08] for acute kidney injury+/chronic kidney disease-; and 1.07 [1.02-1.11] for acute kidney injury-/chronic kidney disease-). There was a significant interaction between acute kidney injury and chronic kidney disease on cumulative fluid balance (p =0.005) such that different cumulative fluid balance cut-offs with the best prognostic accuracy for hospital mortality were identified: 5.9 L for acute kidney injury+/chronic kidney disease+; 3.8 L for acute kidney injury-/chronic kidney disease+; 4.3 L for acute kidney injury+/chronic kidney disease-; and 1.5 L for acute kidney injury-/chronic kidney disease-. The addition of cumulative fluid balance to the admission Sequential Organ Failure Assessment score had increased prognostic utility for hospital mortality when compared with Sequential Organ Failure Assessment alone, particularly in patients with acute kidney injury.

CONCLUSIONS

Higher cumulative fluid balance at 72 hours of ICU admission was independently associated with hospital mortality regardless of acute kidney injury or chronic kidney disease presence. We characterized cumulative fluid balance cut-offs associated with hospital mortality based on acute kidney injury/chronic kidney disease status, underpinning the heterogeneity of fluid regulation in sepsis and kidney disease.

Echocardiography as a guide for fluid management

Background

In critically ill patients at risk for organ failure, the administration of intravenous fluids has equal chances of resulting in benefit or harm. While the intent of intravenous fluid is to increase cardiac output and oxygen delivery, unwelcome results in those patients who do not increase their cardiac output are tissue edema, hypoxemia, and excess mortality. Here we briefly review bedside methods to assess fluid responsiveness, focusing upon the strengths and pitfalls of echocardiography in spontaneously breathing mechanically ventilated patients as a means to guide fluid management. We also provide new data to help clinicians anticipate bedside echocardiography findings in vasopressor-dependent, volume-resuscitated patients.

Objective

To review bedside ultrasound as a method to judge whether additional intravenous fluid will increase cardiac output. Special emphasis is placed on the respiratory effort of the patient.

Conclusions

Point-of-care echocardiography has the unique ability to screen for unexpected structural findings while providing a quantifiable probability of a patient’s cardiovascular response to fluids. Measuring changes in stroke volume in response to either passive leg raising or changes in thoracic pressure during controlled mechanical ventilation offer good performance characteristics but may be limited by operator skill, arrhythmia, and open lung ventilation strategies. Measuring changes in vena caval diameter induced by controlled mechanical ventilation demands less training of the operator and performs well during arrythmia. In modern delivery of critical care, however, most patients are nursed awake, even during mechanical ventilation. In patients making respiratory efforts we suggest that ventilator settings must be standardized before assessing this promising technology as a guide for fluid management.

Assessment of Postresuscitation Volume Status by Bioimpedance Analysis in Patients with Sepsis in the Intensive Care Unit: A Pilot Observational Study

Background. Bioimpedance analysis (BIA) is a novel method of assessing a patient's volume status. Objective. We sought to determine the feasibility of using vector length (VL), derived from bioimpedance analysis (BIA), in the assessment of postresuscitation volume status in intensive care unit (ICU) patients with sepsis. Method. This was a prospective observational single-center study. Our primary outcome was feasibility. Secondary clinical outcomes included ventilator status and acute kidney injury. Proof of concept was sought by correlating baseline VL measurements with other known measures of volume status. Results. BIA was feasible to perform in the ICU. We screened 655 patients, identified 78 eligible patients, and approached 64 for consent. We enrolled 60 patients (consent rate of 93.8%) over 12 months. For each 50-unit increase in VL, there was an associated 22% increase in the probability of not requiring invasive mechanical ventilation (IMV) (p = 0.13). Baseline VL correlated with other measures of volume expansion including serum pro-BNP levels, peripheral edema, and central venous pressure (CVP). Conclusion. It is feasible to use BIA to predict postresuscitation volume status and patient-important outcomes in septic ICU patients. Trial Registration. This trial is registered with clinicaltrials.gov NCT01379404 registered on June 7, 2011.

Comparison of Urine Output among Patients Treated with More Intensive Versus Less Intensive RRT: Results from the Acute Renal Failure Trial Network Study

BACKGROUND AND OBJECTIVES

Intensive RRT may have adverse effects that account for the absence of benefit observed in randomized trials of more intensive versus less intensive RRT. We wished to determine the association of more intensive RRT with changes in urine output as a marker of worsening residual renal function in critically ill patients with severe AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Acute Renal Failure Trial Network Study (n=1124) was a multicenter trial that randomized critically ill patients requiring initiation of RRT to more intensive (hemodialysis or sustained low-efficiency dialysis six times per week or continuous venovenous hemodiafiltration at 35 ml/kg per hour) versus less intensive (hemodialysis or sustained low-efficiency dialysis three times per week or continuous venovenous hemodiafiltration at 20 ml/kg per hour) RRT. Mixed linear regression models were fit to estimate the association of RRT intensity with change in daily urine output in survivors through day 7 (n=871); Cox regression models were fit to determine the association of RRT intensity with time to ≥50% decline in urine output in all patients through day 28.

RESULTS

Mean age of participants was 60±15 years old, 72% were men, and 30% were diabetic. In unadjusted models, among patients who survived ≥7 days, mean urine output was, on average, 31.7 ml/d higher (95% confidence interval, 8.2 to 55.2 ml/d) for the less intensive group compared with the more intensive group (P=0.01). More intensive RRT was associated with 29% greater unadjusted risk of decline in urine output of ≥50% (hazard ratio, 1.29; 95% confidence interval, 1.10 to 1.51).

CONCLUSIONS

More intensive versus less intensive RRT is associated with a greater reduction in urine output during the first 7 days of therapy and a greater risk of developing a decline in urine output of ≥50% in critically ill patients with severe AKI.

A comparison of preemptive versus standard renal replacement therapy for acute kidney injury after cardiac surgery

BACKGROUND

The optimal timing of renal replacement therapy (RRT) initiation in patients undergoing cardiac surgery remains controversial. This study aimed to determine whether preemptive RRT or standard RRT was associated with hospital mortality in cardiac surgical patients with acute kidney injury (AKI).

METHODS

Data were retrospectively collected from patients who underwent cardiac surgery and experienced postoperative AKI requiring RRT at Zhongshan Hospital of Fudan University from September 1, 2006 to December 31, 2013. The patients were divided into two groups according to the RRT strategy applied.

RESULTS

A total of 213 patients were enrolled in this study; 59 patients were categorized into the preemptive RRT group and 154 into the standard RRT group. The preemptive RRT group exhibited significantly lower mortality (33.90% versus 51.95%, P = 0.018) and time to recovery of renal function than the standard RRT group (15.34 ± 14.46 versus 22.88 ± 14.08 d, P = 0.022). Moreover, the preemptive RRT group showed significantly lower serum creatinine levels and higher proportions of recovery of renal function and weaning from RRT at death or discharge than the standard RRT group. There was no significant difference in the duration of mechanical ventilation, RRT, intensive care unit stay, or hospital stay between the two groups.

CONCLUSIONS

In patients after cardiac surgery, preemptive RRT was associated with lower hospital mortality and faster and more frequent recovery of renal function than standard RRT. However, preemptive RRT did not affect other patient-centered outcomes including mechanical ventilation time, RRT time, or length of intensive care unit or hospital stay.

The Dose Response Multicentre Investigation on Fluid Assessment (DoReMIFA) in critically ill patients

Background

The previously published “Dose Response Multicentre International Collaborative Initiative (DoReMi)” study concluded that the high mortality of critically ill patients with acute kidney injury (AKI) was unlikely to be related to an inadequate dose of renal replacement therapy (RRT) and other factors were contributing. This follow-up study aimed to investigate the impact of daily fluid balance and fluid accumulation on mortality of critically ill patients without AKI (N-AKI), with AKI (AKI) and with AKI on RRT (AKI-RRT) receiving an adequate dose of RRT.

Methods

We prospectively enrolled all consecutive patients admitted to 21 intensive care units (ICUs) from nine countries and collected baseline characteristics, comorbidities, severity of illness, presence of sepsis, daily physiologic parameters and fluid intake-output, AKI stage, need for RRT and survival status. Daily fluid balance was computed and fluid overload (FO) was defined as percentage of admission body weight (BW). Maximum fluid overload (MFO) was the peak value of FO.

Results

We analysed 1734 patients. A total of 991 (57 %) had N-AKI, 560 (32 %) had AKI but did not have RRT and 183 (11 %) had AKI-RRT. ICU mortality was 22.3 % in AKI patients and 5.6 % in those without AKI (p < 0.0001). Progressive fluid accumulation was seen in all three groups. Maximum fluid accumulation occurred on day 2 in N-AKI patients (2.8 % of BW), on day 3 in AKI patients not receiving RRT (4.3 % of BW) and on day 5 in AKI-RRT patients (7.9 % of BW). The main findings were: (1) the odds ratio (OR) for hospital mortality increased by 1.075 (95 % confidence interval 1.055–1.095) with every 1 % increase of MFO. When adjusting for severity of illness and AKI status, the OR changed to 1.044. This phenomenon was a continuum and independent of thresholds as previously reported. (2) Multivariate analysis confirmed that the speed of fluid accumulation was independently associated with ICU mortality. (3) Fluid accumulation increased significantly in the 3-day period prior to the diagnosis of AKI and peaked 3 days later.

Conclusions

In critically ill patients, the severity and speed of fluid accumulation are independent risk factors for ICU mortality. Fluid balance abnormality precedes and follows the diagnosis of AKI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1355-9) contains supplementary material, which is available to authorized users.

Continuous renal replacement therapy versus intermittent hemodialysis in intensive care patients: impact on mortality and renal recovery

PURPOSE

The best renal replacement therapy (RRT) modality remains controversial. We compared mortality and short- and long-term renal recovery between patients treated with continuous RRT and intermittent hemodialysis.

METHODS

Patients of the prospective observational multicenter cohort database OUTCOMEREA™ were included if they underwent at least one RRT session between 2004 and 2014. Differences in patients' baseline and daily characteristics between treatment groups were taken into account by using a marginal structural Cox model, allowing one to substantially reduce the bias resulting from confounding factors in observational longitudinal data analysis. The composite primary endpoint was 30-day mortality and dialysis dependency.

RESULTS

Among 1360 included patients with RRT, 544 (40.0 %) and 816 (60.0 %) were initially treated by continuous RRT and intermittent hemodialysis, respectively. At day 30, 39.6 % patients were dead. Among survivors, 23.8 % still required RRT. There was no difference between groups for the primary endpoint in global population (HR 1.00, 95 % CI 0.77-1.29; p = 0.97). In patients with higher weight gain at RRT initiation, mortality and dialysis dependency were significantly lower with continuous RRT (HR 0.54, 95 % CI 0.29-0.99; p = 0.05). Conversely, this technique appeared to be deleterious in patients without shock (HR 2.24, 95 % CI 1.24-4.04; p = 0.01). Six-month mortality and persistent renal dysfunction were not influenced by the RRT modality in patients with dialysis dependence at ICU discharge.

CONCLUSION

Continuous RRT did not appear to improve 30-day and 6-month patient outcomes. It seems beneficial for patients with fluid overload, but might be deleterious in the absence of hemodynamic failure.

Fluid as a Drug: Balancing Resuscitation and Fluid Overload in the Intensive Care Setting

Intravenous fluid resuscitation is ubiquitous throughout medicine and is often considered a benign procedure. Yet, there is now clear recognition of the potential harms of fluid overload after initial resuscitation. In recent years, there has also been an increasing focus on comparing various resuscitation fluids with respect to both benefits and risks. Studies have examined colloids, such as albumin and starches, against the clinical standard of crystalloids. In addition, evidence has emerged to suggest that outcomes may be different between resuscitation with chloride-rich vs balanced crystalloid solutions. In this article, we review the current literature regarding choice of intravenous fluids for resuscitation in the intensive care setting and describe the dangers associated with fluid overload in critically ill patients.

Immediate Consequences of Acute Kidney Injury: The Impact of Traditional and Nontraditional Complications on Mortality in Acute Kidney Injury

Acute kidney injury (AKI) that requires renal replacement therapy is associated with a mortality rate that exceeds 50% in the intensive care unit, which is greater than other serious illnesses such as acute lung injury and myocardial infarction. Much information is now available regarding the complications of AKI that contribute to mortality and may be usefully categorized as "traditional" and "nontraditional". Traditional complications are the long-recognized complications of AKI such as hyperkalemia, acidosis, and volume overload, which may be typically corrected with renal replacement therapy. "Nontraditional" complications include complications such as sepsis, lung injury, and heart failure that may arise due to the effects of AKI on inflammatory cytokines, immune function, and cell death pathways such as apoptosis. In this review, we discuss both traditional and nontraditional complications of AKI with a focus on factors that contribute to mortality, considering both pathophysiology and potential remedies. Because AKI is the most common inpatient consult to nephrologists, it is essential to be aware of the complications of AKI that contribute to mortality to devise appropriate treatment strategies to prevent and manage AKI complications with the ultimate goal of reducing the unacceptably high mortality rate of AKI.

Impact of hyperhydration on the mortality risk in critically ill patients admitted in intensive care units: comparison between bioelectrical impedance vector analysis and cumulative fluid balance recording

BACKGROUND

Studies have demonstrated a positive correlation between fluid overload (FO) and adverse outcomes in critically ill patients. The present study aims at defining the impact of hyperhydration on the Intensive Care Unit (ICU) mortality risk, comparing Bioelectrical Impedance Vector Analysis (BIVA) assessment with cumulative fluid balance (CFB) recording.

METHODS

We performed a prospective, dual-centre, clinician-blinded, observational study of consecutive patients admitted to ICU with an expected length of ICU stay of at least 72 hours. During observational period (72-120 hours), CFB was recorded and cumulative FO was calculated. At the admission and daily during the observational period, BIVA was performed. We considered FO between 5% and 9.99% as moderate and a FO ≥ 10% as severe. According to BIVA hydration scale of lean body mass, patients were classified as normohydrated (>72.7%-74.3%), mild (>71%-72.7%), moderate (>69%-71%) and severe (≤ 69%) dehydrated and mild (>74.3%-81%), moderate (>81%-87%) and severe (>87%) hyperhydrated. Two multivariate logistic regression models were performed: the ICU mortality was the response variable, while the predictor variables were hyperhydration, measured by BIVA (BIVA model), and FO (FO model). A p-value <0.05 was considered to indicate statistical significance.

RESULTS

One hundred and twenty-five patients were enrolled (mean age 64.8 ± 16.0 years, 65.6% male). Five hundred and fifteen BIVA measurements were performed. The mean CFB recorded at the end of the observational period was 2.7 ± 4.1 L, while the maximum hydration of lean body mass estimated by BIVA was 83.67 ± 6.39%. Severe hyperhydration measured by BIVA was the only variable found to be significantly associated with ICU mortality (OR 22.91; 95% CI 2.38-220.07; p < 0.01).

CONCLUSIONS

The hydration status measured by BIVA seems to predict mortality risk in ICU patients better than the conventional method of fluid balance recording. Moreover, it appears to be safe, easy to use and adequate for bedside evaluation. Randomized clinical trials with an adequate sample size are needed to validate the diagnostic properties of BIVA in the goal-directed fluid management of critically ill patients in ICU.

Impact of positive fluid balance on mortality and length of stay in septic shock patients

BACKGROUND

Fluid management is important in critically patients. The aim of this study was to determine the relationship between fluid balance and adverse outcomes of septic shock.

METHODS

A retrospective study was conducted in the medical Intensive Care Unit (ICU) of a tertiary university hospital in Thailand, over a 7-year period.

RESULTS

A total of 1048 patients with an ICU mortality rate of 47% were enrolled. The median cumulative fluid intake at 24, 48, and 72 h from septic shock onset were 4.2, 7.7, and 10.5 L, respectively. Nonsurvivors had a significantly higher median cumulative fluid intake at 24, 48, and 72 h (4.6 vs. 3.9 L, 8.2 vs. 7.1 L, and 11.4 vs. 9.9 L, respectively, P < 0.001 for all). Nonsurvivors also had a significantly higher cumulative and mean fluid balance within 72 h (5.4 vs. 4.4 L and 2.8 vs. 1.6 L, P < 0.001 for both). In multivariate logistic regression analysis, mean fluid balance quartile within 72 h, was independently associated with an increase in ICU and hospital mortality. Quartile 3 and 4 have statistically significant increases in mortality compared with quartile 1 (odds ratio [95% confidence interval] 3.04 [1.9-4.48] and 4.16 [2.49-6.95] for ICU mortality and 2.75 [1.74-4.36] and 3.16 [1.87-5.35] for hospital mortality, respectively, P < 0.001 for all). In addition, the higher amount of mean fluid balance was associated with prolonged ICU stays.

CONCLUSIONS

Positive fluid balance over 3 days is associated with increased ICU and hospital mortality along with prolonged ICU stays in septic shock patients.

Early fluid overload is associated with acute kidney injury and PICU mortality in critically ill children

Fluid overload (FO) has been associated with an increased risk for adverse outcomes in critically ill patients. Information on the impact of FO on mortality in a general population of pediatric intensive care unit (PICU) is limited. We aimed to determine the association of early FO with the development of acute kidney injury (AKI) and mortality during PICU stay and evaluate whether early FO predicts mortality, even after adjustment for illness severity assessed by pediatric risk of mortality (PRISM) III. This prospective study enrolled 370 critically ill children. The early FO was calculated based on the first 24-h total of fluid intake and output after admission and defined as cumulative fluid accumulation ≥5% of admission body weight. Of the patients, 64 (17.3 %) developed early FO during the first 24 h after admission. The PICU mortality rate of the whole cohort was 18 of 370 (4.9%). The independent factors significantly associated with early FO were PRISM III, age, AKI, and blood bicarbonate level. The early FO was associated with AKI (odds ratio [OR] = 1.34, p < 0.001) and mortality (OR = 1.36, p < 0.001). The association of early FO with mortality remained significant after adjustment for potential confounders including AKI and illness severity. The area under the receiver operating characteristic curve (AUC) of early FO for predicting mortality was 0.78 (p < 0.001). This result, however, was not better than PRISM III (AUC = 0.85, p < 0.001).

CONCLUSION

Early FO was associated with increased risk for AKI and mortality in critically ill children.

WHAT IS KNOWN

Fluid overload is associated with an increased risk for adverse outcomes in specific clinical settings of pediatric population. What is New: Early fluid overload during the first 24 h after PICU admission is independently associated with increased risk for acute kidney injury and mortality in critically ill children.

The role of brain natriuretic peptide in predicting renal outcome and fluid management in critically ill patients

BACKGROUND/PURPOSE

Fluid overload is associated with acute kidney injury (AKI) and mortality. There is no convenient precise method to guide fluid therapy in critically ill patients. We aimed to investigate whether brain natriuretic peptide (BNP) can predict the renal outcome and mortality of critically ill patients and be used to guide fluid management.

METHODS

This prospective observational study included patients who were admitted to the intensive care unit (ICU). Patients with underlying heart disease and heart dysfunction were excluded. Plasma BNP levels were obtained on admission (D0), at 24 hours (D1), and at 48 hours (D2). The primary outcome was AKI development during the ICU stay and recovery of AKI at ICU discharge. The secondary outcome was in-ICU mortality.

RESULTS

One hundred and sixty-three patients were enrolled for analysis. The delta-BNP level within the initial 24 hours after ICU admission rather than fluid accumulation was significantly correlated with delta-central venous pressure levels (r = 0.219, p = 0.010). Delta-Brain natriuretic peptide levels of < 81.8% within the initial 24 hours was an independent predictor of better renal outcome (i.e., no AKI or AKI with recovery). The increment in the BNP level from D0 to D1 was also a significant risk factor of mortality. In the a priori subgroup analysis for patients with sepsis, delta-BNP levels from D0 to D1 remained a significant predictor of renal outcome and mortality.

CONCLUSION

Our study showed that delta-BNP levels within 24 hours of admission to the ICU are better than fluid accumulation as a predictor of AKI, recovery, and mortality.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Postoperative Fluid Overload is a Useful Predictor of the Short-Term Outcome of Renal Replacement Therapy for Acute Kidney Injury After Cardiac Surgery

To analyze the predictive value of postoperative percent fluid overload (PFO) of renal replacement therapy (RRT) for acute kidney injury (AKI) patients after cardiac surgery.Data from 280 cardiac surgery patients between 2005 January and 2012 April were collected for retrospective analyses. A receiver operating characteristic (ROC) curve was used to compare the predictive values of cumulative PFO at different times after surgery for 90-day mortality.The cumulative PFO before RRT initiation was 7.9% ± 7.1% and the median PFO 6.1%. The cumulative PFO before and after RRT initiation in intensive care unit (ICU) was higher in the death group than in the survival group (8.8% ± 7.6% vs 6.1% ± 5.6%, P = 0.001; -0.5[-5.6, 5.1]% vs 6.9[2.2, 14.6]%, P < 0.001). The cumulative PFO during the whole ICU stay was 14.3% ± 15.8% and the median PFO was 10.7%. The areas under the ROC curves to predict the 90-day mortality by PFO at 24 hours, cumulative PFO before and after RRT initiation, and PFO during the whole ICU stay postoperatively were 0.625, 0.627, 0.731, and 0.752. PFO during the whole ICU stay ≥7.2% was determined as the cut-off point for 90-day mortality prediction with a sensitivity of 77% and a specificity of 64%. Kaplan-Meier survival estimates showed a significant difference in survival among patients with cumulative PFO ≥ 7.2% and PFO < 7.2% after cardiac surgery (log-rank P < 0.001).Postoperative cumulative PFO during the whole ICU stay ≥7.2% would have an adverse effect on 90-day short-term outcome, which may provide a strategy for the volume control of AKI-RRT patients after cardiac surgery.

A Prospective International Multicenter Study of AKI in the Intensive Care Unit

BACKGROUND AND OBJECTIVES

AKI is frequent and is associated with poor outcomes. There is limited information on the epidemiology of AKI worldwide. This study compared patients with AKI in emerging and developed countries to determine the association of clinical factors and processes of care with outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This prospective observational study was conducted among intensive care unit patients from nine centers in developed countries and five centers in emerging countries. AKI was defined as an increase in creatinine of ≥0.3 mg/dl within 48 hours.

RESULTS

Between 2008 and 2012, 6647 patients were screened, of whom 1275 (19.2%) developed AKI. A total of 745 (58% of those with AKI) agreed to participate and had complete data. Patients in developed countries had more sepsis (52.1% versus 38.0%) and higher Acute Physiology and Chronic Health Evaluation (APACHE) scores (mean±SD, 61.1±27.5 versus 51.1±25.2); those from emerging countries had more CKD (54.3% versus 38.3%), GN (6.3% versus 0.9%), and interstitial nephritis (7.0% versus 0.6%) (all P<0.05). Patients from developed countries were less often treated with dialysis (15.5% versus 30.2%; P<0.001) and started dialysis later after AKI diagnosis (2.0 [interquartile range, 0.75-5.0] days versus 0 [interquartile range, 0-5.0] days; P=0.02). Hospital mortality was 22.0%, and 13.3% of survivors were dialysis dependent at discharge. Independent risk factors associated with hospital mortality included older age, residence in an emerging country, use of vasopressors (emerging countries only), dialysis and mechanical ventilation, and higher APACHE score and cumulative fluid balance (developed countries only). A lower probability of renal recovery was associated with residence in an emerging country, higher APACHE score (emerging countries only) and dialysis, while mechanical ventilation was associated with renal recovery (developed countries only).

CONCLUSIONS

This study contrasts the clinical features and management of AKI and demonstrates worse outcomes in emerging than in developed countries. Differences in variations in care may explain these findings and should be considered in future trials.

Promoting Kidney Function Recovery in Patients with AKI Requiring RRT

AKI requiring RRT is associated with high mortality, morbidity, and long-term consequences, including CKD and ESRD. Many patients never recover kidney function; in others, kidney function improves over a period of many weeks or months. Methodologic constraints of the available literature limit our understanding of the recovery process and hamper adequate intervention. Current management strategies have focused on acute care and short-term mortality, but new data indicate that long-term consequences of AKI requiring RRT are substantial. Promotion of kidney function recovery is a neglected focus of research and intervention. This lack of emphasis on recovery is illustrated by the relative paucity of research in this area and by the lack of demonstrated effective management strategies. In this article the epidemiologic implications of kidney recovery after AKI requiring RRT are discussed, the available literature and its methodologic constraints are reviewed, and strategies to improve the understanding of factors that affect kidney function recovery are proposed. Measures to promote kidney function recovery are a serious unmet need, with a great potential to improve short- and long-term patient outcomes.

Associations of fluid overload with mortality and kidney recovery in patients with acute kidney injury: A systematic review and meta-analysis

PURPOSE

Fluid resuscitation is commonly administered to maintain adequate renal perfusion in critically ill patients to prevent or even treat acute kidney injury (AKI). However, recent studies show that fluid overload is common and might be associated with poor outcomes in patients with AKI. Hence, the objective of this study was to assess the associations of fluid overload with mortality and kidney recovery in patients with AKI.

MATERIALS AND METHODS

We electronically searched original articles published in peer-reviewed journals from their inception to January 2015 in PubMed, EMBASE, the Cochrane Library databases, Google Scholar, and Chinese database (SinoMed). We additionally searched the reference lists of all retrieved articles. We performed a systematic review and meta-analysis of all eligible cohort or case-control studies of fluid overload in patients with AKI. The primary outcomes were mortality and kidney recovery. We pooled adjusted odds ratios (ORs) with 95% confidence intervals (95% CIs) by using Review Manager 5.2 (The Cochrane Collaboration, Oxford, UK).

RESULTS

A total of 5095 patients from 12 cohort studies published from 2008 to 2014 were included. A significant positive association was found between fluid overload and mortality in patients with AKI (OR, 2.23; 95% CI, 1.66-3.01), with similar findings in sepsis (OR, 2.27; 95% CI, 1.69-to 3.03) and nonsepsis subgroups (OR, 3.40; 95% CI, 2.50-4.63). There was also a significant association between mean fluid balance (continuous variables) and mortality (OR, 1.16; 95% CI, 1.07-1.27). Although there was a trend of lower rate of kidney recovery in the fluid overload group, there was no significant association between fluid overload and kidney recovery (OR, 0.66; 95% CI, 0.37-1.15), or dialysis dependence (OR, 0.72; 95% CI, 0.38-1.35).

CONCLUSIONS

Fluid overload is associated with an increased risk of mortality in patients with AKI. The evidence of the relationship between fluid overload and kidney recovery is insufficient.

The relationship of intravenous fluid chloride content to kidney function in patients with severe sepsis or septic shock

BACKGROUND

Previous studies suggest a relationship between chloride-rich intravenous fluids and acute kidney injury in critically ill patients.

OBJECTIVES

The aim of this study was to evaluate the relationship of intravenous fluid chloride content to kidney function in patients with severe sepsis or septic shock.

METHODS

A retrospective chart review was performed to determine (1) quantity and type of bolus intravenous fluids, (2) serum creatinine (Cr) at presentation and upon discharge, and (3) need for emergent hemodialysis (HD) or renal replacement therapy (RRT). Linear regression was used for continuous outcomes, and logistic regression was used for binary outcomes and results were controlled for initial Cr. The primary outcome was change in Cr from admission to discharge. Secondary outcomes were need for HD/RRT, length of stay (LOS), mortality, and organ dysfunction.

RESULTS

There were 95 patients included in the final analysis; 48% (46) of patients presented with acute kidney injury, 8% (8) required first-time HD or RRT, 61% (58) were culture positive, 55% (52) were in shock, and overall mortality was 20% (19). There was no significant relationship between quantity of chloride administered in the first 24 hours with change in Cr (β = -0.0001, t = -0.86, R(2) = 0.92, P = .39), need for HD or RRT (odds ratio [OR] = 0.999; 95% confidence interval [CI], 0.999-1.000; P = .77), LOS >14 days (OR = 1.000; 95% CI, 0.999-1.000; P = .68), mortality (OR = 0.999; 95% CI, 0.999-1.000; P = .88), or any type of organ dysfunction.

CONCLUSION

Chloride administered in the first 24 hours did not influence kidney function in this cohort with severe sepsis or septic shock.