Timing, dose and mode of dialysis in acute kidney injury:

Effects of hydrophilic polymer-embedded membrane on permeability and cell adhesion during continuous hemofiltration

Background and Aims

Clotting within the membrane and/or venous ‘air trap’ chamber is common problems during continuous blood purification therapy. Frequent clotting during continuous blood purification therapy leads to inadequate solute removal, an increased circuit and filter cost, and an increased burden for the medical staff. Improvements in filter membrane materials may reduce the extent of clotting and prolong the filter life. The purpose of the present study was to clarify the characteristics of an NV polymer-embedded membrane (NV-PS) after long-term use, especially the adhesiveness of blood cells and changes in the solute removal performance.

Methods

Continuous hemofiltration (CHF) experiments using a permeate recycle mode were performed for 24 h using the same porcine whole blood divided into two portions to compare the NV-PS with a conventional polysulfone membrane (PS). The activated clotting time was adjusted to within a range of 300–400 s. The change in the dextran sieving coefficient (SC) of the membrane and the residual blood clots in the filters were evaluated after the completion of the CHF experiment.

Results

The increase in the transmembrane pressure and the pressure drop of the hemofilter were significantly smaller using the NV-PS than with the PS. For larger molecules (SC $$ \leqq $$ ≦ 0.4), the reduction in SC after blood contact was significantly smaller for the NV-PS. Fewer blood cells remained in the residual blood clots when the NV-PS was used.

Conclusion

NV-PS has the advantages of showing a lower degree of reduction of the solute removal performance and also a lower degree of clogging of the hollow fibers during prolonged circulation. These characteristics may be expected to be advantageous when this membrane is used for continuous blood purification therapy in acute-phase patients.

Acute kidney injury following adult lung transplantation

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication following lung transplantation (LTx), and it is associated with high mortality and morbidity. This study assessed the incidence of AKI after LTx and analyzed the associated perioperative factors and clinical outcomes.

METHODS

This retrospective study included all adult LTx recipients at the China-Japan Friendship Hospital in Beijing between March 2017 and December 2019. The outcomes were AKI incidence, risk factors, mortality, and kidney recovery. Multivariate analysis was performed to identify independent risk factors. Survival analysis was presented using the Kaplan-Meier curves.

RESULTS

AKI occurred in 137 of the 191 patients (71.7%), with transient AKI in 43 (22.5%) and persistent AKI in 94 (49.2%). AKI stage 1 occurred in 27/191 (14.1%), stage 2 in 46/191 (24.1%), and stage 3 in 64/191 (33.5%) of the AKI patients. Renal replacement therapy (RRT) was administered to 35/191 (18.3%) of the patients. Male sex, older age, mechanical ventilation (MV), severe hypotension, septic shock, multiple organ dysfunction (MODS), prolonged extracorporeal membrane oxygenation (ECMO), reintubation, and nephrotoxic agents were associated with AKI (P < 0.050). Persistent AKI was independently associated with pre-operative pulmonary hypertension, severe hypotension, post-operative MODS, and nephrotoxic agents. Severe hypotension, septic shock, MODS, reintubation, prolonged MV, and ECMO during or after LTx were related to severe AKI (stage 3) (P < 0.050). Patients with persistent and severe AKI had a significantly longer duration of MV, longer duration in the intensive care unit (ICU), worse downstream kidney function, and reduced survival (P < 0.050).

CONCLUSIONS

AKI is common after LTx, but the pathogenic mechanism of AKI is complicated, and prerenal causes are important. Persistent and severe AKI were associated with poor short- and long-term kidney function and reduced survival in LTx patients.

Predictors of 15-Day Survival for the Intensive Care Unit Patient on Continuous Renal Replacement Therapy: A Retrospective Analysis

Purpose

In the intensive care unit (ICU), acute renal failure is mostly part of multiple organ dysfunction syndromes with mortality ranging from 28%-90%, continuous renal replacement therapy (CRRT) is the predominant mode of RRT used in ICU. The main objective of the study was to evaluate the outcomes in patients with acute kidney injury (AKI) on CRRT in the ICU.

Methods

A retrospective chart review was conducted for all ICU patients with acute renal failure on CRRT in a tertiary care teaching hospital. A subgroup analysis was conducted between 15 days in hospital survivors and non-survivors to look for predictors of survival for patients on CRRT.

Results

Two-hundred twenty-six patients underwent CRRT from January 2007 to December 2013. The overall in-hospital mortality was 84.1%. Fifty-six patients (24.77%) survived to the 15-day post-CRRT mark. Acute respiratory failure requiring mechanical ventilation was associated with significantly increased mortality; 89.2% vs. 97.6% (P=0.008), ICU length of stay was significantly longer in the survivor group than the nonsurvivor group. Median±IQR; {20±24 vs 6±7(P: <0.0001)} and so were the ventilator-associated days {16±24 vs 4±6.5 (P: <0.0001)} and duration of CRRT {4.5±5.5 vs 2±2.0(P: <0.0001)}. Patients who survived had a lower incidence of metabolic acidosis {44.6% vs 62.9% (P: 0. 016)} and uremic encephalopathy {12.5% vs 26.5%; (P: 0.031)} but a greater incidence of volume overload {28.6% vs 15.9% (P: 0.031)} as compared to the non-survivor. Acute Physiology And Chronic Health Evaluation II (APACHE II) scores were significantly higher in the non-survivor group (mean SD) 26.9±28.0 vs. 23.9±25.8 (P: 0.0136).

Conclusions

This observational study in patients undergoing CRRT in an ICU setting revealed that the overall mortality was 84.1%. Fluid overload as an indication of CRRT was associated with improved 15 days’ survival whereas higher APACHE II scores and the use of mechanical ventilation were associated with reduced 15 days’ survival.

Prognostic Impact of Early Versus Late Initiation of Renal Replacement Therapy Based on Early Warning Algorithm in Critical Care Patients With Acute Kidney Injury

The aim of our study is to evaluate the impact of early vs. late initiation of continuous renal replacement therapy (CRRT), defined by clinical information system (CIS) software using an early warning algorithm based on acute kidney injury network (AKIN) stages, on survival outcome of critically ill intensive care unit (ICU) patients with acute kidney injury (AKI). Of 1144 patients (mean [SD] age: 61.3 [17.9] years, 57.7% were males) hospitalized in ICU over a 2-year-period from January 2016 to December 2017, a total of 272 patients who had developed AKI requiring CRRT were included in this retrospective cross-sectional study. Data on patient demographics (age, gender), reason for ICU hospitalization, AKIN stage, Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, indications for CRRT, and time of CRRT initiation with respect to AKIN early warning algorithm were retrieved from hospital records and the CIS software database. Survivorship status was assessed based on total, in-hospital and 90-day post-discharge mortality rates and analyzed with respect to CRRT onset before vs. after AKIN alarm. CRRT was initiated before the AKIN alarm in 41(15.0%) patients, and after the AKIN alarm in 231(85.0%) patients involving treatment within 0-24 h of alarm in 146 (63.2%) patients and within 24-120 h of alarm in 85 (36.8%) patients. Mortality occurred in 175 (64.3%) patients involving 25 (61.0%) out of 41 patients who received CRRT before AKIN alarm and 150 (64.9%) out of 231 patients who received CRRT after AKIN alarm. Mortality rate was significantly higher in those who received CRRT 24-120 h vs. 0-24 h after the AKIN alarm (82.4% vs. 54.8%, P < 0.001). Pre- and post-CRRT SOFA scores were significantly lower in patients who received CRRT 0-24 h vs. 24-120 h after the AKIN alarm (P = 0.009 and P = 0.004, respectively), while pre-CRRT APACHE II scores were significantly lower in patients who received CRRT before vs. after the AKIN alarm (P = 0.008). In conclusion, our findings indicate the potential role of using AKIN stage-based early warning system in guiding time to start CRRT and improved survival in critically ill patients with AKI, provided that the CRRT was initiated within the early (first 24 h) of the alarming AKIN Stage II-III events. Future well-designed clinical trials addressing early vs. late initiation of CRRT in critical care patients with AKI are needed to find and answer to the ongoing controversy and help clinicians in refining their indications for starting CRRT.

Acute kidney injury in cancer patients: A nationwide survey in China

Cancer patients have a high risk for acute kidney injury (AKI); however, the incidence, severity, and risk factors of malignancy-related AKI (MR-AKI) are unclear. This study aimed to assess MR-AKI risk factors and provide reliable data for AKI prevention, diagnosis, and management in China. This cross-sectional study analysed data from 44 academic and local hospitals in China. AKI patients were identified based on 2 screening criteria: the 2012 Kidney Disease: Improving Global Outcomes-AKI definition and the expanded screening criteria for patients with no repeated serum creatinine (SCr) test within 7 days and those who recovered from AKI. Patients whose SCr level increased or decreased by 50% during hospitalization, compared with that at admission, were considered to have AKI according to the expanded criteria. A total of 7,604 AKI patients were enrolled (1,418 with MR-AKI). Patient characteristics were compared between the MR-AKI and non-MR-AKI groups. Multivariate logistic models were used to statistically assess risk factors. The proportions of MR-AKI patients in academic and local hospitals were 20.2% and 14.1%, respectively. The incidence of MR-AKI was higher in mid-China (the affluent region), elderly patients, and groups with higher per capita gross domestic product. Among MR-AKI cases, gastrointestinal cancer (50.1%) was the most common malignancy, followed by cancers of the reproductive (15.3%), haematological (13.1%), respiratory (11.8%), and other systems (8.3%), and cancers of unknown classification (1.4%). Of 268 hospital deaths, respiratory, haematological, gastrointestinal, reproductive, other system, and unknown classification cancers accounted for 29.3%, 18.8%, 18.6%, 12.9%, 16.9%, and 20.0%, respectively. Increased age, advanced AKI stage at peak, level of per capita gross domestic product, geographic region, and renal replacement therapy indication were risk factors for hospital mortality in patients with gastrointestinal MR-AKI, whereas cardiovascular disease history, AKI stage at peak, and geographic region were risk factors for mortality in patients with reproductive MR-AKI. The incidence and mortality of MR-AKI vary by hospital, economic level, age, geographic region, and malignancy type. High MR-AKI incidence was associated with gastrointestinal cancers and higher level of medical care provided by academic hospitals in affluent regions such as Beijing, Shanghai, and other provincial-level cities. Elderly patients with advanced gastrointestinal cancer in mid-China showed the highest incidence of MR-AKI and in-hospital mortality, and thus require special attention.

Validation of Four Prediction Scores for Cardiac Surgery-Associated Acute Kidney Injury in Chinese Patients

Objective

To assess the clinical value of four models for the prediction of cardiac surgery-associated acute kidney injury (CSA-AKI) and severe AKI which renal replacement therapy was needed (RRT-AKI) in Chinese patients.

Methods

1587 patients who underwent cardiac surgery in the department of cardiac surgery in the Zhongshan Hospital, Fudan University, between January 2013 and December 2013 were enrolled in this research. Evaluating the predicting value for cardiac surgery-associated AKI (AKICS score) and RRT-AKI (Cleveland score, SRI and Mehta score) by Hosmer-Lemeshow goodness-of-fit test for the calibration and area under receiver operating characteristic curve (AUROC) for the discrimination.

Results

Based on 2012 KDIGO (Kidney Disease: Improving Global Outcomes) AKI definition, the incidence of AKI and RRT-AKI was 37.4% (594/1587) and 1.1% (18/1587), respectively. The mortality of AKI and RRT-AKI was 6.1% (36/594) and 66.7% (12/18), respectively, while the total mortality was 2.8% (44/1587). The discrimination (AUROC=0.610) for the prediction of CSA-AKI of AKICS was low, while the calibration (x²=7.55, P=0.109) was fair. For the prediction of RRT-AKI, the discrimination of Cleveland score (AUROC=0.684), Mehta score (AUROC=0.708) and SRI (AUROC=0.622) were not good; while the calibration of them were fair (Cleveland score x²=1.918, P=0.166; Mehta score x²=9.209, P=0.238; SRI x²=2.976, P=0.271).

Conclusion

In our single-center study, based upon valve surgery dominant and less diabetes mellitus patients, according to KDIGO AKI definition, the predictive value of the four models, combining discrimination and calibration, for respective primary event, were not convincible.

A 2-year-old boy with circulatory failure owing to streptococcal toxic shock syndrome: case report

A 2-year-old boy presented with severe hypotension and acute kidney injury after a prodrome of non-bloody diarrhoea and fever in the preceding 3 days. He had a mild Ebstein cardiac anomaly but otherwise a normal past history and growth. On examination, he looked ill, his temperature was 37.5 °C, circulation was poor, and there were several purpuric lesions on the face, hands and scrotum. Haemoglobin was 7.8 g/dL (11-14), total white cell count 27 × 10⁹/L, platelets 62 × 10⁹/L, blood urea nitrogen 20.7 mmol/L (4.2-17.1), serum creatinine 95.4 μmol/L (21.2-36.2), CRP 154 mg/L (<5), AST 296 U/L (11-50), ALT 909 U/L (7-40) and C₃ component of complement 0.8 g/L (0.9-1.8). Activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged and fibrinogen level was 1.0 g/L (2-4). He received immediate fluid resuscitation (IV 0.9% saline solution, 2 × 10 ml/kg boluses, followed by glucose 5/0.45% sodium chloride solution, 2 × 10 ml/kg) and antibiotics (ciprofloxacin and amikacin) but circulation continued to deteriorate with development of decreased consciousness. He was placed on mechanical ventilation and vasopressor agents were added. Despite improved circulation over the next 2 days, he developed oliguria, progressive fluid overload, generalised oedema and a right-sided pleural effusion. Dialysis was commenced on day 3 of admission. Differential diagnosis included sepsis, atypical haemolytic uraemic syndrome and lupus nephritis. Blood and urine cultures remained negative but an anti-streptolysin O titre of 1318 (<200) IU/mL led to the diagnosis of streptococcal toxic shock syndrome which is rare in early childhood and associated with high mortality. Haemodialysis was commenced and continued for 10 days with successful treatment of fluid overload and subsequent extubation. Renal function was completely restored over the following 6 weeks and he was discharged in good clinical condition about 2 months after intial admission. The clinical course and outcome are discussed, and the importance of timely initiation of dialysis when there is fluid overload is emphasised.

Continuous Renal Replacement Therapy: Forty-year Anniversary

In 1977 Peter Kramer performed the first CAVH (continuous arteriovenous hemofiltration) treatment in Gottingen, Germany. CAVH soon became a reliable alternative to hemo- or peritoneal dialysis in critically ill patients. The limitations of CAVH spurred new research and the discovery of new treatments such as CVVH and CVVHD (continuous veno-venous hemofiltration and continuous veno-venous hemodialysis). The alliance with industry led to development of new specialized equipment with improved accuracy and performance in delivering continuous renal replacement therapies (CRRTs). Machines and filters have progressively undergone a series of technological steps, reaching a high level of sophistication. The evolution of technology has continued, leading to the development and clinical application of new membranes, new techniques and new treatment modalities. With the progress of technology, the entire field of critical care nephrology moved forward, expanding the areas of application of extracorporeal therapies to cardiac, liver and pulmonary support. A great deal of research made extracorporeal therapies an interesting option for the treatment of sepsis and intoxication and the additional use of sorbents was explored. With the progress in understanding the pathophysiology of acute kidney injury (AKI), new guidelines were developed, driving indications, modalities of prescription, monitoring techniques and quality assurance programs. Information technology and precision medicine have recently contributed to further evolution of CRRT, with the possibility of collecting data in large databases and evaluating policies and practice patterns. This is likely to ultimately result in improved patient care. CRRTs are 40 years old today, but they are still young and full of potential for further evolution.

Renal replacement therapy in acute kidney injury from a Chinese cross-sectional study: patient, clinical, socioeconomic and health service predictors of treatment

Background

Renal replacement therapy (RRT) is important to support critically ill patients with acute kidney injury (AKI). This study, a part of a nation-wide survey for AKI conducted by the ISN AKF 0 by 25 China Consortium, aims to study the current RRT practical situation and problems in China.

Methods

The current study is a part of a nation-wide survey for AKI conducted by ISN AKF 0 by 25 China Consortium. The survey included 44 sites all over the country, including 22 academic hospitals in big cities and 22 local hospitals in smaller cities or rural areas. Of the 44 sites, all have access to PD and IHD, 93.5% are capable to perform CRRT. Of total 7604 AKI cases, 896 cases (11.8%) had indications for RRT and were included in the current abstract.

Results

of the 896 patients that had indications for RRT, only 59.3% received RRT. Patients who were older, male, from lower income areas, in local hospitals, or with severe comorbidities, were less likely to receive RRT. RRT treatment was associated with lower mortality (OR = 0.58, 95%CI 0.38–0.89). The RRT modalities were continuous renal replacement therapy (CRRT) in 53.9%, intermittent hemodialysis (IHD) in 38.0%, CRRT complemented by IHD in 6.2%, CRRT complemented by peritoneal dialysis (PD) in 0.8% and PD in 1.1%. Of the subgroup of patients receiving RRT who did not have an indication for modality of CRRT, 36.8% in fact received CRRT, and their medical cost and mortality rate was higher (7944[4248, 16,055] vs. 5100[2948, 9396] US dollars, p < 0.001 and 10.6% vs. 4.4%, p = 0.047, respectively) compared with those treated with other RRT modalities).

Conclusions

Extrapolated to the whole of China our results indicate that an estimated 139,000 patients with an indication of RRT are under treated without RRT over a year. Non-clinical factors influence RRT prescription for severe AKI patients. CRRT may be over-utilized in the treatment of severe AKI and the use of PD is extremely rare. These findings have implications for the effective application of medical resources in the treatment of severe AKI.

Community-Acquired Acute Kidney Injury: A Nationwide Survey in China

BACKGROUND

This study aimed to describe the burden of community-acquired acute kidney injury (AKI) in China based on a nationwide survey about AKI.

STUDY DESIGN

Cross-sectional and retrospective study.

SETTING & PARTICIPANTS

A national sample of 2,223,230 hospitalized adult patients from 44 academic/local hospitals in Mainland China was used. AKI was defined according to the 2012 KDIGO AKI creatinine criteria or an increase or decrease in serum creatinine level of 50% during the hospital stay. Community-acquired AKI was identified when a patient had AKI that could be defined at hospital admission.

PREDICTORS

The rate, cause, recognition, and treatment of community-acquired AKI were stratified according to hospital type, latitude, and economic development of the regions in which the patients were admitted.

OUTCOMES

All-cause in-hospital mortality and recovery of kidney function at hospital discharge.

RESULTS

4,136 patients with community-acquired AKI were identified during the 2 single-month snapshots (January 2013 and July 2013). Of these, 2,020 (48.8%) had cases related to decreased kidney perfusion; 1,111 (26.9%), to intrinsic kidney disease; and 499 (12.1%), to urinary tract obstruction. In the north versus the south, more patients were exposed to nephrotoxins or had urinary tract obstructions. 536 (13.0%) patients with community-acquired AKI had indications for renal replacement therapy (RRT), but only 347 (64.7%) of them received RRT. Rates of timely diagnosis and appropriate use of RRT were higher in regions with higher per capita gross domestic product. All-cause in-hospital mortality was 7.3% (295 of 4,068). Delayed AKI recognition and being located in northern China were independent risk factors for in-hospital mortality, and referral to nephrology providers was an independent protective factor.

LIMITATIONS

Possible misclassification of AKI and community-acquired AKI due to nonstandard definitions and missing data for serum creatinine.

CONCLUSIONS

The features of community-acquired AKI varied substantially in different regions of China and were closely linked to the environment, economy, and medical resources.

Early initiation of renal replacement treatment in patients with acute kidney injury: A systematic review and meta-analysis

BACKGROUND

Acute kidney injury (AKI) is associated with a substantially increased risk of mortality for many hospitalized patients. It has been suggested that early initiation of renal replacement treatment has a favorable outcome in critically ill patients complicated with AKI. However, results of studies evaluating the effect of early initiation strategy of renal replacement treatment on AKI have been controversial and contradictory. The aim of this meta-analysis is to examine the effect of early initiation of renal replacement treatment on patients with AKI.

METHODS

The authors searched relevant studies in PubMed, EMBASE, and the Cochrane Library through August 2016. We searched for all eligible randomized controlled trials with regard to the role of early initiation of renal replacement treatment in mortality among patients with AKI. We extracted the following information from each study: mortality, length of stay in intensive care unit (ICU), and length of stay in hospital. Random and fixed effect models were used for pooling data.

RESULTS

Twelve trials including 1756 patients were included. The results of this meta-analysis showed that there was no significant difference between the mortality of early and delayed strategy for the initiation of renal replacement treatment using the random effect model (odds ratio = 0.78; 95% confidence interval [CI], 0.52-1.19; P = 0.25), with wild heterogeneity (chi = 33.50; I = 67%). Analyses from subgroup sepsis and postsurgery came to similar results. In addition, compared with delayed initiation strategy, early initiation showed no significant advantage in length of stay in ICU (mean difference = -0.80; 95% CI, -2.59 to 0.99; P = 0.56) and length of stay in hospital (mean difference = -7.69; 95% CI, -16.14 to 0.76; P = 0.07).

CONCLUSION

According to the results from present meta-analysis, early initiation of renal replacement treatment showed no survival benefits in patients with AKI. To achieve optimal timing of renal replacement treatment, further large multicenter randomized trials, with widely accepted and standardized definition of early initiation, are still needed.

Renal Replacement Therapy

During the last few years, due to medical and surgical evolution, patients with increasingly severe diseases causing multiorgan dysfunction are frequently admitted to intensive care units. Therapeutic options, when organ failure occurs, are frequently nonspecific and mostly directed towards supporting vital function. In these scenarios, the kidneys are almost always involved and, therefore, renal replacement therapies have become a common routine practice in critically ill patients with acute kidney injury. Recent technological improvement has led to the production of safe, versatile and efficient dialysis machines. In addition, emerging evidence may allow better individualization of treatment with tailored prescription depending on the patients' clinical picture (e.g. sepsis, fluid overload, pediatric). The aim of the present review is to give a general overview of current practice in renal replacement therapies for critically ill patients. The main clinical aspects, including dose prescription, modality of dialysis delivery, anticoagulation strategies and timing will be addressed. In addition, some technical issues on physical principles governing blood purification, filters characteristics, and vascular access, will be covered. Finally, a section on current standard nomenclature of renal replacement therapy is devoted to clarify the "Tower of Babel" of critical care nephrology.

Dynamic prediction of the need for renal replacement therapy in intensive care unit patients using a simple and robust model

We aimed at identifying a model that dynamically predicts future need for renal replacement therapy (RRT) in intensive care unit (ICU) patients and can easily be implemented for online monitoring at the bedside. 7290 interdisciplinary ICU admissions were investigated. Patients with <3 days of stay or RRT in the first 2 days were excluded. 1624 of the remaining 2625 patients had a normal serum creatinine at admission. Every second of these 1624 patients was used for model calibration whereas the other half and, in addition, the 1001 patients with elevated serum creatinine were exclusively used for validation. Discriminant analysis was used to determine and validate a combination of clinical parameters that predicts the need for RRT 72 h ahead. Based on the calibration sample, stepwise discriminant analysis selected the serum values of (1) current urea, (2) current lactate, (3) the ratio of current and admission serum creatinine, and (4) the mean urine output of the previous 24 h. In the validation datasets, the model reached areas under the receiver operating characteristic curve of 0.866 and 0.833 in patients with normal and elevated serum creatinine at admission, respectively. Moreover, the model's predictive value extended to at least 5 days prior to initiation of RRT and exceeded that of the RIFLE classification at all investigated prediction intervals. We identified a robust model that dynamically predicts the future need for RRT successfully. This tool may help improve timing of therapy and prognosis in ICU patients.

Challenges and pitfalls when implementing renal replacement therapy in the ICU

Several new methods of renal replacement therapy (RRT) are now available for treating patients in the ICU setting. However, utilization of RRT in the ICU is subject to considerable variation and the need for RRT is associated with worse outcomes. Several factors influence the application of dialysis and reflect the interplay of patient and process of care elements that are dynamic in nature. Despite multiple studies evaluating RRT and its application, there are gaps in our knowledge that must be overcome to improve outcomes. This article discusses some of the important issues that require attention in delivering RRT in critically ill patients and provides a framework for the optimal use of RRT in the ICU.

Early Fluid Resuscitation and High Volume Hemofiltration Decrease Septic Shock Progression in Swine

This study aimed to assess the effects of early fluid resuscitation (EFR) combined with high volume hemofiltration (HVHF) on the cardiopulmonary function and removal of inflammatory mediators in a septic shock swine model. Eighteen swine were randomized into three groups: control (n = 6) (extracorporeal circulating blood only), continuous renal replacement therapy (CRRT) (n = 6; ultrafiltration volume = 25 mL/Kg/h), and HVHF (n = 6; ultrafiltration volume = 85 mL/Kg/h). The septic shock model was established by intravenous infusion of lipopolysaccharides (50 µg/kg/h). Hemodynamic parameters (arterial pressure, heart rate, cardiac output, stroke volume variability, left ventricular contractility, systemic vascular resistance, and central venous pressure), vasoactive drug parameters (dose and time of norepinephrine and hourly fluid intake), pulmonary function (partial oxygen pressure and vascular permeability), and cytokines (interleukin-6 and interleukin-10) were observed. Treatment resulted in significant changes at 4-6 h. HVHF was beneficial, as shown by the dose of vasoactive drugs, fluid intake volume, left ventricular contractility index, and partial oxygen pressure. Both CRRT and HVHF groups showed improved removal of inflammatory mediators compared with controls. In conclusion, EFR combined with HVHF improved septic shock in this swine model. The combination decreased shock progression, reduced the need for vasoactive drugs, and alleviated the damage to cardiopulmonary functions.

Acute kidney injury in China: a cross-sectional survey

BACKGROUND

Acute kidney injury (AKI) has become a worldwide public health problem, but little information is available about the disease burden in China. We aimed to evaluate the burden of AKI and assess the availability of diagnosis and treatment in China.

METHODS

We launched a nationwide, cross-sectional survey of adult patients who were admitted to hospital in 2013 in academic or local hospitals from 22 provinces in mainland China. Patients with suspected AKI were screened out on the basis of changes in serum creatinine by the Laboratory Information System, and we reviewed medical records for 2 months (January and July) to confirm diagnoses. We assessed rates of AKI according to two identification criteria: the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) AKI definition and an increase or decrease in serum creatinine by 50% during hospital stay (expanded criteria). We estimated national rates with data from the 2013 report by the Chinese National Health and Family Planning Commission and National Bureau of Statistics.

FINDINGS

Of 2,223,230 patients admitted to the 44 hospitals screened in 2013, 154,950 (7·0%) were suspected of having AKI by electronic screening, of whom 26,086 patients (from 374,286 total admissions) were reviewed with medical records to confirm the diagnosis of AKI. The detection rate of AKI was 0·99% (3687 of 374,286) by KDIGO criteria and 2·03% (7604 of 374,286) by expanded criteria, from which we estimate that 1·4-2·9 million people with AKI were admitted to hospital in China in 2013. The non-recognition rate of AKI was 74·2% (5608 of 7555 with available data). Renal referral was done in 21·4% (1625 of 7604) of the AKI cases, and renal replacement therapy was done in 59·3% (531 of 896) of those who had the indications. Delayed AKI recognition was an independent risk factor for in-hospital mortality, and renal referral was an independent protective factor for AKI under-recognition and mortality

INTERPRETATION

AKI has become a huge medical burden in China, with substantial underdiagnosis and undertreatment. Nephrologists should take the responsibility for leading the battle against AKI.

FUNDING

National 985 Project of China, National Natural Science Foundation of China, Beijing Training Program for Talents, International Society of Nephrology Research Committee, and Bethune Fund Management Committee.

Renal Replacement Therapy

Renal replacement therapy (RRT) is a cornerstone in the clinical management of patients with acute kidney injury. Results from different studies agree that early renal support therapy (aimed to support the residual kidney function during early phases of organ dysfunction) may reduce mortality with respect to late RRT (aimed to substitute the complete loss of function during the advanced kidney insufficiency). Although it seems plausible that a timely initiation of RRT may be associated with improved renal and nonrenal outcomes in these patients, there is scarce evidence in literature to exactly identify the most adequate onset timing for RRT.

Sustained low-efficiency dialysis with regional citrate anticoagulation in medical intensive care unit patients with liver failure: A prospective study

PURPOSE

Patients with liver failure requiring dialysis are at increased risk for citrate accumulation during sustained low-efficiency dialysis (SLED). The aim of this study was to evaluate the feasibilty of citrate SLED in critical ill patients with liver failure and investigate predictive parameters regarding citrate accumulation.

MATERIALS AND METHODS

This is a prospective study in 24 medical intensive care unit patients with liver failure and a total of 43 SLED runs (maximum of 3 runs per patient) using citrate anticoagulation. Liver function was characterized before SLED using not only laboratory parameters but also determination of the plasma disappearance rate of indocyanine green. In addition, blood gas parameters as well total calcium and citrate in serum were measured at baseline and defined time points during SLED.

RESULTS

Accumulation of citrate could be observed in all SLED runs, which were nearly normalized until the end of SLED and 24 hours after SLED, respectively. However, the critical threshold of total calcium/ionized calcium on ratio of greater than 2.5 was exceeded in only 1 patient. Equalization of initial metabolic acidosis was possible without major disturbances of acid base and electrolyte status. Liver function parameters showed poor predicitve capabilities regarding citrate accumulation.

CONCLUSIONS

Despite substantial accumulation of citrate in serum, SLED is save and feasible in patients with liver failure using a citrate anticoagulation. Careful monitoring of electrolytes and acid base status is mandatory to ensure patient safety.

Comparison of two strategies for initiating renal replacement therapy in the intensive care unit: study protocol for a randomized controlled trial (AKIKI)

BACKGROUND

There is currently no validated strategy for the timing of renal replacement therapy (RRT) for acute kidney injury (AKI) in the intensive care unit (ICU) when short-term life-threatening metabolic abnormalities are absent. No adequately powered prospective randomized study has addressed this issue to date. As a result, significant practice heterogeneity exists and may expose patients to either unnecessary hazardous procedures or undue delay in RRT.

METHODS/DESIGN

This is a multicenter, prospective, randomized, open-label parallel-group clinical trial that compares the effect of two RRT initiation strategies on overall survival of critically ill patients receiving intravenous catecholamines or invasive mechanical ventilation and presenting with AKI classification stage 3 (KDIGO 2012). In the 'early' strategy, RRT is initiated immediately. In the 'delayed' strategy, clinical and metabolic conditions are closely monitored and RRT is initiated only when one or more events (severity criteria) occur, including: oliguria or anuria for more than 72 hours after randomization, serum urea concentration >40 mmol/l, serum potassium concentration >6 mmol/l, serum potassium concentration >5.5 mmol/l persisting despite medical treatment, arterial blood pH <7.15 in a context of pure metabolic acidosis (PaCO2 < 35 mmHg) or in a context of mixed acidosis with a PaCO2 ≥ 50 mmHg without possibility of increasing alveolar ventilation, acute pulmonary edema due to fluid overload despite diuretic therapy leading to severe hypoxemia requiring oxygen flow rate >5 l/min to maintain SpO2 > 95% or FiO2 > 50% under invasive or noninvasive mechanical ventilation. The primary outcome measure is overall survival, measured from randomization (D0) until death, regardless of the cause. The minimum follow-up duration for each patient will be 60 days. Two interim analyses are planned, blinded to group allocation. It is expected that there will be 620 subjects in all.

DISCUSSION

The AKIKI study will be one of the very few large randomized controlled trials evaluating mortality according to the timing of RRT in critically ill patients with AKI classification stage 3 (KDIGO 2012). Results should help clinicians decide when to initiate RRT.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01932190.

Effects of increased surface coverage of polyvinylpyrrolidone over a polysulfone hemofilter membrane on permeability and cell adhesion during continuous hemofiltration

The purpose of the present study was to evaluate the adhesiveness of blood cells and the solute removal performance change of modified polysulfone membranes which have increased polyvinylpyrrolidone (PVP) coverage over their surface. Continuous hemofiltration (CHF) experiments for 24 h were carried out using an ex vivo hemofilter evaluation system to compare a modified polysulfone hemofilter (SHG) with the conventional polysulfone hemofilter (SH). The 25 and 50 % cutoff values of the sieving coefficient of dextran after CHF and the protein concentration in the filtrate was higher in SHG, indicating that less fouling occurred in the SHG membrane. Adhesion of blood cells after 24 h of CHF was significantly higher in the case of SH than in the case of SHG. Blood cell adhesion and membrane fouling were reduced with the use of a polysulfone membrane modified with increased PVP coverage over the surface.

Anticoagulation strategies in venovenous hemodialysis in critically ill patients: a five-year evaluation in a surgical intensive care unit

Renal failure is a common complication among critically ill patients. Timing, dosage, and mode of renal replacement (RRT) are under debate, but also anticoagulation strategies and vascular access interfere with dialysis success. We present a retrospective, five-year evaluation of patients requiring RRT on a multidisciplinary 50-bed surgical intensive care unit of a university hospital with special regard to anticoagulation strategies and vascular access. Anticoagulation was preferably performed with unfractionated heparin or regional citrate application (RAC). Bleeding and suspected HIT-II were most common causes for RAC. In CVVHD mode filter life span was significantly longer under RAC compared to heparin or other anticoagulation strategies (P = 0.001). Femoral vascular access was associated with reduced filter life span (P = 0.012), especially under heparin anticoagulation (P = 0.015). Patients on RAC had higher rates of metabolic alkalosis (P = 0.001), required more transfusions (P = 0.045), and showed higher illness severity measured by SOFA scores (P = 0.001). RRT with unfractionated heparin represented the most common anticoagulation strategy in this study population. However, patients with bleeding risk and severe organ dysfunction were more likely placed on RAC. Citrate provided longer filter life spans regardless of vascular access site. Attention has to be paid to metabolic disturbances.

Choice of renal replacement therapy modality in intensive care units: data from a Japanese Nationwide Administrative Claim Database

PURPOSE

This study was undertaken to assess recent trends of the choice of renal replacement therapy (RRT) modalities in Japanese intensive care units (ICUs).

MATERIALS AND METHODS

Data were extracted from the Japanese Diagnosis Procedure Combination database for 2011. We identified adult patients without end-stage renal disease who had been admitted to ICUs for 3 days or longer and started continuous RRT (CRRT) or intermittent RRT (IRRT). Logistic regression was used to analyze which factors affected the modality choice. We further evaluated in-hospital mortality according to the choice of RRT.

RESULTS

Of 7353 eligible patients, 5854 (79.6%) initially received CRRT. The choice of CRRT was independently associated with sex (female), diagnosis of sepsis, hospital type (academic) and volume, vasoactive agents, mechanical ventilation, colloid administration, blood transfusion, intra-aortic balloon pumping, and venoarterial extracorporeal membrane oxygenation. Particularly, the number of vasoactive drugs was strongly associated with the CRRT choice. Overall in-hospital mortality in the CRRT group was higher than that in the IRRT group (50.0% vs 31.1%) and was increased when IRRT was switched to CRRT (59.1%).

CONCLUSIONS

Continuous RRT is apparently preferred in actual ICU practice, especially for hemodynamically unstable patients, and subsequent RRT modality switch is associated with mortality.

[Renal replacement therapy in Intensive Care Units in Catalonia (Spain)]

OBJECTIVE

To assess the indications, settings and techniques used in renal replacement therapy (RRT) in Intensive Care Units (ICUs).

STUDY DESIGN

A prospective, multicenter observational study was carried out.

SETTING

Intensive Care Units.

PATIENTS

All patients admitted to ICUs during the two-month study period in 2011 who required RRT.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Patient demographic characteristics, baseline clinical data, RRT technique and materials used.

RESULTS

Thirty-three patients were analyzed. RRT was started within the first 24hours after ICU admission in 17 of the 33 patients (52%). At the start of RRT, 18% of the patients (n=6) presented grade R on the RIFLE acute kidney injury (AKI) scale. The most common disorder associated with AKI was multiple organ dysfunction syndrome (64%; n=21). At the start of RRT, most patients (76%; n=25) presented hemodynamic instability, while the remaining 24% (n=8) were considered hemodynamically stable. The most common RRT technique in hemodynamically stable patients was continuous renal replacement therapy (CRRT) (63%; n=5). CRRT was the technique of choice in all 25 of the hemodynamically unstable patients (100%). Anticoagulation was used in 55% (n=18) of the patients. In most cases (61%, n=20), RRT was administered through the right femoral vein. In 84% (n=28) of the patients, the ultrafiltration effluent flow rate was ≤ 35ml/kg/h.

CONCLUSIONS

The ICU physicians in this study followed current RRT guidelines. CRRT was preferred over intermittent renal replacement therapy, regardless of patient hemodynamic status.

Acute kidney injury in critical care: experience of a conservative strategy

PURPOSE

Renal replacement therapy (RRT) is a major supportive treatment of acute kidney injury (AKI) in intensive care unit (ICU), but the timing of its initiation remains open to debate.

MATERIALS AND METHODS

We retrospectively analyzed ICU patients who had AKI associated with at least one usual RRT criteria: serum creatinine concentration greater than 300 μmol/L, serum urea concentration greater than 25 mmol/L, serum potassium concentration greater than 6.5 mmol/L, severe metabolic acidosis (arterial blood pH<7.2), oliguria (urine output<135 mL/8 hours or <400 mL/24 hours), overload pulmonary edema. To estimate the risk of death associated with RRT adjusted for risk factors, we performed a marginal structural Cox model with inverse-probability-of-treatment-weighted estimator.

RESULTS

Among 4173 patients admitted to the ICU, 203 patients fulfilled potential RRT criteria. Ninety-one patients (44.8%) received RRT and 112 (55.2%) did not. Non-RRT and RRT patients differed in terms of severity of illness: Simplified Acute Physiology Score II (55±17 vs 60±19, respectively; P<.05) and Sequential Organ Failure Assessment score (8 [5-10] vs 9 [7-11], respectively; P=.01). Crude analysis indicated a lower ICU mortality for non-RRT compared with RRT patients (18% vs 45%; P<.001). In the marginal structural Cox model, RRT was associated with increased mortality (P<.01).

CONCLUSION

A conservative approach of AKI was not associated with increased mortality.

The effect of continuous versus intermittent renal replacement therapy on the outcome of critically ill patients with acute renal failure (CONVINT): a prospective randomized controlled trial

Introduction

Acute renal failure (ARF) requiring renal replacement therapy (RRT) occurs frequently in ICU patients and significantly affects mortality rates. Previously, few large clinical trials investigated the impact of RRT modalities on patient outcomes. Here we investigated the effect of two major RRT strategies (intermittent hemodialysis (IHD) and continuous veno-venous hemofiltration (CVVH)) on mortality and renal-related outcome measures.

Methods

This single-center prospective randomized controlled trial (“CONVINT”) included 252 critically ill patients (159 male; mean age, 61.5 ± 13.9 years; Acute Physiology and Chronic Health Evaluation (APACHE) II score, 28.6 ± 8.8) with dialysis-dependent ARF treated in the ICUs of a tertiary care academic center. Patients were randomized to receive either daily IHD or CVVH. The primary outcome measure was survival at 14 days after the end of RRT. Secondary outcome measures included 30-day-, intensive care unit-, and intrahospital mortality, as well as course of disease severity/biomarkers and need for organ-support therapy.

Results

At baseline, no differences in disease severity, distributions of age and gender, or suspected reasons for acute renal failure were observed. Survival rates at 14 days after RRT were 39.5% (IHD) versus 43.9% (CVVH) (odds ratio (OR), 0.84; 95% confidence interval (CI), 0.49 to 1.41; P = 0.50). 14-day-, 30-day, and all-cause intrahospital mortality rates were not different between the two groups (all P > 0.5). No differences were observed in days on RRT, vasopressor days, days on ventilator, or ICU-/intrahospital length of stay.

Conclusions

In a monocentric RCT, we observed no statistically significant differences between the investigated treatment modalities regarding mortality, renal-related outcome measures, or survival at 14 days after RRT. Our findings add to mounting data demonstrating that intermittent and continuous RRTs may be considered equivalent approaches for critically ill patients with dialysis-dependent acute renal failure.

Trial registration

NCT01228123, clinicaltrials.gov

[Acute renal replacement therapy in pediatrics]

In pediatric intensive care unit, the available modalities of acute renal replacement therapy include intermittent hemodialysis, peritoneal dialysis and continuous renal replacement therapies. No prospective studies have evaluated to date the effect of dialysis modality on the outcomes of children. The decision about dialysis modality should therefore be based on local expertise, resources available, and the patient's clinical status. Poor hemodynamic tolerance of intermittent hemodialysis is a common problem in critically ill patients. Moreover, many pediatric intensive care units are not equipped with dedicated water circuit. Peritoneal dialysis, a simple and inexpensive alternative, is the most widely available form of acute renal replacement therapy. However, its efficacy may be limited in critically ill patients. The use of continuous renal replacement therapy permits usually to reach a greater estimated dialysis dose, a better control of fluid balance, and additionally, to provide adequate nutrition.

Timing of dialysis initiation in acute kidney injury and acute-on-chronic renal failure

The decision to provide dialytic support and choosing the ideal moment to initiate therapy are common impasses for physicians treating patients with acute kidney injury (AKI). Although renal replacement therapy (RRT) has been extensively used in clinical practice for more than 30 years, there is a paucity of evidence to guide clinicians on the optimal utilization of RRT in AKI. In the absence of traditional or urgent indications, there is no consensus on whether dialysis should be offered and when it should be started. The lack of agreed-upon parameters to guide the decision, the fear of the risk of the procedure, and the possible contribution to worse prognosis with RRT have resulted in a considerable variation in practice among physicians and centers. In this review, we summarize the evidence evaluating time of initiation of RRT and discuss possible approaches for future trials in addressing this issue.

Renal replacement therapy in the critically ill: getting it right

PURPOSE OF REVIEW

Survival of critically ill patients with severe acute kidney injury is still low. The aim of this review is to describe recent scientific evidence on renal replacement therapy (RRT) and its potential implications for future research and clinical practice.

RECENT FINDINGS

Timing, dose and special indications of RRT will be described: recent literature provided new answers and new controversies about these three topics.

SUMMARY

Specific research on RRT timing will be mandatory in the next few years: a standard definition of timing will certainly help to shed new light on how to improve RRT patients' outcome. Dialytic dose of continuous RRT has been recently and definitely standardized to 20-25  ml/kg per hour (dialysis or hemofiltration), however, application to clinical practice still needs to be improved and new evidence on net ultrafiltration prescription showed that fluid balance may be as important as blood purification in critically ill patients with renal dysfunction. Special settings such as septic RRT, pediatric RRT, and RRT during extracorporeal membrane oxygenation recently achieved important results and new applications in clinical practice with important consequences for technical improvement and future care of these patients.

Get to the point in intensive care medicine--the sooner the better?

Timing of therapy plays a pivotal role in intensive care patients. Although being evident and self-explanatory, it has to be considered that the appropriateness of a specific therapeutic intervention is likewise important. In view of antibiotic therapy of critically ill patients, the available evidence supports the concept of hitting hard, early (as soon as possible and at least before the onset of shock) and appropriately. There is increasing evidence that a positive fluid balance is not only a cosmetic problem but is associated with increased morbidity. However, prospective studies are needed to elucidate whether a positive net fluid balance represents the cause or the effect of a specific disease. Since central venous pressure (CVP) is an unreliable marker of fluid responsiveness, its clinical use to guide fluid therapy is questionable. Dynamic hemodynamic parameters seem to be superior to CVP in predicting fluid responsiveness in hemodynamically unstable patients. Sedation is often used to facilitate mechanical ventilation. Since there is no best evidence-based sedation protocol, weaning strategies should take the risk of iatrogenic arterial hypotension secondary to high doses of vasodilatory sedative agents into account. In this regard, the concept of daily wake-up calls should be challenged, because higher cumulative doses of sedatives may be required. The right dose and timing for renal replacement therapy is still discussed controversially and remains a subjective decision of the attending physician. New renal biomarkers may perhaps be helpful to validate when (and how) renal replacement therapy should be performed best. Last but not least, all therapeutic interventions should take the individual co-morbidities and underlying pathophysiological conditions into account.