Hypotension within one-hour from starting CRRT is associated with in-hospital mortality

Impact of Using Blood Warmer During Continuous Kidney Replacement Therapy in Patients With Acute Kidney Injury

PURPOSE

We investigated the impact of blood warmer use on hypotensive episodes in patients with acute kidney injury (AKI) receiving continuous kidney replacement therapy (CKRT).

MATERIALS AND METHODS

We included patients with AKI undergoing CKRT between January 1, 2012, and January 1, 2021, at a tertiary academic hospital. Hypotensive episodes were defined as mean arterial pressure (MAP) <60 mm Hg or a decrease in MAP by ≥10 mm Hg, systolic blood pressure (SBP) < 90 mm Hg or a decrease in SBP by ≥20 mm Hg, or increased vasopressor requirement. These were analyzed by Poisson regression with repeated-measures analysis of variance using generalized estimation equation.

RESULTS

There were 669 patients with AKI that required CKRT. Use of blood warmer on first day of CKRT was in 324 (48%) patients. Incidence rate ratio of hypotensive episodes during the first 24-h of CKRT in patients where a blood warmer was used was 1.06 (95% confidence interval [CI]: 0.98-1.13) compared to those where blood warmer was not used. This did not change in adjusted model. Overall, the within-subject effect of temperature on hypotensive episodes showed that higher temperature was associated with fewer episodes (0.94, 95% CI: 0.9-0.99 per 10 degrees increase, P = .007).

CONCLUSION

Blood rewarming was not associated with hypotensive episodes during CKRT.

Impact of the first 24 h of continuous kidney replacement therapy on hemodynamics, ventilation, and analgo-sedation in critically ill children

BACKGROUND

In a group of children admitted to the paediatric intensive care unit (PICU) receiving continuous kidney replacement therapy (CKRT), we aim to evaluate the data about their hemodynamic, ventilation and analgo-sedation profile in the first 24 h of treatment and possible associations with mortality.

METHODS

Retrospective cohort study of children admitted to the PICU of the University Hospital of Padova undergoing CKRT between January 2011 and March 2021. Data was collected at baseline (T0), after 1 h (T1) and 24 h (T24) of CKRT treatment. The differences in outcome measures were compared between these time points, and between survivors and non-survivors.

RESULTS

Sixty-nine patients received CKRT, of whom 38 (55%) died during the PICU stay. Overall, the vasoactive inotropic score and the adrenaline dose increased at T1 compared to T0 (p = 0.012 and p = 0.022, respectively). Compared to T0, at T24 patients showed an improvement in the following ventilatory parameters: Oxygenation Index (p = 0.005), Oxygenation Saturation Index (p = 0.013) PaO2/FiO2 ratio (p = 0.005), SpO2/FiO2 ratio (p = 0.002) and Mean Airway Pressure (p = 0.016). These improvements remained significant in survivors (p = 0.01, p = 0.027, p = 0.01 and p = 0.015, respectively) but not in non-survivors. No changes in analgo-sedative drugs have been described.

CONCLUSIONS

CKRT showed a significant impact on hemodynamics and ventilation in the first 24 h of treatment. We observed a significant rise in the inotropic/vasoactive support required after 1 h of treatment in the overall population, and an improvement in the ventilation parameters at 24 h only in survivors.

Renal hemodynamic evaluation protocol based on the pathophysiological mechanism of acute kidney injury: Critical Care UltraSound Guided-A(KI)BCDE

The multiple etiological characteristics of acute kidney injury (AKI) have brought great challenges to its clinical diagnosis and treatment. Renal injury in critically ill patients always indicates hemodynamic injury. The Critical Care UltraSound Guided (CCUSG)-A(KI)BCDE protocol developed by the Chinese Critical Ultrasound Study Group (CCUSG), respectively, includes A(KI) diagnosis and risk assessment and uses B-mode ultrasound, Color doppler ultrasound, spectral Doppler ultrasound, and contrast Enhanced ultrasound to obtain the hemodynamic characteristics of the kidney so that the pathophysiological mechanism of the occurrence and progression of AKI can be captured and the prognosis of AKI can be predicted combined with other clinical information; therefore, the corresponding intervention and treatment strategies can be formulated to achieve targeted, protocolized, and individualized therapy.

Restrictive versus Liberal Rate of Extracorporeal Volume Removal Evaluation in Acute Kidney Injury (RELIEVE-AKI): a pilot clinical trial protocol

INTRODUCTION

Observational studies have linked slower and faster net ultrafiltration (UFNET) rates during kidney replacement therapy (KRT) with mortality in critically ill patients with acute kidney injury (AKI) and fluid overload. To inform the design of a larger randomised trial of patient-centered outcomes, we conduct a feasibility study to examine restrictive and liberal approaches to UFNET during continuous KRT (CKRT).

METHODS AND ANALYSIS

This study is an investigator-initiated, unblinded, 2-arm, comparative-effectiveness, stepped-wedged, cluster randomised trial among 112 critically ill patients with AKI treated with CKRT in 10 intensive care units (ICUs) across 2 hospital systems. In the first 6 months, all ICUs started with a liberal UFNET rate strategy. Thereafter, one ICU is randomised to the restrictive UFNET rate strategy every 2 months. In the liberal group, the UFNET rate is maintained between 2.0 and 5.0 mL/kg/hour; in the restrictive group, the UFNET rate is maintained between 0.5 and 1.5 mL/kg/hour. The three coprimary feasibility outcomes are (1) between-group separation in mean delivered UFNET rates; (2) protocol adherence; and (3) patient recruitment rate. Secondary outcomes include daily and cumulative fluid balance, KRT and mechanical ventilation duration, organ failure-free days, ICU and hospital length of stay, hospital mortality and KRT dependence at hospital discharge. Safety endpoints include haemodynamics, electrolyte imbalance, CKRT circuit issues, organ dysfunction related to fluid overload, secondary infections and thrombotic and haematological complications.

ETHICS AND DISSEMINATION

The University of Pittsburgh Human Research Protection Office approved the study, and an independent Data and Safety Monitoring Board monitors the study. A grant from the United States National Institute of Diabetes and Digestive and Kidney Diseases sponsors the study. The trial results will be submitted for publication in peer-reviewed journals and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

This trial has been prospectively registered with clinicaltrials.gov (NCT05306964). Protocol version identifier and date: 1.5; 13 June 2023.

Associations of systolic blood pressure and in-hospital mortality in critically ill patients with acute kidney injury

PURPOSE

Although systolic blood pressure (SBP) is associated with acute renal injury (AKI), the relationship between baseline SBP and prognosis in critically ill patients with AKI is unclear. We aimed to assess the linearity and profile of the relationship between SBP at intensive care unit (ICU) admission and in-hospital mortality in these patients.

METHODS

Data of AKI patients in the ICU settings were extracted from the Medical Information Mart for Intensive Care III database. The association between seven SBP categories (< 100, 100-109, 110-119, 120-129, 130-139, 140-149, and ≥ 150 mmHg) and all-cause in-hospital mortality was assessed by Cox proportional hazard models. Restricted cubic spline analysis for the multivariate Cox model was performed to explore the shape of the relationship between SBP and mortality.

RESULTS

A total of 24,202 patients with AKI were included in this study. A typically U-shaped relationship was found between SBP at admission and in-hospital mortality. Among all SBP categories, the lowest risk of death was observed in patients with SBP around 110-119 mmHg, whereas the highest was noted in patients with extremely low SBP (< 100 mmHg), followed by those with extremely high SBP (≥ 150 mmHg). SBP showed a significant interaction with vasopressor use and AKI stage in relation to the risk of in-hospital mortality.

CONCLUSIONS

SBP upon admission showed a non-linear association with all-cause in-hospital mortality in critically ill patients with AKI. Patients with low or high SBP show an increased risk of mortality compared to patients with normal SBP.

Impact of intradialytic hypotension on mortality following the transition from continuous renal replacement therapy to intermittent hemodialysis

BACKGROUND

The transition of dialysis modalities from continuous renal replacement therapy (CRRT) to intermittent hemodialysis (iHD) is frequently conducted during the recovery phase of critically ill patients with acute kidney injury. Herein, we addressed the occurrence of intradialytic hypotension (IDH) after this transition, and its association with the mortality risk.

METHODS

A total of 541 patients with acute kidney injury who attempted to transition from CRRT to iHD at Seoul National University Hospital, Korea from 2010 to 2020 were retrospectively collected. IDH was defined as a discontinuation of dialysis because of hemodynamic instability plus a nadir systolic blood pressure <90 mm Hg or a decrease in systolic blood pressure ≥30 mm Hg during the first session of iHD. Odds ratios (ORs) of outcomes, such as in-hospital mortality and weaning from RRT, were measured using a logistic regression model after adjusting for multiple variables.

RESULTS

IDH occurred in 197 patients (36%), and their mortality rate (44%) was higher than that of those without IDH (19%; OR, 2.64; 95% confidence interval [CI], 1.70-4.08). For patients exhibiting IDH, the iHD sessions delayed successful weaning from RRT (OR, 0.62; 95% CI, 0.43-0.90) compared with sessions on those without IDH. Factors such as low blood pressure, high pulse rate, low urine output, use of mechanical ventilations and vasopressors, and hypoalbuminemia were associated with IDH risk.

CONCLUSIONS

IDH occurrence following the transition from CRRT to iHD is associated with high mortality and delayed weaning from RRT.

Comprehensive Management of Blood Pressure in Patients with Septic AKI

Acute kidney injury (AKI) is one of the serious complications of sepsis in clinical practice, and is an important cause of prolonged hospitalization, death, increased medical costs, and a huge medical burden to society. The pathogenesis of AKI associated with sepsis is relatively complex and includes hemodynamic abnormalities due to inflammatory response, oxidative stress, and shock, which subsequently cause a decrease in renal perfusion pressure and eventually lead to ischemia and hypoxia in renal tissue. Active clinical correction of hypotension can effectively improve renal microcirculatory disorders and promote the recovery of renal function. Furthermore, it has been found that in patients with a previous history of hypertension, small changes in blood pressure may be even more deleterious for kidney function. Therefore, the management of blood pressure in patients with sepsis-related AKI will directly affect the short-term and long-term renal function prognosis. This review summarizes the pathophysiological mechanisms of microcirculatory disorders affecting renal function, fluid management, vasopressor, the clinical blood pressure target, and kidney replacement therapy to provide a reference for the clinical management of sepsis-related AKI, thereby promoting the recovery of renal function for the purpose of improving patient prognosis.

Echocardiographic parameters and hemodynamic instability at the initiation of continuous kidney replacement therapy

OBJECTIVE

Investigate the association of echocardiographic parameters with hemodynamic instability after initiating continuous kidney replacement therapy (CKRT) in a cohort of intensive care unit (ICU) patients requiring CKRT.

METHODS

Historical cohort study of consecutive adults admitted to the ICU at a tertiary care hospital from December 2006 through November 2015 who underwent CKRT and had an echocardiogram done within seven days before CKRT initiation. The primary outcome was hypotension within one hour of CKRT initiation.

RESULTS

We included 980 patients, 804 (82%) with acute kidney injury (AKI) and 176 (18%) with end-stage kidney disease (ESKD). Median patient age was 63 (± 14) years, and median Sequential Organ Failure Assessment (SOFA) score on the day of CKRT initiation was 12 (IQR 10-14). Multivariable analysis showed that Left (OR 2.01, 95% CI 1.04-3.86), and Right (OR 1.5, 95% CI 1.04-2.25) moderate and severe ventricular enlargement, Vasoactive-Inotropic Score (VIS) one hour before CKRT initiation (OR 1.18 per 10 units increase, 95% CI 1.09-1.28) and high bicarbonate fluid replacement (OR 2.52, 95% CI 1.01-6.2) were associated with hypotension after CKRT initiation.

CONCLUSION

Right and left ventricular enlargement are risk factors associated with hypotension after CKRT initiation.

COVID-19 and hepatorenal syndrome

Coronavirus disease 2019 (COVID-19) is a highly infectious disease which emerged into a global pandemic. Although it primarily causes respiratory symptoms for affected patients, COVID-19 was shown to have multi-organ manifestations. Elevated liver enzymes appear to be commonly observed during the course of COVID-19, and there have been numerous reports of liver injury secondary to COVID-19 infection. It has been established that patients with pre-existing chronic liver disease (CLD) are more likely to have poorer outcomes following COVID-19 infection compared to those without CLD. Co-morbidities such as diabetes, hypertension, obesity, cardiovascular and chronic kidney disease frequently co-exist in individuals living with CLD, and a substantial population may also live with some degree of frailty. The mechanisms of how COVID-19 induces liver injury have been postulated. Hepatorenal syndrome (HRS) is the occurrence of kidney dysfunction in patients with severe CLD/fulminant liver failure in the absence of another identifiable cause, and is usually a marker of severe decompensated liver disease. Select reports of HRS following acute COVID-19 infection have been presented, although the risk factors and pathophysiological mechanisms leading to HRS in COVID-19 infection or following COVID-19 treatment remain largely unestablished due to the relative lack and novelty of published data. Evidence discussing the management of HRS in high-dependency care and intensive care contexts is only emerging. In this article, we provide an overview on the speculative pathophysiological mechanisms of COVID-19 induced HRS and propose strategies for clinical diagnosis and management to optimize outcomes in this scenario.

Prolonged exposure to continuous renal replacement therapy in patients with acute kidney injury

BACKGROUND

Little is known about the process of deciding to discontinue continuous renal replacement therapy (CRRT) in patients with acute kidney injury (AKI) and the impact of CRRT duration on outcomes.

METHODS

We report the clinical parameters of prolonged CRRT exposure and predictors of doubling of serum creatinine or need for dialysis at 90 days after CRRT with propensity score matching, including covariates that were likely to influence patients in the prolonged CRRT group.

RESULTS

Among 104 survey responders, most use urine output (87%) to guide CRRT discontinuation, 24% use improvement in clinical or hemodynamic status. In the cohort study, of 854 included patients, 465 participated in the assessment of kidney recovery. Patients with prolonged CRRT had higher SOFA scores (11.9 vs. 11.2) and were more likely to be mechanically ventilated (99% vs. 84%) at CRRT initiation compared to patients without prolonged CRRT, p-value < 0.05. In multivariable logistic regression, daily urine output and cumulative fluid balance leading to CRRT discontinuation or day seven were independently associated with lower [OR 0.87 per 200 ml/day increase] and higher odds [OR 1.03 per 1-L increase] of requiring prolonged CRRT, respectively. After propensity score matching, prolonged exposure to CRRT was independently associated with increased risk of doubling serum creatinine or dialysis at 90 days, OR 3.1 (95% CI 1.23-8.3 p = 0.017).

CONCLUSIONS

Resolution of critical illness and signs of kidney recovery are important factors when considering CRRT discontinuation. Prolonged CRRT exposure may be associated with less chance of kidney recovery among survivors.

Impact of hypoalbuminemia on mortality in critically ill patients requiring continuous renal replacement therapy

BACKGROUND

This study aimed to assess the association of hypoalbuminemia with mortality in critically ill patients requiring continuous renal replacement therapy (CRRT).

METHODS

This is a retrospective cohort study of critically ill patients receiving CRRT from December 2006 through November 2015 in a tertiary referral hospital in the United States. We used logistic regression to assess serum albumin at CRRT initiation as predictors for 90-day mortality.

RESULTS

A total of 911 patients requiring CRRT were included in this study. The mean serum albumin at CRRT initiation was 3.0 ± 0.7 g/dL. The 90-day mortality was 57%. Serum albumin levels of ≤2.4, 2.5-2.9, 3.0-3.4, and ≥ 3.5 g/dL were noted in 24%, 29%, 24%, and 23% of patients, respectively. In adjusted analysis, serum albumin ≤2.4 g/dL compared with serum albumin of ≥3.5 g/dL was significantly associated with higher 90-day mortality with OR of 1.57 (95% CI 1.02-2.42). Serum albumin 2.5-2.9 and 3.0-3.4 g/dL were not associated with higher mortality. Sensitivity analysis in patients requiring CRRT in the setting of acute kidney injury showed consistent results.

CONCLUSION

Approximately three out of four patients had hypoalbuminemia (<3.5 g/dL) at CRRT initiation. However, only severe hypoalbuminemia <2.5 g/dL was significantly associated with higher mortality.

Incidence- and In-hospital Mortality-Related Risk Factors of Acute Kidney Injury Requiring Continuous Renal Replacement Therapy in Patients Undergoing Surgery for Acute Type a Aortic Dissection

Background: Few studies on the risk factors for postoperative continuous renal replacement therapy (CRRT) in a homogeneous population of patients with acute type A aortic dissection (AAAD). This retrospective analysis aimed to investigate the risk factors for CRRT and in-hospital mortality in the patients undergoing AAAD surgery and to discuss the perioperative comorbidities and short-term outcomes. Methods: The study collected electronic medical records and laboratory data from 432 patients undergoing surgery for AAAD between March 2009 and June 2021. All the patients were divided into CRRT and non-CRRT groups; those in the CRRT group were divided into the survivor and non-survivor groups. The univariable and multivariable analyses were used to identify the independent risk factors for CRRT and in-hospital mortality. Results: The proportion of requiring CRRT and in-hospital mortality in the patients with CRRT was 14.6 and 46.0%, respectively. Baseline serum creatinine (SCr) [odds ratio (OR), 1.006], cystatin C (OR, 1.438), lung infection (OR, 2.292), second thoracotomy (OR, 5.185), diabetes mellitus (OR, 6.868), AKI stage 2-3 (OR, 22.901) were the independent risk factors for receiving CRRT. In-hospital mortality in the CRRT group (46%) was 4.6 times higher than in the non-CRRT group (10%). In the non-survivor (n = 29) and survivor (n = 34) groups, New York Heart Association (NYHA) class III-IV (OR, 10.272, P = 0.019), lactic acidosis (OR, 10.224, P = 0.019) were the independent risk factors for in-hospital mortality in patients receiving CRRT. Conclusion: There was a high rate of CRRT requirement and high in-hospital mortality after AAAD surgery. The risk factors for CRRT and in-hospital mortality in the patients undergoing AAAD surgery were determined to help identify the high-risk patients and make appropriate clinical decisions. Further randomized controlled studies are urgently needed to establish the risk factors for CRRT and in-hospital mortality.

Development and Validation of a Simple-to-Use Nomogram for Predicting In-Hospital Mortality in Patients With Acute Heart Failure Undergoing Continuous Renal Replacement Therapy

Background: Patients with acute heart failure (AHF) who require continuous renal replacement therapy (CRRT) have a high risk of in-hospital mortality. It is clinically important to screen high-risk patients using a model or scoring system. This study aimed to develop and validate a simple-to-use nomogram consisting of independent prognostic variables for the prediction of in-hospital mortality in patients with AHF undergoing CRRT.

Methods: We collected clinical data for 121 patients with a diagnosis of AHF who underwent CRRT in an AHF unit between September 2011 and August 2020 and from 105 patients in the medical information mart for intensive care III (MIMIC-III) database. The nomogram model was created using a visual processing logistic regression model and verified using the standard method.

Results: Patient age, days after admission, lactic acid level, blood glucose concentration, and diastolic blood pressure were the significant prognostic factors in the logistic regression analyses and were included in our model (named D-GLAD) as predictors. The resulting model containing the above-mentioned five factors had good discrimination ability in both the training group (C-index, 0.829) and the validation group (C-index, 0.740). The calibration and clinical effectiveness showed the nomogram to be accurate for the prediction of in-hospital mortality in both the training and validation cohort when compared with other models. The in-hospital mortality rates in the low-risk, moderate-risk, and high-risk groups were 14.46, 40.74, and 71.91%, respectively.

Conclusion: The nomogram allowed the optimal prediction of in-hospital mortality in adults with AHF undergoing CRRT. Using this simple-to-use model, the in-hospital mortality risk can be determined for an individual patient and could be useful for the early identification of high-risk patients. An online version of the D-GLAD model can be accessed at https://ahfcrrt-d-glad.shinyapps.io/DynNomapp/.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT0751838.

The Prognostic Importance of Serum Sodium for Mortality among Critically Ill Patients Requiring Continuous Renal Replacement Therapy

BACKGROUND

Serum sodium derangement is common in critically ill patients requiring continuous renal replacement therapy (CRRT). We aimed to assess the association between serum sodium before and during CRRT with mortality.

METHODS

This is a historical cohort study of 1,520 critically ill patients receiving CRRT from December 2006 through November 2015 in a tertiary hospital in the United States. Using logistic regression analysis, we used serum sodium before CRRT, mean serum sodium, and serum sodium changes during CRRT to predict 90-day mortality after CRRT initiation.

RESULTS

Compared with the normal serum sodium levels, the odds ratio (OR) of 90-day mortality in patients with serum sodium before CRRT of 143-147 and ≥148 mmol/L were 1.45 (95% CI 1.03-2.05) and 2.24 (95% CI 1.33-3.87), respectively. There was no significant increase in 90-day mortality in serum sodium of ≤137 mmol/L. During CRRT, the mean serum sodium levels of ≤137 (OR 1.41; 95% CI 1.01-1.98) and ≥143 mmol/L (OR 1.52; 95% CI 1.14-2.03) were associated with higher 90-day mortality. The greater serum sodium changes during CRRT were associated with higher 90-mortality (OR 1.35; 95% CI 1.21-1.51 per 5-mmol/L increase).

CONCLUSION

Before CRRT initiation, hypernatremia and during CRRT, hypo- and hypernatremia were associated with increased mortality.

Survival and kidney recovery among recipients of continuous renal replacement therapy

Continuous renal replacement therapy (CRRT) is widely used in the care of critically ill patients with acute kidney injury (AKI). Despite hopeful trends suggested by recent studies, mortality among CRRT recipients with severe AKI remains extremely high. Moreover, CRRT does not confer a reduction in mortality in trials comparing CRRT to intermittent RRT modalities. Among AKI survivors, some preliminary studies suggest a higher likelihood of kidney recovery and dialysis independence in CRRT recipients. AKI survivors are at risk for a broad array of adverse outcomes; strategies that may mitigate these risks are discussed.

Serum Albumin Before CRRT Was Associated With the 28- and 90-Day Mortality of Critically Ill Patients With Acute Kidney Injury and Treated With Continuous Renal Replacement Therapy

Introduction: Although low serum albumin (ALB) may worsen acute kidney injury (AKI), additional study is needed to establish the connection between ALB and the prognosis of critically ill patients with AKI and treated with continuous renal replacement therapy (CRRT). Methods:A secondary analysis of a bi-center, retrospective, and observational study, such as critically ill patients with AKI and treated with CRRT from January 2009 to September 2016. The univariate analysis, multi-factor regression analysis, sensitivity analysis, and curve-fitting analysis were applied to explore the association of ALB with the 28 and 90 days mortality of critically ill patients with AKI and treated with CRRT, and the removal efficiency of serum phosphorus. Results: From January 2009 to September 2016, 1,132 cases with AKI and treated with CRRT met the inclusion criteria and enrolled in this study. We found that the higher ALB before CRRT, the lower the 28- and 90-day mortality of patients with AKI and treated with CRRT, the higher removal efficiency of serum phosphorus, the adjusted hazard ratio (HR) value for 28-day mortality in the four models were separately 0.92 (0.90, 0.95), 0.91 (0.89, 0.94), 0.92 (0.89, 0.95), and 0.92 (0.89, 0.95); the adjusted HR value for 90 day mortality in the four models were 0.91 (0.89, 0.94), 0.92 (0.89, 0.95), 0.92 (0.89, 0.95), and 0.92 (0.89, 0.96); the adjusted OR value for the removal efficiency of serum phosphorus in the four models were separately -0.04 (-0.07, -0.01), -0.05 (-0.08, -0.01), -0.04 (-0.08, -0.01), and -0.04 (-0.08, -0.01). The sensitivity analysis and curve-fitting analysis also showed that ALB before CRRT was correlated with the 28 and 90 days mortality of critically ill patients with AKI and treated with CRRT and the removal efficiency of serum phosphorus. Conclusion: The higher the serum ALB before CRRT, the lower the mortality of critically ill patients with AKI and treated with CRRT, and the higher the clearance efficiency of serum phosphorus.

Early restrictive fluid balance is associated with lower hospital mortality independent of acute disease severity in critically ill patients on CRRT

Fluid overload (FO) with coincident acute kidney injury has been associated with increased mortality. However, it is unclear whether FO is an independent determinant of mortality for disease severity. We aimed to explore whether the development of fluid balance (FB) during the first 72 h of continuous renal replacement therapy (CRRT) is independently associated with hospital mortality. All patients admitted to a single centre ICU requiring CRRT for at least 24 h between years 2010–2019 were included. Extracted data included patient demographics and clinical parameters including daily cumulative fluid balance (FB^cum), lactate, SOFA score and vasoactive requirement at the initiation and during the first 72 h of CRRT. 399 patients were included in the analysis. Hospital survivors had a significantly lower FB^cum at CRRT initiation compared to non-survivors (median 1382 versus 3265 ml; p = 0.003). Hourly fluid balance per bodyweight (FB^net) was lower in survivors at 0–24, 24–48 and 48–72 h after initiation of CRRT (p < 0.008 for all comparisons). In the survival analysis (analyzed with counting process model) significant time-dependent explanatory variables for hospital mortality were FB^net (per ml/kg/h: HR: 1.319, 95% CI 1.038–1.677, p = 0.02), lactate (HR: 1.086, 95% CI 1.030–1.145, p = 0.002) and SOFA score (per ml/kg/h: HR: 1.084, 95% CI 1.025–1.146, p = 0.005) during the first 72 h of CRRT. Even after careful adjustment for repeated measures of disease severity, FB^net during the first 72 h of CRRT remains independently associated with hospital mortality, in critically ill patients with AKI.

Machine learning model to predict hypotension after starting continuous renal replacement therapy

Hypotension after starting continuous renal replacement therapy (CRRT) is associated with worse outcomes compared with normotension, but it is difficult to predict because several factors have interactive and complex effects on the risk. The present study applied machine learning algorithms to develop models to predict hypotension after initiating CRRT. Among 2349 adult patients who started CRRT due to acute kidney injury, 70% and 30% were randomly assigned into the training and testing sets, respectively. Hypotension was defined as a reduction in mean arterial pressure (MAP) ≥ 20 mmHg from the initial value within 6 h. The area under the receiver operating characteristic curves (AUROCs) in machine learning models, such as support vector machine (SVM), deep neural network (DNN), light gradient boosting machine (LGBM), and extreme gradient boosting machine (XGB) were compared with those in disease-severity scores such as the Sequential Organ Failure Assessment and Acute Physiology and Chronic Health Evaluation II. The XGB model showed the highest AUROC (0.828 [0.796-0.861]), and the DNN and LGBM models followed with AUROCs of 0.822 (0.789-0.856) and 0.813 (0.780-0.847), respectively; all machine learning AUROC values were higher than those obtained from disease-severity scores (AUROCs < 0.6). Although other definitions of hypotension were used such as a reduction of MAP ≥ 30 mmHg or a reduction occurring within 1 h, the AUROCs of machine learning models were higher than those of disease-severity scores. Machine learning models successfully predict hypotension after starting CRRT and can serve as the basis of systems to predict hypotension before starting CRRT.

Hypocalcemia is associated with hypotension during CRRT: A secondary analysis of the Acute Renal Failure Trial Network Study

PURPOSE

We investigated the effect of potentially modifiable continuous renal replacement therapy (CRRT)-related treatment factors on the risk of severe hypotension.

MATERIALS AND METHODS

We carried out a secondary statistical analysis of the Acute Renal Failure Trial Network (ATN) trial. The primary exposures of interest were CRRT treatment dose, ultrafiltration rate, blood flow rate, ionized calcium level and type of anti-coagulation used. The primary outcome was severe hypotension, defined as vasopressor-inotropic score > 18 and calculated based on treatment doses of vasopressor and inotropic agents.

RESULTS

Of 1124 individuals enrolled in the ATN Trial, 786 were managed with CRRT. 265/786 (33.7%) patients experienced severe hypotension during the trial. A serum ionized calcium <1.02 mmol/l was associated with a higher risk of severe hypotension compared to a serum calcium >1.02 mmol/l (hazard ratio 2.9; 95% CI 1.5-5.7). There was no significant difference in the risk of hypotension associated with other CRRT treatment factors.

CONCLUSIONS

Of the CRRT treatment factors studied, hypocalcemia with a serum ionized calcium <1.02 mmol/l was associated with a significantly increased risk of treatment-associated hypotension. Further studies will be required to assess whether treatment targets for serum calcium improve the risk of hypotension during CRRT.

Ultrafiltration in critically ill patients treated with kidney replacement therapy

Management of fluid overload is one of the most challenging problems in the care of critically ill patients with oliguric acute kidney injury. Various clinical practice guidelines support fluid removal using ultrafiltration during kidney replacement therapy. However, ultrafiltration is associated with considerable risks. Emerging evidence from observational studies suggests that both slow and fast rates of net fluid removal (that is, net ultrafiltration (UFNET)) during continuous kidney replacement therapy are associated with increased mortality compared with moderate UFNET rates. In addition, fast UFNET rates are associated with an increased risk of cardiac arrhythmias. Experimental studies in patients with kidney failure who were treated with intermittent haemodialysis suggest that fast UFNET rates are also associated with ischaemic injury to the heart, brain, kidney and gut. The UFNET rate should be prescribed based on patient body weight in millilitres per kilogramme per hour with close monitoring of patient haemodynamics and fluid balance. Dialysate cooling and sodium modelling may prevent haemodynamic instability and facilitate large volumes of fluid removal in patients with kidney failure who are treated with intermittent haemodialysis, but the effects of this strategy on organ injury are less well studied in critically ill patients treated with continuous kidney replacement therapy. Randomized trials are required to examine whether moderate UFNET rates are associated with a reduced risk of haemodynamic instability, organ injury and improved outcomes in critically ill patients.

Kidney Replacement Therapy for Fluid Management

Emerging evidence from observational studies suggests that both slower and faster net ultrafiltration rates during kidney replacement therapy are associated with increased mortality in critically ill patients with acute kidney injury and fluid overload. Faster rates are associated with ischemic organ injury. The net ultrafiltration rate should be prescribed based on patient body weight in milliliters per kilogram per hour, with close monitoring of patient hemodynamics and fluid balance. Randomized trials are required to examine whether moderate net ultrafiltration rates compared with slower and faster rates are associated with reduced risk of hemodynamic instability, organ injury, and improved outcomes.

Target value of mean arterial pressure in patients undergoing continuous renal replacement therapy due to acute kidney injury

Background

Although patients undergoing continuous renal replacement therapy (CRRT) due to acute kidney injury (AKI) frequently have instability in mean arterial pressure (MAP), no consensus exists on the target value of MAP related to high mortality after CRRT.

Methods

A total of 2,292 patients who underwent CRRT due to AKI in three referral hospitals were retrospectively reviewed. The MAPs were divided into tertiles, and the 3^rd tertile group served as a reference in the analyses. The major outcome was all-cause mortality during the intensive care unit period. The odds ratio (OR) of mortality was calculated using logistic regression after adjustment for multiple covariates. The nonlinear relationship regression model was applied to determine the threshold value of MAP related to increasing mortality.

Results

The mean value of MAP was 80.7 ± 17.3 mmHg at the time of CRRT initiation. The median intensive care unit stay was 5 days (interquartile range, 2–12 days), and during this time, 1,227 (55.5%) patients died. The 1^st tertile group of MAP showed an elevated risk of mortality compared with the 3^rd tertile group (adjusted OR, 1.28 [1.03–1.60]; P = 0.029). In the nonlinear regression analysis, the threshold value of MAP was calculated as 82.7 mmHg. Patients with MAP < 82.7 mmHg had a higher mortality rate than those with ≥ 82.7 mmHg (adjusted OR, 1.21 [1.01–1.45]; P = 0.037).

Conclusions

Low MAP at CRRT initiation is associated with a high risk of mortality, particularly when it is < 82.7 mmHg. This value may be used for risk classification and as a potential therapeutic target.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-020-02227-4.

Modeling acid-base balance during continuous kidney replacement therapy

Clinical studies have suggested that use of bicarbonate-containing substitution and dialysis fluids during continuous kidney replacement therapy may result in excessive increases in the carbon dioxide concentration of blood; however, the technical parameters governing such changes are unclear. The current work used a mathematical model of acid-base chemistry of blood to predict its composition within and exiting the extracorporeal circuit during continuous veno-venous hemofiltration (CVVH) and continuous veno-venous hemodiafiltration (CVVHDF). Model predictions showed that a total substitution fluid infusion rate of 2 L/h (33% predilution) with a bicarbonate concentration of 32 mEq/L during CVVH at a blood flow rate of 200 mL/min resulted in only modest increases in plasma bicarbonate concentration by 2.0 mEq/L and partial pressure of dissolved carbon dioxide by 4.4 mmHg in blood exiting the extracorporeal circuit. The relative increase in bicarbonate concentration (9.7%) was similar to that in partial pressure of dissolved carbon dioxide (8.2%), resulting in no significant change in plasma pH in the blood exiting the CVVH circuit. The changes in plasma acid-base levels were larger with a higher infusion rate of substitution fluid but smaller with a higher blood flow rate or use of substitution fluid with a lower bicarbonate concentration (22 mEq/L). Under comparable flow conditions and substitution fluid composition, model predicted changes in acid-base levels during CVVHDF were similar, but smaller, than those during CVVH. The described mathematical model can predict the effect of operating conditions on acid-base balance within and exiting the extracorporeal circuit during continuous kidney replacement therapy.

A Case Series: Continuous Kidney Replacement Therapy in Neonates With Low Body Weight

Emerging data indicate that acute kidney injury (AKI) may contribute to a worse prognosis in the infant population. Kidney replacement therapy (KRT) can be used to treat patients with AKI; however, this technique is challenging in patients in the neonatal intensive care units (NICUs) due to the low body weights and blood volumes in this population. Peritoneal dialysis (PD) is a potential modality since it is technically less challenging. However, PD has been associated with several disadvantages, including poor fluid status control, catheter-associated leakage, and peritonitis. Unfortunately, these complications can cause the temporary cessation of PD. Continuous kidney replacement therapy (CKRT) may represent a suitable alternative for PD. CKRT may be technically feasible in infants; however, little is known about the application of CKRT in neonates with low body weights. In this report, we discuss three cases of CKRT who were treated in the NICU at a tertiary medical center in southern Taiwan. We selected an adequate catheter diameter and achieved vascular access via an internal jugular vein or umbilical vein. The prescription of an appropriate dose of heparin was then used to prolong the circuit life of the CKRT. The maintenance of circuit durability in neonates with low body weight remains problematic. We hope that our experience can assist with the future clinical management of CKRT in neonates with low body weight.

New-onset atrial fibrillation in patients with acute kidney injury on continuous renal replacement therapy

PURPOSE

The mortality of critically ill patients with acute kidney injury (AKI) who require continuous renal replacement therapy (CRRT) remains high. We assessed the incidence and predictors of new-onset atrial fibrillation (NOAF) in this population and its impact on outcomes.

MATERIALS AND METHODS

This is a retrospective cohort study of adult intensive care units (ICU) patients who had AKI and received CRRT from December 2006 through November 2015 in a tertiary academic medical center. Cox proportional hazard model was used to evaluate the impact of NOAF on overall mortality.

RESULTS

Out of 1398 screened patients, NOAF occurred in 193 (14%) cases. NOAF occurring on CRRT was independently associated with an increased hazard of death at follow-up (HR: 1.26; 95% CI: 1.03-1.56), compared to the group who did not have NOAF. In the multivariable analysis using time-dependent covariates, higher potassium (HR 1.24, 95%CI: 1.01-1.54) and bicarbonate (HR 0.95, 95%CI: 0.92-0.98) levels were associated with increased and decreased risk of NOAF on CRRT, respectively.

CONCLUSIONS

NOAF in critically ill patients with AKI receiving CRRT is common and carries an unfavorable prognosis. Prospective studies are required to elucidate modifiable risk factors for NOAF occurring on CRRT.

Change in right ventricular systolic function after continuous renal replacement therapy initiation and renal recovery

OBJECTIVE

To describe the associations between right ventricular (RV) function and outcomes of patients with acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT).

METHODS

This is a retrospective study, conducted 2006-2015 at an academic hospital in USA. We included patients with AKI requiring CRRT who had paired echocardiograms within 2 weeks before and after CRRT initiation. We defined improvement in RV systolic function as 2-point improvement on the semiquantitative scale.

RESULTS

The cohort included 201 patients. The mean(±SD) age was 59(±16) years with 83(41%) female. The median time of the pre and post echocardiograms relative to CRRT initiation were - 1 day (IQR-3;0) prior to and 3 days (IQR1;7) after CRRT initiation. Thirty-one (15%) patients showed an improvement in their RV function. Using a multivariable logistic regression model, improvement in RV systolic function was associated with lower odds of major adverse kidney events (composite of mortality, need for dialysis or persistently elevated serum creatinine) at 90 days with odds ratio (OR) of 0.37(95%CI:0.17-0.84, p.016). Positive cumulative fluid balance was associated with lower odds of improvement in RV function (OR 0.95 per 1-l increase, p 0.045).

CONCLUSION

Serial assessment of RV function among patients with AKI requiring CRRT could provide prognostic value.

Factors Associated with In-Hospital Mortality after Continuous Renal Replacement Therapy for Critically Ill Patients: A Systematic Review and Meta-Analysis

Continuous renal replacement therapy (CRRT) is a broadly-accepted treatment for critically ill patients with acute kidney injury to optimize fluid and electrolyte management. Despite intensive dialysis care, there is a high mortality rate among these patients. There is uncertainty regarding the factors associated with in-hospital mortality among patients requiring CRRT. This review evaluates how various risk factors influence the in-hospital mortality of critically ill patients who require CRRT. Five databases were surveyed to gather relevant publications up to 30 June 2020. We identified 752 works, of which we retrieved 38 in full text. Finally, six cohort studies that evaluated 1190 patients were eligible. The in-hospital mortality rate in these studies ranged from 38.6 to 62.4%. Our meta-analysis results showed that older age, lower body mass index, higher APACHE II and SOFA scores, lower systolic and diastolic blood pressure, decreased serum creatinine level, and increased serum sodium level were significantly associated with increased in-hospital mortality in critically ill patients who received CRRT. These results suggest that there are multiple modifiable factors that influence the risk of in-hospital mortality in critically ill patients undergoing CRRT. Further, healthcare professionals should take more care when CRRT is performed on older adults.

Contemporary Management of Severe Acute Kidney Injury and Refractory Cardiorenal Syndrome: JACC Council Perspectives

Acute kidney injury (AKI) and cardiorenal syndrome (CRS) are increasingly prevalent in hospitalized patients with cardiovascular disease and remain associated with poor short- and long-term outcomes. There are no specific therapies to reduce mortality related to either AKI or CRS, apart from supportive care and volume status management. Acute renal replacement therapies (RRTs), including ultrafiltration, intermittent hemodialysis, and continuous RRT are used to manage complications of medically refractory AKI and CRS and may restore normal electrolyte, acid-base, and fluid balance before renal recovery. Patients who require acute RRT have a significant risk of mortality and long-term dialysis dependence, emphasizing the importance of appropriate patient selection. Despite the growing use of RRT in the cardiac intensive care unit, there are few resources for the cardiovascular specialist that integrate the epidemiology, diagnostic workup, and medical management of AKI and CRS with an overview of indications, multidisciplinary team management, and transition off of RRT.

AKI-A Relevant Safety End Point?

Acute kidney injury (AKI) is a common outcome evaluated in clinical studies, often as a safety end point in a variety of cardiovascular, kidney disease, and other clinical trials. AKI end points that include modest increases in serum creatinine levels from baseline may not associate with patient-centered outcomes such as initiation of dialysis, sustained decline in kidney function, or death. Surprisingly, data from several randomized controlled trials have suggested that in certain settings, the development of AKI may be associated with favorable outcomes. AKI safety end points that are nonspecific and may not associate with patient-centered outcomes could result in beneficial therapies being inappropriately withheld or never developed for commercial use. We review several issues related to commonly used AKI definitions and suggest that future work in AKI use more patient-centered AKI end points such as major adverse kidney events at 30 days or other later time points.