Fluid Accumulation in Critically Ill Children

Heterogeneity in the definition of major adverse kidney events: a scoping review

Acute kidney injury (AKI) is associated with persistent renal dysfunction, the receipt of dialysis, dialysis dependence, and mortality. Accordingly, the concept of major adverse kidney events (MAKE) has been adopted as an endpoint for assessing the impact of AKI. However, applied criteria or observation periods for operationalizing MAKE appear to vary across studies. To evaluate this heterogeneity for MAKE evaluation, we performed a systematic scoping review of studies that employed MAKE as an AKI endpoint. Four major academic databases were searched, and we identified 122 studies with increasing numbers over time. We found marked heterogeneity in applied criteria and observation periods for MAKE across these studies, with some even lacking a description of criteria. Moreover, 13 different observation periods were employed, with 30 days and 90 days as the most common. Persistent renal dysfunction was evaluated by estimated glomerular filtration rate (34%) or serum creatinine concentration (48%); however, 37 different definitions for this component were employed in terms of parameters, cut-off criteria, and assessment periods. The definition for the dialysis component also showed significant heterogeneity regarding assessment periods and duration of dialysis requirement (chronic vs temporary). Finally, MAKE rates could vary by 7% [interquartile range: 1.7-16.7%] with different observation periods or by 36.4% with different dialysis component definitions. Our findings revealed marked heterogeneity in MAKE definitions, particularly regarding component assessment and observation periods. Dedicated discussion is needed to establish uniform and acceptable standards to operationalize MAKE in terms of selection and applied criteria of components, observation period, and reporting criteria for future trials on AKI and related conditions.

An update on the role of fluid overload in the prediction of outcome in acute kidney injury

Over the past two decades, our understanding of the impact of acute kidney injury, disorders of fluid balance, and their interplay have increased significantly. In recent years, the epidemiology and impact of fluid balance, including the pathologic state of fluid overload on outcomes has been studied extensively across multiple pediatric and neonatal populations. A detailed understating of fluid balance has become increasingly important as it is recognized as a target for intervention to continue to work to improve outcomes in these populations. In this review, we provide an update on the epidemiology and outcomes associated with fluid balance disorders and the development of fluid overload in children with acute kidney injury (AKI). This will include a detailed review of consensus definitions of fluid balance, fluid overload, and the methodologies to define them, impact of fluid balance on the diagnosis of AKI and the concept of fluid corrected serum creatinine. This review will also provide detailed descriptions of future directions and the changing paradigms around fluid balance and AKI in critical care nephrology, including the incorporation of the sequential utilization of risk stratification, novel biomarkers, and functional kidney tests (furosemide stress test) into research and ultimately clinical care. Finally, the review will conclude with novel methods currently under study to assess fluid balance and distribution (point of care ultrasound and bioimpedance).

Evaluating fluid overload in critically ill children

PURPOSE OF REVIEW

To review the evaluation and management of fluid overload in critically ill children.

RECENT FINDINGS

Emerging evidence associates fluid overload, i.e. having a positive cumulative fluid balance, with adverse outcome in critically ill children. This is most likely the result of impaired organ function due to increased extravascular water content. The combination of a number of parameters, including physical, laboratory and radiographic markers, may aid the clinician in monitoring and quantifying fluid status, but all have important limitations, in particular to discriminate between intra- and extravascular water volume. Current guidelines advocate a restrictive fluid management, initiated early during the disease course, but are hampered by the lack of high quality evidence.

SUMMARY

Recent advances in early evaluation of fluid status and (tailored) restrictive fluid management in critically ill children may decrease complications of fluid overload, potentially improving outcome. Further clinical trials are necessary to provide the clinician with solid recommendations.

Influence of fluid accumulation on major adverse kidney events in critically ill patients - an observational cohort study

BACKGROUND

Fluid accumulation (FA) is known to be associated with acute kidney injury (AKI) during intensive care unit (ICU) stay but data on mid-term renal outcome is scarce. The aim of this study was to investigate the association between FA at ICU day 3 and major adverse kidney events in the first 30 days after ICU admission (MAKE30).

METHODS

Retrospective, single-center cohort study including adult ICU patients with sufficient data to compute FA and MAKE30. We defined FA as a positive cumulative fluid balance greater than 5% of bodyweight. The association between FA and MAKE30, including its sub-components, as well as the serum creatinine trajectories during ICU stay were examined. In addition, we performed a sensitivity analysis for the stage of AKI and the presence of chronic kidney disease (CKD).

RESULTS

Out of 13,326 included patients, 1,100 (8.3%) met the FA definition. FA at ICU day 3 was significantly associated with MAKE30 (adjusted odds ratio [aOR] 1.96; 95% confidence interval [CI] 1.67-2.30; p < 0.001) and all sub-components: need for renal replacement therapy (aOR 3.83; 95%CI 3.02-4.84), persistent renal dysfunction (aOR 1.72; 95%CI 1.40-2.12), and 30-day mortality (aOR 1.70; 95%CI 1.38-2.09), p all < 0.001. The sensitivity analysis showed an association of FA with MAKE30 independent from a pre-existing CKD, but exclusively in patients with AKI stage 3. Furthermore, FA was independently associated with the creatinine trajectory over the whole observation period.

CONCLUSIONS

Fluid accumulation is significantly associated with MAKE30 in critically ill patients. This association is independent from pre-existing CKD and strongest in patients with AKI stage 3.

Fluid assessment, fluid balance, and fluid overload in sick children: a report from the Pediatric Acute Disease Quality Initiative (ADQI) conference

BACKGROUND

The impact of disorders of fluid balance, including the pathologic state of fluid overload in sick children has become increasingly apparent. With this understanding, there has been a shift from application of absolute thresholds of fluid accumulation to an appreciation of the intricacies of fluid balance, including the impact of timing, trajectory, and disease pathophysiology.

METHODS

The 26th Acute Disease Quality Initiative was the first to be exclusively dedicated to pediatric and neonatal acute kidney injury (pADQI). As part of the consensus panel, a multidisciplinary working group dedicated to fluid balance, fluid accumulation, and fluid overload was created. Through a search, review, and appraisal of the literature, summative consensus statements, along with identification of knowledge gaps and recommendations for clinical practice and research were developed.

CONCLUSIONS

The 26th pADQI conference proposed harmonized terminology for fluid balance and for describing a pathologic state of fluid overload for clinical practice and research. Recommendations include that the terms daily fluid balance, cumulative fluid balance, and percent cumulative fluid balance be utilized to describe the fluid status of sick children. The term fluid overload is to be preserved for describing a pathologic state of positive fluid balance associated with adverse events. Several recommendations for research were proposed including focused validation of the definition of fluid balance, fluid overload, and proposed methodologic approaches and endpoints for clinical trials.

Advances in pediatric acute kidney injury pharmacology and nutrition: a report from the 26th Acute Disease Quality Initiative (ADQI) consensus conference

BACKGROUND

In the past decade, there have been substantial advances in our understanding of pediatric AKI. Despite this progress, large gaps remain in our understanding of pharmacology and nutritional therapy in pediatric AKI.

METHODS

During the 26th Acute Disease Quality Initiative (ADQI) Consensus Conference, a multidisciplinary group of experts reviewed the evidence and used a modified Delphi process to achieve consensus on recommendations for gaps and advances in care for pharmacologic and nutritional management of pediatric AKI. The current evidence as well as gaps and opportunities were discussed, and recommendations were summarized.

RESULTS

Two consensus statements were developed. (1) High-value, kidney-eliminated medications should be selected for a detailed characterization of their pharmacokinetics, pharmacodynamics, and pharmaco-"omics" in sick children across the developmental continuum. This will allow for the optimization of real-time modeling with the goal of improving patient care. Nephrotoxin stewardship will be identified as an organizational priority and supported with necessary resources and infrastructure. (2) Patient-centered outcomes (functional status, quality of life, and optimal growth and development) must drive targeted nutritional interventions to optimize short- and long-term nutrition. Measures of acute and chronic changes of anthropometrics, body composition, physical function, and metabolic control should be incorporated into nutritional assessments.

CONCLUSIONS

Neonates and children have unique metabolic and growth parameters compared to adult patients. Strategic investments in multidisciplinary translational research efforts are required to fill the knowledge gaps in nutritional requirements and pharmacological best practices for children with or at risk for AKI.

Pattern of Fluid Overload and its Impact on Mortality Among Mechanically Ventilated Children: Secondary Analysis of the ReLiSCh Trial

OBJECTIVES

To assess the pattern of fluid overload (FO) and its impact on mortality among mechanically ventilated children.

METHODS

In this secondary analysis of an open-label randomized controlled trial (ReLiSCh trial, October 2020-September 2021), hemodynamically stable mechanically ventilated children (n = 100) admitted to a tertiary level pediatric intensive care unit (PICU) in North India were enrolled. The primary outcome was pattern of FO (FO% >10% and cumulative FO% from day 1-7); and secondary outcomes were pattern of FO among survivors and non-survivors, and prescription practices of maintenance fluid.

RESULTS

The median (IQR) age was 3.5 (0.85-7.5) y and 57% were males. Common diagnoses were pneumonia (27%), scrub typhus (14%), Landry-Guillain-Barré syndrome (9%), dengue (8%), central nervous system infections (7%) and staphylococcal sepsis (6%). Common organ dysfunction included acute respiratory distress syndrome (ARDS) (41%), shock (38%), and acute kidney injury (AKI) (9%). The duration PICU stay was 11 (7-17) d and mortality was 12%. The FO% >10% was noted in 19% children; and there was significant increase in cumulative FO% from day 1-7 [1.2 (0.2-2.6)% to 8.5 (1.7-14.3)%, (p = 0.000)]. Among non-survivors, higher proportion had FO% >10% (66.7% vs. 12.5%, p 0.0001); and trend towards higher cumulative FO% on first seven days. From day 1-7, the percentage of maintenance fluid received increased from 60 (50-71)% to 70 (60-77)% (p = 0.691).

CONCLUSIONS

One-fifth of mechanically ventilated children had FO% >10% and there was significant increase in cumulative FO% from day 1-7. Non-survivors had significantly higher degree of FO.

Furosemide in pediatric intensive care: a retrospective cohort analysis

Introduction

Furosemide is the most commonly used medication in pediatric intensive care. Growing data indicates improved hemodynamic stability and efficacy of furosemide infusions compared to intermittent injections, thereby suggesting furosemide infusions might be considered as first line therapy in critically ill, paediatric patients. The objective of this study is to examine furosemide treatment as either continuous infusions or intermittent injections and subsequent patient outcomes.

Methods

This is a retrospective cohort analysis of patients treated in a pediatric intensive care unit (ICU) over a nine year period (July 31st 2006 and July 31, 2015). Eligible patients were admitted to either the general pediatric or cardiac specific ICU for a duration of at least 6 hours and who received intravenous furosemide treatment.

Results

A total of 7,478 patients were identified who received a total of 118,438 furosemide administrations for a total of 113,951 (96%) intermittent doses and 4,487 (4%) infusions running for a total of 1,588,750 hours. A total of 5,996 (80%) patients received exclusively furosemide injections and 1,482 (20%) patients received at least one furosemide infusion. A total of 193 patients died during ICU admission, amounting to 87 (6%) of the 1,482 patients who received an infusion and 106 (2%) of the 5,996 who received intermittent injections. Multivariable regression analysis showed no statistically significant decrease in adjusted mortality for patients who received furosemide injections compared to furosemide infusions (aOR 1.20, CI 0.76-1.89).

Discussion

This retrospective study observed similar mortality for patients who received furosemide infusions compared to furosemide injections. More research on furosemide in the ICU could provide insights on fluid management, drug effectiveness, and pharmacologic stewardship for critically ill children.

Revisiting Post-ICU Admission Fluid Balance Across Pediatric Sepsis Mortality Risk Strata: A Secondary Analysis of a Prospective Observational Cohort Study

OBJECTIVES

Post-ICU admission cumulative positive fluid balance (PFB) is associated with increased mortality among critically ill patients. We sought to test whether this risk varied across biomarker-based risk strata upon adjusting for illness severity, presence of severe acute kidney injury (acute kidney injury), and use of continuous renal replacement therapy (CRRT) in pediatric septic shock.

DESIGN

Ongoing multicenter prospective observational cohort.

SETTING

Thirteen PICUs in the United States (2003-2023).

PATIENTS

Six hundred and eighty-one children with septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cumulative percent PFB between days 1 and 7 (days 1-7 %PFB) was determined. Primary outcome of interest was complicated course defined as death or persistence of greater than or equal to two organ dysfunctions by day 7. Pediatric Sepsis Biomarker Risk Model (PERSEVERE)-II biomarkers were used to assign mortality probability and categorize patients into high mortality (n = 91), intermediate mortality (n = 134), and low mortality (n = 456) risk strata. Cox proportional hazard regression models with adjustment for PERSEVERE-II mortality probability, presence of sepsis-associated acute kidney injury on day 3, and use of CRRT, demonstrated that time-dependent variable days 1-7%PFB was independently associated with an increased hazard of complicated course. Risk-stratified analyses revealed that each 10% increase in days 1-7 %PFB was associated with increased hazard of complicated course only among patients with high mortality risk strata (adjusted hazard ratio 1.24 (95% CI, 1.08-1.43), p = 0.003). However, this association was not causally mediated by PERSEVERE-II biomarkers.

CONCLUSIONS

Our data demonstrate the influence of cumulative %PFB on the risk of complicated course in pediatric septic shock. Contrary to our previous report, this risk was largely driven by patients categorized as having a high mortality risk based on PERSEVERE-II biomarkers. Incorporation of such prognostic enrichment tools in randomized trials of restrictive fluid management or early initiation of de-escalation strategies may inform targeted application of such interventions among at-risk patients.

Pilot randomized controlled trial of restricted versus liberal crystalloid fluid management in pediatric post-operative and trauma patients

BACKGROUND

Intravenous (IV) fluid therapy is essential in the treatment of critically ill pediatric surgery and trauma patients. Recent studies have suggested that aggressive fluids may be detrimental to patients. Prospective studies are needed to compare liberal to restricted fluid management in these patients. The primary objective of this pilot trial is to test study feasibility-recruitment and adherence to the study treatment algorithm.

METHODS

We conducted a two-part pilot randomized controlled trial (RCT) comparing liberal to restricted crystalloid fluid management in 50 pediatric post-operative (1-18 years) and trauma (1-15 years) patients admitted to our pediatric intensive care unit (PICU). Patients were randomized to a high (liberal) volume or low (restricted) volume algorithm using unblinded, blocked randomization. A revised treatment algorithm was used after the 29th patient for the second part of the RCT. The goal of the trial was to determine the feasibility of conducting an RCT at a single site for recruitment and retention. We also collected data on the safety of study interventions and clinical outcomes, including pulmonary, infectious, renal, post-operative, and length of stay outcomes.

RESULTS

Fifty patients were randomized to either liberal (n = 26) or restricted (n = 24) fluid management strategy. After data was obtained on 29 patients, a first study analysis was performed. The volume of fluid administered and triggers for intervention were adapted to optimize the treatment effect and clarity of outcomes. Updated and refined fluid management algorithms were created. These were used for the second part of the RCT on patients 30-50. During this second study period, 54% (21/39, 95% CI 37-70%) of patients approached were enrolled in the study. Of the patients enrolled, 71% (15/21, 95% CI 48-89%) completed the study. This met our a priori recruitment and retention criteria for success. A data safety monitoring committee concluded that no adverse events were related to study interventions. Although the study was not powered to detect differences in outcomes, after the algorithm was revised, we observed a non-significant trend towards improved pulmonary outcomes in patients on the restricted arm, including decreased need for and time on oxygen support and decreased need for mechanical ventilation.

CONCLUSION

We demonstrated the feasibility and safety of conducting a single-site RCT comparing liberal to restricted crystalloid fluid management in critically ill pediatric post-operative and trauma patients. We observed trends in improved pulmonary outcomes in patients undergoing restricted fluid management. A definitive multicenter RCT comparing fluid management strategies in these patients is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04201704 . Registered 17 December 2019-retrospectively registered.

Restricted versus Usual/Liberal Maintenance Fluid Strategy in Mechanically Ventilated Children: An Open-Label Randomized Trial (ReLiSCh Trial)

OBJECTIVES

To assess the impact of restricted vs. usual/liberal maintenance fluid strategy on fluid overload (FO) among mechanically ventilated children.

METHODS

This open-label randomized controlled trial was conducted over a period of 1 y (October 2020-September 2021) in a Pediatric intensive care unit (PICU) in North India. Hemodynamically stable mechanically ventilated children were randomized to 40% (restricted group, n = 50) and 70-80% (usual/liberal group, n = 50) of maintenance fluids. The primary outcome was cumulative fluid overload percentage (FO%) on day 7. Secondary outcomes were FO% >10%; vasoactive inotropic score, sequential organ failure assessment score, pediatric logistic organ dysfunction score and oxygenation index from day 1-7; ventilation free days (VFDs) and PICU free days (PFDs) through day 28; and mortality.

RESULTS

The restricted group had statistically non-significant trend towards lower cumulative FO% at day 7 [7.6 vs. 9.5, p = 0.40]; and proportion of children with FO% >10% (12% vs. 26%, p = 0.21) as compared to usual/liberal group. The increase in FO% from day 1-7 was significant in usual/liberal group as compared to restricted group (p <0.001 and p = 0.134, respectively). Restricted group received significantly lower amount of fluid in the first 5 d; had significantly higher VFDs (23 vs. 17 d, p = 0.008) and PFDs (19 vs. 15 d, p = 0.007); and trend towards lower mortality (8% vs. 16%, p = 0.21).

CONCLUSIONS

Restricted as compared to usual/liberal maintenance fluid strategy among mechanically ventilated children was associated with a trend towards lower rate and severity of FO and mortality; and significantly lower fluid volume received, and higher VFDs and PFDs.

Fluid overload and mortality in critically ill patients with severe heart failure and cardiogenic shock-An observational cohort study

OBJECTIVE

Patients with heart failure (HF) and cardiogenic shock are especially prone to the negative effects of fluid overload (FO); however, fluid resuscitation in respective patients is sometimes necessary resulting in FO. We aimed to study the association of FO at ICU discharge with 30-day mortality in patients admitted to the ICU due to severe heart failure and/or cardiogenic shock.

METHODS

Retrospective, single-center cohort study. Patients with admission diagnoses of severe HF and/or cardiogenic shock were eligible. The following exclusion criteria were applied: (I) patients younger than 16 years, (II) patients admitted to our intermediate care unit, and (III) patients with incomplete data to determine FO at ICU discharge. We used a cumulative weight-adjusted definition of fluid balance and defined more than 5% as FO. The data were analyzed by univariate and adjusted univariate logistic regression.

RESULTS

We included 2,158 patients in our analysis. 185 patients (8.6%) were fluid overloaded at ICU discharge. The mean FO in the FO group was 7.2% [interquartile range (IQR) 5.8-10%]. In patients with FO at ICU discharge, 30-day mortality was 22.7% compared to 11.7% in non-FO patients (p < 0.001). In adjusted univariate logistic regression, we did not observe any association of FO at discharge with 30-day mortality [odds ratio (OR) 1.48; 95% confidence interval (CI) 0.81-2.71, p = 0.2]. No association between FO and 30-day mortality was found in the subgroups with HF only or cardiogenic shock (all p > 0.05). Baseline lactate (adjusted OR 1.27; 95% CI 1.13-1.42; p < 0.001) and cardiac surgery at admission (adjusted OR 1.94; 95% CI 1.0-3.76; p = 0.05) were the main associated factors with FO at ICU discharge.

CONCLUSION

In patients admitted to the ICU due to severe HF and/or cardiogenic shock, FO at ICU discharge seems not to be associated with 30-day mortality.

Outcome prediction for acute kidney injury among hospitalized children via eXtreme Gradient Boosting algorithm

Acute kidney injury (AKI) is common among hospitalized children and is associated with a poor prognosis. The study sought to develop machine learning-based models for predicting adverse outcomes among hospitalized AKI children. We performed a retrospective study of hospitalized AKI patients aged 1 month to 18 years in the Second Xiangya Hospital of Central South University in China from 2015 to 2020. The primary outcomes included major adverse kidney events within 30 days (MAKE30) (death, new renal replacement therapy, and persistent renal dysfunction) and 90-day adverse outcomes (chronic dialysis and death). The state-of-the-art machine learning algorithm, eXtreme Gradient Boosting (XGBoost), and the traditional logistic regression were used to establish prediction models for MAKE30 and 90-day adverse outcomes. The models’ performance was evaluated by split-set test. A total of 1394 pediatric AKI patients were included in the study. The incidence of MAKE30 and 90-day adverse outcomes was 24.1% and 8.1%, respectively. In the test set, the area under the receiver operating characteristic curve (AUC) of the XGBoost model was 0.810 (95% CI 0.763–0.857) for MAKE30 and 0.851 (95% CI 0.785–0.916) for 90-day adverse outcomes, The AUC of the logistic regression model was 0.786 (95% CI 0.731–0.841) for MAKE30 and 0.759 (95% CI 0.654–0.864) for 90-day adverse outcomes. A web-based risk calculator can facilitate the application of the XGBoost models in daily clinical practice. In conclusion, XGBoost showed good performance in predicting MAKE30 and 90-day adverse outcomes, which provided clinicians with useful tools for prognostic assessment in hospitalized AKI children.

Current Practice of Fluid Maintenance and Replacement Therapy in Mechanically Ventilated Critically Ill Children: A European Survey

Appropriate fluid management in mechanically ventilated critically ill children remains an important challenge and topic of active discussion in pediatric intensive care medicine. An increasing number of studies show an association between a positive fluid balance or fluid overload and adverse outcomes. However, to date, no international consensus regarding fluid management or removal strategies exists. The aim of this study was to obtain more insight into the current clinical practice of fluid therapy in mechanically ventilated critically ill children. On behalf of the section of cardiovascular dynamics of the European Society of Pediatric and Neonatal Intensive Care (ESPNIC) we conducted an anonymous survey among pediatric intensive care unit (PICU) specialists in Europe regarding fluid overload and management. A total of 107 study participants responded to the survey. The vast majority of respondents considers fluid overload to be a common phenomenon in mechanically ventilated children and believes this complication is associated with adverse outcomes, such as mortality and duration of respiratory support. Yet, only 75% of the respondents administers a lower volume of fluids (reduction of 20% of normal intake) to mechanically ventilated critically ill children on admission. During PICU stay, a cumulative fluid balance of more than 5% is considered to be an indication to reduce fluid intake and start diuretic treatment in most respondents. Next to fluid balance calculation, the occurrence of peripheral and/or pulmonary edema (as assessed including by chest radiograph and lung ultrasound) was considered an important clinical sign of fluid overload entailing further therapeutic action. In conclusion, fluid overload in mechanically ventilated critically ill children is considered an important problem among PICU specialists, but there is great heterogeneity in the current clinical practice to avoid this complication. We identify a great need for further prospective and randomized investigation of the effects of (restrictive) fluid strategies in the PICU.

Precision of weight measurement in critically ill infants: a technical report

Objectives: To investigate the precision of weight measurements in critically ill infants in a paediatric intensive care unit (PICU). Design: Prospective cohort study. Setting: Royal Children's Hospital PICU. Participants: Mechanically ventilated infants admitted to the Royal Children's Hospital PICU between September 2020 and February 2021. Main outcome measures: Mean percentage difference and agreement of consecutive weight measurements. Results: Thirty infants were enrolled, of which 17 were receiving post-surgical care for congenital heart disease and four were receiving extracorporeal membrane oxygenation (ECMO). The median age was 13 days (interquartile range [IQR], 3.1-52.4 days). The mean difference in weight was 1.3% (standard deviation [SD], 1.0%), and the test-retest agreement intraclass correlation was 0.99 (95% CI, 0.99-0.99; P < 0.01). The percentage difference between measurements was ≤ 2.5% in 26/30 (87%) children, and the range was < 0.1% to 3.6%. In 26 children not receiving ECMO, the mean difference in weight was 1.1% (SD, 1.0%). There were no complications. Conclusions: Weighing mechanically ventilated, critically ill infants in intensive care can be performed safely, with a mean difference between consecutive weights of 1.3%, making it a potentially useful additional measure of fluid accumulation.

Association between early fluid overload and mortality in critically-ill mechanically ventilated children: a single-center retrospective cohort study

Background

Positive fluid overload (FO) may cause adverse effect. This study retrospectively analyzed the relationship between early FO and in-hospital mortality in children with mechanical ventilation (MV) in pediatric intensive care unit (PICU).

Methods

This study retrospectively enrolled 309 children (ages 28 days to 16 years) receiving invasive MV admitted to the PICU of Xinhua Hospital from March 2014 to March 2019. Children receiving MV for less than 48 h were excluded. The FO in the first 3 days of MV was considered to the early FO. Patients were divided into groups according to early FO and survival to evaluate the associations of early FO, percentage FO(%FO) > 10%, and %FO > 20% with in-hospital mortality.

Results

A total of 309 patients were included. The mean early FO was 8.83 ± 8.81%, and the mortality in hospital was 26.2% (81/309). There were no significant differences in mortality among different FO groups (P = 0.053) or in early FO between survivors and non-survivors (P = 0.992). Regression analysis demonstrated that use of more vasoactive drugs, the presence of multiple organ dysfunction syndrome, longer duration of MV, and a non-operative reason for PICU admission were related to increased mortality (P < 0.05). Although early FO and %FO > 10% were not associated with in-hospital mortality (β = 0.030, P = 0.090, 95% CI = 0.995–1.067; β = 0.479, P = 0.153, 95% CI = 0.837–3.117), %FO > 20% was positively correlated with mortality (β = 1.057, OR = 2.878, P = 0.029, 95% CI = 1.116–7.418).

Conclusions

The correlation between early FO and mortality was affected by interventions and the severity of the disease, but %FO > 20% was an independent risk factor for in-hospital mortality in critically ill MV-treated children.

Renal angina index predicts fluid overload in critically ill children: an observational cohort study

Background

Fluid overload and acute kidney injury are common and associated with poor outcomes among critically ill children. The prodrome of renal angina stratifies patients by risk for severe acute kidney injury, but the predictive discrimination for fluid overload is unknown.

Methods

Post-hoc analysis of patients admitted to a tertiary care pediatric intensive care unit (PICU). The primary outcome was the performance of renal angina fulfillment on day of ICU admission to predict fluid overload ≥15% on Day 3.

Results

77/139 children (55%) fulfilled renal angina (RA+). After adjusting for covariates, RA+ was associated with increased odds of fluid overload on Day 3 (adjusted odds ratio (aOR) 5.1, 95% CI 1.23–21.2, p = 0.025, versus RA-). RA- resulted in a 90% negative predictive value for fluid overload on Day 3. Median fluid overload was significantly higher in RA+ patients with severe acute kidney injury compared to RA+ patients without severe acute kidney injury (% fluid overload on Day 3: 8.8% vs. 0.73%, p = 0.002).

Conclusion

Among critically ill children, fulfillment of renal angina was associated with increased odds of fluid overload versus the absence of renal angina and a higher fluid overload among patients who developed acute kidney injury. Renal angina directed risk classification may identify patients at highest risk for fluid accumulation. Expanded study in larger populations is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02540-6.

Cardiorenal Syndrome

Cardiorenal syndrome (CRS) describes a specific acute and chronic clinical picture in which the heart or the kidney are primarily dysfunctioning and secondarily affect each other. CRS is divided into five classes: acute and chronic CRS, acute and chronic renocardiac syndromes, and secondary dysfunction of heart and kidneys. This article specifically details the classification and the epidemiology, some risk factors, and the pathophysiology of CRS. Some emerging aspects of CRS are also discussed, such as CRS in patients with end-stage heart failure, with mechanical ventricular assistance, and after heart transplantation. Finally, some aspects of pediatric CRS are detailed.

Two to Tango: Kidney-Lung Interaction in Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute Kidney Injury (AKI) is an independent risk factor for mortality in hospitalized patients. AKI syndrome leads to fluid overload, electrolyte and acid-base disturbances, immunoparalysis, and propagates multiple organ dysfunction through organ "crosstalk". Preclinical models suggest AKI causes acute lung injury (ALI), and conversely, mechanical ventilation and ALI cause AKI. In the clinical setting, respiratory complications are a key driver of increased mortality in patients with AKI, highlighting the bidirectional relationship. This article highlights the challenging and complex interactions between the lung and kidney in critically ill patients with AKI and acute respiratory distress syndrome (ARDS) and global implications of AKI. We discuss disease-specific molecular mediators and inflammatory pathways involved in organ crosstalk in the AKI-ARDS construct, and highlight the reciprocal hemodynamic effects of elevated pulmonary vascular resistance and central venous pressure (CVP) leading to renal hypoperfusion and pulmonary edema associated with fluid overload and increased right ventricular afterload. Finally, we discuss the notion of different ARDS "phenotypes" and the response to fluid overload, suggesting differential organ crosstalk in specific pathological states. While the directionality of effect remains challenging to distinguish at the bedside due to lag in diagnosis with conventional renal function markers and lack of tangible damage markers, this review provides a paradigm for understanding kidney-lung interactions in the critically ill patient.