Risk factors for acute renal failure requiring dialysis after surgery for congenital heart disease in children

Comparison of Levosimendan Versus Milrinone After the Arterial Switch Operation for Infants ≤3 kg

Background: Various inotropes and inodilators have been utilized to treat low cardiac output syndrome after the arterial switch operation. The use of levosimendan, a calcium sensitizer has been limited in this setting. This study compares the effects of levosimendan with milrinone in managing low cardiac output after the arterial switch operation. Methods: A retrospective, comparative study was conducted in a tertiary care hospital on patients weighing up to 3 kg undergoing the arterial switch operation between January 2017 and January 2022. Patients received a loading dose followed by continuous infusion of either levosimendan or milrinone. Echocardiographic, hemodynamic and biochemical parameters were compared. Results: Forty-three patients received levosimendan and 42 patients received milrinone as the primary test drug. Cardiac index of less than 2.2 L/min/m2 on postoperative day 1 and 2 was found in 9.3% and 2.3% of patients receiving levosimendan versus 26.2% and 11.9% in those receiving milrinone, respectively (P = .04 and .08, respectively). Early lactate-clearance and better central venous oxygen saturations were noted in the levosimendan group. Prevalence of acute kidney injury was higher in the milrinone group (50% vs 28%; P = .03). Use of peritoneal dialysis in the milrinone group versus levosimendan was 31% and 16.3%, respectively (P = .11). There was no difference in hospital mortality between the groups (milrinone, 3; levosimendan, 2, P = .62). Conclusions: Levosimendan is safe and as effective as milrinone to treat low cardiac output syndrome occurring in neonates after the arterial switch operation. In addition we found that levosimendan was renal protective when compared with milrinone.

Intraoperative and Postoperative Hemodynamic Predictors of Acute Kidney Injury in Pediatric Heart Transplant Recipients

Acute kidney injury (AKI) is common after pediatric heart transplantation (HT) and is associated with inferior patient outcomes. Hemodynamic risk factors for pediatric heart transplant recipients who experience AKI are not well described. We performed a retrospective review of 99 pediatric heart transplant patients at Lucile Packard Children's Hospital Stanford from January 1, 2015, to December 31, 2019, in which clinical and demographic characteristics, intraoperative perfusion data, and hemodynamic measurements in the first 48 postoperative hours were analyzed as risk factors for severe AKI (Kidney Disease: Improving Global Outcomes [KDIGO] stage ≥ 2). Univariate analysis was conducted using Fisher's exact test, Chi-square test, and the Wilcoxon rank-sum test, as appropriate. Multivariable analysis was conducted using logistic regression. Thirty-five patients (35%) experienced severe AKI which was associated with lower intraoperative cardiac index ( p  = 0.001), higher hematocrit ( p  < 0.001), lower body temperature ( p  < 0.001), lower renal near-infrared spectroscopy ( p  = 0.001), lower postoperative mean arterial blood pressure (MAP: p  = 0.001), and higher central venous pressure (CVP; p  < 0.001). In multivariable analysis, postoperative CVP >12 mm Hg (odds ratio [OR] = 4.27; 95% confidence interval [CI]: 1.48-12.3, p  = 0.007) and MAP <65 mm Hg (OR = 4.9; 95% CI: 1.07-22.5, p  = 0.04) were associated with early severe AKI. Children with severe AKI experienced longer ventilator, intensive care, and posttransplant hospital days and inferior survival ( p  = 0.01). Lower MAP and higher CVP are associated with severe AKI in pediatric HT recipients. Patients, who experienced AKI, experienced increased intensive care unit (ICU) morbidity and inferior survival. These data may guide the development of perioperative renal protective management strategies to reduce AKI incidence and improve patient outcomes.

Association of underweight and obesity with adverse postoperative renal outcomes in infants and young children undergoing congenital heart surgery

Postoperative acute kidney injury (AKI) is a prevalent condition and associated with increased morbidity and mortality following cardiac surgery. This study aimed to investigate the association of underweight and obesity with adverse postoperative renal outcomes in infants and young children undergoing congenital heart surgery. This retrospective cohort study included patients aged from 1 month to 5 years who underwent congenital heart surgery with cardiopulmonary bypass at the Second Xiangya Hospital of Central South University from January 2016 to March 2022. On the basis of the percentile of body mass index (BMI) for age and sex, eligible participants were divided into three nutritional groups: normal bodyweight, underweight (BMI P5), and obesity (BMI P95). Primary outcomes included postoperative AKI and major adverse kidney events within 30 days (MAKE30). Multivariable logistic regression was performed to determine the association of underweight and obesity with postoperative outcomes. The same analyses were reproduced for classifying patients using weight-for-height instead of BMI. A total of 2,079 eligible patients were included in the analysis, including 1,341 (65%) patients in the normal bodyweight group, 683 (33%) patients in the underweight group, and 55 (2.6%) patients in the obesity group. Postoperative AKI (16% vs. 26% vs. 38%; P < 0.001) and MAKE30 (2.5% vs. 6.4% vs. 9.1%; P < 0.001) were more likely to occur in the underweight and obesity groups. After adjusting for potential confounders, underweight (OR1.39; 95% CI 1.08-1.79; P = 0.008) and obesity (OR 3.85; 95% CI 1.97-7.50; P < 0.001) were found to be associated with an increased risk of postoperative AKI. In addition, both underweight (OR 1.89; 95% CI 1.14-3.14; P = 0.014) and obesity (OR 3.14; 95% CI 1.08-9.09; P = 0.035) were independently associated with MAKE30. Similar results were also found when weight-for-height was used instead of BMI.    Conclusion: In infants and young children undergoing congenital heart surgery, underweight and obesity are independently associated with postoperative AKI and MAKE30. These results may help assess prognosis in underweight and obese patients, and will guide future quality improvement efforts. What is Known: • Postoperative acute kidney injury (AKI) is prevalent and associated with increased morbidity and mortality following pediatric cardiac surgery. • Major adverse kidney events within 30 days (MAKE30) have been recommended as a patient-centered endpoint for evaluating AKI clinical trajectories. A growing concern arises for underweight and obesity in children with congenital heart disease. What is New: • Prevalence of underweight and obesity among infants and young children undergoing congenital heart surgery was 33% and 2.6%, respectively. • Both underweight and obesity were independently associated with postoperative AKI and MAKE30 following congenital heart surgery.

The Potential Use of Near- and Mid-Infrared Spectroscopy in Kidney Diseases

Traditional renal biomarkers such as serum creatinine and albuminuria/proteinuria are rather insensitive since they change later in the course of the disease. In order to determine the extent and type of kidney injury, as well as to administer the proper therapy and enhance patient management, new techniques for the detection of deterioration of the kidney function are urgently needed. Infrared spectroscopy is a label-free and non-destructive technique having the potential to be a vital tool for quick and inexpensive routine clinical diagnosis of kidney disorders. The aim of this review is to provide an overview of near- and mid-infrared spectroscopy applications in patients with acute kidney injury and chronic kidney disease (e.g., diabetic nephropathy and glomerulonephritis).

Acute Kidney Injury Predictors and Outcomes after Cardiac Surgery in Children with Congenital Heart Disease: An Observational Cohort Study

Acute Kidney Injury (AKI) commonly complicates cardiac surgery in children with congenital heart disease (CHD). In this study we assessed incidence, risk factors, and outcomes of postoperative AKI, while testing the hypothesis that, depending on the underlying diagnosis, there would be significant differences in AKI incidence among different diagnostic groups. We conducted an observational cohort study of children with CHD undergoing cardiac surgery in a single tertiary center between January 2019 and August 2021 (n = 362). Kidney Disease Improving Global Outcome (KDIGO) criteria were used to determine the incidence of postoperative AKI. Diagnosis was incorporated into multivariate models using an anatomic-based CHD classification system. Overall survival was estimated using Kaplan−Meier curves. Log-rank test and adjusted Cox proportional hazard modelling were used to test for differences in survival distributions and determine AKI effect on survival function, respectively. AKI occurred in 70 (19.3%), with 21.4% in-hospital mortality for AKI group. Younger age, lower weight, longer cardiopulmonary bypass time, preoperative mechanical ventilation and diagnostic category were associated with postoperative AKI. Resolution rate was 92.7% prior to hospital discharge for survivors. AKI was associated with longer duration of mechanical ventilation, ICU and hospital length of stay. AKI patients had significantly higher probability of all-cause mortality postoperatively when compared to the non-AKI group (log-rank test, p < 0.001). Adjusted hazard ratio for AKI versus non-AKI group was 11.08 (95% CI 2.45−50.01; p = 0.002). Diagnostic category was associated with cardiac surgery-related AKI in children with CHD, a finding supporting the development of lesion specific models for risk stratification. Postoperative AKI had detrimental impact on clinical outcomes and was associated with decreased survival to hospital discharge.

Impact of a clinical pathway on acute kidney injury in patients undergoing heart transplant

BACKGROUND

To evaluate the impact of a clinical pathway on the incidence and severity of acute kidney injury in patients undergoing heart transplant.

METHODS

This was a 2.5-year retrospective evaluation using 3 years of historical controls within a cardiac intensive care unit in an academic children's hospital. Patients undergoing heart transplant between May 27, 2014, and April 5, 2017 (pre-pathway) and May 1, 2017, and November 30, 2019 (pathway) were included. The clinical pathway focused on supporting renal perfusion through hemodynamic management, avoiding or delaying nephrotoxic medications, and providing pharmacoprophylaxis against AKI.

RESULTS

There were 57 consecutive patients included. There was an unadjusted 20% reduction in incidence of any acute kidney injury (p = .05) and a 17% reduction in Stage 2/3 acute kidney injury (p = .09). In multivariable adjusted analysis, avoidance of Stage 2/3 acute kidney injury was independently associated with the clinical pathway era (AOR -1.3 [95% CI -2.5 to -0.2]; p = .03), achieving a central venous pressure of or less than 12 mmHg (AOR -1.3 [95% CI -2.4 to -0.2]; p = .03) and mean arterial pressure above 60 mmHg (AOR -1.6 [95% CI -3.1 to -0.01]; p = .05) in the first 48 h post-transplant, and older age at transplant (AOR - 0.2 [95% CI -0.2 to -0.06]; p = .002).

CONCLUSIONS

This report describes a renal protection clinical pathway associated with a reduction in perioperative acute kidney injury in patients undergoing heart transplant and highlights the importance of normalizing perioperative central venous pressure and mean arterial blood pressure to support optimal renal perfusion.

Acute kidney injury and kidney recovery after cardiopulmonary bypass in children

BACKGROUND

Acute kidney injury (AKI) that improves in the pediatric intensive care unit (PICU) is associated with better outcomes compared to AKI that persists, but no study has investigated whether this also occurs in children undergoing cardiopulmonary bypass (CPB).

METHODS

A retrospective study of children ≤18 years who underwent CPB in three children's hospitals was conducted. Patients were classified into groups by kidney recovery after AKI according to Acute Disease Quality Initiative (ADQI) guidelines. Adjusted regression models evaluated associations between kidney recovery group and hospital outcomes.

RESULTS

Among 3620 children, AKI developed in 701 (19.4%): 610 transient AKI, 47 persistent AKI, and 44 acute kidney disease (AKD). Mortality increased with severity of kidney recovery group: 4.5% in the never developed AKI group, 8.9% in the transient AKI group, 25.5% in the persistent AKI group, and 31.8% in the AKD group (p <0.0001). In adjusted analysis, transient AKI (HR 1.4, CI 1.02, 2), persistent AKI (HR 22.4, CI 10.2, 49.2), and AKD (HR 3.7, CI 1.7, 7.9) had a greater hazard of mortality when compared to the never developed AKI group. Patients with transient AKI had a longer length of PICU stay than those with never developed AKI (HR 5.1, CI 2.9, 7.3).

CONCLUSIONS

Patterns of kidney recovery after AKI were associated with worse PICU outcomes in children after CPB compared to those who did not develop AKI, even after rapid AKI recovery. Identification of factors that increase risk for these AKI patterns is necessary for prevention of AKI during CPB in children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Postoperative Acute Kidney Injury in Williams Syndrome Compared With Matched Controls

OBJECTIVES

Cardiovascular manifestations occur in over 80% of Williams syndrome (WS) patients and are the leading cause of morbidity and mortality. One-third of patients require cardiovascular surgery. Renal artery stenosis (RAS) is common in WS. No studies have assessed postoperative cardiac surgery-related acute kidney injury (CS-AKI) in WS. Our objectives were to assess if WS patients have higher risk of CS-AKI postoperatively than matched controls and if RAS could contribute to CS-AKI.

DESIGN

This was a retrospective study of all patients with WS who underwent cardiac surgery at our center from 2010 to 2020. The WS study cohort was compared with a group of controls matched for age, sex, weight, and surgical procedure.

SETTING

Patients underwent cardiac surgery and postoperative care at Lucile Packard Children's Hospital Stanford.

PATIENTS

There were 27 WS patients and 43 controls (31% vs 42% female; p = 0.36). Median age was 1.8 years (interquartile range [IQR], 0.7-3.8 yr) for WS and 1.7 years (IQR, 0.8-3.1 yr) for controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Postoperative hemodynamics, vasopressor, total volume input, diuretic administration, and urine output were collected in the first 72 hours. Laboratory studies were collected at 8-hour intervals. Multivariable analysis identified predictors of CS-AKI.Controlled for renal perfusion pressure (RPP) and vasoactive inotrope score (VIS), compared with controls, the odds ratio (OR) of CS-AKI in WS was 4.2 (95% CI, 1.1-16; p = 0.034). Higher RPP at postoperative hours 9-16 was associated with decreased OR of CS-AKI (0.88 [0.8-0.96]; p = 0.004). Increased VIS at hour 6 was associated with an increased OR of CS-AKI (1.47 [1.14-1.9]; p = 0.003). Younger age was associated with an increased OR of CS-AKI (1.9 [1.13-3.17]; p = 0.015).

CONCLUSIONS

The OR of CS-AKI is increased in pediatric patients with WS compared with controls. CS-AKI was associated with VIS at the sixth postoperative hour. Increases in RPP and mean arterial pressure were associated with decreased odds of CS-AKI.

Risk factors and occurrence of chronic kidney disease following acute kidney injury in Children

Background

Chronic kidney disease (CKD) is an irreversible progressive condition with diverse etiologies among which acute kidney injury (AKI) is increasingly being recognized as an important one.

Methods

This was a prospective observational study of pediatric intensive care unit (PICU) patients admitted with different etiologies, at a tertiary care hospital for children in Kashmir India, between October 2018 and September 2020. AKI was defined as an increase in absolute serum creatinine (SCr) ≥0.3 mg/dL or by a percentage increase in SCr 50% and/or by a decrease in urine output to <0.5 mL/kg/h for >6 hours (h). Besides analysis of AKI and associated PICU mortality, post-AKI patients after discharge were kept on follow-up for complete 1 year.

Results

From 119 enrolled patients with AKI with no preexisting risk factors, 5.6% (n = 8/119) developed CKD. The AKI-associated mortality rate after 48 h of PICU stay was 13.4% (n = 16/119). At time of discharge from hospital, elevated blood pressure (BP) (n = 5/8) and subnephrotic proteinuria (n = 3/8) were the statistically significant sequels of AKI (P value <0.001) for progression to CKD. After 3 months of follow-up, elevated BP (n = 7/8) and subnephrotic proteinuria (n = 3/8) were significantly associated with progression to CKD at 1 year (P < 0.005).

Conclusions

Occurrence of CKD after an attack of AKI was not uncommon and the risk of long-term consequences in the form of hypertension, proteinuria, and CKD is significant, which may be much higher than observed. It is prudent that all post-AKI PICU discharged patients must be monitored for the long-term consequences of AKI.

Intraoperative Hypotension and Acute Kidney Injury after Noncardiac Surgery in Infants and Children: A Retrospective Cohort Analysis

BACKGROUND

Age- and sex-specific reference nomograms for intraoperative blood pressure have been published, but they do not identify harm thresholds. The authors therefore assessed the relationship between various absolute and relative characterizations of hypotension and acute kidney injury in children having noncardiac surgery.

METHODS

The authors conducted a retrospective cohort study using electronic data from two tertiary care centers. They included inpatients 18 yr or younger who had noncardiac surgery with general anesthesia. Postoperative renal injury was defined using the Kidney Disease Improving Global Outcomes definitions, based on serum creatinine concentrations. The authors evaluated potential renal harm thresholds for absolute lowest intraoperative mean arterial pressure (MAP) or largest MAP reduction from baseline maintained for a cumulative period of 5 min. Separate analyses were performed in children aged 2 yr or younger, 2 to 6 yr, 6 to 12 yr, and 12 to 18 yr.

RESULTS

Among 64,412 children who had noncardiac surgery, 4,506 had creatinine assessed preoperatively and postoperatively. The incidence of acute kidney injury in this population was 11% (499 of 4,506): 17% in children under 6 yr old, 11% in children 6 to 12 yr old, and 6% in adolescents, which is similar to the incidence reported in adults. There was no association between lowest cumulative MAP sustained for 5 min and postoperative kidney injury. Similarly, there was no association between largest cumulative percentage MAP reduction and postoperative kidney injury. The adjusted estimated odds for kidney injury was 0.99 (95% CI, 0.94 to 1.05) for each 5-mmHg decrease in lowest MAP and 1.00 (95% CI, 0.97 to 1.03) for each 5% decrease in largest MAP reduction from baseline.

CONCLUSIONS

In distinct contrast to adults, the authors did not find any association between intraoperative hypotension and postoperative renal injury. Avoiding short periods of hypotension should not be the clinician's primary concern when trying to prevent intraoperative renal injury in pediatric patients.

EDITOR’S PERSPECTIVE

The role of the neutrophil-lymphocyte ratio for pre-operative risk stratification of acute kidney injury after tetralogy of Fallot repair

INTRODUCTION

Acute kidney injury is a risk factor for chronic kidney disease and mortality after congenital heart surgery under cardiopulmonary bypass. The neutrophil-lymphocyte ratio is an inexpensive and easy to measure biomarker for predicting outcomes in children with congenital heart disease undergoing surgical correction.

OBJECTIVE

To identify children at high risk of acute kidney injury after tetralogy of Fallot repair using the neutrophil-lymphocyte ratio.

METHODS

This single-centre retrospective analysis included consecutive patients aged < 18 years who underwent tetralogy of Fallot repair between January 2014 and December 2018. The pre-operative neutrophil-lymphocyte ratio was measured using the last pre-operative complete blood count test. We used the Acute Kidney Injury Network definition.

RESULTS

A total of 116 patients were included, of whom 39 (33.6%) presented with acute kidney injury: 20 (51.3%) had grade I acute kidney injury, nine had grade II acute kidney injury (23.1%), and 10 (25.6%) had grade III acute kidney injury. A high pre-operative neutrophil-lymphocyte ratio was associated with grade III acute kidney injury in the post-operative period (p = 0.04). Patients with acute kidney injury had longer mechanical ventilation time (p = 0.023), intensive care unit stay (p < 0.001), and hospital length of stay (p = 0.002).

CONCLUSION

Our results suggest that the pre-operative neutrophil-lymphocyte ratio can be used to identify patients at risk of developing grade III acute kidney injury after tetralogy of Fallot repair.

Impact of Acute Kidney Injury on Critically Ill Children and Neonates

Acute kidney injury (AKI) is a clinical syndrome that manifests as an abrupt impairment of kidney function. AKI is common in critically ill pediatric patients admitted to the pediatric intensive care units. AKI is a deleterious complication in critically ill children as it is associated with increased morbidity and mortality. This review provides an overview of the incidence, morbidity, and mortality of AKI in critically ill children in general and specific cohorts such as post-cardiac surgeries, sepsis, critically ill neonates, and post stem cell transplantation.

Development of acute kidney injury following pediatric cardiac surgery

Acute kidney injury (AKI) in the pediatric population is a relatively common phenomenon. Specifically, AKI has been found in increasing numbers within the pediatric population following cardiac surgery, with up to 43% of pediatric patients developing AKI post-cardiac surgery. However, recent advances have allowed for the identification of risk factors. These can be divided into preoperative, intraoperative, and postoperative factors. Although the majority of pediatric patients developing AKI after cardiac surgery completely recover, this condition is associated with worse outcomes. These include fluid overload and increased mortality and result in longer hospital and intensive care unit stays. Detecting the presence of AKI has advanced; use of relatively novel biomarkers, including neutrophil gelatinase associated lipocalin, has shown promise in detecting more subtle changes in kidney function when compared to conventional methods. While a single, superior treatment has not been elucidated yet, novel functions of medications, including fenoldopam, theophylline and aminophylline, have been shown to have better outcomes for these patients. With the recent advances in identification of risk factors, outcomes, diagnosis, and management, the medical community can further explain the complexities of AKI in the pediatric population post-cardiac surgery.

Higher Flow on Cardiopulmonary Bypass in Pediatrics Is Associated With a Lower Incidence of Acute Kidney Injury

Adequate perfusion is of paramount concern during cardiopulmonary bypass (CPB) and different methodologies are employed to optimize oxygen delivery. Temperature, hematocrit, and cardiac index (CI) are all modulated during CPB to ensure appropriate support. This study examines 2 different perfusion strategies and their impact on various outcome measures including acute kidney injury (AKI), urine output on CPB, ICU length of stay, time to extubation, and mortality. Predicated upon surgeon preference, the study institution employs 2 different perfusion strategies (PS) during congenital cardiac surgery requiring CPB. One method utilizes a targeted 2.4 L/min/m² CI and nadir hematocrit of 28% (PS1), the other a 3.0 L/min/m² CI with a nadir hematocrit of 25% (PS2). This study retrospectively examines CPB cases during which the 2 perfusion strategies were applied to determine potential differences in packed red blood cell administration, urine output during CPB, AKI post-CPB as defined by the KDIGO criteria, and operative survival as defined by the Society of Thoracic Surgeons. Significant differences were found in urine output while on CPB (P < 0.01) and all combined stages of postoperative AKI (P = 0.01) with the PS2 group faring better in both measures. No significant difference was found between the 2 groups for packed red blood cell administration, mortality, time to extubation, or ICU length of stay. Avoiding a nadir hematocrit less than 25% has been well established but maintaining anything greater than that may not be necessary to achieve adequate oxygen delivery on CPB. Our results indicate that higher CI and oxygen delivery on CPB are associated with a lower rate of AKI and this may be achieved with increased flow rather than increasing the hematocrit thus avoiding unnecessary transfusion.

Increased mortality, morbidities, and costs after heart transplantation in heterotaxy syndrome and other complex situs arrangements

OBJECTIVES

Identify pediatric heart transplant (HT) recipients with heterotaxy and other complex arrangements of cardiac situs (heterotaxy/situs anomaly) and compare mortality, morbidities, length of stay (LOS), and costs to recipients with congenital heart disease without heterotaxy/situs anomaly.

METHODS

Using linked registry data (2001-2016), we identified 186 HT recipients with heterotaxy/situs anomaly and 1254 with congenital heart disease without heterotaxy/situs anomaly. We compared post-HT outcomes in univariable and multivariable time-to-event analyses. LOS and cost from HT to discharge were compared using Wilcoxon rank-sum tests. Sensitivity analyses were performed using stricter heterotaxy/situs anomaly group inclusion criteria and through propensity matching.

RESULTS

HT recipients with heterotaxy/situs anomaly were older (median age, 5.1 vs 1.6 years; P < .001) and more often black, Asian, Hispanic, or "other" nonwhite (54% vs 32%; P < .001). Heterotaxy/situs anomaly was independently associated with increased mortality (hazard ratio, 1.58; 95% confidence interval, 1.19-2.09; P = .002), even among 6-month survivors (hazard ratio, 1.86; 95% confidence interval, 1.09-3.16; P = .021). Heterotaxy/situs anomaly recipients more commonly required dialysis (odds ratio, 2.58; 95% confidence interval, 1.51-4.42; P = .001) and cardiac reoperation (odds ratio, 1.91; 95% confidence interval, 1.17-3.11; P = .010) before discharge. They had longer ischemic times (19.2 additional minutes [range, 10.9-27.5 minutes]; P < .001), post-HT intensive care unit LOS (16 vs 13 days; P = .012), and hospital LOS (26 vs 23 days; P = .005). Post-HT hospitalization costs were also greater ($447,604 vs $379,357; P = .001).

CONCLUSIONS

Heterotaxy and other complex arrangements of cardiac situs are associated with increased mortality, postoperative complications, LOS, and costs after HT. Although increased surgical complexity can account for many of these differences, inferior late survival is not well explained and deserves further study.

Pre-operative level of FGF23 predicts severe acute kidney injury after heart surgery in children

BACKGROUND

Early detection of acute kidney injury (AKI) after cardiac surgery has improved recently with the discovery and validation of novel urinary biomarkers. However, objective tools to predict the risk of AKI before the insult are still missing. We tested the hypothesis that pre-operative serum fibroblast growth factor 23 (FGF23) concentrations would be elevated in children who develop AKI after heart surgery with cardiopulmonary bypass (CPB). We also compared post-operative FGF23 concentrations to other biomarkers for early detection of AKI.

METHODS

Blood and urine samples were collected in a prospective observational study from 83 children with congenital heart disease. Severe AKI (sAKI) development (KDIGO stages II-III) in the first seven days after surgery was the primary outcome.

RESULTS

Thirty of 76 (39.5%) and 11/76 (14.5%) of patients developed AKI and sAKI, respectively. Pre-operative serum creatinine, cystatin C, and urine biomarker concentrations did not differ between sAKI patients and controls. Pre-operative serum FGF23 levels were higher in patients who developed sAKI (median [IQR] value of 819 RU/ml [397.7, 1196.8] vs. 324.3 RU/ml [124.6, 679.8] (p = 0.02). FGF23 12-24 h after the termination of CPB was also associated with sAKI in the first week after surgery (498 RU/ml [226, 928] vs. 1435 RU/ml [831, 12,996]).

CONCLUSIONS

Pre- and post-operative FGF23 levels are higher in children who develop sAKI after cardiac surgery. We suggest FGF23 may be able to detect sub-clinical kidney injury and can be used with demographic AKI risk factors to enhance post-operative sAKI risk prediction.

Risk factors of acute kidney injury in children after cardiac surgery

BACKGROUND

The objective of this retrospective study was to determine the risk factors for acute kidney injury (AKI), including albumin, in children who underwent cardiac surgery. In addition, we evaluated the association between preoperative serum albumin level and postoperative AKI in these patients.

METHODS

This retrospective study included 505 pediatric patients who underwent congenital cardiac surgery. Preoperative and perioperative risk factors for AKI, including serum albumin level, were assessed. AKI incidence within 7 postoperative days was determined using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Multivariable logistic regression analysis was performed to evaluate the association between possible risk factors and postoperative AKI.

RESULTS

Of 505 pediatric patients, 185 (36.6%) developed postoperative AKI. The preoperative serum albumin level was associated with postoperative AKI (odds ratio [OR] 0.506, 95% confidence interval [CI] 0.325-0.788; P = 0.003). Other independent factors associated with AKI were age <12 months (OR 1.911, 95% CI 1.166-3.132; P = 0.007), preoperative pulmonary hypertension (OR 1.853, 95% CI 1.182-2.907; P = 0.01), and cardiopulmonary bypass (CPB) duration (OR 1.006, 95% CI 1.003-1.009; P = 0.002). Patients with AKI had higher incidence of postoperative complications, longer mechanical ventilation times, and more prolonged intensive care unit and hospital stays than patients without AKI.

CONCLUSIONS

Preoperative serum albumin level, age <12 months, preoperative pulmonary hypertension, and CPB duration were associated with risk for postoperative AKI in children who underwent congenital cardiac surgery.

Cardiac Surgery-Associated Kidney Injury in Children and Renal Oximetry

OBJECTIVES

Cardiac surgery-associated acute kidney injury is common in children and associates with negative outcomes. Novel interventions to reduce cardiac surgery-associated acute kidney injury require knowledge of its pathophysiology. States of altered perfusion, oxygen delivery, and energy consumption occur during cardiopulmonary bypass and could protect against or contribute to renal cellular injury and recovery. Near-infrared spectroscopy is noninvasive technology for monitoring regional blood flow and tissue oxygenation. This study evaluated the relationship between renal regional oxygen saturation and cardiac surgery-associated acute kidney injury, using near-infrared spectroscopy monitoring before, during, and after cardiopulmonary bypass in children.

DESIGN

Prospective cohort study.

SETTING

Single-center, tertiary care pediatric hospital (Stollery Children's Hospital, Edmonton, AB, Canada).

PATIENTS

Children less than or equal to 10 kg undergoing congenital heart disease repair with cardiopulmonary bypass. Heart transplant, preoperative dialysis, sepsis, extracorporeal life support, congenital renal disease, and preoperative nephrotoxins were exclusions.

INTERVENTIONS

Renal regional near-infrared spectroscopy monitoring before, during, and after cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Outcome measure was cardiac surgery-associated acute kidney injury (defined according to Kidney Disease: Improving Global Outcomes criteria). Regional oxygen saturation was measured continuously using near-infrared spectroscopy (INVOS 5100C Cerebral/Somatic Oximeter; Medronic, Troy, MI) from time of anesthesia to time of transfer to intensive care. Cardiac surgery-associated acute kidney injury occurred in 65%. Lower baseline (precardiopulmonary bypass) regional oxygen saturation was associated with decreased risk of cardiac surgery-associated acute kidney injury (p = 0.01); children with baseline regional oxygen saturation in the highest tertile were 7.14 times more likely to get cardiac surgery- associated acute kidney injury (vs lowest tertile). Area under the curve for ability of baseline regional oxygen saturation to predict cardiac surgery-associated acute kidney injury was 0.73 (95% CI, 0.60-0.85). Children with lower baseline glomerular filtration rate had lower mean renal regional oxygen saturation.

CONCLUSIONS

Findings demonstrate that preoperative oxygen supply/demand balance is an important predictor of cardiac surgery-associated acute kidney injury, suggesting lower preoperative (and intraoperative) renal blood flow may be protective. There is not yet a definite link between remote ischemic preconditioning and prevention of cardiac surgery-associated acute kidney injury; however, renal protective effects of sublethal ischemia should continue to be explored.

Intraoperative Completion Angiogram May Be Superior to Transesophageal Echocardiogram for Detection of Pulmonary Artery Residual Lesions in Congenital Heart Surgery

The purpose of this study was to assess the diagnostic capabilities of transesophageal echocardiography (TEE) compared to completion angiography for detection of residual post-operative pulmonary artery lesions. This is a retrospective review of 19 consecutive surgical cases involving the pulmonary arteries that had post-operative TEE and completion angiography from 2014 to 2017. The echocardiograms were reviewed by 2 blinded examiners and categorized as adequate or inadequate visualization of the surgical repair. Based on TEE images, the surgical repair was graded as no revision necessary, residual lesion present requiring revision, or unable to assess. TEE was compared to completion angiography to determine the ability of each method to detect residual pulmonary artery lesions. Fifty-three percent of TEE imaging was graded as inadequate. Based on TEE, surgical revision was indicated in 2 of 19 cases. Completion angiography documented 4 additional residual lesions resulting in surgical revision in 6 of 19 patients. TEE sensitivity for detecting residual pulmonary artery lesions was 40%. One Glenn patient with adequate image quality and repair by TEE had moderate left pulmonary artery stenosis by completion angiography. All other discrepancies occurred in patients with inadequate TEE imaging. No patient with pulmonary artery abnormalities had hemodynamic instability or excessive desaturations. Completion angiography-related complications included three transient arrhythmias with no increased incidence of acute kidney injury. Completion angiography may be more effective than TEE at detecting post-operative pulmonary artery lesions even in patients not manifesting clinical symptoms. Documentation of residual lesions with completion angiography allows immediate surgical revision potentially limiting necessity for future interventions.

Preoperative levels of urinary uromodulin predict acute kidney injury after pediatric cardiopulmonary bypass surgery

BACKGROUND

Acute kidney injury (AKI) is a common complication of cardiopulmonary bypass surgery (CPB) in children. Several promising postoperative AKI biomarkers have been identified, but no preoperative biomarkers are available. We evaluated the association of urinary uromodulin (uUMOD) with postoperative AKI.

METHODS

One hundred and one children undergoing CPB were enrolled. Urine was collected prior to CPB, and AKI was defined as ≧50% increase in serum creatinine from preoperative baseline within 48 h of surgery.

RESULTS

Forty-seven patients (47%) developed AKI, and 92% of participants in the lowest quartile of preoperative uUMOD concentrations developed AKI compared with 8% in the highest quartile. Patients with preoperative uUMOD levels in the lowest quartile had 132.3× increased risk of postoperative AKI versus the highest quartile. Raw uUMOD levels were significantly lower in patients with AKI vs. no AKI. Significance was unchanged after correcting uUMOD levels for urinary creatinine. Receiver operating characteristic analysis showed preoperative uUMOD strongly predicted postoperative AKI, with area under the curve (AUC) 0.90. Stepwise logistic regression analysis revealed a model combining uUMOD, and bypass time predicted AKI at p<0.001. Neither Risk Adjustment for Congenital Heart Surgery 1 (RACHS) score nor age improved the model's ability to predict AKI. Independent analysis demonstrated that while bypass time was associated with AKI, the predictive ability of bypass time (AUC 0.77) was less than that of preoperative uUMOD levels (AUC 0.9).

CONCLUSIONS

Children with lowest preoperative levels of uUMOD have greatly increased risk of AKI post-CPB. If uUMOD were used to risk-stratify patients undergoing CPB, clinical measures could be taken to minimize AKI development.

Acute kidney injury in congenital cardiac surgery: Pediatric risk-injury-failure-loss-end-stage renal disease and Acute Kidney Injury Network

BACKGROUND

Acute kidney injury (AKI) is associated with an increased risk of mortality, especially in pediatric intensive care units. The aim of this study was to determine the risk factors of AKI in children undergoing cardiac surgery for congenital heart disease and to compare two different classification systems: pediatric risk-injury-failure-loss-end-stage renal disease (pRIFLE) and Acute Kidney Injury Network (AKIN).

METHODS

We retrospectively analyzed 145 patients undergoing pediatric congenital heart surgery who were between 1 month and 18 years of years, and treated at a cardiovascular surgery department from January 2009 to October 2011.

RESULTS

One hundred and thirty-seven patients (mean age, 36.6 ± 43.3 months) were enrolled: 84 (61.3%) developed AKI according to the pRIFLE criteria (25.5%, risk; 20.4%, injury; 15.3%, failure); and 65 patients (47.4%) developed AKI according to the AKIN criteria (15.3%, stage I; 18.2%, stage II; and 13.9%, stage III). Children younger than 11 months were more likely to develop AKI (P < 0.005). Longer cardiopulmonary bypass time was associated with an increased risk of AKI (P < 0.05). pRIFLE identified AKI more frequently than AKIN (P < 0.0005). pRIFLE may help in the early identification of patient at risk for AKI and seems to be more sensitive in pediatric patients (P < 0.05). Any degree of AKI in both classifications was associated with increased mortality (pRIFLE: OR, 15.1; AKIN: OR, 11.2; P = 0.007).

CONCLUSION

pRIFLE identified AKI more frequently than the AKIN criteria. pRIFLE identified patients at risk for AKI earlier, and was more sensitive in pediatric patients. Any degree of AKI in both classifications was associated with increased mortality. Both sets of criteria had the same association with mortality.

Natural history of nonimmune-mediated thrombocytopenia and acute kidney injury in pediatric open-heart surgery

OBJECTIVE

Thrombocytopenia and acute kidney injury (AKI) are common following pediatric cardiac surgery with cardiopulmonary bypass (CPB). However, the relationship between postoperative nadir platelet counts and AKI has not been investigated in the pediatric population. Our objective was to investigate this relationship and examine independent predictors of AKI.

DESIGN

After IRB approval, we performed a retrospective review of the institution's medical records and database.

SETTING

This study was performed at a single institution over a 5-year period.

PATIENTS

We included patients <21 years of age undergoing cardiac surgery with CPB.

INTERVENTIONS

Demographics, laboratory, and surgical characteristics were captured, and clinical event rates were recorded.

MEASUREMENTS

Descriptive statistics were used to evaluate platelet and creatinine distributions. T-tests and chi-squared tests were used to compare characteristics among Acute Kidney Injury Network groups. Multivariable logistic and ordinal logistic regression models were used to determine the association of our predictor of interest, postoperative nadir platelet count and AKI.

RESULTS

Eight hundred and fourteen patients (23% infants and 23% neonates) were included in the analysis. Postoperative platelet counts decreased 48% from baseline reaching a mean nadir value of 150 × 10⁹ ·l^-1 on postoperative day 3. AKI occurred in 37% of patients including 13%, 17%, and 6% with Acute Kidney Injury Network stages 1, 2, and 3, respectively. The magnitude of nadir platelet counts correlated with the severity of AKI. Independent predictors of severity of AKI include nadir platelet counts, CPB time, Aristotle score, patient weight, intra-operative packed red blood cell transfusion, and having a heart transplant procedure.

CONCLUSIONS

In pediatric open-heart surgery, thrombocytopenia and AKI occur commonly following CPB. Our findings show a strong association between nadir platelet counts and the severity of AKI.

Acute Kidney Injury in Patients Undergoing the Extracardiac Fontan Operation With and Without the Use of Cardiopulmonary Bypass

OBJECTIVES

To describe the prevalence and risk factors for acute kidney injury in patients undergoing the extracardiac Fontan operation with and without cardiopulmonary bypass, and to determine whether acute kidney injury is associated with duration of mechanical ventilation, cardiovascular ICU and hospital postoperative length of stay, and early mortality.

DESIGN

Single-center retrospective cohort study.

SETTING

Pediatric cardiovascular ICU, university-affiliated children's hospital.

PATIENTS

Patients with a preoperative creatinine before undergoing first-time extracardiac Fontan between January 1, 2004, and April 30, 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Acute kidney injury occurred in 55 of 138 patients (39.9%), including 41 (29.7%) with stage 1, six (4.4%) with stage 2, and eight (5.8%) with stage 3 acute kidney injury. Cardiopulmonary bypass was strongly associated with a higher risk of any acute kidney injury (adjusted odds ratio, 4.8 [95% CI, 1.4-16.0]; p = 0.01) but not stage 2/3 acute kidney injury. Lower renal perfusion pressure on the day of surgery (postoperative day, 0) was associated with a higher risk of stage 2/3 acute kidney injury (adjusted odds ratio, 1.2 [95% CI, 1.0-1.5]; p = 0.03). Higher vasoactive-inotropic score on postoperative day 0 was associated with a higher risk for stage 2/3 acute kidney injury (adjusted odds ratio, 1.9 [95% CI, 1.0-3.4]; p = 0.04). Stage 2/3 acute kidney injury was associated with longer cardiovascular ICU length of stay (mean, 7.3 greater d [95% CI, 3.4-11.3]; p < 0.001) and hospital postoperative length of stay (mean, 6.4 greater d [95% CI, 0.06-12.5]; p = 0.04).

CONCLUSIONS

Postoperative acute kidney injury in patients undergoing the extracardiac Fontan operation is common and is associated with lower postoperative renal perfusion pressure and higher vasoactive-inotropic score. Cardiopulmonary bypass was strongly associated with any acute kidney injury, although not stage 2/3 acute kidney injury. Stage 2/3 acute kidney injury is a compelling risk factor for longer cardiovascular ICU and hospital postoperative length of stay. Increased attention to and management of renal perfusion pressure may reduce postoperative acute kidney injury and improve outcomes.

Risk Factors for Acute Kidney Injury after Congenital Cardiac Surgery in Infants and Children: A Retrospective Observational Study

Acute kidney injury (AKI) after pediatric cardiac surgery is associated with high morbidity and mortality. Modifiable risk factors for postoperative AKI including perioperative anesthesia-related parameters were assessed. The authors conducted a single-center, retrospective cohort study of 220 patients (aged 10 days to 19 years) who underwent congenital cardiac surgery between January and December 2012. The incidence of AKI within 7 days postoperatively was determined using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Ninety-two patients (41.8%) developed AKI and 18 (8.2%) required renal replacement therapy within the first postoperative week. Among patients who developed AKI, 57 patients (25.9%) were KDIGO stage 1, 27 patients (12.3%) were KDIGO stage 2, and eight patients (3.6%) were KDIGO stage 3. RACHS-1 (Risk-Adjusted classification for Congenital Heart Surgery) category, perioperative transfusion and fluid administration as well as fluid overload were compared between patients with and without AKI. Multivariable logistic regression analyses determined the risk factors for AKI. AKI was associated with longer hospital stay or ICU stay, and frequent sternal wound infections. Younger age (<12 months) [odds ratio (OR), 4.01; 95% confidence interval (CI), 1.77–9.06], longer cardiopulmonary bypass (CPB) time (OR, 2.45; 95% CI, 1.24–4.84), and low preoperative hemoglobin (OR, 2.40; 95% CI, 1.07–5.40) were independent risk factors for AKI. Fluid overload was not a significant predictor for AKI. When a variable of hemoglobin concentration increase (>3 g/dl) from preoperative level on POD1 was entered into the multivariable analysis, it was independently associated with postoperative AKI (OR, 6.51; 95% CI, 2.23–19.03 compared with no increase). This association was significant after adjustment with patient demographics, medication history and RACHS-1 category (hemoglobin increase >3g/dl vs. no increase: adjusted OR, 6.94; 95% CI, 2.33–20.69), regardless of different age groups and cyanotic or non-cyanotic heart disease. Prospective trials are required to evaluate whether correction of preoperative anemia and prevention of hemoconcentration may ameliorate postoperative AKI in patients who underwent congenital cardiac surgery.

Structural equation modelling exploration of the key pathophysiological processes involved in cardiac surgery-related acute kidney injury in infants

Background

Uncertainties about the pathophysiological processes resulting in cardiac surgery-related acute kidney injury (AKI) in infants concern the relative impact of the most prominent risk factors, the clinical relevance of changes in glomerular filtration rate vs tubular injury, and the usefulness of available diagnostic tools. Structural equation modelling could allow for the assessment of these complex relationships.

Methods

A structural model was specified using data from a prospective observational cohort of 200 patients <1 year of age undergoing cardiopulmonary bypass surgery. It included four latent variables: AKI, modelled as a construct of perioperative creatinine variation, of oliguria and of urine neutrophil gelatinase-associated lipocalin (uNGAL) concentrations; the cardiopulmonary bypass characteristics; the occurrence of a post-operative low cardiac output syndrome and the post-operative outcome.

Results

The model showed a good fit, and all path coefficients were statistically significant. The bypass was the most prominent risk factor, with a path coefficient of 0.820 (95 % CI 0.527–0.979), translating to a 67.2 % explanation for the risk of AKI. A strong relationships was found between AKI and early uNGAL excretion, and between AKI and the post-operative outcome, with path coefficients of 0.611 (95 % CI 0.347–0.777) and 0.741 (95 % CI 0.610–0.988), respectively. The path coefficient between AKI and a >50 % increase in serum creatinine was smaller, with a path coefficient of 0.443 (95 % CI 0.273–0.596), and was intermediate for oliguria, defined as urine output <0.5 ml kg⁻¹ h⁻¹, with a path coefficient of 0.495 (95 % CI 0.250–0.864). A path coefficient of −0.229 (95 % CI −0.319 to 0.060) suggested that the risk of AKI during the first year of life did not increase with younger age at surgery.

Conclusions

These findings suggest that cardiac surgery-related AKI in infants is a translation of tubular injury, predominately driven by the cardiopulmonary bypass, and linked to early uNGAL excretion and to post-operative outcome.

Trial registration

ClinicalTrials.gov identifier NCT01219998. Registered 11 October 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1350-1) contains supplementary material, which is available to authorized users.

Unplanned Readmission to the Pediatric Cardiac Intensive Care Unit: Prevalence, Outcomes, and Risk Factors

BACKGROUND

Factors leading to cardiac intensive care unit (CICU) readmission and the impact on mortality have yet to be well delineated. We sought to define the prevalence and outcome for unscheduled CICU readmission. Secondary objectives were to identify indications and risk factors for unscheduled CICU readmission.

METHODS

Retrospective analysis of prospectively collected registry data at a tertiary care children's hospital. Pediatric and adult patients with congenital and acquired heart disease who survived to initial CICU discharge were included. Patients with unexpected return to the CICU for acute change in clinical status were defined as unscheduled readmissions.

RESULTS

Of the 645 discharges that met inclusion criteria, 37 resulted in unplanned readmission to the CICU. Patients requiring unscheduled readmission had higher mortality rates (16.2% vs 0.5%, P < .0001). Cardiac symptoms were the most common reason for readmission. On multivariate analysis, genetic anomaly (P = .001) and longer length of stay (LOS) during the index CICU admission (P = .01) were independently associated with readmission. For surgical patients, genetic anomaly (P = .001), single-ventricle anatomy (P = .05), and longer surgical support time (P < .001) were independently associated with readmission.

CONCLUSION

Unscheduled readmission to the CICU within the same hospitalization was uncommon but associated with a higher mortality rate. Genetic anomaly and longer initial LOS were important risk factors for the entire cohort. Single-ventricle anatomy and longer intraoperative course were risk factors for surgical readmissions.

Acute kidney injury in children after cardiopulmonary bypass: risk factors and outcome

OBJECTIVE

To determine the incidence, risk factors and outcomes of acute kidney injury in children undergoing cardiac surgery for congenital heart disease.

METHODS

We enrolled 208 patients undergoing cardiac surgery for congenital heart disease during January 2012 to March 2013. Acute kidney injury was defined as per Acute Kidney Injury Network criteria.

RESULTS

Twenty patients had Acute kidney injury; 14 were infants. Age <1 yr, cardiopulmonary bypass time, prolonged ventilator requirement, pump failure, sepsis and hematological complications were identified as independent risk factors for any degree for acute kidney injury. All patients with acute kidney injury recovered the kidney function at the time of discharge.

CONCLUSIONS

Acute kidney injury is common in children after cardiac surgery, especially in infants.

Acute kidney injury after heart transplant in young children: risk factors and outcomes

BACKGROUND

Critical illness following heart transplantation can include acute kidney injury (AKI). Study objectives were to define the epidemiology of, risk factors for, or impact on outcomes of AKI after pediatric heart transplant.

METHODS

Using data from a prospective study of 66 young children, we evaluated: (1) post-operative AKI rate (by pediatric modified RIFLE criteria); (2) pre, intra, and early post-operative AKI risk factors using stepwise logistic regression (3) effect of AKI on short-term outcomes (ventilation and length of pediatric intensive care unit (PICU) stay) using stepwise multiple regression.

RESULTS

AKI occurred in 73 % of children. Pre-transplant ventilation and higher baseline estimated creatinine clearance (eCCl) were independent risk factors for AKI. Pre-operative inotrope use was associated with reduced risk of AKI. Tacrolimus level emerged as important in multivariable risk prediction. Children with AKI had a longer duration of ventilation and length of pediatric intensive care unit (PICU) stay, with AKI being an independent predictor.

CONCLUSIONS

AKI was common after heart transplant and associated with more complicated early post-transplant course. Lower baseline eCCl was associated with lower incidence of AKI; this merits further investigation. The association of pre-operative inotropes with less AKI may reflect a pathophysiological mechanism or be a surrogate for clinical factors and management prior to transplant. Avoiding high tacrolimus levels may be a modifiable risk factor for AKI.

Acute Kidney Injury and Fluid Overload in Neonates Following Surgery for Congenital Heart Disease

BACKGROUND

Acute kidney injury (AKI) and fluid overload have been shown to increase morbidity and mortality. The reported incidence of AKI in pediatric patients following surgery for congenital heart disease is between 15% and 59%. Limited data exist looking at risk factors and outcomes of AKI or fluid overload in neonates undergoing surgery for congenital heart disease.

METHODS

Neonates aged 6 to 29 days who underwent surgery for congenital heart disease and who were without preoperative kidney disease were included in the study. The AKI was determined utilizing the Acute Kidney Injury Network criteria.

RESULTS

Ninety-five neonates were included in the study. The incidence of neonatal AKI was 45% (n = 43), of which 86% had stage 1 AKI. Risk factors for AKI included cardiopulmonary bypass time, selective cerebral perfusion, preoperative aminoglycoside use, small kidneys by renal ultrasound, and risk adjustment for congenital heart surgery category. There were eight mortalities (five from stage 1 AKI group, three from stage 2, and zero from stage 3). Fluid overload and AKI both increased hospital length of stay and postoperative ventilator days.

CONCLUSION

To avoid increased risk of morbidity and possibly mortality, every attempt should be made to identify and intervene on those risk factors, which may be modifiable or identifiable preoperatively, such as small kidneys by renal ultrasound.

Prevalence, implication, and determinants of worsening renal function after surgery for congenital heart disease

Accumulating data in adults indicate the prognostic importance of worsening renal function (WRF) during treatment of acute heart failure. Venous congestion appears to play a dominant role in WRF; however, data regarding WRF in children with congenital heart disease (CHD) are limited. The present study was conducted to elucidate the prevalence and characteristics of WRF after surgery for CHD in children. We also tested our hypothesis that, similar to adult heart failure, venous congestion is an important determinant of WRF independent of cardiac output in this population. Fifty-five consecutive pediatric patients who underwent cardiovascular surgery for CHD were studied (median age 0.7 years; range 3 days to 17 years). The degree of WRF was assessed by the difference between the maximum levels of postoperative serum creatinine (Cr) and preoperative serum Cr. There was a high prevalence of WRF in the present cohort: an increase in Cr level was observed in 47 patients (85 %) and a Cr increase ≥0.3 mg/dL was seen in 23 (42 %). Importantly, WRF was significantly associated with a worse clinical outcome of a longer stay in the intensive care unit and hospital (both p < 0.05), even after controlling for age and operative factors. In addition, multivariate regression analysis revealed that central venous pressure, rather than cardiac output, was an independent determinant of WRF. Postoperative management to relieve venous congestion may help ameliorate or prevent WRF and thereby improve outcomes in patients with CHD.

Outcomes associated with the use of renal replacement therapy in children receiving extracorporeal membrane oxygenation after heart surgery: a multi-institutional analysis

BACKGROUND

The primary objective of this investigation was to study the association between renal replacement therapy (RRT) and outcomes in children receiving extracorporeal membrane oxygenation (ECMO).

METHODS

Patients aged ≤18 years receiving ECMO before or after a pediatric heart operation at a Pediatric Health Information System (PHIS)-participating hospital (2004-2013) were included. The associations between RRT and study outcomes were computed using multivariate logistic regression analysis.

RESULTS

A total of 3,502 patients from 43 hospitals qualified for inclusion. Of these, 484 (14 %) patients received RRT at some point during their hospital stay. After adjusting for patient and center characteristics, the odds of mortality were significantly higher in the RRT group (OR: 1.86, 95 % CI: 1.46- 2.37, p < 0.0001). However, there were considerable reductions in adjusted odds of mortality, compared to unadjusted odds of mortality. In adjusted models, length of ECMO was longer by 0.81 days (95 % CI: 0.13- 1.49, p = 0.02) in patients receiving RRT.

CONCLUSIONS

We demonstrated worsening outcomes in children receiving ECMO with RRT compared to children receiving ECMO without RRT. Although the results could reflect confounding by severity of illness, they provide a rationale for prospective testing of use of RRT in critically ill children receiving ECMO with heart surgery.

Cardiac biomarkers and acute kidney injury after cardiac surgery

OBJECTIVES

To examine the relationship of cardiac biomarkers with postoperative acute kidney injury (AKI) among pediatric patients undergoing cardiac surgery.

METHODS

Data from TRIBE-AKI, a prospective study of children undergoing cardiac surgery, were used to examine the association of cardiac biomarkers (N-type pro-B-type natriuretic peptide, creatine kinase-MB [CK-MB], heart-type fatty acid binding protein [h-FABP], and troponins I and T) with the development of postoperative AKI. Cardiac biomarkers were collected before and 0 to 6 hours after surgery. AKI was defined as a ≥ 50% or 0.3 mg/dL increase in serum creatinine, within 7 days of surgery.

RESULTS

Of the 106 patients included in this study, 55 (52%) developed AKI after cardiac surgery. Patients who developed AKI had higher median levels of pre- and postoperative cardiac biomarkers compared with patients without AKI (all P < .01). Preoperatively, higher levels of CK-MB and h-FABP were associated with increased odds of developing AKI (CK-MB: adjusted odds ratio 4.58, 95% confidence interval [CI] 1.56-13.41; h-FABP: adjusted odds ratio 2.76, 95% CI 1.27-6.03). When combined with clinical models, both preoperative CK-MB and h-FABP provided good discrimination (area under the curve 0.77, 95% CI 0.68-0.87, and 0.78, 95% CI 0.68-0.87, respectively) and improved reclassification indices. Cardiac biomarkers collected postoperatively did not significantly improve the prediction of AKI beyond clinical models.

CONCLUSIONS

Preoperative CK-MB and h-FABP are associated with increased risk of postoperative AKI and provide good discrimination of patients who develop AKI. These biomarkers may be useful for risk stratifying patients undergoing cardiac surgery.

Long-term mortality associated with acute kidney injury in children following congenital cardiac surgery

OBJECTIVE

Children undergoing congenital cardiac surgery (CCS) are at increased risk for acute kidney injury (AKI) due to a number of factors. Recent evidence suggests AKI may influence mortality beyond the immediate postoperative period and hospitalization. We sought to determine the association between renal failure and longer-term mortality in children following CCS.

METHODS

Our Study population included all patients that underwent cardiac surgery at our institution during a period of 3 years from 2004 through 2006. The primary definition of acute renal injury was based on pRIFLE using estimated creatinine clearance (pRIFLE eCCL).

RESULTS

Predictors of mortality. Age, single ventricle status, and renal failure as defined by pRIFLE stage F were associated with mortality. The hazard ratio for a patient with renal failure as defined by pRIFLE stage F was 3.82 (CI 1.89-7.75). Predictors of AKI as defined by pRIFLE. Duration of cardiopulmonary bypass (CPB) and age were the only variables associated with pRIFLE by univariate analysis. However, in the ordinal or survival model, age was the only variable associated with renal failure as defined by pRIFLE. As patient age increases from 0.30 to 3.5 years, the risks of having renal injury (pRIFLE stage I) or failure (pRIFLE stage F) decreases (OR 0.44, CI 0.21-0.94).

CONCLUSION

Mortality risk following CCS is increased in younger patients and those experiencing postoperative renal failure as defined by pRIFLE for a period of time that extends well beyond the immediate postoperative period and the time of hospitalization.

Renal replacement therapy in neonates

The incidence of acute kidney injury (AKI) has steadily increased in the last decade in neonates and infants. Despite the extensive proposed pharmacologic approaches to treat or prevent AKI, renal replacement therapy is the only available therapeutic approach to manage the consequences of significant AKI and maintain electrolyte homeostasis and fluid balance in infants with AKI. The objective of this article is to summarize the different approaches and modalities of renal replacement therapy in neonatal intensive care units.

Perioperative steroids administration in pediatric cardiac surgery: a meta-analysis of randomized controlled trials*

OBJECTIVE

To evaluate the effects of prophylactic perioperative corticosteroid administration, compared with placebo, on postoperative mortality and clinical outcomes (renal dysfunction, duration of mechanical ventilation, and ICU length of stay) in pediatric patients undergoing cardiac surgery with cardiopulmonary bypass.

DATA SOURCES

MEDLINE and Cochrane Library were screened through August 2013 for randomized controlled trials in which perioperative steroid treatment was adopted.

STUDY SELECTION

Included were randomized controlled trials conducted on pediatric population that reported clinical outcomes about mortality and morbidity.

DATA EXTRACTION

Eighty citations (PubMed, 48 citations; Cochrane, 32 citations) were identified, of which 14 articles were analyzed in depth and six articles fulfilled eligibility criteria and reported mortality data (232 patients), two studies reported ICU length of stay and mechanical ventilation duration (60 patients), and two studies reported renal dysfunction (49 patients).

DATA SYNTHESIS

A nonsignificant trend of reduced mortality was observed in steroid-treated patients (11 [4.7%] vs 4 [1.7%] patients; odds ratio, 0.41; 95% CI, 0.14-1.15; p = 0.089). Steroids had no effects on mechanical ventilation time (117.4 ± 95.9 hr vs 137.3 ± 102.4 hr; p = 0.43) and ICU length of stay (9.6 ± 4.6 d vs 9.9 ± 5.9 d; p = 0.8). Perioperative steroid administration reduced the prevalence of renal dysfunction (13 [54.2%] vs 2 [8%] patients; odds ratio, 0.07; 95% CI, 0.01-0.38; p = 0.002).

CONCLUSION

Despite a demonstrated attenuation of cardiopulmonary bypass-induced inflammatory response by steroid administration, a systematic review of randomized controlled trials performed so far reveals that steroid administration has potential clinical advantages (lower mortality and significant reduction of renal function deterioration). A larger prospective randomized study is needed to verify clearly the effects of steroid prophylaxis in pediatric patients.

Serum brain natriuretic peptide and risk of acute kidney injury after cardiac operations in children

BACKGROUND

Acute kidney injury (AKI) after pediatric cardiac operations is associated with poor outcomes and is difficult to predict. We conducted a prospective study to evaluate whether preoperative brain natriuretic peptide (BNP) levels predict postoperative AKI among children undergoing cardiac operations.

METHODS

This was a three-center, prospective study (2007-2009) of 277 children undergoing cardiac operations (n = 121, aged <2 years) with available preoperative BNP values. Preoperative BNP was measured and categorized into tertiles. The performance of BNP was evaluated alone and in combination with clinical factors. AKI was defined as doubling of serum creatinine or need for acute dialysis.

RESULTS

Postoperative AKI occurred in 165 children (60%), with 118 cases (43%) being mild and 47 cases (17%) severe. Preoperative BNP was not associated with increased risk of mild or severe postoperative AKI and did not significantly improve AKI risk prediction when added to clinical models. Preoperative BNP was, however, associated with several clinical outcomes, including length of stay and mechanical ventilation. The results were similar when the analysis was repeated in the subset of children younger than 2 years of age or when the association of postoperative BNP and AKI was evaluated.

CONCLUSIONS

Preoperative BNP levels did not predict postoperative AKI in this cohort of children undergoing cardiac operations. Both preoperative and postoperative BNP levels are associated with postoperative outcomes. Clinical Trial Registration at Clinicaltrials.gov as NCT00774137.

Predictive performance of urine neutrophil gelatinase-associated lipocalin for dialysis requirement and death following cardiac surgery in neonates and infants

BACKGROUND AND OBJECTIVES

Urine neutrophil gelatinase-associated lipocalin (uNGAL) has been shown to accurately predict and allow early detection of AKI, as assessed by an increase in serum creatinine in children and adults. The present study explores the accuracy of uNGAL for the prediction of severe AKI-related outcomes in neonates and infants undergoing cardiac surgery: dialysis requirement and/or death within 30 days.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Prospective, observational cohort study conducted in a tertiary referral pediatric cardiac intensive care unit, including 75 neonates and 125 infants undergoing surgery with cardiopulmonary bypass between August 1, 2010, and May 31, 2011. Urine samples were collected before surgery and at median of five time points within 48 hours of bypass. Urine NGAL was quantified as absolute concentration, creatinine-normalized concentration, and absolute excretion rate, and a clusterization algorithm was applied to the individual uNGAL kinetics. The accuracy for the prediction of the outcome was assessed using receiver-operating characteristic areas, likelihood ratios, diagnostic odds ratios, net reclassification index, integrated reclassification improvement, and number needed to screen.

RESULTS

A total of 1176 urine samples were collected. Of all patients, 8% required dialysis and 4% died. Three clusters of uNGAL kinetics were identified, including patients with significantly different outcomes. The uNGAL level peaked between 1 and 3 hours of bypass and remained high in half of all patients who required dialysis or died. The uNGAL levels measured within 24 hours of bypass accurately predicted the outcome and performed best after normalization to creatinine, with varying cutoffs according to the time elapsed since bypass. The number needed to screen to correctly identify the risk of dialysis or death in one patient varied between 1.5 and 2.6 within 12 hours of bypass.

CONCLUSIONS

uNGAL is a valuable predictive tool of dialysis requirement and death in neonates and infants with AKI after cardiac surgery.

Limitations of early serum creatinine variations for the assessment of kidney injury in neonates and infants with cardiac surgery

Background

Changes in kidney function, as assessed by early and even small variations in serum creatinine (ΔsCr), affect survival in adults following cardiac surgery but such associations have not been reported in infants. This raises the question of the adequate assessment of kidney function by early ΔsCr in infants undergoing cardiac surgery.

Methodology

The ability of ΔsCr within 2 days of surgery to assess the severity of kidney injury, accounted for by the risk of 30-day mortality, was explored retrospectively in 1019 consecutive neonates and infants. Patients aged ≤ 10 days were analyzed separately because of the physiological improvement in glomerular filtration early after birth. The Kml algorithm, an implementation of k-means for longitudinal data, was used to describe creatinine kinetics, and the receiver operating characteristic and the reclassification methodology to assess discrimination and the predictive ability of the risk of death.

Results

Three clusters of ΔsCr were identified: in 50% of all patients creatinine decreased, in 41.4% it increased slightly, and in 8.6% it rose abruptly. Mortality rates were not significantly different between the first and second clusters, 1.6% [0.0–4.1] vs 5.9% [1.9–10.9], respectively, in patients aged ≤ 10 days, and 1.6% [0.5–3.0] vs 3.8% [1.9–6.0] in older ones. Mortality rates were significantly higher when creatinine rose abruptly, 30.3% [15.1–46.2] in patients aged ≤ 10 days, and 15.1% [5.9–25.5] in older ones. However, only 41.3% of all patients who died had an abrupt increase in creatinine. ΔsCr improved prediction in survivors, but not in patients who died, and did not improve discrimination over a clinical mortality model.

Conclusions

The present results suggest that a postoperative decrease in creatinine represents the normal course in neonates and infants with cardiac surgery, and that early creatinine variations lack sensitivity for the assessment of the severity of kidney injury.

Acute kidney injury and its association with in-hospital mortality among children with acute infections

BACKGROUND

We investigated prevalence of acute kidney injury (AKI) at hospitalization and its association with in-hospital mortality among Ugandan children hospitalized with common acute infections, and predictors of mortality among AKI children.

METHODS

We enrolled 2,055 children hospitalized with primary diagnoses of acute gastroenteritis, malaria, or pneumonia. Serum creatinine, albumin, electrolytes, hemoglobin, and urine protein were obtained on admission. Participants were assessed for AKI based on serum creatinine levels. Demographic and clinical data were obtained using a primary care provider survey and medical chart review. Logistic regression was used to determine predictors of in-hospital mortality.

RESULTS

A total of 278 (13.5%) of children had AKI on admission; for 76.2%, AKI was stage 2 (98/278) or stage 3 (114/278) defined as serum creatinine >2- or 3-fold above normal upper limit for age, respectively. AKI prevalence was particularly high in gastroenteritis (28.6%) and underweight children (20.7%). Twenty-five percent of children with AKI died during hospitalization, compared to 9.9% with no AKI (adjusted odds ratio (aOR) 3.5 (95% CI, 2.2-5.5)). In-hospital mortality risk did not differ by AKI stage. Predictors of in-hospital mortality among AKI children included primary diagnosis of pneumonia, aOR 4.5 (95% CI, 1.8-11.2); proteinuria, aOR = 2.1 (95% CI, 1.0-4.9) and positive human immunodeficiency virus (HIV) status, aOR 5.0 (95% CI, 2.0-12.9).

CONCLUSIONS

Among children hospitalized with gastroenteritis, malaria, or pneumonia, AKI at admission was common and associated with high in-hospital mortality.

Early initiation of peritoneal dialysis in neonates and infants with acute kidney injury following cardiac surgery is associated with a significant decrease in mortality

Association between early renal replacement therapy and better survival has been reported in adults with postoperative kidney injury, but not in children undergoing cardiac surgery. We conducted a retrospective cohort study of 146 neonates and infants requiring peritoneal dialysis following cardiac surgery in a tertiary referral hospital. A propensity score was used to limit selection bias due to timing of dialysis, and included baseline and intraoperative characteristics, requirement for postoperative extracorporeal membrane oxygenation, and creatinine clearance variation. Inverse probability of treatment weighting resulted in good balance between groups for all baseline and intraoperative variables. After weighting, 30-day and 90-day mortality were compared between the 109 patients placed on dialysis early, within the first day of surgery, and those with delayed dialysis, commencing on the second day of surgery or later, using logistic regression and survival analysis. Mortality was 28.1% at 30 days, and was 36.3% during follow-up. Early dialysis was associated with a 46.7% decrease in the 30-day and a 43.5% decrease in the 90-day mortality rate when compared with delayed dialysis. All other short-term outcome variables were similar. Thus, initiation of peritoneal dialysis on the day of or the first day following surgery was associated with a significant decrease in mortality in neonates and infants with acute kidney injury.

[Use of peritoneal dialysis in newborns undergoing cardiac surgery with cardiopulmonary bypass]

INTRODUCTION

Renal replacement therapy is required in up to 10% of children undergoing cardiac surgery. Peritoneal dialysis (PD) is the preferred treatment method in the neonatal period.

OBJECTIVE

To evaluate safety, efficacy and perioperative factors associated with the need for PD.

MATERIAL AND METHODS

Retrospective review of clinical charts over a two-year period of newborns undergoing cardiac surgery with cardiopulmonary bypass (CPB). The group of cases requiring PD were compared with a group of random controls that did not require any renal replacement therapy.

RESULTS

A total of 76 infants underwent cardiac surgery with CPB, of which 24 required PD. The need for PD was associated with low cardiac output in the immediate postoperative period and longer mechanical ventilation. The most frequent indication was fluid overload. The technique was effective in 66% of patients. Complications were only recorded in one patient.

CONCLUSIONS

The most common indication for PD after cardiac surgery with CPB in neonates is fluid overload. The need for renal replacement therapy is associated with low cardiac output and a longer duration of mechanical ventilation. PD is an effective technique with few complications in these patients.

Urinary biomarkers and renal near-infrared spectroscopy predict intensive care unit outcomes after cardiac surgery in infants younger than 6 months of age

OBJECTIVE

To assess the ability of urinary acute kidney injury biomarkers and renal near-infrared spectroscopy (NIRS) to predict outcomes in infants after surgery for congenital heart disease.

METHODS

Urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), and cystatin C were measured preoperatively and postoperatively in 49 infants younger than 6 months of age. Renal NIRS was monitored for the first 24 hours after surgery. A composite poor outcome was defined as death, the need for renal replacement therapy, prolonged time to first extubation, or prolonged intensive care unit length of stay.

RESULTS

Forty-two (86%) patients had acute kidney injury as indicated by at least Acute Kidney Injury Network/Kidney Disease: Improving Global Outcomes (AKIN/KDIGO) stage 1 criteria, and 17 (35%) patients had poor outcomes, including 3 deaths. With the exception of KIM-1, all biomarkers demonstrated significant increases within 24 hours postoperatively among patients with poor outcomes. Low levels of NGAL and IL-18 demonstrated high negative predictive values (91%) within 2 hours postoperatively. Poor outcome infants had greater cumulative time with NIRS saturations less than 50% (60 vs 1.5 minutes; P = .02) in the first 24 hours.

CONCLUSIONS

Within the first 24 hours after cardiopulmonary bypass, infants at increased risk for poor outcomes demonstrated elevated urinary NGAL, IL-18, and cystatin C and increased time with low NIRS saturations. These findings suggest that urinary biomarkers and renal NIRS may differentiate patients with good versus poor outcomes in the early postoperative period, which could assist clinicians when counseling families and inform the development of future clinical trials.