Persistent acute kidney injury and fluid accumulation with outcomes after the Norwood procedure: report from NEPHRON

BACKGROUND

Cardiac surgery-associated acute kidney injury (CS-AKI) is common, but its impact on clinical outcomes is variable. Parsing AKI into sub-phenotype(s) and integrating pathologic positive cumulative fluid balance (CFB) may better inform prognosis. We sought to determine whether durational sub-phenotyping of CS-AKI with CFB strengthens association with outcomes among neonates undergoing the Norwood procedure.

METHODS

Multicenter, retrospective cohort study from the Neonatal and Pediatric Heart and Renal Outcomes Network. Transient CS-AKI: present only on post-operative day (POD) 1 and/or 2; persistent CS-AKI: continued after POD 2. CFB was evaluated per day and peak CFB during the first 7 postoperative days. Primary and secondary outcomes were mortality, respiratory support-free and hospital-free days (at 28, 60 days, respectively). The primary predictor was persistent CS-AKI, defined by modified neonatal Kidney Disease: Improving Global Outcomes criteria.

RESULTS

CS-AKI occurred in 59% (205/347) neonates: 36.6% (127/347) transient and 22.5% (78/347) persistent; CFB > 10% occurred in 18.7% (65/347). Patients with either persistent CS-AKI or peak CFB > 10% had higher mortality. Combined persistent CS-AKI with peak CFB > 10% (n = 21) associated with increased mortality (aOR: 7.8, 95% CI: 1.4, 45.5; p = 0.02), decreased respiratory support-free (predicted mean 12 vs. 19; p < 0.001) and hospital-free days (17 vs. 29; p = 0.048) compared to those with neither.

CONCLUSIONS

The combination of persistent CS-AKI and peak CFB > 10% after the Norwood procedure is associated with mortality and hospital resource utilization. Prospective studies targeting intra- and postoperative CS-AKI risk factors and reducing CFB have the potential to improve outcomes.

Acute kidney injury in hypoplastic left heart syndrome patients following the comprehensive stage two palliation

BACKGROUND

An alternative surgical approach for hypoplastic left heart syndrome is the Hybrid pathway, which delays the risk of acute kidney injury outside of the newborn period. We sought to determine the incidence, and associated morbidity, of acute kidney injury after the comprehensive stage 2 and the cumulative incidence after the first two operations in the Hybrid pathway.

DESIGN

A single centre, retrospective study was conducted of hypoplastic left heart patients completing the second-stage palliation in the Hybrid pathway from 2009 to 2018. Acute kidney injury was defined utilising Kidney Diseases Improving Global Outcomes criteria. Perioperative and post-operative characteristics were analysed.

RESULTS

Sixty-one patients were included in the study cohort. The incidence of acute kidney injury was 63.9%, with 36.1% developing severe injury. Cumulatively after the Hybrid Stage 1 and comprehensive stage 2 procedures, 69% developed acute kidney injury with 36% developing severe injury. The presence of post-operative acute kidney injury was not associated with an increase in 30-day mortality (acute kidney injury 7.7% versus none 9.1%; p = > 0.9). There was a significantly longer median duration of intubation among those with acute kidney injury (acute kidney injury 32 (8, 155) hours vs. no injury 9 (0, 94) hours; p = 0.018).

CONCLUSIONS

Acute kidney injury after the comprehensive stage two procedure is common and accounts for most of the kidney injury in the first two operations of the Hybrid pathway. No difference in mortality was detected between those with acute kidney injury and those without, although there may be an increase in morbidity.

A proposed framework for advancing acute kidney injury risk stratification and diagnosis in children: a report from the 26th Acute Disease Quality Initiative (ADQI) conference

Acute kidney injury (AKI) in children is associated with increased morbidity, reduced health-related quality of life, greater resource utilization, and higher mortality. Improvements in the timeliness and precision of AKI diagnosis in children are needed. In this report, we highlight existing, novel, and on-the-horizon diagnostic and risk-stratification tools for pediatric AKI, and outline opportunities for integration into clinical practice. We also summarize pediatric-specific high-risk diagnoses and exposures for AKI, as well as the potential role of real-time risk stratification and clinical decision support to improve outcomes. Lastly, the key characteristics of important pediatric AKI phenotypes will be outlined. Throughout, we identify key knowledge gaps, which represent prioritized areas of focus for future research that will facilitate a comprehensive, timely and personalized approach to pediatric AKI diagnosis and management.

Urinary biomarkers associated with acute kidney injury in pediatric mechanical circulatory support patients

BACKGROUND

In patients requiring mechanical circulatory support (MCS), the incidence of acute kidney injury (AKI) is between 37 and 63%. In this study, we performed an exploratory analysis evaluating the relationship of multiple urine biomarkers with AKI development in pediatric MCS patients.

METHODS

This is a single center retrospective study in a pediatric cohort receiving MCS from August 2014 to November 2020. We measured 14 urine biomarkers of kidney injury on day 1 following MCS initiation and analyzed their association with development of AKI in the first 7 days of MCS initiation.

RESULTS

Sixty patients met inclusion criteria. Patients with AKI were more likely to be supported by venoarterial extracorporeal membrane oxygenation (65% vs. 8.3%, p < 0.001), compared to the no AKI group and less likely to have ventricular assist devices (10% vs. 50%, p < 0.001). There was a significant increase in the median urine albumin and urine osteoactivin in the AKI group, compared to the no AKI group (p = 0.020 and p = 0.018, respectively). When normalized to urine creatinine (UCr), an increased log osteoactivin/UCr was associated with higher odds of AKI development (OR: 2.05; 95% CI: 1.07, 4.44; p = 0.028), and higher log epidermal growth factor (EGF)/UCr (OR: 0.41; 95% CI: 0.15, 0.96) was associated with decreased odds of AKI.

CONCLUSIONS

Early increase in urine osteoactivin is associated with AKI development within 7 days of MCS initiation in pediatric patients. Contrary, an increased urine EGF is associated with kidney protection. A higher resolution version of the Graphical abstract is available as Supplementary information.

Peritoneal catheters in neonates undergoing complex cardiac surgery: a multi-centre descriptive study

BACKGROUND

The use of peritoneal catheters for prophylactic dialysis or drainage to prevent fluid overload after neonatal cardiac surgery is common in some centres; however, the multi-centre variability and details of peritoneal catheter use are not well described.

METHODS

Twenty-two-centre NEonatal and Pediatric Heart Renal Outcomes Network (NEPHRON) study to describe multi-centre peritoneal catheter use after STAT category 3-5 neonatal cardiac surgery using cardiopulmonary bypass. Patient characteristics and acute kidney injury/fluid outcomes for six post-operative days are described among three cohorts: peritoneal catheter with dialysis, peritoneal catheter with passive drainage, and no peritoneal catheter.

RESULTS

Of 1490 neonates, 471 (32%) had an intraoperative peritoneal catheter placed; 177 (12%) received prophylactic dialysis and 294 (20%) received passive drainage. Sixteen (73%) centres used peritoneal catheter at some frequency, including six centres in >50% of neonates. Four centres utilised prophylactic peritoneal dialysis. Time to post-operative dialysis initiation was 3 hours [1, 5] with the duration of 56 hours [37, 90]; passive drainage cohort drained for 92 hours [64, 163]. Peritoneal catheter were more common among patients receiving pre-operative mechanical ventilation, single ventricle physiology, and higher complexity surgery. There was no association with adverse events. Serum creatinine and daily fluid balance were not clinically different on any post-operative day. Mortality was similar.

CONCLUSIONS

In neonates undergoing complex cardiac surgery, peritoneal catheter use is not rare, with substantial variability among centres. Peritoneal catheters are used more commonly with higher surgical complexity. Adverse event rates, including mortality, are not different with peritoneal catheter use. Fluid overload and creatinine-based acute kidney injury rates are not different in peritoneal catheter cohorts.

The development and efficacy of a paediatric cardiology fellowship online preparatory course

BACKGROUND

The transition from residency to paediatric cardiology fellowship is challenging due to the new knowledge and technical skills required. Online learning can be an effective didactic modality that can be widely accessed by trainees. We sought to evaluate the effectiveness of a paediatric cardiology Fellowship Online Preparatory Course prior to the start of fellowship.

METHODS

The Online Preparatory Course contained 18 online learning modules covering basic concepts in anatomy, auscultation, echocardiography, catheterisation, cardiovascular intensive care, electrophysiology, pulmonary hypertension, heart failure, and cardiac surgery. Each online learning module included an instructional video with pre-and post-video tests. Participants completed pre- and post-Online Preparatory Course knowledge-based exams and surveys. Pre- and post-Online Preparatory Course survey and knowledge-based examination results were compared via Wilcoxon sign and paired t-tests.

RESULTS

151 incoming paediatric cardiology fellows from programmes across the USA participated in the 3 months prior to starting fellowship training between 2017 and 2019. There was significant improvement between pre- and post-video test scores for all 18 online learning modules. There was also significant improvement between pre- and post-Online Preparatory Course exam scores (PRE 43.6 ± 11% versus POST 60.3 ± 10%, p < 0.001). Comparing pre- and post-Online Preparatory Course surveys, there was a statistically significant improvement in the participants' comfort level in 35 of 36 (97%) assessment areas. Nearly all participants (98%) agreed or strongly agreed that the Online Preparatory Course was a valuable learning experience and helped alleviate some anxieties (77% agreed or strongly agreed) related to starting fellowship.

CONCLUSION

An Online Preparatory Course prior to starting fellowship can provide a foundation of knowledge, decrease anxiety, and serve as an effective educational springboard for paediatric cardiology fellows.

Early postoperative weight-based fluid overload is associated with worse outcomes after neonatal cardiac surgery

OBJECTIVES

Evaluate the association of postoperative day (POD) 2 weight-based fluid balance (FB-W) > 10% with outcomes after neonatal cardiac surgery.

METHODS

Retrospective cohort study of 22 hospitals in the NEonatal and Pediatric Heart and Renal Outcomes Network (NEPHRON) registry from September 2015 to January 2018. Of 2240 eligible patients, 997 neonates (cardiopulmonary bypass (CPB) n = 658, non-CPB n = 339) were weighed on POD2 and included.

RESULTS

Forty-five percent (n = 444) of patients had FB-W > 10%. Patients with POD2 FB-W > 10% had higher acuity of illness and worse outcomes. Hospital mortality was 2.8% (n = 28) and not independently associated with POD2 FB-W > 10% (OR 1.04; 95% CI 0.29-3.68). POD2 FB-W > 10% was associated with all utilization outcomes, including duration of mechanical ventilation (multiplicative rate of 1.19; 95% CI 1.04-1.36), respiratory support (1.28; 95% CI 1.07-1.54), inotropic support (1.38; 95% CI 1.10-1.73), and postoperative hospital length of stay (LOS 1.15; 95% CI 1.03-1.27). In secondary analyses, POD2 FB-W as a continuous variable demonstrated association with prolonged durations of mechanical ventilation (OR 1.04; 95% CI 1.02-1.06], respiratory support (1.03; 95% CI 1.01-1.05), inotropic support (1.03; 95% CI 1.00-1.05), and postoperative hospital LOS (1.02; 95% CI 1.00-1.04). POD2 intake-output based fluid balance (FB-IO) was not associated with any outcome.

CONCLUSIONS

POD2 weight-based fluid balance > 10% occurs frequently after neonatal cardiac surgery and is associated with longer cardiorespiratory support and postoperative hospital LOS. However, POD2 FB-IO was not associated with clinical outcomes. Mitigating early postoperative fluid accumulation may improve outcomes but requires safely weighing neonates in the early postoperative period. A higher resolution version of the Graphical abstract is available as Supplementary information.

Increasing the Percentage of Neonates Consuming Human Milk in a Pediatric Cardiothoracic Intensive Care Unit: A Quality Improvement Initiative

OBJECTIVE

To address a known nutritional deficit and enhance the overall health of critically ill babies, this project sought to increase the percentage of cardiothoracic intensive care unit (CTICU) neonates consuming human milk from a 2019 baseline of 55% to 75% by December 2020 and 90% by December 2021.

STUDY DESIGN

This was a quality improvement initiative targeted to all neonates admitted to the CTICU, with baseline data obtained from January 2019 through February 2020. We implemented 11 interventions from March 2020 to January 2022 to address the key drivers of "education of parents and providers," "environment/equipment," and "process." We tracked the monthly percentage of neonates who were human milk fed with a statistical process control p-chart. The balancing measure of critical human milk feeding errors was also monitored.

RESULTS

The baseline percentage of CTICU neonates consuming human milk was 55%. This percentage increased to 73% by the end of 2020 and 92% by the year end 2021. Most neonates who received human milk were fed mother's milk with a minority receiving donor human milk. The number of aborted, critical human milk administration errors decreased during the intervention period.

CONCLUSIONS

In this quality improvement initiative, we significantly increased the percentage of CTICU neonates consuming human milk without an increase in critical human milk errors. Interventions directly increasing the ease with which lactating mothers can provide/store their milk were likely the most effective.

Assessment of fluid balance after neonatal cardiac surgery: a description of intake/output vs. weight-based methods

BACKGROUND

Fluid overload associates with poor outcomes after neonatal cardiac surgery, but consensus does not exist for the most clinically relevant method of measuring fluid balance (FB). While weight change-based FB (FB-W) is standard in neonatal intensive care units, weighing infants after cardiac surgery may be challenging. We aimed to identify characteristics associated with obtaining weights and to understand how intake/output-based FB (FB-IO) and FB-W compare in the early postoperative period in this population.

METHODS

Observational retrospective study of 2235 neonates undergoing cardiac surgery from 22 hospitals comprising the NEonatal and Pediatric Heart and Renal Outcomes Network (NEPHRON) database.

RESULTS

Forty-five percent (n = 998) of patients were weighed on postoperative day (POD) 2, varying from 2 to 98% among centers. Odds of being weighed were lower for STAT categories 4 and 5 (OR 0.72; 95% CI 0.53-0.98), cardiopulmonary bypass (0.59; 0.42-0.83), delayed sternal closure (0.27; 0.19-0.38), prophylactic peritoneal dialysis use (0.58; 0.34-0.99), and mechanical ventilation on POD 2 (0.23; 0.16-0.33). Correlation between FB-IO and FB-W was weak for every POD 1-6 and within the entire cohort (correlation coefficient 0.15; 95% CI 0.12-0.17). FB-W measured higher than paired FB-IO (mean bias 12.5%; 95% CI 11.6-13.4%) with wide 95% limits of agreement (- 15.4-40.4%).

CONCLUSIONS

Weighing neonates early after cardiac surgery is uncommon, with significant practice variation among centers. Patients with increased severity of illness are less likely to be weighed. FB-W and FB-IO have weak correlation, and further study is needed to determine which cumulative FB metric most associates with adverse outcomes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Proactive Risk Mitigation for Cardiac Arrest Prevention in High-Risk Congenital Heart Disease Patients

Objective

The prevalence of postoperative cardiac arrest (CA) increases with cardiothoracic surgical case complexity and is associated with a 40% to 50% mortality. Despite having a low overall surgical mortality rate at our center, our postoperative CA rates were higher than expected, with an observed-to-expected ratio of 2.6. Utilizing quality improvement methodology, we evaluated the influence of proactive risk mitigation on postprocedure CA in a high-risk cohort of pediatric cardiac patients.

Methods

This single-center study utilized the Institute for Healthcare Improvement model. We created and implemented our Proactive Mitigation to Decrease Serious Adverse Events program in July 2020, prospectively enrolling preidentified high-risk patients. Enrolled patients underwent scheduled multidisciplinary reviews via virtual platform at 2 periprocedural time points with discussion of patient-specific risks and the subsequent development of proactive risk mitigation plans. Primary outcome measures were derived from the Pediatric Cardiac Critical Care Consortium national registry and included rate of postprocedure CA within 7 days and an institution-specific observed-to-expected ratio for postoperative CA.

Results

Our baseline median number of high-risk cases between postprocedure CAs was 3. Following project initiation, median high-risk cases between events increased to 7. Our observed-to-expected ratio for postoperative CA decreased from 2.56 during the 12 months before Proactive Mitigation to Decrease Serious Adverse Events program implementation to 1.01 during the 12 months after Proactive Mitigation to Decrease Serious Adverse Events program implementation, and hospital length of stay decreased by ∼10 days.

Conclusions

Implementation of periprocedure-related proactive risk mitigation strategies in high-risk pediatric cardiac patients led to improvement in postprocedure CA with a 133% increase in high-risk cases between events.

Modifying the Renal Angina Index for Predicting AKI and Related Adverse Outcomes in Pediatric Heart Surgery

Background:Reliable prediction of severe acute kidney injury (AKI) and related poor outcomes has the potential to optimize treatment. The purpose of this study was to modify the renal angina index in pediatric cardiac surgery to predict severe AKI and related poor outcomes. Methods: We performed a multicenter retrospective study with the population divided into a derivation and validation cohort to assess the performance of a modified renal angina index assessed at 8 h after cardiac intensive care unit (CICU) admission to predict a complex outcome of severe day 3 AKI or related poor outcomes (ventilation duration >7 days, CICU length of stay >14 days, and mortality). The derivation sample was used to determine the optimal cut-off value. Results: There were 298 and 299 patients in the derivation and validation cohorts, respectively. The incidence of severe day 3 AKI and the complex outcome was 1.7% and 28% in the derivation and validation cohort. The sensitivity analysis for fulfillment of renal angina was a score >8 with a sensitivity of 63%, specificity of 73%, and negative predictive value of 83%. The cardiac renal angina index predicted the composite outcome with an area under the curve of 0.7 (95% confidence interval: 0.62-0.78). Renal angina patients had a significantly higher probability of the complex outcome when compared to individual risk and injury categories. Conclusions: We operationalized the renal angina index for use after cardiac surgery. Further revision and modification of the construct with integration of biomarkers in a prospective cohort are necessary to refine the prediction model.

Hemodynamic Predictors of Renal Function After Pediatric Left Ventricular Assist Device Implantation

Although renal function often improves after pediatric left ventricular assist device (LVAD) implantation, recovery is inconsistent. We aimed to identify hemodynamic parameters associated with improved renal function after pediatric LVAD placement. A single-center retrospective cohort study was conducted in patients less than 21 years who underwent LVAD placement between June 2004 and December 2015. The relationship between hemodynamic parameters and estimated glomerular filtration rate (eGFR) was assessed using univariate and multivariate modeling. Among 54 patients, higher preoperative central venous pressure (CVP) was associated with eGFR improvement after implantation (p = 0.012). However, 48 hours postimplantation, an increase in CVP from baseline was associated with eGFR decline over time (p = 0.01). In subgroup analysis, these associations were significant only for those with normal pre-ventricular assist device renal function (p = 0.026). In patients with preexisting renal dysfunction, higher absolute CVP values 48 and 72 hours after implantation predicted better renal outcome (p = 0.005). Our results illustrate a complex relationship between ventricular function, volume status, and renal function. Additionally, they highlight the challenge of using CVP to guide management of renal dysfunction in pediatric heart failure. Better methods for evaluating right heart function and volume status are needed to improve our understanding of how hemodynamics impact renal function in this population.

Incidence, Predictors, and Impact of Postoperative Acute Kidney Injury Following Fontan Conversion Surgery in Young Adult Fontan Survivors

Acute kidney injury (AKI) is a common complication following single ventricle congenital heart surgery. Data regarding AKI following Fontan conversion (FC) surgery are limited. This study evaluated the incidence, predictors of, and prognostic value of AKI following FC. Single-center retrospective cohort study, including consecutive FC patients from December 1994 to December 2016. Medical records were reviewed. AKI was classified into AKI-1/AKI-2/AKI-3 using Kidney Disease: Improving Global Outcomes criteria. Multivariable logistic regression identified risk factors for AKI≥2. Chi-square and 2-sample t-tests assessed associations between AKI≥2 and postoperative outcomes. Mid-term heart-transplant-free survival among AKI0-1 vs AKI2-3 groups was compared using Kaplan-Meier curves and log-rank test. We included 139 FC patients: age at FC 24 (25th-75th, 19-31) years; 81% initial atrio-pulmonary Fontan; follow-up 8.3 ± 5.3 years following FC. Post-FC, 63 patients (45%) developed AKI (AKI-1 = 37 [27%]; AKI-2 = 10 [7%]; AKI-3 = 16 [11%]). AKI recovered by hospital discharge in 86%, 80%, and 19% of patients with AKI-1/AKI-2/AKI-3, respectively. Independent risk factors for AKI≥2 included older age (OR 1.07, 95%CI 1.01-1.15; P = 0.027); ≥3 prior sternotomies (OR = 6.11; 95%CI = 1.59-23.47; P = 0.009); greater preoperative right atrial pressure (OR 1.19; 1.02-1.38; P = 0.024), and prior catheter ablation procedure (OR 3.45; 1.17-10.18; P = 0.036). AKI≥2 was associated with: longer chest tube duration (9 [5-57] vs 7 [3-28] days; P = 0.01); longer mechanical ventilation time (2 [1-117] vs 1 [1-6] days; P = 0.01); greater need for dialysis (31% v s0%; P < 0.001); and longer postoperative length of stay (18 [8-135] vs 10 [6-58] days; P < 0.001). AKI 2-3 patients had worse mid-term heart-transplant-free survival. Half of the patients undergoing FC develop AKI. AKI 2-3 is associated with worse early postoperative outcomes and reduced mid-term transplant-free survival following FC. Knowledge of AKI predictors may allow for improved FC risk stratification, patient selection, and perioperative management in this high-risk population.

Incidence, Predictors, and Impact of Postoperative Acute Kidney Injury Following Fontan Conversion Surgery in Young Adult Fontan Survivors

Acute kidney injury (AKI) is a common complication following single ventricle congenital heart surgery. Data regarding AKI following Fontan conversion (FC) surgery are limited. This study evaluated the incidence, predictors of, and prognostic value of AKI following FC. Single-center retrospective cohort study, including consecutive FC patients from December 1994 to December 2016. Medical records were reviewed. AKI was classified into AKI-1/AKI-2/AKI-3 using Kidney Disease: Improving Global Outcomes criteria. Multivariable logistic regression identified risk factors for AKI≥2. Chi-square and 2-sample t-tests assessed associations between AKI≥2 and postoperative outcomes. Mid-term heart-transplant-free survival among AKI0-1 vs AKI2-3 groups was compared using Kaplan-Meier curves and log-rank test. We included 139 FC patients: age at FC 24 (25th-75th, 19-31) years; 81% initial atrio-pulmonary Fontan; follow-up 8.3 ± 5.3 years following FC. Post-FC, 63 patients (45%) developed AKI (AKI-1 = 37 [27%]; AKI-2 = 10 [7%]; AKI-3 = 16 [11%]). AKI recovered by hospital discharge in 86%, 80%, and 19% of patients with AKI-1/AKI-2/AKI-3, respectively. Independent risk factors for AKI≥2 included older age (OR 1.07, 95%CI 1.01-1.15; P = 0.027); ≥3 prior sternotomies (OR = 6.11; 95%CI = 1.59-23.47; P = 0.009); greater preoperative right atrial pressure (OR 1.19; 1.02-1.38; P = 0.024), and prior catheter ablation procedure (OR 3.45; 1.17-10.18; P = 0.036). AKI≥2 was associated with: longer chest tube duration (9 [5-57] vs 7 [3-28] days; P = 0.01); longer mechanical ventilation time (2 [1-117] vs 1 [1-6] days; P = 0.01); greater need for dialysis (31% v s0%; P < 0.001); and longer postoperative length of stay (18 [8-135] vs 10 [6-58] days; P < 0.001). AKI 2-3 patients had worse mid-term heart-transplant-free survival. Half of the patients undergoing FC develop AKI. AKI 2-3 is associated with worse early postoperative outcomes and reduced mid-term transplant-free survival following FC. Knowledge of AKI predictors may allow for improved FC risk stratification, patient selection, and perioperative management in this high-risk population.

Pharmacologic Control of Blood Pressure in Infants and Children

Alterations in blood pressure are common during the perioperative period in infants and children. Perioperative hypertension may be the result of renal failure, volume overload, or activation of the sympathetic nervous system. Concerns regarding end-organ effects or postoperative bleeding may mandate regulation of blood pressure. During the perioperative period, various pharmacologic agents have been used for blood pressure control including sodium nitroprusside, nitroglycerin, β-adrenergic antagonists, fenoldopam, and calcium channel antagonists. The following manuscript outlines the commonly used pharmacologic agents for perioperative BP including dosing regimens and adverse effect profiles. Previously published clinical trials are discussed and efficacy in the perioperative period reviewed.

"Echo pause" for postoperative transthoracic echocardiographic surveillance

BACKGROUND

No guidelines exist for inpatient postoperative transthoracic echocardiographic (TTE) surveillance in congenital heart disease. We prospectively evaluated indications for postoperative TTEs in patients with congenital heart disease to identify areas to improve upon (Phase 1) and then assessed the impact of a simple pilot intervention (Phase 2).

METHODS

We included patients with RACHS-1 (Risk Adjustment for Congenital Heart Surgery) scores of 2 and 3 to keep the cohort homogenous. During Phase 1, we collected data prospectively to identify postoperative TTEs for which there were no new findings and no associated clinical management decisions ("potentially redundant" TTEs). During Phase 2, prior to placement of a TTE order, an "Echo Pause" was performed during rounds to prompt review of prior TTE results and indication for the current order. The number of "potentially redundant" TTEs during Phase 1 vs. Phase 2 was compared.

RESULTS

During Phase 1, 98 postoperative TTEs were performed on 51 patients. Potentially "redundant" TTEs were identified in two main areas: (a) TTEs ordered to evaluate pericardial effusion and (b) TTEs ordered with the indication of "postoperative," "follow-up," or "discharge" in the setting of a prior complete postoperative TTE and no apparent change in clinical status. During Phase 2, 101 TTEs were performed on 63 patients. The number of "potentially redundant" TTEs decreased from 14/98 (14%) to 5/101 (5%) (P = .026).

CONCLUSION

Our results suggest that the number of "potentially redundant" TTEs during inpatient postoperative surveillance of patients with congenital heart disease can be decreased by a simple intervention during rounds such as an "Echo Pause."

Application-Based Translaryngeal Ultrasound for the Assessment of Vocal Fold Mobility in Children

Objective

To compare the evaluation of vocal fold mobility between flexible nasal laryngoscopy (FNL) and a handheld application-based translaryngeal ultrasound (TLUS) platform.

Study Design

Prospective analysis included patients with unknown vocal fold mobility status who underwent FNL and TLUS.

Setting

Tertiary referral center.

Subjects and Methods

TLUS was performed on 23 consecutive children (<18 years old) presenting for laryngoscopy due to unknown vocal fold mobility status. After the recording of three 10-second TLUS videos as well as FNL, the study was divided into 2 parts: parental assessment of laryngeal ultrasound at the time of patient evaluation and random practitioner assessment of ultrasound videos.

Results

We describe 23 patients who underwent TLUS and FNL. Ten patients (43.5%) had normal vocal fold function bilaterally, and 13 (56.5%) had either left or right vocal fold immobility. Family members and physicians correctly identified the presence and laterality of impaired vocal fold mobility in 22 of 23 cases (κ = 0.96). The sensitivity, specificity, positive predictive value, and negative predictive value of FLUS in diagnosing vocal fold immobility were 92.3%, 100%, 100%, and 90.9%, respectively. Random practitioners accurately identified the presence and laterality of vocal fold immobility under all circumstances.

Conclusion

A handheld application-based ultrasound platform is both sensitive and specific in its ability to identify vocal fold motion impairment. Portable handheld TLUS has the potential to serve as a validated screening examination, even by inexperienced providers, and in specific cases may obviate the need for an invasive transnasal laryngoscopy.

Cardiopulmonary Bypass and AKI: AKI Is Bad, So Let's Get Beyond the Diagnosis

It is now well-established that AKI is a serious and common complication following cardiopulmonary bypass (CPB) in both children and adults, adverse outcomes may occur in the short term as well as long term, with higher incidence of chronic kidney disease, increased healthcare utilization and higher frequency of cardiovascular events in patients who develop post-CPB AKI. Despite the advances in our understanding of the pathogenesis of the disease and the improvement in diagnostic tools, our therapeutic options have remained suboptimal. There are multiple challenges in designing a clinical therapeutic AKI trial, including a multi-factorial etiology, difficulties with accurate diagnosis of AKI, achievement of adequate study power, and determination of appropriate outcomes. We are often left with "supportive" care. Studies have shown some benefit to AKI bundles, but adherence to bundle guidelines may be suboptimal. Current best practices should include maintenance of adequate renal perfusion pressure and avoidance of fluid overload, with consideration of early renal replacement therapy. Finally, multi-center trials of AKI therapies are crucial to finding treatment for this devastating complication of CPB.

Nephrotoxin exposure and acute kidney injury in critically ill children undergoing congenital cardiac surgery

BACKGROUND

Though acute kidney injury (AKI) is often multifactorial, investigators are now emphasizing the specific contribution of nephrotoxins. This study examines the epidemiology of nephrotoxin exposure and nephrotoxin-associated AKI among children undergoing congenital heart surgery (CHS).

METHODS

This is a retrospective cohort study of children admitted following CHS between June 1, 2014, and September 30, 2014. Nephrotoxins were defined according to the Nephrotoxic Injury Negated by Just-in-time-Action (NINJA) collaborative; high nephrotoxin exposure was defined as receipt of ≥ 3 nephrotoxins concurrently. AKI was diagnosed according to KDIGO creatinine criteria. Severe AKI was defined as KDIGO stage ≥ 2. Poisson models were used to compute adjusted relative risk (aRR) of high nephrotoxin exposure for AKI.

RESULTS

One hundred fifty-four children (median age 20.4 months, IQR 2.3-59.5) were included. One hundred thirty-one (85.1%) received at least one nephrotoxin; 32 (20.8%) received ≥ 3 nephrotoxins. The most commonly administered medications were ketorolac (n = 74, 48.1%), aspirin (n = 62, 40.3%), ibuprofen (n = 51, 33.1%), vancomycin (n = 39, 25.3%), piperacillin/tazobactam (n = 35, 22.7%), and enalapril (n = 14, 9.1%). AKI occurred more commonly in those exposed to ≥ 3 nephrotoxins (62.5 vs. 50.8%); this was not statistically significant after adjusting for confounders (aRR = 1.2, 95% CI 0.9-1.7). Severe AKI was similar between those with and without high nephrotoxin exposure (21.9 vs. 19.7%, p = 0.78).

CONCLUSIONS

Nephrotoxin use is common following pediatric CHS. While we found no association between high nephrotoxin exposure and AKI, this may be related to the multifactorial nature of AKI in this population. For many common nephrotoxins, less injurious agents exist and nephrotoxin exposure may represent a modifiable risk factor for AKI.

The Impact of the Left Ventricle on Right Ventricular Function and Clinical Outcomes in Infants with Single-Right Ventricle Anomalies up to 14 Months of Age

BACKGROUND

Children with single-right ventricle anomalies such as hypoplastic left heart syndrome (HLHS) have left ventricles of variable size and function. The impact of the left ventricle on the performance of the right ventricle and on survival remains unclear. The aim of this study was to identify whether left ventricular (LV) size and function influence right ventricular (RV) function and clinical outcome after staged palliation for single-right ventricle anomalies.

METHODS

In the Single Ventricle Reconstruction trial, echocardiography-derived measures of LV size and function were compared with measures of RV systolic and diastolic function, tricuspid regurgitation, and outcomes (death and/or heart transplantation) at baseline (preoperatively), early after Norwood palliation, before stage 2 palliation, and at 14 months of age.

RESULTS

Of the 522 subjects who met the study inclusion criteria, 381 (73%) had measurable left ventricles. The HLHS subtype of aortic atresia/mitral atresia was significantly less likely to have a measurable left ventricle (41%) compared with the other HLHS subtypes: aortic stenosis/mitral stenosis (100%), aortic atresia/mitral stenosis (96%), and those without HLHS (83%). RV end-diastolic and end-systolic volumes were significantly larger, while diastolic indices suggested better diastolic properties in those subjects with no left ventricles compared with those with measurable left ventricles. However, RV ejection fraction was not different on the basis of LV size and function after staged palliation. Moreover, there was no difference in transplantation-free survival to Norwood discharge, through the interstage period, or at 14 months of age between those subjects who had measurable left ventricles compared with those who did not.

CONCLUSIONS

LV size varies by anatomic subtype in infants with single-right ventricle anomalies. Although indices of RV size and diastolic function were influenced by the presence of a left ventricle, there was no difference in RV systolic function or transplantation-free survival on the basis of LV measures.

Association of dead space ventilation and prolonged ventilation after repair of tetralogy of Fallot with pulmonary atresia

BACKGROUND

We set out to determine whether patients with tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral arteries (TOF/PA/MAPCA) are at risk for elevated dead space ventilation fraction (VD/VT), and whether this is associated with prolonged mechanical ventilation. We hypothesized that elevated VD/VT (>20%) in the first 24 hours after unifocalization surgery is associated with increased risk for prolonged mechanical ventilation (>7 days).

METHODS

All patients with TOF/PA/MAPCA undergoing unifocalization surgery between January 2003 and December 2015 were included in this study. Average VD/VT was calculated over the first 24 hours after surgery. Demographic and surgical data were collected. Outcome data included duration of mechanical ventilation. Patients were separated into 2 groups: elevated VD/VT and normal DVSF. Groups were compared using the Student t test, Wilcoxon rank-sum test, and χ² test. Univariable and multivariable regression analyses were performed with VD/VT as a continuous variable to test for association.

RESULTS

Of the 265 included patients, 127 (48%) had an elevated VD/VT. The 2 groups did not differ significantly in any demographic characteristic. Patients with an elevated VD/VT had longer cardiopulmonary bypass times (P = .03), were more likely to have delayed sternal closure, and more likely to have prolonged respiratory failure (odds ratio, 2.2; 95% confidence interval, 1.2-4.0; P = .007). The percent VD/VT was associated with duration of mechanical ventilation in univariable (P < .001) and multivariable (P < .001) regression analyses when controlled for age, weight and bypass time.

CONCLUSIONS

Elevated postoperative VD/VT is associated with prolonged mechanical ventilation in patients with TOF/PA/MAPCA following unifocalization. Elevated postoperative VD/VT may be an early indicator of patients who will require prolonged duration of mechanical ventilation, allowing optimization of medical management to promote better outcomes.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

Acute kidney injury and fluid overload in infants and children after cardiac surgery

Acute kidney injury is a common and serious complication after congenital heart surgery, particularly among infants. This comorbidity has been independently associated with adverse outcomes including an increase in mortality. Postoperative acute kidney injury has a complex pathophysiology with many risk factors, and therefore no single medication or therapy has been demonstrated to be effective for treatment or prevention. However, it has been established that the associated fluid overload is one of the major determinants of morbidity, particularly in infants after cardiac surgery. Therefore, in the absence of an intervention to prevent acute kidney injury, much of the effort to improve outcomes has focused on treating and preventing fluid overload. Early renal replacement therapy, often in the form of peritoneal dialysis, has been shown to be safe and beneficial in infants with oliguria after heart surgery. As understanding of the pathophysiology of acute kidney injury and the ability to confidently diagnose it earlier continues to evolve, it is likely that novel preventative and therapeutic interventions will be available in the future.

Development of quality metrics for ambulatory pediatric cardiology: Infection prevention

INTRODUCTION

In 2012, the American College of Cardiology's (ACC) Adult Congenital and Pediatric Cardiology Council established a program to develop quality metrics to guide ambulatory practices for pediatric cardiology. The council chose five areas on which to focus their efforts; chest pain, Kawasaki Disease, tetralogy of Fallot, transposition of the great arteries after arterial switch, and infection prevention. Here, we sought to describe the process, evaluation, and results of the Infection Prevention Committee's metric design process.

METHODS

The infection prevention metrics team consisted of 12 members from 11 institutions in North America. The group agreed to work on specific infection prevention topics including antibiotic prophylaxis for endocarditis, rheumatic fever, and asplenia/hyposplenism; influenza vaccination and respiratory syncytial virus prophylaxis (palivizumab); preoperative methods to reduce intraoperative infections; vaccinations after cardiopulmonary bypass; hand hygiene; and testing to identify splenic function in patients with heterotaxy. An extensive literature review was performed. When available, previously published guidelines were used fully in determining metrics.

RESULTS

The committee chose eight metrics to submit to the ACC Quality Metric Expert Panel for review. Ultimately, metrics regarding hand hygiene and influenza vaccination recommendation for patients did not pass the RAND analysis. Both endocarditis prophylaxis metrics and the RSV/palivizumab metric passed the RAND analysis but fell out during the open comment period. Three metrics passed all analyses, including those for antibiotic prophylaxis in patients with heterotaxy/asplenia, for influenza vaccination compliance in healthcare personnel, and for adherence to recommended regimens of secondary prevention of rheumatic fever.

CONCLUSIONS

The lack of convincing data to guide quality improvement initiatives in pediatric cardiology is widespread, particularly in infection prevention. Despite this, three metrics were able to be developed for use in the ACC's quality efforts for ambulatory practice.

Peritoneal Dialysis vs Furosemide for Prevention of Fluid Overload in Infants After Cardiac Surgery: A Randomized Clinical Trial

IMPORTANCE

Fluid overload after congenital heart surgery is frequent and a major cause of morbidity and mortality among infants. Many programs have adopted the use of peritoneal dialysis (PD) for fluid management; however, its benefits compared with those of traditional diuretic administration are unknown.

OBJECTIVE

To determine whether infants randomized to PD vs furosemide for the treatment of oliguria have a higher incidence of negative fluid balance on postoperative day 1, as well as avoidance of 10% fluid overload; shorter duration of mechanical ventilation, intensive care unit stay, and inotrope use; and fewer electrolyte abnormalities.

DESIGN, SETTING, AND PARTICIPANTS

This single-center, unblinded, randomized clinical trial compared methods of fluid removal after cardiac surgery from October 1, 2011, through March 13, 2015, in a large tertiary pediatric hospital in Ohio. The parents or guardians of all eligible infants (aged <6 months) undergoing cardiac surgery with catheter placement for PD were approached for inclusion. No patients were withdrawn for adverse effects. Recruitment was powered for the primary outcome, and analysis was based on intention to treat. Patients randomized to PD were hypothesized to have superior outcomes.

INTERVENTIONS

Infants received intravenous furosemide (1 mg/kg every 6 hours) or a standardized PD regimen.

MAIN OUTCOMES AND MEASURES

The primary end point was incidence of negative fluid balance on postoperative day 1. Secondary end points included incidence of fluid overload, duration of mechanical ventilation and intensive care unit stay, electrolyte abnormalities and repletion doses, duration of inotropic administration, and mortality.

RESULTS

Seventy-three patients (47 boys [64%] and 26 girls [35%]; median age, 8 [interquartile range (IQR), 6-14] days) received treatment and completed the trial. No difference was found between the PD and furosemide groups in the incidence of negative fluid balance on the first postoperative day. The furosemide group was 3 times more likely to have 10% fluid overload (odds ratio [OR], 3.0; 95% CI, 1.3-6.9), was more likely to have prolonged ventilator use (OR, 3.1; 95% CI, 1.2-8.2), and had a longer duration of inotrope use (median, 5.5 [IQR, 4-8] vs 4.0 [IQR, 3-6] days) and higher electrolyte abnormality scores (median, 6 [IQR, 4-7] vs 3 [IQR, 2-5]) compared with the PD group. No statistically significant differences in mortality (3 patients [9.4%] in the furosemide group vs 1 patient [3.1%] in the PD group) or length of cardiac intensive care unit (median, 7 [IQR, 6-12] vs 9 [IQR, 5-15] days) or hospital (15 [IQR, 10-28] vs 14 [IQR, 9-22] days) stay were observed. No serious complications were observed. Dialysis was discontinued early in 9 of 41 patients in the PD group for pleural-peritoneal communication.

CONCLUSIONS AND RELEVANCE

Use of PD is safe and allows for superior fluid management with improved clinical outcomes compared with diuretic administration. Use of PD should be strongly considered among infants at high risk for postoperative acute kidney injury and fluid overload.

TRIAL REGISTRATION

clinicaltrials.gov Identifer: NCT01709227.

Advances in Pediatric Cardiology Boot Camp: Boot Camp Training Promotes Fellowship Readiness and Enables Retention of Knowledge

We previously demonstrated that a pediatric cardiology boot camp can improve knowledge acquisition and decrease anxiety for trainees. We sought to determine if boot camp participants entered fellowship with a knowledge advantage over fellows who did not attend and if there was moderate-term retention of that knowledge. A 2-day training program was provided for incoming pediatric cardiology fellows from eight fellowship programs in April 2016. Hands-on, immersive experiences and simulations were provided in all major areas of pediatric cardiology. Knowledge-based examinations were completed by each participant prior to boot camp (PRE), immediately post-training (POST), and prior to the start of fellowship in June 2016 (F/U). A control group of fellows who did not attend boot camp also completed an examination prior to fellowship (CTRL). Comparisons of scores were made for individual participants and between participants and controls. A total of 16 participants and 16 control subjects were included. Baseline exam scores were similar between participants and controls (PRE 47 ± 11% vs. CTRL 52 ± 10%; p = 0.22). Participants' knowledge improved with boot camp training (PRE 47 ± 11% vs. POST 70 ± 8%; p < 0.001) and there was excellent moderate-term retention of the information taught at boot camp (PRE 47 ± 11% vs. F/U 71 ± 8%; p < 0.001). Testing done at the beginning of fellowship demonstrated significantly better scores in participants versus controls (F/U 71 ± 8% vs. CTRL 52 ± 10%; p < 0.001). Boot camp participants demonstrated a significant improvement in basic cardiology knowledge after the training program and had excellent moderate-term retention of that knowledge. Participants began fellowship with a larger fund of knowledge than those fellows who did not attend.

The Kidney in Critical Cardiac Disease: Proceedings From the 10th International Conference of the Pediatric Cardiac Intensive Care Society

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The focus of intensive care unit care has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating the care of both postoperative patients and those with heart failure. Patients who become fluid overloaded and/or require dialysis are at high risk of mortality, but even minor degrees of AKI portend a significant increase in mortality and morbidity. Clinicians continue to seek methods of early diagnosis and risk stratification of AKI to prevent its adverse sequelae. Previous conventional wisdom that survivors of AKI fully recover renal function without subsequent consequences may be flawed.

Initial Observations of the Effects of Calcium Chloride Infusions in Pediatric Patients with Low Cardiac Output

Myocardial contractility and relaxation are highly dependent on calcium homeostasis. Immature myocardium, as in pediatric patients, is thought to be more dependent on extracellular calcium for optimal function. For this reason, intravenous calcium chloride infusions may improve myocardial function in the pediatric patient. The objectives of this study were to report the hemodynamic changes seen after administration of continuous calcium chloride to critically ill children. We retrospectively identified pediatric patients (newborn to 17 years old) with hemodynamic instability admitted to the cardiac ICU between May 2011 and May 2012 who received a continuous infusion of calcium chloride. The primary outcome was improvement in cardiac output, assessed by arterial-mixed venous oxygen saturation (A-V) difference. Sixty-eight patients, mean age 0.87 ± 2.67 years, received a total of 116 calcium infusions. Calcium chloride infusions resulted in significant improvements in primary and secondary measures of cardiac output at 2 and 6 h. Six hours after calcium initiation, A-V oxygen saturation difference decreased by 7.4 % (32.6 ± 2.1 to 25.2 ± 2.0 %, p < 0.001), rSO2 increased by 5.5 % (63.1 vs 68.6 %, p < 0.001), and serum lactate decreased by 0.9 mmol/l (3.3 vs 2.4 mmol/l, p < 0.001) with no change in HR (149.1 vs 145.6 bpm p = 0.07). Urine output increased 0.66 ml/kg/h in the 8-h period after calcium initiation when compared to pre-initiation (p = 0.003). Neonates had the strongest evidence of effectiveness with other age groups trending toward significance. Calcium chloride infusions improve markers of cardiac output in a heterogenous group of pediatric patients in a cardiac ICU. Neonates appear to derive the most benefit from utilization of these infusions.

Follow-Up Renal Assessment of Injury Long-Term After Acute Kidney Injury (FRAIL-AKI)

BACKGROUND AND OBJECTIVES

Novel urinary kidney damage biomarkers detect AKI after cardiac surgery using cardiopulmonary bypass (CPB-AKI). Although there is growing focus on whether AKI leads to CKD, no studies have assessed whether novel urinary biomarkers remain elevated long term after CPB-AKI. We assessed whether there was clinical or biomarker evidence of long-term kidney injury in patients with CPB-AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a cross-sectional evaluation for signs of chronic kidney injury using both traditional measures and novel urinary biomarkers in a population of 372 potentially eligible children (119 AKI positive and 253 AKI negative) who underwent surgery using cardiopulmonary bypass for congenital heart disease at Cincinnati Children's Hospital Medical Center between 2004 and 2007. A total of 51 patients (33 AKI positive and 18 AKI negative) agreed to long-term assessment. We also compared the urinary biomarker levels in these 51 patients with those in healthy controls of similar age.

RESULTS

At long-term follow-up (mean duration±SD, 7±0.98 years), AKI-positive and AKI-negative patients had similarly normal assessments of kidney function by eGFR, proteinuria, and BP measurement. However, AKI-positive patients had higher urine concentrations of IL-18 (48.5 pg/ml versus 20.3 pg/ml [P=0.01] and 20.5 pg/ml [P<0.001]) and liver-type fatty acid-binding protein (L-FABP) (5.9 ng/ml versus 3.9 ng/ml [P=0.001] and 3.2 ng/ml [P<0.001]) than did AKI-negative patients and healthy controls.

CONCLUSIONS

Novel urinary biomarkers remain elevated 7 years after an episode of CPB-AKI in children. However, there is no conventional evidence of CKD in these children. These biomarkers may be a more sensitive marker of chronic kidney injury after CPB-AKI. Future studies are needed to understand the clinical relevance of persistent elevations in IL-18, kidney injury molecule-1, and L-FABP in assessments for potential long-term kidney consequences of CPB-AKI.

Association of definition of acute kidney injury by cystatin C rise with biomarkers and clinical outcomes in children undergoing cardiac surgery

IMPORTANCE

Research has identified improved biomarkers of acute kidney injury (AKI). Cystatin C (CysC) is a better glomerular filtration rate marker than serum creatinine (SCr) and may improve AKI definition.

OBJECTIVE

To determine if defining clinical AKI by increases in CysC vs SCr alters associations with biomarkers and clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Three-center prospective cohort study of intensive care units in New Haven, Connecticut, Cincinnati, Ohio, and Montreal, Quebec, Canada. Participants were 287 patients 18 years or younger without preoperative AKI or end-stage renal disease who were undergoing cardiac surgery. The study dates were July 1, 2007, through December 31, 2009.

EXPOSURES

For biomarker vs clinical AKI associations, the exposures were first postoperative (0-6 hours after surgery) urine interleukin 18, neutrophil gelatinase-associated lipocalin, kidney injury molecule 1, and liver fatty acid-binding protein. For clinical AKI outcome associations, the exposure was Kidney Disease: Improving Global Outcomes AKI definition (based on SCr or CysC).

MAIN OUTCOMES AND MEASURES

Clinical AKI, length of stay, and length of mechanical ventilation. We determined areas under the receiver operating characteristic curve and odds ratios for first postoperative biomarkers to predict AKI.

RESULTS

The SCr-defined vs CysC-defined AKI incidence differed substantially (43.6% vs 20.6%). Percentage agreement was 71% (κ = 0.38); stage 2 or worse AKI percentage agreement was 95%. Interleukin 18 and kidney injury molecule 1 discriminated for CysC-defined AKI better than for SCr-defined AKI. For interleukin 18 and kidney injury molecule 1, the areas under the receiver operating characteristic curve were 0.74 and 0.65, respectively, for CysC-defined AKI, and 0.66 and 0.58, respectively, for SCr-defined AKI. Fifth (vs first) quintile concentrations of both biomarkers were more strongly associated with CysC-defined AKI. For interleukin 18 and kidney injury molecule 1, the odds ratios were 16.19 (95% CI, 3.55-73.93) and 6.93 (95% CI, 1.88-25.59), respectively, for CysC-defined AKI vs 6.60 (95% CI, 2.76-15.76) and 2.04 (95% CI, 0.94-4.38), respectively, for SCr-defined AKI. Neutrophil gelatinase-associated lipocalin and liver fatty acid-binding protein associations with both definitions were similar. The CysC definitions and SCr definitions were similarly associated with clinical outcomes of resource use.

CONCLUSIONS AND RELEVANCE

Compared with the SCr-based definition, the CysC-based definition is more strongly associated with urine interleukin 18 and kidney injury molecule 1 in children undergoing cardiac surgery. Consideration should be made for defining AKI based on CysC in clinical care and future studies.

Long-term Stability of Urinary Biomarkers of Acute Kidney Injury in Children

BACKGROUND

Recent meta-analyses support the utility of urinary biomarkers for the diagnosis and prognosis of acute kidney injury. It is critical to establish optimal sample handling conditions for short-term processing and long-term urinary storage prior to widespread clinical deployment and meaningful use in prospective clinical trials.

STUDY DESIGN

Prospective study.

SETTING & PARTICIPANTS

80 children (median age, 1.1 [IQR, 0.5-4.2] years) undergoing cardiac surgery with cardiopulmonary bypass at our center. 50% of patients had acute kidney injury (defined as ≥50% increase in serum creatinine from baseline).

PREDICTORS

We tested the effect on biomarker concentrations of short-term urine storage in ambient, refrigerator, and freezer conditions. We also tested the effects of multiple freeze-thaw cycles, as well as prolonged storage for 5 years.

OUTCOMES

Urine concentrations of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), and interleukin 18 (IL-18).

MEASUREMENTS

All biomarkers were measured using commercially available kits.

RESULTS

All 3 biomarkers were stable in urine stored at 4°C for 24 hours, but showed significant degradation (5.6%-10.1% from baseline) when stored at 25°C. All 3 biomarkers showed only a small although significant decrease in concentration (0.77%-2.9% from baseline) after 3 freeze-thaw cycles. Similarly, all 3 biomarkers displayed only a small but significant decrease in concentration (0.84%-3.2%) after storage for 5 years.

LIMITATIONS

Only the 3 most widely studied biomarkers were tested. Protease inhibitors were not evaluated.

CONCLUSIONS

Short-term storage of urine samples for measurement of NGAL, KIM-1, and IL-18 may be performed at 4°C for up to 24 hours, but not at room temperature. These urinary biomarkers are stable at -80°C for up to 5 years of storage. Our results are reassuring for the deployment of these assays as biomarkers in clinical practice, as well as in prospective clinical studies requiring long-term urine storage.

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.

Combining functional and tubular damage biomarkers improves diagnostic precision for acute kidney injury after cardiac surgery

BACKGROUND

Increases in serum creatinine (ΔSCr) from baseline signify acute kidney injury (AKI) but offer little granular information regarding its characteristics. The 10th Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) suggested that combining AKI biomarkers would provide better precision for AKI course prognostication.

OBJECTIVES

This study investigated the value of combining a functional damage biomarker (plasma cystatin C [pCysC]) with a tubular damage biomarker (urine neutrophil gelatinase-associated lipocalin [uNGAL]), forming a composite biomarker for prediction of discrete characteristics of AKI.

METHODS

Data from 345 children after cardiopulmonary bypass (CPB) were analyzed. Severe AKI was defined as Kidney Disease Global Outcomes Initiative stages 2 to 3 (≥100% ΔSCr) within 7 days of CPB. Persistent AKI lasted >2 days. SCr in reversible AKI returned to baseline ≤48 h after CPB. The composite of uNGAL (>200 ng/mg urine Cr = positive [+]) and pCysC (>0.8 mg/l = positive [+]), uNGAL+/pCysC+, measured 2 h after CPB initiation, was compared to ΔSCr increases of ≥50% for correlation with AKI characteristics by using predictive probabilities, likelihood ratios (LR), and area under the curve receiver operating curve (AUC-ROC) values [Corrected].

RESULTS

Severe AKI occurred in 18% of patients. The composite uNGAL+/pCysC+ demonstrated a greater likelihood than ΔSCr for severe AKI (+LR: 34.2 [13.0:94.0] vs. 3.8 [1.9:7.2]) and persistent AKI (+LR: 15.6 [8.8:27.5] versus 4.5 [2.3:8.8]). In AKI patients, the uNGAL-/pCysC+ composite was superior to ΔSCr for prediction of transient AKI. Biomarker composites carried greater probability for specific outcomes than ΔSCr strata.

CONCLUSIONS

Composites of functional and tubular damage biomarkers are superior to ΔSCr for predicting discrete characteristics of AKI.

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.

Transplantation-free survival and interventions at 3 years in the single ventricle reconstruction trial

BACKGROUND

In the Single Ventricle Reconstruction (SVR) trial, 1-year transplantation-free survival was better for the Norwood procedure with right ventricle-to-pulmonary artery shunt (RVPAS) compared with a modified Blalock-Taussig shunt (MBTS). At 3 years, we compared transplantation-free survival, echocardiographic right ventricular ejection fraction, and unplanned interventions in the treatment groups.

METHODS AND RESULTS

Vital status and medical history were ascertained from annual medical records, death indexes, and phone interviews. The cohort included 549 patients randomized and treated in the SVR trial. Transplantation-free survival for the RVPAS versus MBTS groups did not differ at 3 years (67% versus 61%; P=0.15) or with all available follow-up of 4.8±1.1 years (log-rank P=0.14). Pre-Fontan right ventricular ejection fraction was lower in the RVPAS group than in the MBTS group (41.7±5.1% versus 44.7±6.0%; P=0.007), and right ventricular ejection fraction deteriorated in RVPAS (P=0.004) but not MBTS (P=0.40) subjects (pre-Fontan minus 14-month mean, -3.25±8.24% versus 0.99±8.80%; P=0.009). The RVPAS versus MBTS treatment effect had nonproportional hazards (P=0.004); the hazard ratio favored the RVPAS before 5 months (hazard ratio=0.63; 95% confidence interval, 0.45-0.88) but the MBTS beyond 1 year (hazard ratio=2.22; 95% confidence interval, 1.07-4.62). By 3 years, RVPAS subjects had a higher incidence of catheter interventions (P<0.001) with an increasing HR over time (P=0.005): <5 months, 1.14 (95% confidence interval, 0.81-1.60); from 5 months to 1 year, 1.94 (95% confidence interval, 1.02-3.69); and >1 year, 2.48 (95% confidence interval, 1.28-4.80).

CONCLUSIONS

By 3 years, the Norwood procedure with RVPAS compared with MBTS was no longer associated with superior transplantation-free survival. Moreover, RVPAS subjects had slightly worse right ventricular ejection fraction and underwent more catheter interventions with increasing hazard ratio over time.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Acute kidney injury and critical cardiac disease

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The survival of patients with critical congenital heart disease is seldom in question. Consequently, the focus has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating 30% to 40% of adult and pediatric cardiac surgeries. Patients who require dialysis are at high risk of mortality, but even minor degrees of postoperative AKI portend a significant increase in mortality and morbidity.

Developing a heart institute: the execution of a strategic plan

The Heart Institute at Cincinnati Children's Hospital Medical Center was chartered in July 2008 with the purpose of integrating clinical cardiovascular medicine with basic science research to foster innovations in care of patients with congenital heart problems. The initial administrative steering committee included representation from a basic scientist, a cardiologist, and a cardiothoracic surgeon and was charged with the development of a strategic plan for the evolution of the Institute over a five-year horizon. Using structured focus groups and staff interviews, the vision, mission, and goals were identified and refined. An integrated implementation plan addressing recruitment, capitalization, infrastructure, and market opportunities was created and executed. The preliminary results demonstrated clinical outcome improvements, increased scientific and academic productivity, and financial sustainability. All of the goals identified in the initial planning sequence were achieved within the five-year time frame, prompting an early evaluation and revision of the strategic plan.

Performance of kidney injury molecule-1 and liver fatty acid-binding protein and combined biomarkers of AKI after cardiac surgery

BACKGROUND AND OBJECTIVES

AKI is common and novel biomarkers may help provide earlier diagnosis and prognosis of AKI in the postoperative period.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective, multicenter cohort study involving 1219 adults and 311 children consecutively enrolled at eight academic medical centers. Performance of two urine biomarkers, kidney injury molecule-1 (KIM-1) and liver fatty acid-binding protein (L-FABP), alone or in combination with other injury biomarkers during the perioperative period was evaluated. AKI was defined as doubling of serum creatinine or need for acute dialysis.

RESULTS

KIM-1 peaked 2 days after surgery in adults and 1 day after surgery in children, whereas L-FABP peaked within 6 hours after surgery in both age groups. In multivariable analyses, the highest quintile of the first postoperative KIM-1 level was associated with AKI compared with the lowest quintile in adults, whereas the first postoperative L-FABP was not associated with AKI. Both KIM-1 and L-FABP were not significantly associated with AKI in adults or children after adjusting for other kidney injury biomarkers (neutrophil gelatinase-associated lipocalin and IL-18). The highest area under the curves achievable for discrimination for AKI were 0.78 in adults using urine KIM-1 from 6 to 12 hours, urine IL-18 from day 2, and plasma neutrophil gelatinase-associated lipocalin from day 2 and 0.78 in children using urine IL-18 from 0 to 6 hours and urine L-FABP from day 2.

CONCLUSIONS

Postoperative elevations of KIM-1 associate with AKI and adverse outcmes in adults but were not independent of other AKI biomarkers. A panel of multiple biomarkers provided moderate discrimination for AKI.

Semaphorin 3A is a new early diagnostic biomarker of experimental and pediatric acute kidney injury

BACKGROUND

Semaphorin 3A is a secreted protein that regulates cell motility and attachment in axon guidance, vascular growth, immune cell regulation and tumor progression. However, nothing is known about its role in kidney pathophysiology. Here, we determined whether semaphorin3A is induced after acute kidney injury (AKI) and whether urinary semaphorin 3A can predict AKI in humans undergoing cardiopulmonary bypass (CPB).

METHODS AND PRINCIPAL FINDINGS

In animals, semaphorin 3A is localized in distal tubules of the kidney and excretion increased within 3 hr after reperfusion of the kidney whereas serum creatinine was significantly raised at 24 hr. In humans, using serum creatinine, AKI was detected on average only 48 hours after CPB. In contrast, urine semaphorin increased at 2 hours after CPB, peaked at 6 hours (2596±591 pg/mg creatinine), and was no longer significantly elevated 12 hours after CPB. The predictive power of semaphorin 3A as demonstrated by area under the receiver-operating characteristic curve for diagnosis of AKI at 2, 6, and 12 hours after CPB was 0.88, 0.81, and 0.74, respectively. The 2-hour urine semaphorin measurement strongly correlated with duration and severity of AKI, as well as length of hospital stay. Adjusting for CPB time and gender, the 2-hour semaphorin remained an independent predictor of AKI, with an odds ratio of 2.19.

CONCLUSION

Our results suggest that semaphorin 3A is an early, predictive biomarker in experimental and pediatric AKI, and may allow for the reliable early diagnosis and prognosis of AKI after CPB, much before the rise in serum creatinine.

Biomarkers of acute kidney injury in pediatric cardiac patients

Acute kidney injury is a common and significant complication among pediatric patients with congenital heart disease, occurring most commonly after cardiopulmonary bypass. Current laboratory methods of diagnosis are not timely enough to guide management decisions, thus spurring interest in discovering new biomarkers of acute injury. Several promising candidates, including NGAL, IL-18 and KIM-1, have been the subject of recent investigation and may facilitate earlier and more accurate diagnosis of renal injury within this cohort. There is little evidence demonstrating that it will be possible to rely upon one particular biomarker as a single agent, and evidence supports that the use of biomarker panels will be most effective. Further clinical validation and broader commercial availability of these novel biomarkers will probably revolutionize the care of pediatric cardiac patients with renal injury.

The association of albumin/creatinine ratio with postoperative AKI in children undergoing cardiac surgery

BACKGROUND AND OBJECTIVES

This study determined if preoperative and postoperative urine albumin/creatinine ratios (ACRs) predict postoperative AKI in children undergoing cardiac surgery (CS).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a three-center, prospective study (2007-2009) of 294 children undergoing CS (n=145 aged <2 years). Urine ACR was measured preoperatively and 0-6 hours after intensive care unit arrival. AKI outcomes were based on the Acute Kidney Injury Network serum creatinine (SCr) criteria (stage 1 AKI, ≥50% or 0.3 mg/dl SCr rise from baseline; and stage 2 or worse AKI, ≥SCr doubling or dialysis). AKI was predicted using preoperative and postoperative ACRs and postoperative ACR performance was compared with other AKI biomarkers.

RESULTS

Preoperative ACR did not predict AKI in younger or older children. In children aged <2 years, first postoperative ACR ≥908 mg/g (103 mg/mmol) predicted stage 2 AKI development (adjusted relative risk, 3.4; 95% confidence interval, 1.2-9.4). In children aged ≥2 years, postoperative ACR ≥169 mg/g (19.1 mg/mmol) predicted stage 1 AKI (adjusted relative risk, 2.1; 95% confidence interval, 1.1-4.1). In children aged ≥2 years, first postoperative ACR improved AKI prediction from other biomarker and clinical prediction models, estimated by net reclassification improvement (P≤0.03), but only when serum cystatin C was also included in the model.

CONCLUSIONS

Postoperative ACR is a readily available early diagnostic test for AKI after pediatric CS that performs similarly to other AKI biomarkers; however, its use is enhanced in children aged ≥2 years and in combination with serum cystatin C.

Temporal relationship and predictive value of urinary acute kidney injury biomarkers after pediatric cardiopulmonary bypass

OBJECTIVES

We investigated the temporal pattern and predictive value (alone and in combination) of 4 urinary biomarkers (neutrophil gelatinase-associated lipocalin [NGAL], interleukin [IL]-18, liver fatty acid-binding protein [L-FABP], and kidney injury molecule [KIM]-1) for cardiac surgery-associated acute kidney injury (AKI).

BACKGROUND

Serum creatinine (S(Cr)) is a delayed marker for AKI after cardiopulmonary bypass (CPB). Rapidly detectable AKI biomarkers could allow early intervention and improve outcomes.

METHODS

Data from 220 pediatric patients were analyzed. Urine samples were obtained before and at intervals after CPB initiation. AKI was defined as a ≥50% increase in S(Cr) from baseline within 48 h after CPB. The temporal pattern of biomarker elevation was established, and biomarker elevations were correlated with AKI severity and clinical outcomes. Biomarker predictive abilities were evaluated by area under the curve (AUC), net reclassification improvement, and integrated discrimination improvement.

RESULTS

AKI occurred in 27% of patients. Urine NGAL significantly increased in AKI patients at 2 h after CPB initiation. IL-18 and L-FABP increased at 6 h, and KIM-1 increased at 12 h. Biomarker elevations were correlated with AKI severity and clinical outcomes and improved AKI prediction above a clinical model. At 2 h, addition of NGAL increased the AUC from 0.74 to 0.85 (p < 0.0001). At 6 h, NGAL, IL-18, and L-FABP each improved the AUC from 0.72 to 0.91, 0.84, and 0.77, respectively (all p < 0.05). The added predictive ability of the biomarkers was supported by net reclassification improvement and integrated discrimination improvement. Biomarker combinations further improved AKI prediction.

CONCLUSIONS

Urine NGAL, IL-18, L-FABP, and KIM-1 are sequential predictive biomarkers for AKI and are correlated with disease severity and clinical outcomes after pediatric CPB. These biomarkers, particularly in combination, may help establish the timing of injury and allow earlier intervention in AKI.

Postoperative biomarkers predict acute kidney injury and poor outcomes after pediatric cardiac surgery

Acute kidney injury (AKI) occurs commonly after pediatric cardiac surgery and associates with poor outcomes. Biomarkers may help the prediction or early identification of AKI, potentially increasing opportunities for therapeutic interventions. Here, we conducted a prospective, multicenter cohort study involving 311 children undergoing surgery for congenital cardiac lesions to evaluate whether early postoperative measures of urine IL-18, urine neutrophil gelatinase-associated lipocalin (NGAL), or plasma NGAL could identify which patients would develop AKI and other adverse outcomes. Urine IL-18 and urine and plasma NGAL levels peaked within 6 hours after surgery. Severe AKI, defined by dialysis or doubling in serum creatinine during hospital stay, occurred in 53 participants at a median of 2 days after surgery. The first postoperative urine IL-18 and urine NGAL levels strongly associated with severe AKI. After multivariable adjustment, the highest quintiles of urine IL-18 and urine NGAL associated with 6.9- and 4.1-fold higher odds of AKI, respectively, compared with the lowest quintiles. Elevated urine IL-18 and urine NGAL levels associated with longer hospital stay, longer intensive care unit stay, and duration of mechanical ventilation. The accuracy of urine IL-18 and urine NGAL for diagnosis of severe AKI was moderate, with areas under the curve of 0.72 and 0.71, respectively. The addition of these urine biomarkers improved risk prediction over clinical models alone as measured by net reclassification improvement and integrated discrimination improvement. In conclusion, urine IL-18 and urine NGAL, but not plasma NGAL, associate with subsequent AKI and poor outcomes among children undergoing cardiac surgery.

Postoperative biomarkers predict acute kidney injury and poor outcomes after adult cardiac surgery

Acute kidney injury (AKI) is a frequent complication of cardiac surgery and increases morbidity and mortality. The identification of reliable biomarkers that allow earlier diagnosis of AKI in the postoperative period may increase the success of therapeutic interventions. Here, we conducted a prospective, multicenter cohort study involving 1219 adults undergoing cardiac surgery to evaluate whether early postoperative measures of urine IL-18, urine neutrophil gelatinase-associated lipocalin (NGAL), or plasma NGAL could identify which patients would develop AKI and other adverse patient outcomes. Urine IL-18 and urine and plasma NGAL levels peaked within 6 hours after surgery. After multivariable adjustment, the highest quintiles of urine IL-18 and plasma NGAL associated with 6.8-fold and 5-fold higher odds of AKI, respectively, compared with the lowest quintiles. Elevated urine IL-18 and urine and plasma NGAL levels associated with longer length of hospital stay, longer intensive care unit stay, and higher risk for dialysis or death. The clinical prediction model for AKI had an area under the receiver-operating characteristic curve (AUC) of 0.69. Urine IL-18 and plasma NGAL significantly improved the AUC to 0.76 and 0.75, respectively. Urine IL-18 and plasma NGAL significantly improved risk prediction over the clinical models alone as measured by net reclassification improvement (NRI) and integrated discrimination improvement (IDI). In conclusion, urine IL-18, urine NGAL, and plasma NGAL associate with subsequent AKI and poor outcomes among adults undergoing cardiac surgery.