Catherine D. Krawczeski

Comparison of shunt types in the Norwood procedure for single-ventricle lesions.

BACKGROUND The Norwood procedure with a modified Blalock-Taussig (MBT) shunt, the first palliative stage for single-ventricle lesions with systemic outflow obstruction, is associated with high mortality. The right ventricle-pulmonary artery (RVPA) shunt may improve coronary flow but requires a ventriculotomy. We compared the two shunts in infants with hypoplastic heart syndrome or related anomalies. METHODS Infants undergoing the Norwood procedure were randomly assigned to the MBT shunt (275 infants) or the RVPA shunt (274 infants) at 15 North American centers. The primary outcome was death or cardiac transplantation 12 months after randomization. Secondary outcomes included unintended cardiovascular interventions and right ventricular size and function at 14 months and transplantation-free survival until the last subject reached 14 months of age. RESULTS Transplantation-free survival 12 months after randomization was higher with the RVPA shunt than with the MBT shunt (74% vs. 64%, P=0.01). However, the RVPA shunt group had more unintended interventions (P=0.003) and complications (P=0.002). Right ventricular size and function at the age of 14 months and the rate of nonfatal serious adverse events at the age of 12 months were similar in the two groups. Data collected over a mean (+/-SD) follow-up period of 32+/-11 months showed a nonsignificant difference in transplantation-free survival between the two groups (P=0.06). On nonproportional-hazards analysis, the size of the treatment effect differed before and after 12 months (P=0.02). CONCLUSIONS In children undergoing the Norwood procedure, transplantation-free survival at 12 months was better with the RVPA shunt than with the MBT shunt. After 12 months, available data showed no significant difference in transplantation-free survival between the two groups. (ClinicalTrials.gov number, NCT00115934.)

The Outcome of Neutrophil Gelatinase-Associated Lipocalin-Positive Subclinical Acute Kidney Injury: A Multicenter Pooled Analysis of Prospective Studies

OBJECTIVES The aim of this study was to test the hypothesis that, without diagnostic changes in serum creatinine, increased neutrophil gelatinase-associated lipocalin (NGAL) levels identify patients with subclinical acute kidney injury (AKI) and therefore worse prognosis. BACKGROUND Neutrophil gelatinase-associated lipocalin detects subclinical AKI hours to days before increases in serum creatinine indicate manifest loss of renal function. METHODS We analyzed pooled data from 2,322 critically ill patients with predominantly cardiorenal syndrome from 10 prospective observational studies of NGAL. We used the terms NGAL(-) or NGAL(+) according to study-specific NGAL cutoff for optimal AKI prediction and the terms sCREA(-) or sCREA(+) according to consensus diagnostic increases in serum creatinine defining AKI. A priori-defined outcomes included need for renal replacement therapy (primary endpoint), hospital mortality, their combination, and duration of stay in intensive care and in-hospital. RESULTS Of study patients, 1,296 (55.8%) were NGAL(-)/sCREA(-), 445 (19.2%) were NGAL(+)/sCREA(-), 107 (4.6%) were NGAL(-)/sCREA(+), and 474 (20.4%) were NGAL(+)/sCREA(+). According to the 4 study groups, there was a stepwise increase in subsequent renal replacement therapy initiation-NGAL(-)/sCREA(-): 0.0015% versus NGAL(+)/sCREA(-): 2.5% (odds ratio: 16.4, 95% confidence interval: 3.6 to 76.9, p < 0.001), NGAL(-)/sCREA(+): 7.5%, and NGAL(+)/sCREA(+): 8.0%, respectively, hospital mortality (4.8%, 12.4%, 8.4%, 14.7%, respectively) and their combination (4-group comparisons: all p < 0.001). There was a similar and consistent progressive increase in median number of intensive care and in-hospital days with increasing biomarker positivity: NGAL(-)/sCREA(-): 4.2 and 8.8 days; NGAL(+)/sCREA(-): 7.1 and 17.0 days; NGAL(-)/sCREA(+): 6.5 and 17.8 days; NGAL(+)/sCREA(+): 9.0 and 21.9 days; 4-group comparisons: p = 0.003 and p = 0.040, respectively. Urine and plasma NGAL indicated a similar outcome pattern. CONCLUSIONS In the absence of diagnostic increases in serum creatinine, NGAL detects patients with likely subclinical AKI who have an increased risk of adverse outcomes. The concept and definition of AKI might need re-assessment.

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.

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.

Incidence, risk factors, and outcomes of acute kidney injury after pediatric cardiac surgery – a prospective multicenter study

Objective: To determine the incidence, severity, and risk factors of acute kidney injury in children undergoing cardiac surgery for congenital heart defects. Design: Prospective observational multicenter cohort study. Setting: Three pediatric intensive care units at academic centers. Patients: Three hundred eleven children between the ages of 1 month and 18 yrs undergoing pediatric cardiac surgery. Interventions: None. Measurements and Main Results: Acute kidney injury was defined as a ≥50% increase in serum creatinine from the preoperative value. Secondary outcomes were length of mechanical ventilation, length of intensive care unit and hospital stays, acute dialysis, and in-hospital mortality. The cohort had an average age of 3.8 yrs and was 45% women and mostly white (82%). One-third had prior cardiothoracic surgery, 91% of the surgeries were elective, and almost all patients required cardiopulmonary bypass. Acute kidney injury occurred in 42% (130 patients) within 3 days after surgery. Children ≥2 yrs old and <13 yrs old had a 72% lower likelihood of acute kidney injury (adjusted odds ratio: 0.28, 95% confidence interval: 0.16, 0.48), and patients 13 yrs and older had 70% lower likelihood of acute kidney injury (adjusted odds ratio: 0.30, 95% confidence interval: 0.10, 0.88) compared to patients <2 yrs old. Longer cardiopulmonary bypass time was linearly and independently associated with acute kidney injury. The development of acute kidney injury was independently associated with prolonged ventilation and with increased length of hospital stay. Conclusions: Acute kidney injury is common after pediatric cardiac surgery and is associated with prolonged mechanical ventilation and increased hospital stay. Cardiopulmonary bypass time and age were independently associated with acute kidney injury risk. Cardiopulmonary bypass time may be a marker for case complexity.

Early Developmental Outcome in Children With Hypoplastic Left Heart Syndrome and Related Anomalies The Single Ventricle Reconstruction Trial

Background— Survivors of the Norwood procedure may experience neurodevelopmental impairment. Clinical trials to improve outcomes have focused primarily on methods of vital organ support during cardiopulmonary bypass. Methods and Results— In the Single Ventricle Reconstruction trial of the Norwood procedure with modified Blalock-Taussig shunt versus right-ventricle-to-pulmonary-artery shunt, 14-month neurodevelopmental outcome was assessed by use of the Psychomotor Development Index (PDI) and Mental Development Index (MDI) of the Bayley Scales of Infant Development-II. We used multivariable regression to identify risk factors for adverse outcome. Among 373 transplant-free survivors, 321 (86%) returned at age 14.3±1.1 (mean±SD) months. Mean PDI (74±19) and MDI (89±18) scores were lower than normative means (each P<0.001). Neither PDI nor MDI score was associated with type of Norwood shunt. Independent predictors of lower PDI score (R2=26%) were clinical center (P=0.003), birth weight <2.5 kg (P=0.023), longer Norwood hospitalization (P<0.001), and more complications between Norwood procedure discharge and age 12 months (P<0.001). Independent risk factors for lower MDI score (R2=34%) included center (P<0.001), birth weight <2.5 kg (P=0.04), genetic syndrome/anomalies (P=0.04), lower maternal education (P=0.04), longer mechanical ventilation after the Norwood procedure (P<0.001), and more complications after Norwood discharge to age 12 months (P<0.001). We found no significant relationship of PDI or MDI score to perfusion type, other aspects of vital organ support (eg, hematocrit, pH strategy), or cardiac anatomy. Conclusions— Neurodevelopmental impairment in Norwood survivors is more highly associated with innate patient factors and overall morbidity in the first year than with intraoperative management strategies. Improved outcomes are likely to require interventions that occur outside the operating room. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Ventilator-Associated Pneumonia in the Pediatric Intensive Care Unit: Characterizing the Problem and Implementing a Sustainable Solution

OBJECTIVES To characterize ventilator-associated pneumonia (VAP) in our pediatric intensive care unit (PICU), implement an evidence-based pediatric VAP prevention bundle, and reduce VAP rates. STUDY DESIGN The setting is a 25-bed PICU in a 475-bed free-standing pediatric academic medical center. VAP was diagnosed according to Centers for Disease Control and National Nosocomial Infections Surveillance System definitions. A pediatric VAP prevention bundle was established and implemented. Baseline VAP rates were compared with implementation and post-bundle-implementation periods. RESULTS VAP is significantly associated with increased PICU length of stay, mechanical ventilator days, and mortality rates (length of stay VAP 19.5+/-15.0 vs non-VAP 7.5+/-9.2, P< .001; ventilator days VAP 16.3+/-14.7 vs non-VAP 5.3+/-8.4, P< .001; mortality VAP 19.1% vs non-VAP 7.2%, P= .01). The VAP rate was reduced from 5.6 (baseline) to 0.3 infections per 1000 ventilator days after bundle implementation; P< .0001. Subglottic/tracheal stenosis, trauma, and tracheostomy are significantly associated with VAP. CONCLUSIONS PICU VAP is associated with increased morbidity and mortality rates. A multidisciplinary improvement team can implement a sustainable pediatric-specific VAP prevention bundle, resulting in VAP rate reduction.

Serum Interleukin-6 and interleukin-8 are early biomarkers of acute kidney injury and predict prolonged mechanical ventilation in children undergoing cardiac surgery: a case-control study

IntroductionAcute kidney injury (AKI) is associated with high mortality rates. New biomarkers that can identify subjects with early AKI (before the increase in serum creatinine) are needed to facilitate appropriate treatment. The purpose of this study was to test the role of serum cytokines as biomarkers for AKI and prolonged mechanical ventilation.MethodsThis was a case-control study of children undergoing cardiac surgery. AKI was defined as a 50% increase in serum creatinine from baseline within 3 days. Levels of serum interleukin (IL)-1β, IL-5, IL-6, IL-8, IL-10, IL-17, interferon (IFN)-γ, tumor necrosis factor-α (TNF-α), granulocyte colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were measured using a bead-based multiplex cytokine kit in conjunction with flow-based protein detection and the Luminex LabMAP multiplex system in 18 cases and 21 controls. Levels of IL-6 and IL-8 were confirmed with single-analyte ELISA; IL-18 was also measured with single-analyte ELISA.ResultsIL-6 levels at 2 and 12 hours after cardiopulmonary bypass (CPB) and IL-8 levels at 2, 12 and 24 hours were associated with the development of AKI using the Wilcoxon rank-sum test and after adjustment for age, gender, race, and prior cardiac surgery in multivariate logistic regression analysis. In patients with AKI, IL-6 levels at 2 hours had excellent predictive value for prolonged mechanical ventilation (defined as mechanical ventilation for more than 24 hours postoperatively) by receiver operator curve (ROC) analysis, with an area under the ROC curve of 0.95. IL-8 levels at 2 hours had excellent predictive value for prolonged mechanical ventilation in all patients. Serum IL-18 levels were not different between those with and without AKI.ConclusionsSerum IL-6 and IL-8 values identify AKI early in patients undergoing CPB surgery. Furthermore, among patients with AKI, high IL-6 levels are associated with prolonged mechanical ventilation, suggesting that circulating cytokines in patients with AKI may have deleterious effects on other organs, including the lungs.

Neutrophil Gelatinase-Associated Lipocalin Concentrations Predict Development of Acute Kidney Injury in Neonates and Children after Cardiopulmonary Bypass

OBJECTIVES To investigate neutrophil gelatinase-associated lipocalin (NGAL) as an early acute kidney injury (AKI) biomarker after neonatal and pediatric cardiopulmonary bypass (CPB). STUDY DESIGN Serum and urine samples were obtained before and at intervals after CPB from 374 patients. AKI was defined as a serum creatinine (S(Cr)) concentration increase from baseline ≥0.3 mg/dL in neonates and ≥50% in children within 48 hours of CPB. Logistic regression was used to assess predictors and clinical outcomes associated with AKI. RESULTS AKI developed in 30% of patients. Plasma and urine NGAL thresholds significantly increased in patients with AKI at 2 hours after CPB and remained elevated at all points, with 2-hour NGAL the earliest, strongest predictor of AKI. In non-neonates, 2-hour plasma and urine NGAL thresholds strongly correlated with length of hospital stay and severity and duration of AKI. CONCLUSION Plasma and urine NGAL thresholds are early predictive biomarkers for AKI and its clinical outcomes after CPB. In neonates, we recommend a 2-hour plasma NGAL threshold of 100 ng/mL and 2-hour urine NGAL threshold of 185 ng/mL for diagnosis of AKI. In non-neonates, recommended AKI thresholds are 50 ng/mL for both 2-hour plasma and urine NGAL.

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.