Mirela Bojan

Comparative study of the Aristotle Comprehensive Complexity and the Risk Adjustment in Congenital Heart Surgery scores.

BACKGROUND The Aristotle Comprehensive Complexity (ACC) and the Risk Adjustment in Congenital Heart Surgery (RACHS-1) scores have been proposed for complexity adjustment in the analysis of outcome after congenital heart surgery. Previous studies found RACHS-1 to be a better predictor of outcome than the Aristotle Basic Complexity score. We compared the ability to predict operative mortality and morbidity between ACC, the latest update of the Aristotle method and RACHS-1. Morbidity was assessed by length of intensive care unit stay. METHODS We retrospectively enrolled patients undergoing congenital heart surgery. We modeled each score as a continuous variable, mortality as a binary variable, and length of stay as a censored variable. We compared performance between mortality and morbidity models using likelihood ratio tests for nested models and paired concordance statistics. RESULTS Among all 1,384 patients enrolled, 30-day mortality rate was 3.5% and median length of intensive care unit stay was 3 days. Both scores strongly related to mortality, but ACC made better prediction than RACHS-1; c-indexes 0.87 (0.84, 0.91) vs 0.75 (0.65, 0.82). Both scores related to overall length of stay only during the first postoperative week, but ACC made better predictions than RACHS-1; U statistic=0.22, p<0.001. No significant difference was noted after adjusting RACHS-1 models on age, prematurity, and major extracardiac abnormalities. CONCLUSIONS The ACC was a better predictor of operative mortality and length of intensive care unit stay than RACHS-1. In order to achieve similar performance, regression models including RACHS-1 need to be further adjusted on age, prematurity, and major extracardiac abnormalities.

The Aristotle Comprehensive Complexity Score Predicts Mortality and Morbidity After Congenital Heart Surgery

BACKGROUND The Aristotle Comprehensive Complexity (ACC) score has been proposed for complexity adjustment in the analysis of outcome after congenital heart surgery. The score is the sum of the Aristotle Basic Complexity score, largely used but poorly related to mortality and morbidity, and of the Comprehensive Complexity items accounting for comorbidities and procedure-specific and anatomic variability. This study aims to demonstrate the ability of the ACC score to predict 30-day mortality and morbidity assessed by the length of the intensive care unit (ICU) stay. METHODS We retrospectively enrolled patients undergoing congenital heart surgery in our institution. We modeled the ACC score as a continuous variable, mortality as a binary variable, and length of ICU stay as a censored variable. For each mortality and morbidity model we performed internal validation by bootstrapping and assessed overall performance by R(2), calibration by the calibration slope, and discrimination by the c index. RESULTS Among all 1,454 patients enrolled, 30-day mortality rate was 3.4% and median length of ICU stay was 3 days. The ACC score strongly related to mortality, but related to length of ICU stay only during the first postoperative week. For the mortality model, R(2) = 0.24, calibration slope = 0.98, c index = 0.86, and 95% confidence interval was 0.82 to 0.91. For the morbidity model, R(2) = 0.094, calibration slope = 0.94, c index = 0.64, and 95% confidence interval was 0.62 to 0.66. CONCLUSIONS The ACC score predicts 30-day mortality and length of ICU stay during the first postoperative week. The score is an adequate tool for complexity adjustment in the analysis of outcome after congenital heart surgery.

Cold histidine-tryptophan-ketoglutarate solution and repeated oxygenated warm blood cardioplegia in neonates with arterial switch operation.

BACKGROUND The present study aimed to compare myocardial protection, as assessed by cardiac troponin-I release, and short-term outcomes between two groups of neonates undergoing the arterial switch operation (ASO) with either Custodiol cardioplegia (Custodiol HTK, Köhler Chemie GmbH, Bensheim, Germany) or repeated oxygenated warm blood cardioplegia. METHODS A total of 218 neonates were enrolled retrospectively from February 2007 through February 2011. All analyses were stratified on the type of procedure (ASO±ventricular septal defect closure ± aortic arch repair). Troponin concentrations within the first week of surgery were analyzed using mixed models for repeated measurements. To counteract the confounding effect of the coronary anatomy, a sensitivity analysis was conducted after 1:1 matching. RESULTS Overall 30 patients had Custodiol cardioplegia, and 188 had warm blood cardioplegia. High-risk coronary anatomy (single right coronary artery giving rise to the left, intramural course) was associated with higher troponin concentrations and a higher 30-day mortality rate postoperatively, and was more prevalent in the Custodiol group when compared with the warm blood cardioplegia group. Postoperative troponin concentrations were higher in the Custodiol group both before (p<0.001) and after matching on the coronary anatomy (p=0.03). The 30-day mortality rate was higher in the Custodiol group, 10% versus 1.1% (p=0.009), but only a nonsignificant trend was noted after matching. CONCLUSIONS The use of Custodiol cardioplegia in neonates undergoing ASO was associated with a larger troponin release when compared with warm blood cardioplegia, suggesting poor myocardial protection. The difference noted in 30-day mortality was not due to the use of Custodiol.

Predictive Performance of Urine Neutrophil Gelatinase-Associated Lipocalin for Dialysis Requirement and Death Following Cardiac Surgery in Neonates and Infants

BACKGROUND AND OBJECTIVES Urine neutrophil gelatinase-associated lipocalin (uNGAL) has been shown to accurately predict and allow early detection of AKI, as assessed by an increase in serum creatinine in children and adults. The present study explores the accuracy of uNGAL for the prediction of severe AKI-related outcomes in neonates and infants undergoing cardiac surgery: dialysis requirement and/or death within 30 days. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Prospective, observational cohort study conducted in a tertiary referral pediatric cardiac intensive care unit, including 75 neonates and 125 infants undergoing surgery with cardiopulmonary bypass between August 1, 2010, and May 31, 2011. Urine samples were collected before surgery and at median of five time points within 48 hours of bypass. Urine NGAL was quantified as absolute concentration, creatinine-normalized concentration, and absolute excretion rate, and a clusterization algorithm was applied to the individual uNGAL kinetics. The accuracy for the prediction of the outcome was assessed using receiver-operating characteristic areas, likelihood ratios, diagnostic odds ratios, net reclassification index, integrated reclassification improvement, and number needed to screen. RESULTS A total of 1176 urine samples were collected. Of all patients, 8% required dialysis and 4% died. Three clusters of uNGAL kinetics were identified, including patients with significantly different outcomes. The uNGAL level peaked between 1 and 3 hours of bypass and remained high in half of all patients who required dialysis or died. The uNGAL levels measured within 24 hours of bypass accurately predicted the outcome and performed best after normalization to creatinine, with varying cutoffs according to the time elapsed since bypass. The number needed to screen to correctly identify the risk of dialysis or death in one patient varied between 1.5 and 2.6 within 12 hours of bypass. CONCLUSIONS uNGAL is a valuable predictive tool of dialysis requirement and death in neonates and infants with AKI after cardiac surgery.

High-frequency oscillatory ventilation and short-term outcome in neonates and infants undergoing cardiac surgery: a propensity score analysis

IntroductionExperience with high-frequency oscillatory ventilation (HFOV) after congenital cardiac surgery is limited despite evidence about reduction in pulmonary vascular resistance after the Fontan procedure. HFOV is recommended in adults and children with acute respiratory distress syndrome. The aim of the present study was to assess associations between commencement of HFOV on the day of surgery and length of mechanical ventilation, length of Intensive Care Unit (ICU) stay and mortality in neonates and infants with respiratory distress following cardiac surgery.MethodsA logistic regression model was used to develop a propensity score, which accounted for the probability of being switched from conventional mechanical ventilation (CMV) to HFOV on the day of surgery. It included baseline characteristics, type of procedure and postoperative variables, and was used to match each patient with HFOV with a control patient, in whom CMV was used exclusively. Length of mechanical ventilation, ICU stay and mortality rates were compared in the matched set.ResultsOverall, 3,549 neonates and infants underwent cardiac surgery from January 2001 through June 2010, 120 patients were switched to HFOV and matched with 120 controls. After adjustment for the delay to sternal closure, duration of renal replacement therapy, occurrence of pulmonary hypertension and year of surgery, the probability of successful weaning over time and the probability of ICU delivery over time were significantly higher in patients with HFOV, adjusted hazard ratios and 95% confidence intervals: 1.63, 1.17 to 2.26 (P = 0.004). and 1.65, 95% confidence intervals: 1.20 to 2.28 (P = 0.002) respectively. No association was found with mortality.ConclusionsWhen commenced on the day of surgery in neonates and infants with respiratory distress following cardiac surgery, HFOV was associated with shorter lengths of mechanical ventilation and ICU stay than CMV.

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

Background Changes in kidney function, as assessed by early and even small variations in serum creatinine (ΔsCr), affect survival in adults following cardiac surgery but such associations have not been reported in infants. This raises the question of the adequate assessment of kidney function by early ΔsCr in infants undergoing cardiac surgery. Methodology The ability of ΔsCr within 2 days of surgery to assess the severity of kidney injury, accounted for by the risk of 30-day mortality, was explored retrospectively in 1019 consecutive neonates and infants. Patients aged ≤ 10 days were analyzed separately because of the physiological improvement in glomerular filtration early after birth. The Kml algorithm, an implementation of k-means for longitudinal data, was used to describe creatinine kinetics, and the receiver operating characteristic and the reclassification methodology to assess discrimination and the predictive ability of the risk of death. Results Three clusters of ΔsCr were identified: in 50% of all patients creatinine decreased, in 41.4% it increased slightly, and in 8.6% it rose abruptly. Mortality rates were not significantly different between the first and second clusters, 1.6% [0.0–4.1] vs 5.9% [1.9–10.9], respectively, in patients aged ≤ 10 days, and 1.6% [0.5–3.0] vs 3.8% [1.9–6.0] in older ones. Mortality rates were significantly higher when creatinine rose abruptly, 30.3% [15.1–46.2] in patients aged ≤ 10 days, and 15.1% [5.9–25.5] in older ones. However, only 41.3% of all patients who died had an abrupt increase in creatinine. ΔsCr improved prediction in survivors, but not in patients who died, and did not improve discrimination over a clinical mortality model. Conclusions The present results suggest that a postoperative decrease in creatinine represents the normal course in neonates and infants with cardiac surgery, and that early creatinine variations lack sensitivity for the assessment of the severity of kidney injury.

Aprotinin, transfusions, and kidney injury in neonates and infants undergoing cardiac surgery

BACKGROUND A significantly increased risk of acute kidney injury (AKI) with the prophylactic use of aprotinin has been reported in adults undergoing cardiac surgery, but not in children. Blood product transfusions have also been shown to carry an independent risk of AKI. The present study assessed associations between AKI, aprotinin, and transfusions in neonates and infants undergoing cardiac surgery. METHODS All neonates and infants undergoing surgery with cardiopulmonary bypass over a 42 month period, before and after the withdrawal of aprotinin, were included retrospectively. AKI was assessed by the Acute-Kidney-Injury-Network classifications. A propensity score was used to balance treated and untreated groups. RESULTS Three hundred and ninety patients received aprotinin and 568 patients did not. Inverse probability of treatment weighting resulted in good balance between groups for baseline and surgical characteristics. Controls underwent surgery with smaller bypass circuits and fewer transfusions. After adjustment for the use of miniaturized circuits and for the year of surgery, no significant association between the incidence of AKI, dialysis, and aprotinin was noted. Red blood cell transfusions were associated with an increased risk of AKI and dialysis: odds ratios (ORs) 1.64 (1.12-2.41) and 2.07 (1.13-3.73), respectively; as were fresh frozen plasma transfusions, ORs 2.28 (1.68-3.09) and 3.11 (1.95-4.97), respectively. Platelet transfusions were associated with an increased risk of dialysis: OR 2.20 (1.21-4.01). CONCLUSIONS Blood product transfusions, but not the prophylactic use of aprotinin, are significantly associated with AKI after cardiac surgery in neonates and infants.

Neonatal Cardiopulmonary Bypass

Cardiac surgery with cardiopulmonary bypass is routinely used in neonates who require early repair of congenital heart diseases. However, the bypass temperature and use of deep hypothermic circulatory arrest, the composition of the priming and the acceptable degree of hemodilution, the prophylactic use of antifibrinolytic agents and steroids, the choice of myocardial protection, the best PaO2, and even the pump flow, are still subjects of debate, despite major improvements in neonatal bypass over the last decade. Nevertheless, there are some techniques that have reached a near-consensus and are highly recommended in neonates: the use of minaturized bypass circuits to reduce blood product transfusions and inflammation, ultrafiltration, and the continuous monitoring of mixed venous and regional oxygen saturations to assess adequacy of perfusion. Nevertheless, surprisingly many different techniques may lead to the same results and mortality rate. As operative mortality rates have declined, the comparison endpoints between techniques have moved and focus on morbidity rates, extubation delay, ICU and hospital length of stay; in other words, the cost and (of course) the late functional outcome are certainly the new goals of neonatal cardiopulmonary bypass.

Evaluation of a New Tool for Morbidity Assessment in Congenital Cardiac Surgery

BACKGROUND To date, no instrument to assess morbidity in congenital cardiac surgery has been validated. In the Aristotle system, morbidity is accounted for by a subjective assessment of length of intensive care unit stay. A previously published Morbidity Index (MI), still in development, has been derived from objective data. The present study aims to assess the feasibility and utility of the MI at a single institution and its association with the Aristotle Comprehensive Complexity (ACC) score. METHODS Patients undergoing congenital cardiac surgery at our institution were enrolled retrospectively. The MI was calculated from the nonweighted sum of its components. The ability of the ACC to predict the components was estimated. RESULTS The MI increased more than length of stay across procedures with increasing complexity. Renal failure requiring long-term dialysis was not observed. A requirement for temporary dialysis, which is not an MI component, correlated well with the MI (r = 0.51, p < 0.001). The ACC was a good predictor for most components of the MI: length of intensive care unit stay 3 days or more, time to extubation, postoperative extracorporeal assistance, and, for temporary dialysis, with areas under the receiver operating characteristics curve of 0.67 (0.65, 0.70), 0.71 (0.68, 0.74) , 0.84 (0.75, 0.91), and 0.83 (0.77, 0.87) respectively. CONCLUSIONS Implementation of the MI in the Aristotle system will improve prediction of complications and long lengths of stay, making it a better morbidity indicator than length of intensive care unit stay. Requirement for temporary dialysis may be considered as an MI component.

High-dose aprotinin, blood product transfusions, and short-term outcome in neonates and infants: a pediatric cardiac surgery center experience.

Background:  The efficacy of aprotinin, the most popular antifibrinolytic agent in congenital cardiac surgery, was still uncertain in small infants when its prophylactic use was suspended for safety reasons. The aim of this study is to describe associations between the prophylactic use of high‐dose aprotinin, the need for blood product transfusions, and short‐term outcome in neonates and infants with cardiac surgery.