Hyperoxia During Cardiopulmonary Bypass Is Associated With Mortality in Infants Undergoing Cardiac Surgery.

OBJECTIVES: Patients undergoing cardiac surgery using cardiopulmonary bypass have variable degrees of blood oxygen tension during surgery. Hyperoxia has been associated with adverse outcomes in critical illness. Data are not available regarding the association of hyperoxia and outcomes in infants undergoing cardiopulmonary bypass. We hypothesize that among infants undergoing cardiac surgery, hyperoxia during cardiopulmonary bypass is associated with greater odds of morbidity and mortality. DESIGN: Retrospective study. SETTING: Single center at an academic tertiary children's hospital. PATIENTS: All infants (< 1 yr) undergoing cardiopulmonary bypass between January 1, 2015, and December 31, 2017, excluding two patients who were initiated on extracorporeal membrane oxygenation in the operating room. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The study included 469 infants with a median age of 97 days (interquartile range, 14-179 d), weight 4.9 kg (interquartile range, 3.4-6.4 kg), and cardiopulmonary bypass time 128 minutes (interquartile range, 91-185 min). A Pao2 of 313 mm Hg (hyperoxia) on cardiopulmonary bypass had highest sensitivity with specificity greater than 50% for association with operative mortality. Approximately, half of the population (237/469) had hyperoxia on cardiopulmonary bypass. Infants with hyperoxia were more likely to have acute kidney injury, prolonged postoperative length of stay, and mortality. They were younger, weighed less, had longer cardiopulmonary bypass times, and had higher Society of Thoracic Surgeons and the European Association for Cardio-Thoracic Surgery mortality scores. There was no difference in sex, race, preoperative creatinine, single ventricle physiology, or presence of genetic syndrome. On multivariable analysis, hyperoxia was associated with greater odds of mortality (odds ratio, 4.3; 95% CI, 1.4-13.2) but failed to identify an association with acute kidney injury or prolonged postoperative length of stay. Hyperoxia was associated with greater odds of mortality in subgroup analysis of neonatal patients. CONCLUSIONS: Hyperoxia occurred in a substantial portion of infants undergoing cardiopulmonary bypass for cardiac surgery. Hyperoxia during cardiopulmonary bypass was an independent risk factor for mortality and may be a modifiable risk factor. Furthermore, hyperoxia during cardiopulmonary bypass was associated with four-fold greater odds of mortality within 30 days of surgery. Hyperoxia failed to identify an association with development of acute kidney injury or prolonged postoperative length of stay when controlling for covariables. Validation of our data among other populations is necessary to better understand and elucidate potential mechanisms underlying the association between excess oxygen delivery during cardiopulmonary bypass and outcome.

The Use of Clevidipine for Hypertension in Pediatric Patients Receiving Mechanical Circulatory Support.

OBJECTIVES: Limited data exist regarding the management of hypertension in pediatric patients on mechanical circulatory support. Hypertension is a known risk factor for stroke and low cardiac output in patients requiring mechanical circulatory support and a narrow therapeutic window of blood pressure is often targeted. Traditional short-acting infusions to treat hypertension, such as sodium nitroprusside, may lead to accumulation of toxic metabolites in patients with renal dysfunction. Our primary objective was to describe use of clevidipine, a continuous short-acting calcium channel blocking medication, for blood pressure control in pediatric patients on mechanical circulatory support. DESIGN: Single-center retrospective cohort study. SETTING: A 26-bed quaternary cardiovascular ICU in a university-based pediatric hospital in California. PATIENTS: Mechanical circulatory support patients admitted to cardiovascular ICU who received clevidipine infusions between October 1, 2016, and March 31, 2019. INTERVENTIONS: Clevidipine infusion. MEASUREMENTS AND MAIN RESULTS: Data from a cohort of 38 patients who received a total of 45 clevidipine infusions were reviewed. The cohort had a median age of 2.7 years and included neonates. No patient had record of hypotensive events, code events, or received low-dose epinephrine or code-dosed epinephrine related to a clevidipine infusion. Median duration of clevidipine infusion was 4.1 days (1.5-9.2 d). Eleven patients transitioned from clevidipine to enteral antihypertensive agents, and 26 clevidipine infusions were administered as a single agent without sodium nitroprusside. Seven patients were switched from sodium nitroprusside to clevidipine to avoid cyanide toxicity, a majority of whom had elevated serum creatinine. CONCLUSIONS: In this pediatric cardiac cohort, clevidipine infusions were effective at hypertension management and were not associated with hypotensive or code events. This report details the largest cohort and longest duration of clevidipine administration within a pediatric population and did not demonstrate hypotensive events, even among neonatal populations. Clevidipine may be a reasonable cost-effective alternative antihypertensive medication compared to traditional short-acting agents.

Perfusion Methods and Modifications to the Cardiopulmonary Bypass Circuit for Midline Unifocalization Procedures.

Pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (PA/VSD/MAPCAs) is a rare form of congenital heart disease. The midline unifocalization procedure has been developed for the treatment of PA/VSD/MAPCAs. These are complex and very lengthy procedures that require an entirely different method of perfusion. The purpose of this study was to review our perfusion modifications to support these unifocalization procedures. Sixty-four unifocalization procedures have been performed at our institution during the past 3 years. The median age was 4.1 months (range 1 month-3.5 years) and the median weight at surgery was 4.5 kg (range 3.5-19 kg). The median duration of cardiopulmonary bypass was 352 minutes (range 128-629 minutes), and the median duration of cross-clamp was 24 minutes (range 14-72 minutes). The conduct of surgery included cooling to a rectal perfusion temperature of 25° and a flow rate of 100 mL/kg/min. A pH-stat strategy and del Nido cardioplegia were used. Modifications to the cardiopulmonary bypass circuit include upsizing the oxygenator, reservoir, cannulae, vent catheter, and tubing. All circuits were modified to include the capability of performing an intraoperative flow study. This study is used to determine whether the VSD can be closed during surgery. A collateral flow study circuit is also set up for first-time operations to measure the residual collateral flow after all of the MAPCAs have been harvested. Patients who require midline unifocalization will invariably require very lengthy periods of support on cardiopulmonary bypass. We have adapted our perfusion circuitry to prepare for the demands on the bypass circuit to meet the requirements of this patient population. Our institution has developed a systematic approach for the conduct of perfusion to best serve our patients presenting with PA/VSD/MAPCAs.

Neurorehabilitation in a Pediatric Stroke Patient Supported on a CentriMag.

Patients supported on ventricular assist devices (VADs) benefit from rehabilitation while awaiting heart transplantation to recover from surgery, prevent deconditioning, and, in most cases, optimize transplant candidacy. With bleeding and neurological dysfunction as the most common VAD complications, the importance of rehabilitation dramatically increases when a patient on a VAD also suffers from a neurological injury. The rehabilitation needs for cardiac conditioning and neurological reeducation are not the same. Patients with severe neurological deficits require intense rehabilitation that often includes base-of-support challenges, usage of bolsters and balls, partial weight-bearing treadmill training, and assumption of various body positions in prone, kneeling, or quadruped for neuromotor reeducation. However, some devices are more conducive to rehabilitation than others. For children supported by the CentriMag in particular, rehabilitation is challenged by short cannula tubing, an external motor, a large interface, and an intensive care unit (ICU) admission. We report a safe and successful physical therapy course of a pediatric stroke patient with a diagnosis of Ebstein's anomaly supported by a CentriMag right VAD (RVAD) while awaiting heart transplant in the ICU.

Clinical Predictive Tool for Pediatric Cardiac Patients on Extracorporeal Membrane Oxygenation Therapy and Ultrafiltration.

Fluid overload is common among pediatric cardiac patients receiving extracorporeal membrane oxygenation (ECMO) and is often treated with in-line ultrafiltration (UF) or continuous renal replacement therapy (CRRT). We assessed whether CRRT was associated with poor outcomes versus UF alone. Additionally, we identified characteristics associated with progression from UF to CRRT. Retrospective chart review of 131 patients age ≤18 years treated with ECMO at a single quaternary center. Data were collected to compare patient demographics, characteristics, and outcomes. A receiver operator curve (ROC) was used to create a tool predictive of the need for CRRT at the time of UF initiation. Patients who required CRRT had a higher creatinine and blood urea nitrogen at time of UF initiation ( p = 0.03 and p < 0.01), longer total ECMO duration ( p < 0.01), lower renal recovery incidence ( p = 0.02), and higher mortality ( p ≤ 0.01). Using ROC analysis, presence of ≤3 of 7 risk variables had a positive predictive value of 87.5% and negative predictive value of 50.0% for use of UF alone (area under the curve 0.801; 95% CI: 0.638-0.965, p = 0.002). Pediatric cardiac patients treated with ECMO and UF who require CRRT demonstrate worse outcomes versus UF alone. A novel clinical tool may assist in stratifying patients at UF initiation.

Functional Status Change Among Infants, Children, and Adolescents Following Extracorporeal Life Support: a Multicenter Report.

In our retrospective multicenter study of patients 0 to 18 years of age who survived extracorporeal life support (ECLS) between January 2010 and December 2018, we sought to characterize the functional status scale (FSS) of ECLS survivors, determine the change in FSS from admission to discharge, and examine risk factors associated with development of new morbidity and unfavorable outcome. During the study period, there were 1,325 ECLS runs, 746 (56%) survived to hospital discharge. Pediatric patients accounted for 56%. Most common ECLS indication was respiratory failure (47%). ECLS support was nearly evenly split between veno-arterial and veno-venous (51% vs . 49%). Median duration of ECLS in survivors was 5.5 days. Forty percent of survivors had new morbidity, and 16% had an unfavorable outcome. In a logistic regression, African American patients (OR 1.68, p = 0.01), longer duration of ECLS (OR 1.002, p = 0.004), mechanical (OR 1.79, p = 0.002), and renal (OR 1.64, p = 0.015) complications had higher odds of new morbidity. Other races (Pacific Islanders, and Native Americans) (OR 2.89, p = 0.013), longer duration of ECLS (OR 1.002, p = 0.002), and mechanical complications (OR 1.67, p = 0.026) had higher odds of unfavorable outcomes. In conclusion, in our multi-center 9-year ECLS experience, 56% survived, 40% developed new morbidity, and 84% had favorable outcome. Future studies with larger populations could help identify modifiable risk factors that could help guide clinicians in this fragile patient population.

A Scoping Review and Appraisal of Extracorporeal Membrane Oxygenation Education Literature.

Background: Despite a recent rise in publications describing extracorporeal membrane oxygenation (ECMO) education, the scope and quality of ECMO educational research and curricular assessments have not previously been evaluated. Objective: The purposes of this study are 1) to categorize published ECMO educational scholarship according to Bloom's educational domains, learner groups, and content delivery methods; 2) to assess ECMO educational scholarship quality; and 3) to identify areas of focus for future curricular development and educational research. Methods: A multidisciplinary research team conducted a scoping review of ECMO literature published between January 2009 and October 2021 using established frameworks. The Medical Education Research Study Quality Instrument (MERSQI) was applied to assess quality. Results: A total of 1,028 references were retrieved; 36 were selected for review. ECMO education studies frequently targeted the cognitive domain (78%), with 17% of studies targeting the psychomotor domain alone and 33% of studies targeting combinations of the cognitive, psychomotor, and affective domains. Thirty-three studies qualified for MERSQI scoring, with a median score of 11 (interquartile range, 4; possible range, 5-18). Simulation-based training was used in 97%, with 50% of studies targeting physicians and one other discipline. Conclusion: ECMO education frequently incorporates simulation and spans all domains of Bloom's taxonomy. Overall, MERSQI scores for ECMO education studies are similar to those for other simulation-based medical education studies. However, developing assessment tools with multisource validity evidence and conducting multienvironment studies would strengthen future work. The creation of a collaborative ECMO educational network would increase standardization and reproducibility in ECMO training, ultimately improving patient outcomes.

Mid-Term Outcomes After Unifocalization Guided by Intraoperative Pulmonary Flow Study.

BACKGROUND: Repair of tetralogy of Fallot (TOF) with major aortopulmonary collateral arteries (MAPCAs) requires unifocalization of pulmonary circulation, intracardiac repair with the closure of the ventricular septal defect, and placement of a right ventricle (RV) to pulmonary artery (PA) conduit. The decision to perform complete repair is sometimes aided by an intraoperative flow study to estimate the total resistance of the reconstructed pulmonary circulation. METHODS: We reviewed patients who underwent unifocalization and PA reconstruction for TOF/MAPCAs to evaluate acute and mid-term outcomes after repair with and without flow studies and to characterize the relationship between PA pressure during the flow study and postrepair RV pressure. RESULTS: Among 579 patients who underwent unifocalization and PA reconstruction for TOF/MAPCAs, 99 (17%) had an intraoperative flow study during one (n = 91) or more (n = 8) operations to determine the suitability for a complete repair. There was a reasonably good correlation between mean PA pressure at 3 L/min/m2 during the flow study and postrepair RV pressure and RV:aortic pressure ratio. Acute and mid-term outcomes (median: 3.8 years) after complete repair in the flow study patients (n = 78) did not differ significantly from those in whom the flow study was not performed (n = 444). Furthermore, prior failed flow study was not associated with differences in outcome after subsequent intracardiac repair. CONCLUSIONS: The intraoperative flow study remains a useful adjunct for determining the suitability for complete repair in a subset of patients undergoing surgery for TOF/MAPCAs, as it is reasonably accurate for estimating postoperative PA pressure and serves as a reliable guide for the feasibility of single-stage complete repair.

Measurement of Residual Collateral Flow in Pulmonary Atresia With Major Aortopulmonary Collaterals.

BACKGROUND: Pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (MAPCAs) is a rare form of congenital heart disease characterized by the entirety of pulmonary blood flow originating from systemic vessels. This study measured the residual collateral flow after harvesting of the MAPCAs for surgical repair. METHODS: The study enrolled 32 patients with pulmonary atresia with ventricular septal defect and MAPCAs who were undergoing their first surgical procedure. The median age was 6.8 months, and median weight was 5.7 kg. The patients had a mean of 4.2 ± 0.7 MAPCAs. The cardiopulmonary bypass circuit was modified to contain a diversion loop in the left ventricular vent system to accurately measure residual collateral flow. During the period of aortic cross-clamp (for ventricular septal defect repair), the diversion loop was opened for 1-minute intervals, and the residual collateral flow collected. The systemic perfusion temperature was 25° and flow rate was 100 mL · kg-1 · min-1. RESULTS: The mean residual collateral flow was 5.5 mL · kg-1 · min-1 (range, 0.8 to 15.2 mL · kg-1 · min-1). The corresponding calculated pulmonary blood flow-to-systemic blood flow ratio values ranged from 1.01 to 1.36. There was a significant correlation between residual collateral flow and preoperative saturation (p < 0.05). CONCLUSIONS: The data demonstrate a wide range of residual collateral flow values after harvesting of the MAPCAs. The amount of residual collateral flow was correlated with preoperative saturation. These results suggest that some patients at the higher end of this spectrum may require adjustments in pump flow to assure adequate systemic perfusion.