Reducing Hyperoxia Exposure in Infants Requiring Veno-Arterial Extracorporeal Membrane Oxygenation after Cardiac Surgery.

Recent studies have suggested worse outcomes in patients exposed to hyperoxia while supported on veno-arterial extracorporeal membrane oxygenation (VA-ECMO). However, there are no data regarding the effect of reducing hyperoxia exposure in this population by adjusting the fraction of inspired oxygen (FiO2) of the sweep gas of the ECMO circuit. A retrospective review of 143 patients less than 1 year of age requiring VA-ECMO following cardiac surgery from 2007 to 2018 was completed. 64 patients had a FiO2 of the sweep gas < 100% with an average PaO2 of 210 mm Hg in the first 48 h of support [vs 405 mm Hg in the group with a FiO2 = 100% (p < 0.0001)]. There was no difference in mortality at 30 days after surgery or other markers of end-organ injury with respect to whether the FiO2 was adjusted. At least one PaO2 value < 200 mm Hg in the first 24 h on ECMO in patients with a FiO2 < 100% trended toward a significant association (OR = 0.45, 95% CI = 0.21-1.01) with decreased risk of 30-day mortality when compared to those patients with a FiO2 = 100% and all PaO2 values > 200 mm Hg. Only 47% of patients with a FiO2 < 100% had an average PaO2 less than 200 mm Hg which indicates that the intervention of reducing the FiO2 of the sweep gas was not entirely effective at reducing hyperoxia exposure. Future research is needed for developing clinical protocols to avoid hyperoxia and to identify mechanisms for hyperoxia-induced injury on VA-ECMO.

Failed Extubation in Neonates After Cardiac Surgery: A Single-Center, Retrospective Study.

OBJECTIVES: To describe factors associated with failed extubation (FE) in neonates following cardiovascular surgery, and the relationship with clinical outcomes. DESIGN: Retrospective cohort study. SETTING: Twenty-bed pediatric cardiac ICU (PCICU) in an academic tertiary care children's hospital. PATIENTS: Neonates admitted to the PCICU following cardiac surgery between July 2015 and June 2018. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients who experienced FE were compared with patients who were successfully extubated. Variables associated with FE ( p < 0.05) from univariate analysis were considered for inclusion in multivariable logistic regression. Univariate associations of FE with clinical outcomes were also examined. Of 240 patients, 40 (17%) experienced FE. Univariate analyses revealed associations of FE with upper airway (UA) abnormality (25% vs 8%, p = 0.003) and delayed sternal closure (50% vs 24%, p = 0.001). There were weaker associations of FE with hypoplastic left heart syndrome (25% vs 13%, p = 0.04), postoperative ventilation greater than 7 days (33% vs 15%, p = 0.01), Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) category 5 operations (38% vs 21%, p = 0.02), and respiratory rate during spontaneous breathing trial (median 42 vs 37 breaths/min, p = 0.01). In multivariable analysis, UA abnormalities (adjusted odds ratio [AOR] 3.5; 95% CI, 1.4-9.0), postoperative ventilation greater than 7 days (AOR 2.3; 95% CI, 1.0-5.2), and STAT category 5 operations (AOR 2.4; 95% CI, 1.1-5.2) were independently associated with FE. FE was also associated with unplanned reoperation/reintervention during hospital course (38% vs 22%, p = 0.04), longer hospitalization (median 29 vs 16.5 d, p < 0.0001), and in-hospital mortality (13% vs 3%, p = 0.02). CONCLUSIONS: FE in neonates occurs relatively commonly following cardiac surgery and is associated with adverse clinical outcomes. Additional data are needed to further optimize periextubation decision-making in patients with multiple clinical factors associated with FE.

Standardized Training for Physicians Practicing Pediatric Cardiac Critical Care.

OBJECTIVES: In the vast majority of Children's Hospitals, the critically ill patient can be found in one of three locations: the PICU, the neonatal ICU, and the cardiac ICU. Training, certification, and maintenance of certification for neonatology and critical care medicine are over seen by the Accreditation Council for Graduate Medical Education and American Board of Pediatrics. There is no standardization of training or oversight of certification and maintenance of certification for pediatric cardiac critical care. DATA SOURCES: The curricula from the twenty 4th year pediatric cardiac critical care training programs were collated, along with the learning objectives from the Pediatric Cardiac Intensive Care Society published "Curriculum for Pediatric Cardiac Critical Care Medicine." STUDY SELECTION: This initiative is endorsed by the Pediatric Cardiac Intensive Care Society as a first step toward Accreditation Council for Graduate Medical Education oversight of training and American Board of Pediatrics oversight of maintenance of certification. DATA EXTRACTION: A taskforce was established of cardiac intensivists, including the directors of all 4th year pediatric cardiac critical care training programs. DATA SYNTHESIS: Using modified Delphi methodology, learning objectives, rotational requirements, and institutional requirements for providing training were developed. CONCLUSIONS: In the current era of increasing specialized care in pediatric cardiac critical care, standardized training for pediatric cardiac critical care is paramount to optimizing outcomes.

Prediction of extubation failure in the paediatric cardiac ICU using machine learning and high-frequency physiologic data.

BACKGROUND: Cardiac intensivists frequently assess patient readiness to wean off mechanical ventilation with an extubation readiness trial despite it being no more effective than clinician judgement alone. We evaluated the utility of high-frequency physiologic data and machine learning for improving the prediction of extubation failure in children with cardiovascular disease. METHODS: This was a retrospective analysis of clinical registry data and streamed physiologic extubation readiness trial data from one paediatric cardiac ICU (12/2016-3/2018). We analysed patients' final extubation readiness trial. Machine learning methods (classification and regression tree, Boosting, Random Forest) were performed using clinical/demographic data, physiologic data, and both datasets. Extubation failure was defined as reintubation within 48 hrs. Classifier performance was assessed on prediction accuracy and area under the receiver operating characteristic curve. RESULTS: Of 178 episodes, 11.2% (N = 20) failed extubation. Using clinical/demographic data, our machine learning methods identified variables such as age, weight, height, and ventilation duration as being important in predicting extubation failure. Best classifier performance with this data was Boosting (prediction accuracy: 0.88; area under the receiver operating characteristic curve: 0.74). Using physiologic data, our machine learning methods found oxygen saturation extremes and descriptors of dynamic compliance, central venous pressure, and heart/respiratory rate to be of importance. The best classifier in this setting was Random Forest (prediction accuracy: 0.89; area under the receiver operating characteristic curve: 0.75). Combining both datasets produced classifiers highlighting the importance of physiologic variables in determining extubation failure, though predictive performance was not improved. CONCLUSION: Physiologic variables not routinely scrutinised during extubation readiness trials were identified as potential extubation failure predictors. Larger analyses are necessary to investigate whether these markers can improve clinical decision-making.

Predicting and Surviving Prolonged Critical Illness After Congenital Heart Surgery.

OBJECTIVES: Prolonged critical illness after congenital heart surgery disproportionately harms patients and the healthcare system, yet much remains unknown. We aimed to define prolonged critical illness, delineate between nonmodifiable and potentially preventable predictors of prolonged critical illness and prolonged critical illness mortality, and understand the interhospital variation in prolonged critical illness. DESIGN: Observational analysis. SETTING: Pediatric Cardiac Critical Care Consortium clinical registry. PATIENTS: All patients, stratified into neonates (≤28 d) and nonneonates (29 d to 18 yr), admitted to the pediatric cardiac ICU after congenital heart surgery at Pediatric Cardiac Critical Care Consortium hospitals. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 2,419 neonates and 10,687 nonneonates from 22 hospitals. The prolonged critical illness cutoff (90th percentile length of stay) was greater than or equal to 35 and greater than or equal to 10 days for neonates and nonneonates, respectively. Cardiac ICU prolonged critical illness mortality was 24% in neonates and 8% in nonneonates (vs 5% and 0.4%, respectively, in nonprolonged critical illness patients). Multivariable logistic regression identified 10 neonatal and 19 nonneonatal prolonged critical illness predictors within strata and eight predictors of mortality. Only mechanical ventilation days and acute renal failure requiring renal replacement therapy predicted prolonged critical illness and prolonged critical illness mortality in both strata. Approximately 40% of the prolonged critical illness predictors were nonmodifiable (preoperative/patient and operative factors), whereas only one of eight prolonged critical illness mortality predictors was nonmodifiable. The remainders were potentially preventable (postoperative critical care delivery variables and complications). Case-mix-adjusted prolonged critical illness rates were compared across hospitals; six hospitals each had lower- and higher-than-expected prolonged critical illness frequency. CONCLUSIONS: Although many prolonged critical illness predictors are nonmodifiable, we identified several predictors to target for improvement. Furthermore, we observed that complications and prolonged critical care therapy drive prolonged critical illness mortality. Wide variation of prolonged critical illness frequency suggests that identifying practices at hospitals with lower-than-expected prolonged critical illness could lead to broader quality improvement initiatives.

Three-dimensional US Fractional Moving Blood Volume: Validation of Renal Perfusion Quantification.

Background Three-dimensional (3D) fractional moving blood volume (FMBV) derived from 3D power Doppler US has been proposed for noninvasive approximation of perfusion. However, 3D FMBV has never been applied in animals against a ground truth. Purpose To determine the correlation between 3D FMBV and the reference standard of fluorescent microspheres (FMS) for measurement of renal perfusion in a porcine model. Materials and Methods From February 2017 to September 2017, adult pigs were administered FMS before and after measurement of renal 3D FMBV at baseline (100%) and approximately 75%, 50%, and 25% flow levels by using US machines from two different vendors. The 3D power Doppler US volumes were converted and segmented, and correlations between FMS and 3D FMBV were made with simple linear regression (r2). Similarity and reproducibility of manual segmentation were determined with the Dice similarity coefficient and 3D FMBV reproducibility (intraclass correlation coefficient [ICC]). Results Thirteen pigs were studied with 33 flow measurements. Kidney volume (mean Dice similarity coefficient ± standard deviation, 0.89 ± 0.01) and renal segmentation (coefficient of variation = 12.6%; ICC = 0.86) were consistent. The 3D FMBV calculations had high reproducibility (ICC = 0.97; 95% confidence interval: 0.96, 0.98). The 3D FMBV per-pig correlation showed excellent correlation for US machines from both vendors (mean r2 = 0.96 [range, 0.92-1.0] and 0.93 [range, 0.78-1.0], respectively). The correlation between 3D FMBV and perfusion measured with microspheres was high for both US machines (r2 = 0.80 [P < .001] and 0.70 [P < .001], respectively). Conclusion The strong correlation between three-dimensional (3D) fractional moving blood volume (FMBV) and fluorescent microspheres indicates that 3D FMBV shows excellent correlation to perfusion and good reproducibility. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Morrell et al in this issue.

Functional Status Change Among Children With Extracorporeal Membrane Oxygenation to Support Cardiopulmonary Resuscitation in a Pediatric Cardiac ICU: A Single Institution Report.

OBJECTIVES: The purpose of this study is to describe the functional status of survivors from extracorporeal cardiopulmonary resuscitation instituted during in-hospital cardiac arrest using the Functional Status Scale. We aimed to determine risk factors leading to the development of new morbidity and unfavorable functional outcomes. DESIGN: This was a single-center retrospective chart review abstracting patient characteristics/demographic data, duration of cardiopulmonary resuscitation, duration of extracorporeal membrane oxygenation support, as well as maximum lactate levels within 2 hours before and after extracorporeal cardiopulmonary resuscitation. Cardiac arrest was defined as the administration of chest compressions for a nonperfusing cardiac rhythm. Extracorporeal cardiopulmonary resuscitation was defined by instituting extracorporeal membrane oxygenation during active chest compressions. Functional Status Scale scores were calculated at admission and on hospital discharge for patients who survived. SETTING: Patients admitted in the pediatric cardiac ICU at C.S. Mott Children's Hospital from January 1, 2005, to December 31, 2015. PATIENTS: Children less than 18 years who underwent extracorporeal cardiopulmonary resuscitation. INTERVENTIONS: Not applicable. MEASUREMENTS AND MAIN RESULTS: Of 608 extracorporeal membrane oxygenation events during the study period, 80 were extracorporeal cardiopulmonary resuscitation (14%). There were 40 female patients (50%). Median age was 40 days (interquartile range, 9-342 d). Survival to hospital discharge was 48% (38/80). Median Functional Status Scale score at admission was 6 (interquartile range, 6-6) and at hospital discharge 9 (interquartile range, 8-11). Out of 38 survivors, 19 (50%) had a change of Functional Status Scale score greater than or equal to 3, that is consistent with new morbidity, and 26 (68%) had favorable functional outcomes with a change in Functional Status Scale score of less than 5. CONCLUSIONS: This is the first extracorporeal cardiopulmonary resuscitation report to examine changes in Functional Status Scale from admission (baseline) to discharge as a measure of overall functional outcome. Half of surviving patients (19/38) had new morbidity, while 68% (26/38) had favorable outcomes. Lactate levels, duration of cardiopulmonary resuscitation, and duration of extracorporeal membrane oxygenation were not found to be risk factors for the development of new morbidity and poor functional outcomes. Functional Status Scale may be used as a metric to monitor improvement of extracorporeal cardiopulmonary resuscitation outcomes and help guide research initiatives to decrease morbidity in this patient population.

Incidence of Fever and Positive Bacterial Cultures in Neonates Receiving Prostaglandin.

Prostaglandin E (PGE1) is necessary to maintain ductus arteriosus patency in many newborns with congenital heart disease. Because PGE1 therapy commonly leads to fever, and given this population's fragile state, a complete sepsis workup is often performed in febrile, but otherwise asymptomatic, patients. This practice of liberal evaluation with bacterial cultures, empiric antibiotic treatment, and delays in essential surgical intervention may result in poor resource utilization and lead to increased iatrogenic morbidity. This study sought to determine the incidence of fever and culture-positive infection in patients receiving PGE1, and identify diagnostic variables that predict culture-positive infection. The study included a single-center retrospective review of all neonates receiving PGE1 between 2011 and 2014. Logistic regression and receiver operator characteristic analysis were used to identify significant predictors of positive bacterial cultures. Among 435 neonates, 175 (40%) had fevers (≥ 38.3 °C) while concurrently receiving PGE1, but only 9 (2%) had culture-positive infection and 1 (< 1%) had culture-positive bacteremia. Among 558 cultures collected, only 16 (3%) had bacterial growth. Multivariable analysis revealed age (p = 0.049, AUC 0.604), hospital length of stay (p = 0.002, AUC 0.764) and hypoxemia (p = 0.044, AUC 0.727) as the only significant predictors of positive cultures. Fever (p = 0.998, AUC 0.424) was not a significant predictor. In conclusion, given that fever occurs frequently in neonates receiving PGE1 and it is a very non-specific marker and not a predictor of positive cultures, the common practice of complete sepsis workup should be re-examined in febrile patients at low risk of bacterial illness.

Extracorporeal Life Support as a Rescue Measure for Managing Life-Threatening Arrythmia and Brugada Syndrome.

We describe the use of extracorporeal cardiopulmonary resuscitation (E-CPR) to transiently stabilize a 3-month-old patient who presented with ventricular tachyarrhythmias leading to spontaneous cardiac arrest. The patient required 4 days of extracorporeal life support (ECLS) where he was diagnosed with probable Brugada syndrome (BS). The patient was discharged home in stable condition after implantable cardioverter defibrillator placement. This case highlights the importance of early transfer to extracorporeal membrane oxygenation (ECMO) center in the setting of unexplained cardiac arrhythmia in a pediatric patient. BS is an autosomal dominant genetic disorder with variable expression characterized by abnormal findings on electrocardiogram (ECG) in conjunction with an increased risk of ventricular tachyarrhythmias and sudden cardiac arrest (SCA). Early management is critical and early consideration to transfer to an institution where extracorporeal life support (ECLS/ECMO) is present to support the patient while further diagnostic work up is in progress is lifesaving.

Thrombolytic-Enhanced Extracorporeal Cardiopulmonary Resuscitation After Prolonged Cardiac Arrest.

OBJECTIVE: To investigate the effects of the combination of extracorporeal cardiopulmonary resuscitation and thrombolytic therapy on the recovery of vital organ function after prolonged cardiac arrest. DESIGN: Laboratory investigation. SETTING: University laboratory. SUBJECTS: Pigs. INTERVENTIONS: Animals underwent 30-minute untreated ventricular fibrillation cardiac arrest followed by extracorporeal cardiopulmonary resuscitation for 6 hours. Animals were allocated into two experimental groups: t-extracorporeal cardiopulmonary resuscitation (t-ECPR) group, which received streptokinase 1 million units, and control extracorporeal cardiopulmonary resuscitation (c-ECPR), which did not receive streptokinase. In both groups, the resuscitation protocol included the following physiologic targets: mean arterial pressure greater than 70 mm Hg, cerebral perfusion pressure greater than 50 mm Hg, PaO2 150 ± 50 torr (20 ± 7 kPa), PaCO2 40 ± 5 torr (5 ± 1 kPa), and core temperature 33°C ± 1°C. Defibrillation was attempted after 30 minutes of extracorporeal cardiopulmonary resuscitation. MEASUREMENTS AND MAIN RESULTS: A cardiac resuscitability score was assessed on the basis of success of defibrillation, return of spontaneous heart beat, weanability from extracorporeal cardiopulmonary resuscitation, and left ventricular systolic function after weaning. The addition of thrombolytic to extracorporeal cardiopulmonary resuscitation significantly improved cardiac resuscitability (3.7 ± 1.6 in t-ECPR vs 1.0 ± 1.5 in c-ECPR). Arterial lactate clearance was higher in t-ECPR than in c-ECPR (40% ± 15% vs 18% ± 21%). At the end of the experiment, the intracranial pressure was significantly higher in c-ECPR than in t-ECPR. Recovery of brain electrical activity, as assessed by quantitative analysis of electroencephalogram signal, and ischemic neuronal injury on histopathologic examination did not differ between groups. Animals in t-ECPR group did not have increased bleeding complications, including intracerebral hemorrhages. CONCLUSIONS: In a porcine model of prolonged cardiac arrest, t-ECPR improved cardiac resuscitability and reduced brain edema, without increasing bleeding complications. However, early electroencephalogram recovery and ischemic neuronal injury were not improved.

Hyperoxia Is Associated With Poor Outcomes in Pediatric Cardiac Patients Supported on Venoarterial Extracorporeal Membrane Oxygenation.

OBJECTIVES: Patients who require venoarterial extracorporeal membrane oxygenation because of cardiac failure frequently have supranormal blood oxygen tensions (hyperoxia). Recent studies have suggested worse outcomes in patients with hyperoxia after resuscitation from cardiac or respiratory arrests, presumably because of oxidative stress. There are limited data regarding the effect of hyperoxia on outcomes in pediatric patients on venoarterial extracorporeal membrane oxygenation. DESIGN: Retrospective chart review. SETTING: Pediatric cardiothoracic ICU. PATIENTS: Cardiac surgery patients less than 1 year old requiring venoarterial extracorporeal membrane oxygenation in the postoperative period from 2007 to 2013. MEASUREMENTS AND MAIN RESULTS: In 93 infants (median time on extracorporeal membrane oxygenation, 5 d), mortality at 30 days post surgery (primary outcome) was 38%. Using a receiver operating characteristic curve, a mean PaO2 of 193 mm Hg in the first 48 hours of extracorporeal membrane oxygenation was determined to have good discriminatory ability with regard to 30-day mortality. Univariate analysis identified a mean PaO2 greater than 193 mm Hg (p = 0.001), longer cardiopulmonary bypass times (p = 0.09), longer duration of extracorporeal membrane oxygenation (p < 0.0001), and higher extracorporeal membrane oxygenation pump flows (p = 0.052) as possible risk factors for 30-day mortality. In multivariable analysis controlling for the variables listed above, a mean PaO2 greater than 193 mm Hg remained an independent risk factor for mortality (p = 0.03). In addition, a mean PaO2 greater than 193 mm Hg was associated with the need for renal dialysis (p = 0.02) but not with neurologic injury (p = 0.41) during the hospitalization. CONCLUSIONS: In infants with congenital heart disease who are placed on venoarterial extracorporeal membrane oxygenation postoperatively, hyperoxia (defined as a mean PaO2 > 193 mm Hg in the first 48 hr of extracorporeal membrane oxygenation) was an independent risk factor for 30-day mortality after surgery. Future studies are needed to delineate the causative or associative role of hyperoxia with outcomes, especially in children with baseline cyanosis who may be more susceptible to the effects of oxidative stress.

Hemodynamic and Hematologic Effects of Histotripsy of Free-Flowing Blood: Implications for Ultrasound-Mediated Thrombolysis.

PURPOSE: To investigate the extent and consequences of histotripsy-induced hemolysis in vivo. MATERIALS AND METHODS: Porcine femoral venous blood was treated with histotripsy in 11 animals with systemic heparinization and 11 without heparin. Serum and hemodynamic measurements were obtained at 0, 2, 5, 10, 15, and 30 minutes and 48-72 hours after the procedure. Fisher exact test was used to determine differences in mortality between heparinized and nonheparinized groups. A linear mixed effects model was used to test for differences in blood analytes and hemodynamic variables over time. RESULTS: Of 11 animals in the nonheparinized group, 5 died during or immediately after histotripsy (45% nonheparin mortality vs 0% heparin mortality, P = .035). Serum hematocrit, free hemoglobin, lactate dehydrogenase (LDH), and right ventricular systolic pressure changed significantly (P < .001) over the treatment time. Serum hematocrit decreased slightly (from 32.5% ± 3.6% to 29.4% ± 4.2%), whereas increases were seen in free hemoglobin (from 6.2 mg/dL ± 4.6 to 348 mg/dL ± 100), LDH (from 365 U/L ± 67.8 ± to 722 U/L ± 84.7), and right ventricular systolic pressure (from 23.2 mm Hg ± 7.2 to 39.7 mm Hg ± 12.3). After 48-72 hours, hematocrit remained slightly decreased (P = .005), whereas LDH and free hemoglobin remained slightly increased compared with baseline (both P < .001). CONCLUSIONS: Intravascular histotripsy applied to free-flowing venous blood is safe with systemic heparinization, causing only transient hemodynamic and metabolic disturbances, supporting its use as a future noninvasive thrombolytic therapy modality.

Splanchnic near-infrared spectroscopy and risk of necrotizing enterocolitis after neonatal heart surgery.

Infants with critical congenital heart disease, especially patients with a single-ventricle (SV) physiology, are at increased risk for the development of necrotizing enterocolitis (NEC). Decreased splanchnic oxygen delivery may contribute to the development of NEC and may be detected by regional oximetry (rSO2) via splanchnic near-infrared spectroscopy (NIRS). This prospective study enrolled 64 neonates undergoing biventricular (BV) repair or SV palliation for CHD and monitored postoperative splanchnic rSO2 before and during initiation of enteral feedings to determine whether changes in rSO2 are associated with risk of NEC. Suspected or proven NEC was observed in 32 % (11/34) of the SV subjects and 0 % (0/30) of the BV subjects (p = 0.001). Compared with the BV subjects, the SV palliated subjects had significantly lower splanchnic rSO2 before and during initiation of enteral feedings, but the groups showed no difference after correction for lower pulse oximetry (SpO2) in the SV group. The clinical parameters were similar among the SV subjects with and without NEC except for cardiopulmonary bypass times, which were longer for the patients who experienced NEC (126 vs 85 min; p = 0.03). No difference was observed in splanchnic rSO2 or in the SpO2-rSO2 difference between the SV subjects with and without NEC. Compared with the patients who had suspected or no NEC, the subjects with proven NEC had a lower average splanchnic rSO2 (32.6 vs 47.0 %; p = 0.05), more time with rSO2 less than 30 % (48.8 vs 6.7 %; p = 0.04) at one-fourth-volume feeds, and more time with SpO2-rSO2 exceeding 50 % (33.3 vs 0 %; p = 0.03) before feeds were initiated. These data suggest that splanchnic NIRS may be a useful tool for assessing risk of NEC, especially in patients with an SV physiology.

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.

Methods to Enhance Causal Inference for Assessing Impact of Clinical Informatics Platform Implementation.

BACKGROUND: Hospitals are increasingly likely to implement clinical informatics tools to improve quality of care, necessitating rigorous approaches to evaluate effectiveness. We leveraged a multi-institutional data repository and applied causal inference methods to assess implementation of a commercial data visualization software in our pediatric cardiac intensive care unit. METHODS: Natural experiment in the University of Michigan (UM) Cardiac Intensive Care Unit pre and postimplementation of data visualization software analyzed within the Pediatric Cardiac Critical Care Consortium clinical registry; we identified N=21 control hospitals that contributed contemporaneous registry data during the study period. We used the platform during multiple daily rounds to visualize clinical data trends. We evaluated outcomes-case-mix adjusted postoperative mortality, cardiac arrest and unplanned readmission rates, and postoperative length of stay-most likely impacted by this change. There were no quality improvement initiatives focused specifically on these outcomes nor any organizational changes at UM in either era. We performed a difference-in-differences analysis to compare changes in UM outcomes to those at control hospitals across the pre versus postimplementation eras. RESULTS: We compared 1436 pre versus 779 postimplementation admissions at UM to 19 854 (pre) versus 14 160 (post) at controls. Admission characteristics were similar between eras. Postimplementation at UM we observed relative reductions in cardiac arrests among medical admissions, unplanned readmissions, and postoperative length of stay by -14%, -41%, and -18%, respectively. The difference-in-differences estimate for each outcome was statistically significant (P<0.05), suggesting the difference in outcomes at UM pre versus postimplementation is statistically significantly different from control hospitals during the same time. CONCLUSIONS: Clinical registries provide opportunities to thoroughly evaluate implementation of new informatics tools at single institutions. Borrowing strength from multi-institutional data and drawing ideas from causal inference, our analysis solidified greater belief in the effectiveness of this software across our institution.

A Model of High-Speed Endovascular Sonothrombolysis with Vortex Ultrasound-Induced Shear Stress to Treat Cerebral Venous Sinus Thrombosis.

This research aims to demonstrate a novel vortex ultrasound enabled endovascular thrombolysis method designed for treating cerebral venous sinus thrombosis (CVST). This is a topic of substantial importance since current treatment modalities for CVST still fail in as many as 20% to 40% of the cases, and the incidence of CVST has increased since the outbreak of the coronavirus disease 2019 pandemic. Compared with conventional anticoagulant or thrombolytic drugs, sonothrombolysis has the potential to remarkably shorten the required treatment time owing to the direct clot targeting with acoustic waves. However, previously reported strategies for sonothrombolysis have not demonstrated clinically meaningful outcomes (e.g., recanalization within 30 min) in treating large, completely occluded veins or arteries. Here, we demonstrated a new vortex ultrasound technique for endovascular sonothrombolysis utilizing wave-matter interaction-induced shear stress to enhance the lytic rate substantially. Our in vitro experiment showed that the lytic rate was increased by at least 64.3% compared with the nonvortex endovascular ultrasound treatment. A 3.1-g, 7.5-cm-long, completely occluded in vitro 3-dimensional model of acute CVST was fully recanalized within 8 min with a record-high lytic rate of 237.5 mg/min for acute bovine clot in vitro. Furthermore, we confirmed that the vortex ultrasound causes no vessel wall damage over ex vivo canine veins. This vortex ultrasound thrombolysis technique potentially presents a new life-saving tool for severe CVST cases that cannot be efficaciously treated using existing therapies.

Intermediate-term effects of intracardiac communications created noninvasively by therapeutic ultrasound (histotripsy) in a porcine model.

The authors have demonstrated that histotripsy (pulsed cavitational ultrasound) can create atrial septal defects and ventricular septal defects (VSDs) in an open-chest canine model transcutaneously through the intact chest of neonatal pigs. To assess the potential untoward effects of these applications, the clinical, systemic, and pathologic effects of histotripsy-induced intracardiac communications were analyzed. Six neonatal pigs received noninvasive ultrasound therapy to their ventricular septa, then were allowed to survive 1 month for evaluation of intermediate-term effects. The results were compared with those of six previous animals killed immediately and three others killed 2-3 days after the procedure. Brain magnetic resonance imaging (MRI) and an assessment of cardiac function were performed with long-term survivors, and pathologic specimens were obtained when the animals were killed. In all 15 animals, VSDs 2-6.5 mm wide were successfully created. No fatalities occurred, and all the animals thrived, achieving normal weight gain by the time they were killed. Brain MRI and lung pathology exhibited no evidence of thromboembolic events. No damage to intervening tissue was observed. Pathologic analysis showed demarcated damage to the ventricular septa. Flanking injury and hemorrhage observed acutely were resolved by 1 month, with tissue remodeling present. Transcutaneous histotripsy is a safe and effective technique for creating intracardiac communications noninvasively without intermediate-term untoward effects. With further refinement and development, histotripsy has the potential to become an effective tool for palliation of congenital heart disease.

Twenty-four-hour normothermic perfusion of isolated ex vivo hearts using plasma exchange.

OBJECTIVE: Cross-circulation of plasma from a paracorporeal animal allows successful ex vivo heart perfusion (EVHP) for 3 days. Little is known about the feasibility of prolonged EVHP without a paracorporeal animal. These experiments evaluated plasma exchange (PX) that infuses fresh plasma, whereas an equal amount is removed to replace paracorporeal cross-circulation. METHODS: Ten hearts were procured from 8 to 10 kg piglets and maintained with EVHP. The EVHP circuit was primed with platelet- and leukocyte-reduced blood. Plasma obtained from stored porcine blood (4°C for ≤7 days) was infused and removed with a plasma separator at 1 mL/h/g cardiac tissue (n = 5) in the PX group. Controls (n = 5) used the same EVHP without PX. Antegrade aortic perfusion was adjusted to reach physiologic coronary flow of 0.7 to 1.2 mL/min/g, normothermia (37°C), and hemoglobin ≥8 g/dL. Viability was assessed by hemodynamic metrics, metabolic assays, and histopathology. RESULTS: All PX hearts remained viable for 24 hours compared with only 1 control (P = .015). Coronary resistance was higher in the PX versus controls (1.06 ± 0.06 mm Hg/mL/min; 0.58 ± 0.02 mm Hg/mL/min [P < .05]). Lactate levels were lower in PX (2.8-4.2 mmol/L) versus controls (3.6-7.6 mmol/L) (P < .05). PX demonstrated a trend toward preservation of left ventricle systolic pressure (63.0 ± 10.9 mm Hg) versus controls (37 ± 22.0 mm Hg) (P > .05). In mixed effect models, oxygen consumption was higher with PX (P < .05). Histopathologic evaluation confirmed extensive myocardial degeneration and worse interstitial edema in controls. CONCLUSIONS: These results demonstrate that EVHP can be successfully maintained for at least 24 hours using continuous PX. This eliminates the need for a paracorporeal animal and provides an important step toward clinical application.

Prolonged (24-hour) Normothermic ex vivo Heart Perfusion Facilitated by Perfusate Hemofiltration.

Currently, normothermic ex vivo heart perfusion (NEVHP) is limited to 6-12 hours. NEVHP for 24 hours or more would allow organ treatment, assessment of organ function, and near-perfect recipient matching. We present a model of NEVHP using continuous hemofiltration (HFn) with sustained myocardial viability up to 24 hours. Twenty hearts from 6-10 kg piglets were procured and maintained on our NEVHP circuit. HFn hearts (n = 10) underwent NEVHP with HFn, whereas controls (n = 10) used NEVHP alone. All HFn vs. four controls were viable at 24 h (p = 0.004). At end perfusion, HFn hearts had higher left ventricular systolic pressure (51.5 ± 6.8 mm Hg, 38.3 ± 5.2 mm Hg, p = 0.05), lower coronary resistance (0.83 ± 0.11 mm Hg/mL/min, 1.18 ± 0.21mmHg/mL/min, p < 0.05), and lower serum lactate levels (2.9 ± 0.4 mmol/L, 4.1 ± 0.6 mmol/L, p < 0.0001) when compared to control hearts. HFn hearts also had less extensive myocardial damage and significantly less edema than control hearts with lower weight gain and wet-dry ratios. Using our circuit, NEVHP for 24 hours is possible with HFn and allows for preservation of myocardial function, improved tissue viability, decreased tissue edema, and less myocardial injury.

Noninvasive creation of an atrial septal defect by histotripsy in a canine model.

BACKGROUND: The primary objective of this study was to develop an image-guided, noninvasive procedure to create or enlarge an atrial septal defect for the treatment of neonates with hypoplastic left heart syndrome and an intact or restrictive atrial septum. Histotripsy is an innovative ultrasonic technique that produces nonthermal, mechanical tissue fractionation through the use of high-intensity ultrasound pulses. This article reports the pilot in vivo study to create an atrial septal defect through the use of extracardiac application of histotripsy in an open-chest canine model. METHODS AND RESULTS: In 10 canines, the atrial septum was exposed to histotripsy by an ultrasound transducer positioned outside the heart. Ultrasound pulses of 6-microsecond duration at a peak negative pressure of 15 MPa and a pulse repetition frequency of 3.3 kHz were generated by a 1-MHz focused transducer. The procedure was guided and monitored by real-time ultrasound imaging. In 9 of 10 canines, an atrial septal defect was produced, and shunting across the atrial septum was visualized. Pathology of the hearts showed atrial septal defects with minimal damage to surrounding tissue. No damage was found on the epicardial surface of the heart or other structures. CONCLUSIONS: Under real-time ultrasound guidance, atrial septal defects were successfully created with extracardiac histotripsy in a live canine model. Although further studies in an intact animal model are needed, these results provide promise of histotripsy becoming a valuable clinical tool.