Normoxic Management during Cardiopulmonary Bypass Does Not Reduce Cerebral Mitochondrial Dysfunction in Neonatal Swine.

Optimal oxygen management during pediatric cardiopulmonary bypass (CPB) is unknown. We previously demonstrated an increase in cortical mitochondrial reactive oxygen species and decreased mitochondrial function after CPB using hyperoxic oxygen management. This study investigates whether controlled oxygenation (normoxia) during CPB reduces cortical mitochondrial dysfunction and oxidative injury. Ten neonatal swine underwent three hours of continuous CPB at 34 °C (flow > 100 mL/kg/min) via cervical cannulation targeting a partial pressure of arterial oxygen (PaO2) goal < 150 mmHg (normoxia, n = 5) or >300 mmHg (hyperoxia, n = 5). The animals underwent continuous hemodynamic monitoring and serial arterial blood sampling. Cortical microdialysate was serially sampled to quantify the glycerol concentration (represents neuronal injury) and lactate-to-pyruvate ratio (represents bioenergetic dysfunction). The cortical tissue was analyzed via high-resolution respirometry to quantify mitochondrial oxygen consumption and reactive oxygen species generation, and cortical oxidized protein carbonyl concentrations were quantified to assess for oxidative damage. Serum PaO2 was higher in hyperoxia animals throughout CPB (p < 0.001). There were no differences in cortical glycerol concentration between groups (p > 0.2). The cortical lactate-to-pyruvate ratio was modestly elevated in hyperoxia animals (p < 0.03) but the values were not clinically significant (<30). There were no differences in cortical mitochondrial respiration (p = 0.48), protein carbonyls (p = 0.74), or reactive oxygen species generation (p = 0.93) between groups. Controlled oxygenation during CPB does not significantly affect cortical mitochondrial function or oxidative injury in the acute setting. Further evaluation of the short and long-term effects of oxygen level titration during pediatric CPB on cortical tissue and other at-risk brain regions are needed, especially in the presence of cyanosis.

Early Impairment of Cerebral Bioenergetics After Cardiopulmonary Bypass in Neonatal Swine.

Objectives: We previously demonstrated cerebral mitochondrial dysfunction in neonatal swine immediately following a period of full-flow cardiopulmonary bypass (CPB). The extent to which this dysfunction persists in the postoperative period and its correlation with other markers of cerebral bioenergetic failure and injury is unknown. We utilized a neonatal swine model to investigate the early evolution of mitochondrial function and cerebral bioenergetic failure after CPB. Methods: Twenty piglets (mean weight 4.4 ± 0.5 kg) underwent 3 h of CPB at 34 °C via cervical cannulation and were followed for 8, 12, 18, or 24 h (n = 5 per group). Markers of brain tissue damage (glycerol) and bioenergetic dysfunction (lactate to pyruvate ratio) were continuously measured in cerebral microdialysate samples. Control animals (n = 3, mean weight 4.1 ± 1.2 kg) did not undergo cannulation or CPB. Brain tissue was extracted immediately after euthanasia to obtain ex-vivo cortical mitochondrial respiration and frequency of cortical microglial nodules (indicative of cerebral microinfarctions) via neuropathology. Results: Both the lactate to pyruvate ratio (P < .0001) and glycerol levels (P = .01) increased in cerebral microdialysate within 8 h after CPB. At 24 h post-CPB, cortical mitochondrial respiration was significantly decreased compared with controls (P = .046). The presence of microglial nodules increased throughout the study period (24 h) (P = .01, R2 = 0.9). Conclusion: CPB results in impaired cerebral bioenergetics that persist for at least 24 h. During this period of bioenergetic impairment, there may be increased susceptibility to secondary injury related to alterations in metabolic delivery or demand, such as hypoglycemia, seizures, and decreased cerebral blood flow.

Utility of a Benchmarking Report for Balancing Infection Prevention and Antimicrobial Stewardship in Children with Complicated Appendicitis.

OBJECTIVE: To develop a severity-adjusted, hospital-level benchmarking comparative performance report for postoperative organ space infection and antibiotic utilization in children with complicated appendicitis. BACKGROUND: No benchmarking data exist to aid hospitals in identifying and prioritizing opportunities for infection prevention or antimicrobial stewardship in children with complicated appendicitis. METHODS: This was a multicenter cohort study using NSQIP-Pediatric data from 16 hospitals participating in a regional research consortium, augmented with antibiotic utilization data obtained through supplemental chart review. Children with complicated appendicitis who underwent appendectomy from 07/01/2015 to 06/30/2020 were included. Thirty-day postoperative OSI rates and cumulative antibiotic utilization were compared between hospitals using observed-to-expected (O/E) ratios after adjusting for disease severity using mixed effects models. Hospitals were considered outliers if the 95% confidence interval for O/E ratios did not include 1.0. RESULTS: 1790 patients were included. Overall, the OSI rate was 15.6% (hospital range: 2.6-39.4%) and median cumulative antibiotic utilization was 9.0 days (range: 3.0-13.0). Across hospitals, adjusted O/E ratios ranged 5.7-fold for OSI (0.49-2.80, P=0.03) and 2.4-fold for antibiotic utilization (0.59-1.45, P<0.01). Three (19%) hospitals were outliers for OSI (1 high and 2 low performers), and eight (50%) were outliers for antibiotic utilization (5 high and 3 low utilizers). Ten (63%) hospitals were identified as outliers in one or both measures. CONCLUSIONS: A comparative performance benchmarking report may help hospitals identify and prioritize quality improvement opportunities for infection prevention and antimicrobial stewardship, as well as identify exemplar performers for dissemination of best practices.

Diffuse Optical Monitoring of Cerebral Hemodynamics and Oxygen Metabolism during and after Cardiopulmonary Bypass: Hematocrit Correction and Neurological Vulnerability.

Cardiopulmonary bypass (CPB) provides cerebral oxygenation and blood flow (CBF) during neonatal congenital heart surgery, but the impacts of CPB on brain oxygen supply and metabolic demands are generally unknown. To elucidate this physiology, we used diffuse correlation spectroscopy and frequency-domain diffuse optical spectroscopy to continuously measure CBF, oxygen extraction fraction (OEF), and oxygen metabolism (CMRO2) in 27 neonatal swine before, during, and up to 24 h after CPB. Concurrently, we sampled cerebral microdialysis biomarkers of metabolic distress (lactate-pyruvate ratio) and injury (glycerol). We applied a novel theoretical approach to correct for hematocrit variation during optical quantification of CBF in vivo. Without correction, a mean (95% CI) +53% (42, 63) increase in hematocrit resulted in a physiologically improbable +58% (27, 90) increase in CMRO2 relative to baseline at CPB initiation; following correction, CMRO2 did not differ from baseline at this timepoint. After CPB initiation, OEF increased but CBF and CMRO2 decreased with CPB time; these temporal trends persisted for 0-8 h following CPB and coincided with a 48% (7, 90) elevation of glycerol. The temporal trends and glycerol elevation resolved by 8-24 h. The hematocrit correction improved quantification of cerebral physiologic trends that precede and coincide with neurological injury following CPB.

Contemporary outcomes for functional single ventricle with total anomalous pulmonary venous connection.

OBJECTIVE: In 2004, we reported improved early survival for patients with functional single ventricle anatomy and total anomalous pulmonary venous connection. This study sought to discover if outcomes have been ameliorated in the contemporary era. METHODS: This was a single-center review of patients with single ventricle anatomy and total anomalous pulmonary venous connection who were admitted from 1984 to 2021. The cohort was divided into similarly sized groups by date of admission: Era 1: 1984 to 1992, Era 2: 1993 to 2007, and Era 3: 2008 to 2021. Survival was compared, and Cox proportional hazards models were used to evaluate the likelihood of mortality. RESULTS: We included 190 patients with single ventricle anatomy and total anomalous pulmonary venous connection. Unbalanced atrioventricular canal defect (70%) was the most common primary diagnosis. The most common type of total anomalous pulmonary venous connection was supracardiac (49%). Approximately one-third (32%) of patients had pulmonary venous obstruction. There were no significant differences in patient characteristics across eras. Early survival after initial palliative operation improved between Eras 1 and 2, and then remained stable in Era 3. Overall survival improved from Era 1 to Eras 2 and 3 (P < .001), but not between Era 2 and 3. Survival to 10 years by Eras 1 to 3 was 15%, 51%, and 54%, respectively. The anatomic features associated with worse survival were hypoplastic left heart syndrome diagnosis (hazard ratio, 1.60; 1.04-2.57) and pulmonary venous obstruction (hazard ratio, 1.80; 1.24-2.69). CONCLUSIONS: Overall survival for patients with single ventricle anatomy and total anomalous pulmonary venous connection has plateaued since the early 2000s. Even in the most recent era, survival to age 10 years remains less than 60%. Risk factors for mortality include the diagnosis of hypoplastic left heart syndrome and pulmonary venous obstruction. Further studies should focus on identification of the pathophysiological factors underlying the increased mortality.

Outcomes and Resource Utilization Associated with Use of Routine Pre-Discharge White Blood Cell Count for Clinical Decision-Making in Children with Complicated Appendicitis: A Multicenter Hospital-Level Analysis.

BACKGROUND: The objective was to explore the hospital-level relationship between routine pre-discharge WBC utilization (RPD-WBC) and outcomes in children with complicated appendicitis. METHODS: Multicenter analysis of NSQIP-Pediatric data from 14 consortium hospitals augmented with RPD-WBC data. WBC were considered routine if obtained within one day of discharge in children who did not develop an organ space infection (OSI) or fever during the index admission. Hospital-level observed-to-expected ratios (O/E) for 30-day outcomes (antibiotic days, imaging utilization, healthcare days, and OSI) were calculated after adjusting for appendicitis severity and patient characteristics. Spearman correlation was used to explore the relationship between hospital-level RPD-WBC utilization and O/E's for each outcome. RESULTS: 1528 children were included. Significant variation was found across hospitals in RPD-WBC use (range: 0.7-100%; p < 0.01) and all outcomes (mean antibiotic days: 9.9 [O/E range: 0.56-1.44, p < 0.01]; imaging: 21.9% [O/E range: 0.40-2.75, p < 0.01]; mean healthcare visit days: 5.7 [O/E 0.74-1.27, p < 0.01]); OSI: 14.1% [O/E range: 0.43-3.64, p < 0.01]). No correlation was found between RPD-WBC use and antibiotic days (r = +0.14, p = 0.64), imaging (r = -0.07, p = 0.82), healthcare days (r = +0.35, p = 0.23) or OSI (r = -0.13, p = 0.65). CONCLUSIONS: Increased RPD-WBC utilization in pediatric complicated appendicitis did not correlate with improved outcomes or resource utilization at the hospital level. LEVEL OF EVIDENCE: III. TYPE OF STUDY: Clinical Research.

Association Between Antibiotic Redosing Before Incision and Risk of Incisional Site Infection in Children With Appendicitis.

OBJECTIVE: To evaluate whether redosing antibiotics within an hour of incision is associated with a reduction in incisional surgical site infection (iSSI) in children with appendicitis. BACKGROUND: Existing data remain conflicting as to whether children with appendicitis receiving antibiotics at diagnosis benefit from antibiotic redosing before incision. METHODS: This was a multicenter retrospective cohort study using data from the Pediatric National Surgical Quality Improvement Program augmented with antibiotic utilization and operative report data obtained though supplemental chart review. Children undergoing appendectomy at 14 hospitals participating in the Eastern Pediatric Surgery Network from July 2016 to June 2020 who received antibiotics upon diagnosis of appendicitis between 1 and 6 hours before incision were included. Multivariable logistic regression was used to compare odds of iSSI in those who were and were not redosed with antibiotics within 1 hour of incision, adjusting for patient demographics, disease severity, antibiotic agents, and hospital-level clustering of events. RESULTS: A total of 3533 children from 14 hospitals were included. Overall, 46.5% were redosed (hospital range: 1.8%-94.4%, P <0.001) and iSSI rates were similar between groups [redosed: 1.2% vs non-redosed: 1.3%; odds ratio (OR) 0.84, (95%,CI, 0.39-1.83)]. In subgroup analyses, redosing was associated with lower iSSI rates when cefoxitin was used as the initial antibiotic (redosed: 1.0% vs nonredosed: 2.5%; OR: 0.38, (95% CI, 0.17-0.84)], but no benefit was found with other antibiotic regimens, longer periods between initial antibiotic administration and incision, or with increased disease severity. CONCLUSIONS: Redosing of antibiotics within 1 hour of incision in children who received their initial dose within 6 hours of incision was not associated with reduction in risk of incisional site infection unless cefoxitin was used as the initial antibiotic.

Succinate prodrugs as treatment for acute metabolic crisis during fluoroacetate intoxication in the rat.

Sodium fluoroacetate (FA) is a metabolic poison that systemically inhibits the tricarboxylic acid (TCA) cycle, causing energy deficiency and ultimately multi-organ failure. It poses a significant threat to society because of its high toxicity, potential use as a chemical weapon and lack of effective antidotal therapy. In this study, we investigated cell-permeable succinate prodrugs as potential treatment for acute FA intoxication. We hypothesized that succinate prodrugs would bypass FA-induced mitochondrial dysfunction, provide metabolic support, and prevent metabolic crisis during acute FA intoxication. To test this hypothesis, rats were exposed to FA (0.75 mg/kg) and treated with the succinate prodrug candidate NV354. Treatment efficacy was evaluated based on cardiac and cerebral mitochondrial respiration, mitochondrial content, metabolic profiles and tissue pathology. In the heart, FA increased concentrations of the TCA metabolite citrate (+ 4.2-fold, p < 0.01) and lowered ATP levels (- 1.9-fold, p < 0.001), confirming the inhibition of the TCA cycle by FA. High-resolution respirometry of cardiac mitochondria further revealed an impairment of mitochondrial complex V (CV)-linked metabolism, as evident by a reduced phosphorylation system control ratio (- 41%, p < 0.05). The inhibition of CV-linked metabolism is a novel mechanism of FA cardiac toxicity, which has implications for drug development and which NV354 was unable to counteract at the given dose. In the brain, FA induced the accumulation of ß-hydroxybutyrate (+ 1.4-fold, p < 0.05) and the reduction of mitochondrial complex I (CI)-linked oxidative phosphorylation (OXPHOSCI) (- 20%, p < 0.01), the latter of which was successfully alleviated by NV354. This promising effect of NV354 warrants further investigations to determine its potential neuroprotective effects.

Reintervention for Superior Vena Cava Obstruction After Heart Transplant.

BACKGROUND: Children undergoing orthotopic heart transplant (OHT) may require complex reconstruction of superior vena cava (SVC) anomalies. SVC anatomy and mode of reconstruction are potential risk factors for SVC obstruction. METHODS: A retrospective single-center review was conducted of patients undergoing initial OHT between January 1, 1990, and July 1, 2021. Simple SVC anatomy included a single right SVC to the right atrium or bilateral SVCs with a left SVC to an intact coronary sinus, without prior superior cavopulmonary connection. Presence of anomalous SVC anatomy, superior cavopulmonary connection, or previous atrial switch operation defined complex anatomy. Reconstructive strategies included atrial anastomosis; direct SVC-to-SVC anastomosis; and augmented SVC anastomosis using innominate vein, patch, cavopulmonary connection, or interposition graft. The primary outcome was reintervention for SVC obstruction. RESULTS: Of 288 patients, pretransplant diagnoses included congenital heart disease (n = 155 [54%]), cardiomyopathy (n = 125 [43%]), and other (n = 8 [3%]). Most (n = 208 [72%]) had simple SVC anatomy compared with complex SVC anatomy (80 [28%]). Reintervention for SVC obstruction occurred in 15 of 80 (19%) with complex anatomy and 1 of 208 (0.5%) with simple anatomy (P = .0001). Reintervention was more common when innominate vein or a patch was used (9/25 [36%]) compared with an interposition graft (1/7 [14%]) or direct anastomosis (6/82 [7%]; χ2 = 13.1; P = .001). Most reinterventions occurred within 30 days of OHT (14/16 [88%]). CONCLUSIONS: Patients with complex SVC anatomy have a higher rate of reintervention for SVC obstruction after OHT compared with those with simple SVC anatomy. In cases of complex SVC anatomy, interposition grafts may be associated with less reintervention compared with complex reconstructions using donor tissue.

Association of Gangrenous, Suppurative, and Exudative Findings With Outcomes and Resource Utilization in Children With Nonperforated Appendicitis.

Importance: The clinical significance of gangrenous, suppurative, or exudative (GSE) findings is poorly characterized in children with nonperforated appendicitis. Objective: To evaluate whether GSE findings in children with nonperforated appendicitis are associated with increased risk of surgical site infections and resource utilization. Design, Setting, and Participants: This multicenter cohort study used data from the Appendectomy Targeted Database of the American College of Surgeons Pediatric National Surgical Quality Improvement Program, which were augmented with operative report data obtained by supplemental medical record review. Data were obtained from 15 hospitals participating in the Eastern Pediatric Surgery Network (EPSN) research consortium. The study cohort comprised children (aged ≤18 years) with nonperforated appendicitis who underwent appendectomy from July 1, 2015, to June 30, 2020. Exposures: The presence of GSE findings was established through standardized, keyword-based audits of operative reports by EPSN surgeons. Interrater agreement for the presence or absence of GSE findings was evaluated in a random sample of 900 operative reports. Main Outcomes and Measures: The primary outcome was 30-day postoperative surgical site infections (incisional and organ space infections). Secondary outcomes included rates of hospital revisits, postoperative abdominal imaging, and postoperative length of stay. Multivariable mixed-effects regression was used to adjust measures of association for patient characteristics and clustering within hospitals. Results: Among 6133 children with nonperforated appendicitis, 867 (14.1%) had GSE findings identified from operative report review (hospital range, 4.2%-30.2%; P < .001). Reviewers agreed on presence or absence of GSE findings in 93.3% of cases (weighted κ, 0.89; 95% CI, 0.86-0.92). In multivariable analysis, GSE findings were associated with increased odds of any surgical site infection (4.3% vs 2.2%; odds ratio [OR], 1.91; 95% CI, 1.35-2.71; P < .001), organ space infection (2.8% vs 1.1%; OR, 2.18; 95% CI, 1.30-3.67; P = .003), postoperative imaging (5.8% vs 3.7%; OR, 1.70; 95% CI, 1.23-2.36; P = .002), and prolonged mean postoperative length of stay (1.6 vs 0.9 days; rate ratio, 1.43; 95% CI, 1.32-1.54; P < .001). Conclusions and Relevance: In children with nonperforated appendicitis, findings of gangrene, suppuration, or exudate are associated with increased surgical site infections and resource utilization. Further investigation is needed to establish the role and duration of postoperative antibiotics and inpatient management to optimize outcomes in this cohort of children.