Mathematical analysis of hemoglobin target in univentricular parallel circulation.

OBJECTIVE: The hemoglobin threshold for a decision to transfuse red blood cells in univentricular patients with parallel circulation is unclear. A pediatric expertise initiative put forth a "weak recommendation" for avoiding reflexive transfusion beyond a hemoglobin of 9 g/dL. We have created a mathematical model to assess the impact of hemoglobin thresholds in patients with parallel circulation. METHODS: A univentricular circulation was mathematically modeled. We examined the impact on oxygen extraction ratios and systemic and venous oxygen saturations by varying hemoglobin levels, pulmonary to systemic blood flow ratios, and total cardiac output. RESULTS: Applying a total cardiac index of 6 L/m2/min, oxygen consumption of 150 mL/min/m2, and a Qp/Qs ∼ 1, we found a hemoglobin level of 9 g/dL would lead to severe arterial (arterial oxygen saturation <70%) and venous (systemic venous oxygen saturation <40%) hypoxemia. To operate above the critical oxygen economy boundary (systemic venous oxygen saturation ∼40%) and maintain arterial oxygen saturation >70% would require either increasing the cardiac index to âˆ¼ 9 L/m2/min or increasing the hemoglobin to greater than 13 g/dL. Further, we found a greater improvement in arterial and venous saturation arises when hemoglobin is augmented from levels below 12 g/dL. CONCLUSIONS: Based on our model, a hemoglobin level of 9 g/dL would require a constricted set of features to sustain arterial saturations >70% and systemic venous saturations >40% and would risk unfavorable oxygen economy with elevations in oxygen consumption. Further prospective clinical studies are needed to delineate the impact of restrictive transfusion practices in univentricular circulation.

The acute influence of vasopressin on hemodynamic status and tissue oxygenation following the Norwood procedure.

Objectives: Arginine vasopressin (AVP) is used to treat hypotension. Because AVP increases blood pressure by increasing systemic vascular resistance, it may have an adverse effect on tissue oxygenation following the Norwood procedure. Methods: Retrospective analysis of continuously captured hemodynamic data of neonates receiving AVP following the Norwood procedure. Results: We studied 64 neonates exposed to AVP within 7 days after the Norwood procedure. For the entire group, AVP significantly increased mean blood pressure (2.5 ± 6.3) and cerebral and renal oxygen extraction ratios (4.1% ± 9.6% and 2.0% ± 4.7%, respectively; P < .001 for all values). In the right ventricle to pulmonary artery shunt cohort, AVP significantly increased blood pressure, arterial oxygen saturation (1.4% ± 3.8%; P = .011), pulmonary to systemic perfusion ratio (0.2 ± 0.4; P = .017), and cerebral and renal oxygen extraction ratios (4.6% ± 8.7%; P = .010% and 4.7% ± 9.4%; P = .014, respectively). The Blalock-Taussig shunt cohort experienced a less significant vasopressor response and no change in arterial oxygen saturation, pulmonary to systemic perfusion ratio, or cerebral and renal oxygen extraction ratios. Conclusions: The right ventricle to pulmonary artery shunt cohort experienced a significant vasopressor response to AVP that was associated with a significant increase in pulmonary perfusion and decrease in cerebral and renal perfusion, whereas the Blalock-Taussig shunt cohort experienced a less significant vasopressor response and no change in pulmonary or systemic perfusion. The influence of AVP on tissue oxygenation following the Norwood procedure may have clinical implications that require further study.

Postoperative physiological parameters associated with severe acute kidney injury after pediatric heart transplant.

BACKGROUND: The primary objective was to evaluate associations between perioperative clinical variables and postoperative hemodynamic indices after HT with the development of severe AKI. The secondary objective was to evaluate associations between UOP or creatinine as AKI indicators and morbidity after HT. METHODS: Retrospective study of all patients who underwent HT 1/2016-11/2019 at a quaternary pediatric institution. Severe AKI was defined as KDIGO stage 2 or higher. RESULTS: Of 94 HT patients, 73 met inclusion criteria; 45% of patients developed severe AKI. In univariate analysis, non-Hispanic Black race, preoperative AKI, longer CPB duration, lower weight, and peak lactate within 12 h post-HT were associated with severe AKI. CVP ≤12 h post-HT had a quadratic relationship, rather than linear, with severe AKI. PPV >18% was significantly associated with severe AKI but equated to noncontiguous 10 min of high variation over a 12-h period, and thus was deemed not clinically significant. In multivariate analysis, Black race, longer CPB duration, and higher CVP remained associated with severe AKI (c: 0.84, 95% CI 0.73-0.92). Severe AKI per creatinine, but not UOP criteria, was associated with longer duration of ventilation (p = .012) and longer intensive care unit length of stay (p = .003). CONCLUSIONS: In pediatric HT patients, non-Hispanic Black race, longer CPB time, and higher postoperative CVP ≤12 h post-HT were associated with severe AKI. AKI based on creatinine, not UOP, was associated with postoperative HT morbidity.

Impact of surfactant when utilized during pediatric cardiac surgery admissions: analysis of a nationwide database.

OBJECTIVE: Surfactant has been routinely used in the neonatal population, particularly in the setting of prematurity and neonatal respiratory distress syndrome. Current evidence, however, does not delineate the effect of surfactant use in neonates and older children during cardiac surgery admissions. This study aimed to characterize the impact of surfactant on pediatric cardiac surgery admissions. METHODS: Admissions of those under 18 years of age with cardiac surgery were identified from the Pediatric Health Information System (PHIS) database between 2004 and 2015, using ICD-9 procedure codes. Univariate analyses were conducted to compare admission characteristics between those that did and not utilize surfactant. Variables shown to be significant were then entered as independent variables into the regression analyses. Surfactant was entered into each model as an independent variable. RESULTS: A total of 81,313 admissions met the inclusion criteria. Of these, 109 (0.1%) had surfactant utilized. Univariate analyses identified several differences between admissions with and without surfactant use and demonstrated significantly increased mortality in the surfactant group (38.5% versus 4.6%, p < .01). Regression analyses demonstrated that surfactant was independently associated with increased mortality (odds ratio 6.0, 95% confidence interval 3.9-9.3, p < .01). Univariate analysis in only surfactant admissions demonstrated the following to be associated with inpatient mortality: younger age, prematurity, Ebstein anomaly, and hypoplastic left heart syndrome. CONCLUSIONS: Surfactant administration during pediatric cardiac surgery admissions is independently associated with a sixfold increase in inpatient mortality. It is likely that these findings are mediated by augmentation of the decrease in pulmonary vascular resistance and a subsequent decrease in systemic blood flow in the setting of parallel circulation. Surfactant should be administered with special consideration in neonates with cardiac disease and may be best avoided in those with parallel circulation.

Automated Prediction of Cardiorespiratory Deterioration in Patients With Single Ventricle.

BACKGROUND: Patients with single-ventricle physiology have a significant risk of cardiorespiratory deterioration between their first and second stage palliation surgeries. OBJECTIVES: The objective of this study is to develop and validate a real-time computer algorithm that can automatically recognize physiological precursors of cardiorespiratory deterioration in children with single-ventricle physiology during their interstage hospitalization. METHODS: A retrospective study was conducted from prospectively collected physiological data of subjects with single-ventricle physiology. Deterioration events were defined as a cardiac arrest requiring cardiopulmonary resuscitation or an unplanned intubation. Physiological metrics were derived from the electrocardiogram (heart rate, heart rate variability, ST-segment elevation, and ST-segment variability) and the photoplethysmogram (peripheral oxygen saturation and pleth variability index). A logistic regression model was trained to separate the physiological dynamics of the pre-deterioration phase from all other data generated by study subjects. Data were split 50/50 into model training and validation sets to enable independent model validation. RESULTS: Our cohort consisted of 238 subjects admitted to the cardiac intensive care unit and stepdown units of Texas Children's Hospital over a period of 6 years. Approximately 300,000 h of high-resolution physiological waveform and vital sign data were collected using the Sickbay software platform (Medical Informatics Corp., Houston, Texas). A total of 112 cardiorespiratory deterioration events were observed. Seventy-two of the subjects experienced at least 1 deterioration event. The risk index metric generated by our optimized algorithm was found to be both sensitive and specific for detecting impending events 1 to 2 h in advance of overt extremis (receiver-operating characteristic curve area: 0.958; 95% confidence interval: 0.950 to 0.965). CONCLUSIONS: Our algorithm can provide 1 to 2 h of advanced warning for 62% of all cardiorespiratory deterioration events in children with single-ventricle physiology during their interstage period, with only 1 alarm being generated at the bedside per patient per day.

Demographic predictors of hospitalization and mortality in US children with COVID-19.

Understanding which children are at increased risk for poor outcome with COVID-19 is critical. In this study, we link pediatric population-based data from the US Center for Disease Control and Prevention to COVID-19 hospitalization and in-hospital death. In 27,045 US children with confirmed COVID-19, we demonstrate that African American [OR 2.28 (95% CI: 1.93, 2.70)] or mixed race [OR 2.95 (95% CI: 2.28, 3.82)] and an underlying medical condition [OR 3.55 (95% CI: 3.14, 4.01)] are strong predictors for hospitalization. Death occurred in 39 (0.19%) of 20,096 hospitalized children; children with a prior medical condition had an increased odd for death [OR 8.8 (95% CI: 3.7, 21.1)].Conclusion: Hospitalization and in-hospital death are rare in children diagnosed with COVID-19. However, children at higher risk for these outcomes include those with an underlying medical condition, as well as those of African American descent. What is Known: • Demographic factors are independent prognosticators of poor outcome in children with COVID-19. What is New: • Children with an underlying medical condition and those from an African American or mixed race/ethnicity are at high risk for COVID-19 hospitalization. • History of a comorbidity supersedes age, gender, and race/ethnicity as a risk factor for in-hospital pediatric COVID-19 death.

Patient Characteristics and Treatment Outcomes of Symptomatic Catheter-Related Arterial Thrombosis in Infants: A Retrospective Cohort Study.

OBJECTIVE: To describe the clinical characteristics, outcomes, and adverse events of treatment for symptomatic infant catheter-related arterial thrombosis. STUDY DESIGN: Single-center retrospective medical record review of 99 infants (age <365 days) with catheter-related arterial thrombosis, either following indwelling arterial catheter placement or cardiac catheterization, who were treated with anticoagulation over an 8-year span at a pediatric tertiary care center. Outcomes measured include thrombosis progression, bleeding events, and thrombus resolution following the treatment period. RESULTS: Thromboses were secondary to indwelling arterial catheter placement in 51 (51.5%) and cardiac catheterization in 48 (48.5%). The median age at diagnosis of catheter-related arterial thrombosis was 52 days. All patients received therapeutic anticoagulation with either unfractionated heparin or low molecular weight heparin for a maximum of 28 days. Progression of catheter-related arterial thrombosis occurred in 8 (8.1%) patients. One (1%) major and 3 (3%) minor bleeding events occurred within the cohort. Complete thrombus resolution was observed in 60 (60.6%), partial resolution in 33 (33.3%), and no resolution in 6 (6.1%) following the treatment period. Factors associated with complete thrombus resolution included time from intervention to catheter-related arterial thrombosis diagnosis (median of 1 day vs 5 days in those who experienced thrombus resolution vs those who did not, P = .035), and iliac and/or femoral artery involvement (P = .015). CONCLUSIONS: Our treatment approach to infant catheter-related arterial thrombosis is safe and effective. Limitations of the study are its retrospective nature with a limited number of patients from a single institution. Additional prospective studies are needed to determine the optimal treatment approach to catheter-related arterial thrombosis in infants.

Multisystem inflammatory syndrome in children: A systematic review.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C), also known as pediatric inflammatory multisystem syndrome, is a new dangerous childhood disease that is temporally associated with coronavirus disease 2019 (COVID-19). We aimed to describe the typical presentation and outcomes of children diagnosed with this hyperinflammatory condition. METHODS: We conducted a systematic review to communicate the clinical signs and symptoms, laboratory findings, imaging results, and outcomes of individuals with MIS-C. We searched four medical databases to encompass studies characterizing MIS-C from January 1st, 2020 to July 25th, 2020. Two independent authors screened articles, extracted data, and assessed risk of bias. This review was registered with PROSPERO CRD42020191515. FINDINGS: Our search yielded 39 observational studies (n = 662 patients). While 71·0% of children (n = 470) were admitted to the intensive care unit, only 11 deaths (1·7%) were reported. Average length of hospital stay was 7·9 ± 0·6 days. Fever (100%, n = 662), abdominal pain or diarrhea (73·7%, n = 488), and vomiting (68·3%, n = 452) were the most common clinical presentation. Serum inflammatory, coagulative, and cardiac markers were considerably abnormal. Mechanical ventilation and extracorporeal membrane oxygenation were necessary in 22·2% (n = 147) and 4·4% (n = 29) of patients, respectively. An abnormal echocardiograph was observed in 314 of 581 individuals (54·0%) with depressed ejection fraction (45·1%, n = 262 of 581) comprising the most common aberrancy. INTERPRETATION: Multisystem inflammatory syndrome is a new pediatric disease associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that is dangerous and potentially lethal. With prompt recognition and medical attention, most children will survive but the long-term outcomes from this condition are presently unknown. FUNDING: Parker B. Francis and pilot grant from 2R25-HL126140. Funding agencies had no involvement in the study.

A robust Fourier-based method to measure pulse pressure variability.

OBJECTIVE: To propose a new method to estimate pulse pressure variability (PPV) in the arterial blood pressure waveform. METHODS: Traditional techniques of calculating PPV using peak finding have a fundamental flaw that prevents them from accurately resolving PPV for small tidal volumes, limiting the use of PPV to only mechanical ventilated patients. The improved method described here addresses this limitation using Fourier analysis of an oscillatory signal that exhibits a time-varying modulation of its amplitude. The analysis reveals a constraint on the spectral representation that must be satisfied for any oscillatory signal that exhibits a time-varying modulation of its amplitude. This intrinsic mathematical structure is taken advantage of in order to improve the robustness of the algorithm. RESULTS: The applicability of the method is tested using synthetic data and 100 h of physiologic data collected from patients admitted to Texas Children's Hospital. SIGNIFICANCE AND CONCLUSION: The proposed method accurately recovers values of PPV at signal-to-noise ratios six times smaller than the traditional method. This is a significant advance for the potential use of PPV to recognize fluid responsiveness during low tidal volume ventilation or spontaneous breathing for which the signal-to-noise ratio is expected to be small.

Ventricular Fibrillation and Myocardial Depression Following Pulmonary Valve Replacement in Tetralogy of Fallot With an Intramural Coronary Artery and Coronary Artery Compression by Chest Tube.

We describe the case of a 10-year-old male with a history of repaired Tetralogy of Fallot and known intramural right coronary artery (RCA) who presented for bioprosthetic pulmonary valve replacement. The operation was complicated by postoperative ventricular fibrillation arrest. Selective coronary angiography revealed external compression of the mid-RCA by a mediastinal chest tube that improved immediately upon removal of the tube. Ultimately, the patient required additional unroofing of the intramural coronary for full recovery. This case highlights the need to thoroughly investigate malignant ventricular dysrhythmias following pediatric cardiac surgery and to rule out coronary insufficiency, which may be due to both extrinsic and/or intrinsic lesions.

Use of Sodium Bicarbonate During Pediatric Cardiac Admissions with Cardiac Arrest: Who Gets It and What Does It Do?

The objectives of this study were to characterize the use of sodium bicarbonate in pediatric cardiac admissions that experience cardiac arrest, to determine sodium bicarbonate use over the years, and to determine the impact of sodium bicarbonate on length of admissions, billed charges, and inpatient mortality. A cross-sectional study was conducted utilizing the Pediatric Health Information System database. Characteristics of admissions with and without sodium bicarbonate were initially compared by univariate analyses. The frequency by which sodium bicarbonate was used was compared by year. Regression analyses were conducted to determine the impact of sodium bicarbonate on length of stay, billed charges, and inpatient mortality. A total of 3987 (50.3%) of pediatric cardiac intensive care admissions with cardiac arrest utilized sodium bicarbonate; however, frequency changed from 62.1% in 2004 to 43.7% in 2015. Linear regression analysis demonstrated a decrease in length of stay (-27.5 days, p < 0.01) and billed charges (-$470,906, p < 0.01). Logistic regression analysis demonstrated an increase in mortality (odds ratio 1.77, 95% confidence interval 1.56-2.01). In conclusion, sodium bicarbonate is being used with less frequency over the last years in pediatric cardiac admissions with cardiac arrest. After adjustment for cardiac diagnoses, comorbidities, vasoactive medications, and other resuscitation medications, sodium bicarbonate is independently associated with increased mortality.

Successful treatment of an adolescent with Naegleria fowleri primary amebic meningoencephalitis.

Naegleria fowleri is a thermophilic, free-living ameba that causes primary amebic meningoencephalitis. The infections are nearly always fatal. We present the third well-documented survivor of this infection in North America. The patient's survival most likely resulted from a variety of factors: early identification and treatment, use of a combination of antimicrobial agents (including miltefosine), and management of elevated intracranial pressure based on the principles of traumatic brain injury.