Socioeconomic Factors Influencing Pediatric Peak Oxygen Consumption Prediction.

OBJECTIVE: To determine if socioeconomic status (SES) has a greater effect than standard demographic values on predicted peak oxygen consumption (pVO2). STUDY DESIGN: We conducted a single-institution, retrospective analysis of maximal cardiopulmonary exercise test (CPET) data from 2010 to 2020 for healthy patients age <19 years with body mass index (BMI) percentile (BMI%) between 5-95. Data were sorted by self-identified race, BMI%, and adjusted gross income (AGI); AGI served as a surrogate for SES. Mean percent predicted pVO2 (pppVO2) was compared between groups. Linear regression was used to adjust for differences. RESULTS: A total of 541 CPETs met inclusion criteria. Mean pppVO2 was 97% ± 22.6 predicted (P < .01) with 30% below criterion standard for normal (85% predicted). After excluding unknown AGI and race, 418 CPETs remained. Mean pppVO2 was lower for Blacks (n = 36) and Latinx (n = 26) compared with Whites (n = 333, P < .01). Mean pppVO2 declined as AGI decreased (P < .01). The differences in pppVO2 between racial categories remained significant when adjusted for BMI% (Black r = -7.3, P = .035; Latinx r = -15.4, P < .01). These differences both decreased in magnitude and were no longer significant when adjusted for AGI (Black r = -6.0, P = .150; Latinx r = -9.3, P = .06). CONCLUSIONS: Lower SES correlates with lower measured cardiovascular fitness and may confound data interpretation. When using normative reference ranges in clinical decision making, providers should recognize that social determinants of health may influence predicted fitness. Social inequities should be considered when assessing pediatric cardiovascular fitness.

Predictors of Poor Outcomes in Pediatric Venoarterial Extracorporeal Membrane Oxygenation.

BACKGROUND: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) provides respiratory and hemodynamic support to pediatric patients in severe cardiac failure. We aim to identify risk factors associated with poorer outcomes in this population. METHODS: A retrospective chart review was conducted of pediatric patients requiring VA-ECMO support for cardiac indications at our institution from 2004 to 2015. Data were collected on demographics, indication, markers of cardiac output, ventricular assist device (VAD) insertion, heart transplantation, or left atrial (LA) decompression. Univariate Cox proportional hazards models were used to calculate hazard ratios (HRs) for variables associated with the composite primary outcome of transplant-free survival (TFS). RESULTS: Of the 68 reviewed patients, 65% were male, 84% were white, 38% had a prior surgery, 13% had a prior transplant, 10% had a prior ECMO support, and 87.5% required vasoactive support within six hours of cannulation. The ECMO indications included congenital heart disease repaired >30 days prior (12%), cardiomyopathy (41%), posttransplant rejection (7%), and cardiorespiratory failure (40%). The TFS was 54.5% at discharge and 47.7% at one year. Predictors of transplant and/or death include epinephrine use (hazard ratio [HR] = 2.269, P = .041), elevated lactate (HR = 1.081, P = 0005), and elevated creatinine (HR = 1.081, P = .005) within six hours prior to cannulation. Sixteen (23.6%) patients underwent LA decompression. Placement of VAD occurred in 16 (23.5%) patients, for which nonwhite race (HR = 2.94, P = .034) and prior ECMO (HR = 3.42, P = .053) were the only identified risk factors. CONCLUSIONS: Need for VA-ECMO for cardiac support carries high inpatient morbidity and mortality. Epinephrine use and elevated lactate and creatinine were associated with especially poor outcomes. Patients who survived to discharge had good short-term follow-up results.

Use of Nicardipine After Cardiac Operations Is Safe in Children Regardless of Age.

BACKGROUND: Control of postoperative hypertension is central to the care of infants and children after cardiac operations. Continuous pharmacologic delivery affords the advantage of rapid onset and ease of titration. Although well established in older children and adults, calcium channel blockers are routinely avoided in children aged younger than 1 year secondary to concerns of safety and efficacy in the setting of sarcoplasmic reticulum development. Thus, the purpose of this study was to review a single-institution experience with nicardipine, a selective calcium channel blocker, in pediatric patients after cardiac operations. METHODS: Children undergoing cardiac operations at the University of Virginia from 2010 to 2015 were retrospectively reviewed after selection based on receipt of nicardipine for blood pressure management in the postoperative period. Demographic, operative, laboratory, and postoperative data were collected for adverse effect analysis and outcomes comparisons between infants aged younger than 6 months (group 1) and older than 6 months (group 2). RESULTS: During the study period, 68 children (group 1: n = 33 [48%]; group 2: n = 35 [52%]) received nicardipine after cardiac operations (0.5 to 1 µg · kg-1 · min-1). Nicardipine was initiated at a mean of 6.6 ± 13.1 hours postoperatively in group 1 and 5.4 ± 7.8 hours in group 2. Nine patients (13%) demonstrated clinically significant hypotension necessitating dosing titration with no statistically significant differences between groups. No major adverse events occurred following nicardipine administration. CONCLUSIONS: Nicardipine is well tolerated after cardiac operations in children irrespective of age or underlying pathology. Thus, nicardipine should be considered as safe and effective in children of all ages for control of hypertension after cardiac operations.

Changes in cell-cycle kinetics responsible for limiting somatic growth in mice.

In mammals, the rate of somatic growth is rapid in early postnatal life but then slows with age, approaching zero as the animal approaches adult body size. To investigate the underlying changes in cell-cycle kinetics, [methyl-H]thymidine and 5'-bromo-2'deoxyuridine were used to double-label proliferating cells in 1-, 2-, and 3-wk-old mice for four weeks. Proliferation of renal tubular epithelial cells and hepatocytes decreased with age. The average cell-cycle time did not increase in liver and increased only 1.7 fold in kidney. The fraction of cells in S-phase that will divide again declined approximately 10 fold with age. Concurrently, average cell area increased approximately 2 fold. The findings suggest that somatic growth deceleration primarily results not from an increase in cell-cycle time but from a decrease in growth fraction (fraction of cells that continue to proliferate). During the deceleration phase, cells appear to reach a proliferative limit and undergo their final cell divisions, staggered over time. Concomitantly, cells enlarge to a greater volume, perhaps because they are relieved of the size constraint imposed by cell division. In conclusion, a decline in growth fraction with age causes somatic growth deceleration and thus sets a fundamental limit on adult body size.