Reference Values of Cardiopulmonary Exercise Test Parameters in the Contemporary Paediatric Population.

BACKGROUND: The evaluation of health status by cardiopulmonary exercise test (CPET) has shown increasing interest in the paediatric population. Our group recently established reference Z-score values for paediatric cycle ergometer VO2max, applicable to normal and extreme weights, from a cohort of 1141 healthy children. There are currently no validated reference values for the other CPET parameters in the paediatric population. This study aimed to establish, from the same cohort, reference Z-score values for the main paediatric cycle ergometer CPET parameters, apart from VO2max. RESULTS: In this cross-sectional study, 909 healthy children aged 5-18 years old underwent a CPET. Linear, quadratic, and polynomial mathematical regression equations were applied to identify the best CPET parameters Z-scores, according to anthropometric parameters (sex, age, height, weight, and BMI). This study provided Z-scores for maximal CPET parameters (heart rate, respiratory exchange ratio, workload, and oxygen pulse), submaximal CPET parameters (ventilatory anaerobic threshold, VE/VCO2 slope, and oxygen uptake efficiency slope), and maximum ventilatory CPET parameters (tidal volume, respiratory rate, breathing reserve, and ventilatory equivalent for CO2 and O2). CONCLUSIONS: This study defined paediatric reference Z-score values for the main cycle ergometer CPET parameters, in addition to the existing reference values for VO2max, applicable to children of normal and extreme weights. Providing Z-scores for CPET parameters in the paediatric population should be useful in the follow-up of children with various chronic diseases. Thus, new paediatric research fields are opening up, such as prognostic studies and clinical trials using cardiopulmonary fitness outcomes. Trial registration NCT04876209-Registered 6 May 2021-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04876209 .

Reference values of aerobic fitness in the contemporary paediatric population.

AIMS: There has been a growing interest in the use of markers of aerobic physical fitness (VO2max assessed by cardiopulmonary exercise test (CPET)) in the follow-up of paediatric chronic diseases. The dissemination of CPET in paediatrics requires valid paediatric VO2max reference values to define the upper and lower normal limits. This study aimed to establish VO2max reference Z-score values, from a large cohort of children representative of the contemporary paediatric population, including those with extreme weights. METHODS AND RESULTS: In this cross-sectional study, 909 children aged 5 to 18 years old from the general French population (development cohort) and 232 children from the general German and US populations (validation cohort) underwent a CPET, following the guidelines on high-quality CPET assessment. Linear, quadratic, and polynomial mathematical regression equations were applied to identify the best VO2max Z-score model. Predicted and observed VO2max values using the VO2max Z-score model, and the existing linear equations were compared, in both development and validation cohorts. For both sexes, the mathematical model using natural logarithms of VO2max, height, and BMI was the best fit for the data. This Z-score model could be applied to normal and extreme weights and was more reliable than the existing linear equations, in both internal and external validity analyses (https://play.google.com/store/apps/details?id=com.d2l.zscore). CONCLUSION: This study established reference Z-score values for paediatric cycloergometer VO2max using a logarithmic function of VO2max, height, and BMI, applicable to normal and extreme weights. Providing Z-scores to assess aerobic fitness in the paediatric population should be useful in the follow-up of children with chronic diseases. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT04876209.

Disseminated Mycobacterium kansasii disease in complete DiGeorge syndrome.

PURPOSE: Complete DiGeorge syndrome (cDGS) describes a subset of patients with DiGeorge syndrome that have thymic aplasia, and thus are at risk for severe opportunistic infections. Patients with cDGS and mycobacterial infection have not previously been described. We present this case to illustrate that patients with cDGS are at risk for nontuberculous mycobacterial infections and to discuss further antimicrobial prophylaxis prior to thymic transplantation. METHODS: A 13-month old male was identified as T cell deficient by the T cell receptor excision circle (TREC) assay on newborn screening, and was subsequently confirmed to have cDGS. He presented with fever and cough, and was treated for chronic aspiration pneumonia as well as Pneumocystis jirovecii infection without significant improvement. It was only after biopsy of mediastinal lymph nodes seen on CT that the diagnosis of disseminated Mycobacterium kansasii was made. We reviewed the literature regarding atypical mycobacterial infections and prophylaxis used in other immunocompromised patients, as well as the current data regarding cDGS detection through TREC newborn screening. RESULTS: Multiple cases of cDGS have been diagnosed via TREC newborn screening, however this is the first patient with cDGS and disseminated mycobacterial infection to be reported in literature. Thymic transplantation is the definitive treatment of choice for cDGS. Prophylaxis with either clarithromycin or azithromycin has been shown to reduce mycobacterial infections in children with advanced human immunodeficiency virus infection. CONCLUSIONS: Children with cDGS should receive thymic transplantion as soon as possible, but prior to this are at risk for nontuberculous mycobacterial infections. Severe, opportunistic infections may require invasive testing for diagnosis in patients with cDGS. Antimicrobial prophylaxis should be considered to prevent disseminated mycobacterial infection in these patients.