Objective: To present normative values for maximal respiratory pressures in healthy children and adolescents based on a meta-analysis of reference equations from previous publications. Data Sources: The searches were carried out until May 2020 in the following databases: ScienceDirect, Medical Literature Analysis and Retrieval System Online- MEDLINE (PubMed), Cumulative Index to Nursing and Allied Health Literature - CINAHL, Scientific Electronic Library Online - SciELO. Study Selection: Articles that determined normative values and/or reference equations for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in healthy children and adolescents published in English, Portuguese, or Spanish regardless of the year of publication were included. Data Extraction: Two reviewers selected titles and abstracts to identify the studies. In case of conflict, a third reviewer was requested. Results: Initially, 248 studies were identified, 26 studies were included in the systematic review and 17 in the meta-analysis. The sample consisted of 5,190 individuals, and the MIP and MEP values were stratified by sex and age groups of 4-11 and 12-19 years. Values from 4 to 11 years for females were: 66.4 cmH2O for MIP and 74.8 cmH2O for MEP, and for males, 76.1 cmH2O for MIP and 84.7 cmH2O for MEP. In the age group from 12 to 19 years, for females were: 81.4 cmH2O for MIP and 90.1 cmH2O for MEP, and for males were 95.6 cmH2O for MIP and 108.3 cmH2O for MEP. Conclusions: This meta-analysis suggested normative values for respiratory muscle strength in children and adolescents based on 17 studies.

Introduction Spirometry plays an important role in the assessment of possible respiratory failure in children with neuromuscular disorders (NMDs). However, obtaining reliable spirometry results is a major challenge. We studied the relation between Forced Oscillation Technique (FOT) and spirometry results. FOT is an easy, non-invasive method to measure respiratory mechanics, i.e. respiratory resistance R and respiratory reactance X. We hypothesized an increased resistance R and reduced reactance X in patients with more reduced lung function. Methods In this prospective single center study we included all children with NMDs able to perform spirometry. We consecutively measured respiratory resistance R and reactance X at 5, 11 and 19 Hz and (Forced) Vital Capacity, Peak Expiratory Flow. Spearman correlation coefficients were calculated and regression curves were estimated. Results We included 148 patients, with a median age of 13 years (IQR 8-16). All correlation coefficients were statistically significant with p = 0.000. A negative correlation was found between resistance R and spirometry outcomes (spearman correlation coefficient (ρ) between -0.5 and -0.6). A positive correlation was found between reactance X (i.e. less negative outcomes) and spirometry outcomes (ρ between 0.4 and 0.6). Highest correlation was found at lower frequencies. Regression analysis showed a non-linear relation between FOT and spirometry results. Conclusion We found a non-linear relation between FOT and spirometry results with increased resistance R and reduced reactance X in patients with more restrictive lung function decline. Given the difficulties with performing spirometry, FOT may be a promising surrogate measure of lung function.

Introduction Understanding the impact of scoliosis surgery on lung function is important for counseling patients about risks and benefits of surgery. We prospectively compared the trends in lung function test (LFT) results prior to and after scoliosis surgery in children with neuromuscular diseases, or dysmorphic syndromes. We hypothesized a stabilization. Methods We prospectively included children with neuromuscular or syndromic scoliosis able to perform LFTs. We studied (Forced) Vital Capacity ((F)VC), the ratio of Forced Expiratory Volume in 1 second (FEV1) and FVC, and Peak Expiratory Flow (PEF). Preoperative LFT results were compared with results 3-4 months after surgery. The mean monthly change in LFT results up to 2 years after surgery was compared with the preoperative natural history using linear mixed effects models. Results We included 43 patients. No significant change was observed in absolute values of (F)VC, FEV1/FVC and PEF prior to and after surgery. Median standardized VC, FVC and PEF decreased significantly after surgery from 59 to 58%, 60 to 51% and 61 to 53% respectively. The monthly rate of change in FVC was -0.13 % (95% CI -0.42 to 0.17) prior to surgery and -0.20% (95% CI -0.42 to 0.03) after surgery, mean difference -0.07 (95% CI -0.46 to 0.31; p=0.36). Conclusion No stabilization of lung function 3-4 months after scoliosis surgery was observed in children with neuromuscular and syndromic scoliosis with restrictive lung function disease. The effect of surgery on the rate of lung function decline remains inconclusive.