Are the Reference Equations for Maximal Respiratory Pressure in Children Adequately Predicting Their Value?

Background: This study aimed to investigate the agreement between the measured and estimated respiratory muscle strength in children and adolescents. We hypothesized that when using reference muscle strength equation consistent with the characteristics of the sample population, there would not be differences between the measured and predicted values. Methods: This was a cross-sectional study. One hundred seventy-nine participants were healthy volunteers between 6 and 18 years of age. Those who had lung disease in the previous 4 weeks, abnormalities in the pulmonary function test, chronic cardiopulmonary disease, prematurity or inadequacy when performing the tests were excluded. Maximal inspiratory and expiratory pressures (MIP and MEP) were assessed according to recommendations. The measured MIP and MEP values were compared to predicted values of the six most frequently cited prediction equations for children and adolescents. Results: Mean age was 12.3 +/- 3.7 years and 54% were male. The mean MIP was 87.5 +/- 27.1 cm H 2 O and MEP was 90.8 +/- 23.6 cm H 2 O. Three predicted MIP equations had similar results to the measured values (P > 0.05). For MEP, only one equation had similar values (P = 0.12). Instead, there was weak to moderate agreement of all equations. At Bland-Altman plots, the mean bias was greater than 6 cm H 2 O for all equations, and the 95% confidence interval (CI) was about 30 cm H 2 O. Conclusion: There is significant variability between measured and predicted MIP and MEP values. Some equations showed similarity to measured values; however, the reliability was poor. Int J Clin Pediatr. 2023;12(2):37-44 doi: https://doi.org/10.14740/ijcp517