Pulmonary function tests are crucial to understand respiratory physiology and disease management. 1 In children, they allow monitoring pulmonary growth and development, as well as changes in respiratory mechanics. Additionally, they are involved in epidemiological and clinical researches and indicated for evaluation, control and longterm treatment of children with respiratory diseases [2][3][4] ; the exam is inexpensive and simple which supports its application. 1,5 However, subject's participation influences considerably the quality of spirometry, 6,7 as it involves understanding commands that reproduce specific respiratory manoeuvres, requiring association between motor function and cognitive performance. [8][9][10] There is a consensus among clinicians and health professionals on the difficulty in conducting successful spirometry testing in children from 6 to 10 years old. [10][11][12] During childhood lung disorders are most frequently of obstructive type such as asthma, cystic fibrosis, recurrent wheezing, bronchopulmonary dysplasia, bronchiolitis obliterans, plastic bronchitis among