The Additional Use of Spirometry in Evaluating Chronic Cough in Children. "May the Force Be With You".

Spirometry is the most common and straightforward examination following the mandatory initial steps of personal history and physical examination when assessing chronic and/or recurrent lung symptoms in children, especially cough or specific conditions that can impact lung function. When dealing with a chronic cough (lasting more than four weeks), it is not uncommon to find that no specific clues regarding the cause of the cough can be deduced from the patient's history alone. Moreover, clinical examinations can be quite normal without any abnormal lung sounds. In the next step (spirometry), surprisingly, as the child forcefully expels the air from the lungs, you can hear secretions moving along the bronchi as the rapidly moving air drifts excessive sputum to the upper airways. Less commonly, forceful exhalation during spirometry may uncover a brassy or honking sound, indicating potential collapsibility of the tracheal walls. Secretions in the bronchi can imply specific conditions, such as protracted bacterial bronchitis or suppurative bronchitis. Additionally, forced exhalation may uncover sputum in other chronic lung conditions, such as cystic fibrosis or primary cilia dyskinesia. The presence of tracheomalacia is an important parameter, as it can precipitate several respiratory symptoms, ranging from prolonged cough in acute bronchitis to recurrent and/or chronic wet cough. In conclusion, forceful exhalation during spirometry has the potential to uncover secretions in the bronchi or even tracheomalacia that might otherwise go unnoticed. Before watching the flow-volume loop or interpreting the results of the spirometry parameters, we should first "hear" the spirometry.