Pulmonary Function Testing

Pulmonary function tests (PFTs) remain a cornerstone of respiratory medicine, providing an objective assessment of ventilatory mechanics, gas exchange, and exercise limitation. Recent advances in international standards, interpretation strategies, and emerging techniques are expanding the clinical utility of PFTs beyond conventional spirometry. However, the increasing complexity of available tests presents challenges for their appropriate selection and interpretation in routine clinical practice. In this question-and-answer section, we address common situations encountered in pulmonary function laboratories and respiratory clinics. Key topics include updated recommendations for spirometry, the role of static lung volume measurements, how to interpret complex spirometric patterns, and the clinical use of diffusing capacity measurements (DLCO and DLNO). The relevance of conflicting physiological findings is also discussed. Additionally, tools for assessing small airway disease, such as impulse oscillometry and the pulmonary clearance index, are analyzed. Other sections explore how pulmonary function tests help assess dyspnea of ​​unknown origin, monitor chronic respiratory diseases over time, support preoperative evaluations, and offer a glimpse into potential future advances in pulmonary function laboratories. This review provides a clinical framework for the selection, interpretation, and application of pulmonary function tests in daily practice. The question-and-answer format aims to facilitate practical decision-making and support clinicians in addressing common diagnostic and therapeutic challenges across a broad spectrum of respiratory diseases.