Deep Dive 20: The Physics of Pulmonary Function Testing

This discussion serves as a comprehensive introduction to pulmonary function testing (PFT), a clinical process used to objectively measure how well the lungs facilitate gas exchange. The source outlines the primary objectives of these tests, which include identifying pulmonary impairments, quantifying the severity of diseases like asthma or emphysema, and evaluating the effectiveness of medical treatments. It distinguishes between two major pathophysiologic categories: obstructive lung disease, characterized by increased airway resistance, and restrictive lung disease, defined by reduced lung volumes or compliance. Key diagnostic tools such as spirometry, which measures airflow and volumes like the forced vital capacity (FVC), and specialized assessments like diffusing capacity and bronchoprovocation are detailed to explain how clinicians differentiate between various respiratory conditions. Finally, the text emphasizes the importance of test validity and reliability, noting that accurate results depend on standardized equipment, patient cooperation, and the comparison of data against predicted normal values based on a patient’s unique physical characteristics.