Pulmonary Function Tests: Understanding Lung Volumes and Capacities

Pulmonary function tests (PFTs) are essential diagnostic tools used to assess lung function by measuring different lung volumes and capacities.

Lung Volumes

• Tidal Volume (TV) - The amount of air inhaled or exhaled during normal breathing.
• Inspiratory Reserve Volume (IRV) - The additional air inhaled beyond tidal volume.
• Expiratory Reserve Volume (ERV) - The extra air exhaled after a normal breath.
• Residual Volume (RV) - Air remaining in the lungs after maximal exhalation.

Lung Capacities

• Vital Capacity (VC) - The total amount of air exhaled after maximal inhalation.
• Total Lung Capacity (TLC) - The sum of all lung volumes.
• Inspiratory Capacity (IC) - The maximum amount of air that can be inhaled after normal exhalation.
• Functional Residual Capacity (FRC) - The volume of air remaining in the lungs after normal exhalation.

Clinical Significance

PFTs help diagnose conditions like chronic obstructive pulmonary disease (COPD), asthma, and restrictive lung diseases. These measurements guide treatment decisions and monitor disease progression.