Pulmonary function tests assess how well the lungs are performing. The tests measure lung volume, capacity, rates of flow, and gas exchange. Results from these tests help in the diagnosis and treatment of lung disorders. A complete pulmonary function study takes approximately 45-90 minutes to complete.
PFT is done through two methods: spirometry and plethysmography.
- Spirometry measures exhalation volume and rate. Patients breathe into a spirometer that will record the volume and rate of air breathed. This method can be used to evaluate a broad range of lung disorders.
- Plethysmography is a test used to measure the amount of air that can be held in the lungs. Patients will sit in a small box and will breathe or pant against an open or closed mouth piece. This will cause chest movement that changes the pressure within the box and against the mouth piece. From these pressure changes, doctors are able to get an accurate measurement of the amount of air in the lungs.
PFTs may be conducted for several reasons. They are often used to help diagnose:
- Respiratory infection
- Breathing trouble from injury to chest
- Chronic lung conditions such as asthma, bronchiectasis, emphysema, or chronic bronchitis
- Restrictive airway problems from scoliosis, tumors, or inflammation or scarring of the chest wall