Pulmonary Function Test

Function

Pulmonary Function Tests (PFTs) are a non-invasive group of tests that measure how well the lungs are working. The most common component is spirometry, which measures the volume of air an individual can inhale or exhale as a function of time. These tests assess lung capacity, volume, rates of flow, and gas exchange. By comparing a patient's results to 'predicted values' based on age, height, sex, and ethnicity, clinicians can determine the presence and severity of respiratory impairment.

Why it is Ordered

Physicians order PFTs for several critical reasons:

• Diagnosis: To differentiate between obstructive lung diseases (like asthma or COPD) and restrictive lung diseases (like pulmonary fibrosis).
• Symptom Investigation: To evaluate the cause of chronic cough, wheezing, or shortness of breath.
• Monitoring: To track the progression of chronic lung conditions or the effectiveness of treatments like bronchodilators or steroids.
• Pre-operative Assessment: To ensure a patient has sufficient respiratory reserve to undergo major surgery.
• Occupational Health: To screen individuals exposed to hazardous dust or chemicals in the workplace.

Associated Conditions

PFTs are essential in managing various pathologies. Obstructive patterns (where air is difficult to exhale) are seen in Asthma, COPD, and Bronchitis. Restrictive patterns (where the lungs cannot expand fully) are associated with Interstitial Lung Disease (ILD), Sarcoidosis, and Scoliosis. Additionally, tests measuring Diffusion Capacity (DLCO) can identify damage to the alveolar-capillary membrane, common in Emphysema or Pulmonary Hypertension.