1. Spirometry

Most common and basic PFT

Measures airflow (how much and how quickly you can move air in and out of your lungs)

Key Parameters:

FEV1 (Forced Expiratory Volume in 1 second)

FVC (Forced Vital Capacity)

FEV1/FVC ratio

Used to diagnose: Obstructive (e.g., asthma, COPD) and restrictive lung diseases

2. Lung Volumes

Measures total amount of air in the lungs after full inhalation and how much remains after full exhalation

Cannot be measured by spirometry alone; requires body plethysmography or gas dilution techniques

Key Parameters:

TLC (Total Lung Capacity)

RV (Residual Volume)

FRC (Functional Residual Capacity)

Used to identify: Restrictive lung diseases, hyperinflation, air trapping

3. Diffusion Capacity Test (DLCO)

Measures how well oxygen and carbon monoxide move from the lungs into the blood

DLCO = Diffusing capacity of the lungs for carbon monoxide

Used to assess: Diseases affecting the alveolar-capillary membrane (e.g., pulmonary fibrosis, emphysema, pulmonary vascular disease)

4. Bronchodilator Responsiveness (Reversibility Testing)

Spirometry is performed before and after inhalation of a bronchodilator

Assesses reversibility of airflow obstruction

Used to differentiate: Asthma (reversible) from COPD (typically not reversible)

5. Bronchial Provocation Testing (Methacholine Challenge Test)

Used when asthma is suspected but baseline spirometry is normal

Methacholine (or histamine) is inhaled to provoke bronchoconstriction

Positive test: Significant drop in FEV1

6. Maximal Voluntary Ventilation (MVV)

Measures the greatest amount of air that can be inhaled and exhaled within one minute

Reflects overall respiratory muscle strength and endurance

7. Arterial Blood Gases (ABG)

While not always grouped with PFTs, ABG tests measure oxygen and carbon dioxide levels in arterial blood

Assesses: Gas exchange and acid-base balance