Spirometry is a fundamental pulmonary function test that measures the volume and flow of air inhaled and exhaled by the lungs. It is a key diagnostic tool for evaluating respiratory health, detecting lung disorders, and monitoring the effectiveness of treatment in conditions such as asthma, chronic obstructive pulmonary disease (COPD), restrictive lung disease, and occupational lung diseases.

During the test, the patient breathes into a spirometer through a mouthpiece while wearing a nose clip to prevent air leakage. The test involves a series of controlled breaths, including a full inhalation followed by a rapid and forceful exhalation. The spirometer records measurements such as Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), and the FEV1/FVC ratio. These parameters help determine whether airflow obstruction or restriction is present.

Spirometry is non-invasive, safe, and generally well-tolerated, making it suitable for adults and children above a certain age. The procedure is quick, typically completed in 10–20 minutes, and requires proper patient instruction and cooperation to ensure accurate results. In some cases, bronchodilator testing is performed, where measurements are taken before and after administering a bronchodilator to assess the reversibility of airway obstruction.

The test results are analysed by pulmonologists or trained respiratory therapists, who interpret the values in relation to predicted norms based on age, sex, height, and ethnicity. Spirometry aids in the early detection of lung diseases, assessing severity, guiding therapy, monitoring disease progression, and evaluating response to treatment. It is also widely used in pre-employment and preoperative assessments to ensure respiratory fitness. By providing objective and reproducible measurements of lung function, spirometry is an essential tool in respiratory medicine. It enables timely diagnosis, individualised treatment, and proactive management of lung diseases, improving patient outcomes and overall pulmonary health.