Pulmonary function tests (PFTs) Home A-Z Health Information Health Library A-Z Pulmonary Function Tests (PFTs) Overview A complete pulmonary function test (PFT) is a thorough assessment used to evaluate lung function across various parameters. Conducted in a specialised pulmonary function laboratory, the test involves specific equipment, such as spirometers, body plethysmographs (for lung volumes) and devices for diffusion capacity (DLCO) measurements. Procedure Before the test, patients are advised to avoid smoking, heavy meals, and strenuous exercise, with medication adjustments as needed under medical guidance.The procedure includes several tests performed sequentially.Spirometry is typically the first, measuring how much air a person can inhale and exhale and how quickly they can do so. This test helps diagnose conditions like asthma and COPD based on airflow limitations.Following spirometry, lung volumes are assessed using a body plethysmograph or gas dilution techniques. This part of the test determines parameters such as Total Lung Capacity (TLC) and Residual Volume (RV), which are crucial for distinguishing between obstructive and restrictive lung diseases.Next, a DLCO test is used to evaluate the efficiency of gas exchange in the lungs by measuring the uptake of carbon monoxide during a breath-hold manoeuvre. This is essential for diagnosing conditions affecting the alveolar capillary membrane, such as emphysema and pulmonary fibrosis.Depending on clinical indications, bronchodilator response testing may also be performed to assess for reversible airflow obstruction. Applications Once baseline lung function measurements are established through PFTs, they provide a critical reference point for monitoring disease progression over time. Regular follow-up tests allow the pulmonologist to detect changes in lung function parameters, which may indicate worsening of conditions like COPD, pulmonary fibrosis, or asthma flare-ups. This monitoring aspect of PFTs is essential for predicting long-term outcomes and prognosis for patients, informing healthcare teams about the effectiveness of current treatments or the need for adjustments.Moreover, based on specific diagnoses derived from PFT data (such as obstructive versus restrictive lung disease), healthcare providers can select appropriate medications like bronchodilators to alleviate airway obstruction or corticosteroids to manage inflammation effectively. Furthermore, measurements from PFTs, particularly DLCO, aid in determining the necessity and optimal dosage of supplemental oxygen therapy. For patients with severe conditions, such as advanced COPD, PFT results may also influence considerations for surgical interventions like lung volume reduction surgery or even lung transplant surgery in end-stage lung disease treatment.Additionally, PFTs contribute to the design of pulmonary rehabilitation programmes aimed at improving exercise tolerance, optimising lung function and enhancing the overall quality of life for patients.