A Pulmonary Function Test (PFT) evaluates the volume of air the lungs can hold, the rate at which air can be moved in and out, and how effectively oxygen is transferred into the blood. PFTs provide objective data to help diagnose various respiratory conditions and monitor the progression of known diseases like asthma or Chronic Obstructive Pulmonary Disease (COPD).
The Healthcare Professionals Who Order PFTs
PFTs are ordered by physicians who suspect a lung issue or need to monitor an existing condition. Primary Care Physicians (PCPs) often initiate this process when a patient presents with symptoms like a persistent cough, shortness of breath, or wheezing. A simple spirometry test, which is a component of a PFT, can sometimes be performed in a PCP’s office to evaluate airflow obstruction.
Specialists routinely order more comprehensive PFT panels, including Pulmonologists and Allergists. Pulmonologists use these tests to diagnose complex conditions, classify the severity of a disease, and assess a patient’s response to treatment over time. Allergists may use PFTs to investigate allergic asthma or to perform specialized bronchoprovocation challenges.
Occupational Medicine physicians frequently prescribe PFTs, particularly for workers exposed to environmental hazards like coal dust or asbestos. These tests help establish a baseline lung function and monitor for early changes caused by work-related pollutants. For patients needing major surgery, a PFT may be ordered pre-operatively to determine the patient’s respiratory capacity and ability to tolerate the procedure.
Administering the Procedure
The hands-on administration of a Pulmonary Function Test is performed by highly specialized personnel, most commonly Respiratory Therapists (RTs) or certified Pulmonary Function Technologists. These professionals conduct the tests according to strict international standards to ensure the accuracy and reliability of the data collected. The test results are heavily dependent on the patient’s effort, making the administrator’s role particularly important.
The technologist or therapist must coach the patient through each strenuous maneuver, such as the forced vital capacity (FVC) test. This requires the patient to inhale as deeply as possible and then exhale all the air as hard and fast as they can into the spirometer mouthpiece. Without maximal effort and precise technique, the resulting data, like the Forced Expiratory Volume in one second (FEV1), will be invalid.
In addition to spirometry, the administrator manages other components, such as lung volume measurement, which may involve sitting in a sealed body plethysmograph booth. They also oversee the gas diffusion study, which requires the patient to inhale a small amount of carbon monoxide to measure how efficiently gas transfers from the lungs to the bloodstream. The administrator’s expertise ensures the technical quality of the test, providing the physician with trustworthy numbers for interpretation.
Analyzing the Results
The interpretation of PFT data is typically the responsibility of a Pulmonologist, though other physicians may review basic spirometry. The Pulmonologist correlates the measured values with the patient’s clinical history and symptoms to arrive at a diagnosis. They look for specific patterns across the different test components, such as spirometry, lung volumes, and diffusion capacity.
A low ratio of FEV1 to FVC, for example, is a classic indication of an obstructive lung disease like COPD or asthma, where airflow out of the lungs is hindered. Conversely, a reduced Total Lung Capacity (TLC) with a preserved FEV1/FVC ratio suggests a restrictive lung disease, meaning the lungs cannot fully expand, as seen in conditions like pulmonary fibrosis. The degree of abnormality, determined by comparing the patient’s values to predicted norms, helps the Pulmonologist classify the disease’s severity.
The specialist assesses the reversibility of any obstruction by repeating the spirometry after the patient inhales a bronchodilator medication. A significant improvement in the FEV1 value after the medication suggests a reversible condition, often pointing toward asthma. The final report integrates all these findings, offering a comprehensive assessment that guides the ordering physician in developing or adjusting the patient’s treatment plan.