【Medical Q&A】What is a pulmonary function test? Can it replace lung imaging tests?

Author: Liu Fangjun Children's Hospital Affiliated to Chongqing Medical University

Reviewer: Liu Sha, deputy chief physician, Children's Hospital Affiliated to Chongqing Medical University

Pulmonary function test is a medical examination technique that uses instruments (meters and computers) to measure the volume, flow rate, pressure, etc. of the subject's breathing gas and analyze the composition to understand the physiological function state of the human respiratory system. It is an important examination content for the diagnosis and differential diagnosis of chest and lung diseases, severity assessment, treatment effect and prognosis assessment in clinical practice. Pulmonary function test is non-invasive and radiation-free, and has high sensitivity. It can detect abnormal respiratory function in the early stage of the disease (when clinical symptoms are not obvious), helping early diagnosis and early intervention.

Imaging examinations such as chest X-rays and CT scans usually reflect static histological changes, while pulmonary function tests reflect dynamic functional changes. If we compare lung tissue to a car, then imaging examinations can show the appearance of the car and whether the various parts are damaged, and pulmonary function tests can show whether there are any problems with the performance of the car, but the two are not a one-to-one correspondence. For example, the imaging test results of children with asthma are usually normal, while their pulmonary function test results may show obstructive ventilation dysfunction and airway hyperresponsiveness; children's imaging examinations show lobar space-occupying lesions, but pulmonary function tests may show normal. Therefore, these two tests cannot replace each other but complement each other to more comprehensively discover and evaluate the condition.