What Is Forced Expiratory Volume (FEV)?


I'm applying for disability for emphysema and just read Social Security's disability listing for chronic respiratory disorders, which requires a certain FEV level. What is FEV?


To determine the severity of a claimant's disability in a claim for respiratory and pulmonary diseases, Social Security requires that certain tests be performed. FEV is one measurement that is used; it stands for forced expiratory volume, which is the volume of air forced from the lungs when a person takes a deep breath. Social Security uses FEV results to measure a claimant's pulmonary function; these readings are generally obtained through spirometry tests. The lower the FEV reading, the more severe a patient's disease is.

Spirometry Testing for FEV. The spirometry test measures the amount of air that is inhaled and exhaled during a period of time. During this test, the patient places a mouthpiece over his mouth, inhales deeply, and then forcefully blows out the air. This test gives the doctor an FEV or FEV1, which measures the amount of air blown out in one second. The results can show how much a patient's lung function has deteriorated. With a FEV1 reading obtained through a spirometry test, a doctor can also determine whether prescribed medications are working or whether a respiratory condition is worsening. The highest values of the FEV1 obtained in testing are used to assess the severity of a claimed respiratory impairment.

Other Measures of Pulmonary Function. Social Security uses FEV1 in conjunction with forced vital capacity (FVC) results to measure a disability claimant's pulmonary function. Another test that can be used to document a patient's lung function is the arterial blood gas (ABG) test. The ABG test evaluates levels of oxygen and carbon dioxide in the blood. Testing must be done when the patient is stable; that is, not having an asthmatic attack or currently suffering an acute respiratory infection.

Social Security has recently updated its disability listing for chronic respiratory disorders to require different FEV1 values depending on the applicant's age and gender. For more details on Social Security's requirements for FEV levels and getting disability for emphysema, see our section on article on getting disability for emphysema and bronchitis.

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