What is the role of pulmonary function tests (PFTs) in the diagnosis of respiratory failure?

Updated: Apr 07, 2020
  • Author: Ata Murat Kaynar, MD; Chief Editor: Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM  more...
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Answer

Patients with acute respiratory failure generally are unable to perform PFTs; however, these tests are useful in the evaluation of chronic respiratory failure.

Normal values for forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) suggest a disturbance in respiratory control. A decrease in the FEV1 -to-FVC ratio (FEV1/FVC) indicates airflow obstruction, whereas a reduction in both FEV1 and FVC and maintenance of FEV1/FVC suggest restrictive lung disease.

Respiratory failure is uncommon in obstructive diseases when FEV1 is greater than 1 L and in restrictive diseases when FVC is greater than 1 L.

See Pulmonary Function Testing for further details.


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