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Departments & Programs,UW Hospital and Clinics,Pulmonary Diagnostic Lab

Spirometry and Flow Volume Loop

Spirometry and Flow Volume Loop - Departments & Programs, UW Hospital and Clinics, Pulmonary Diagnostic Lab


Spirometry will provide the following information:

Flow volume curve

Flow volume curve diagram  

A physician may want to evaluate a patient's upper airway; a Flow Volume Loop (FVL) is then requested. An FVL measurement includes all the above data plus measurements of a maximal inspiration. The patient performs an FVC and follows it with a maximal inspiration. This test can provide valuable data in a diagnosis or severity of tracheal stenosis or vocal cord disorder. 

The UW Health Pulmonary Function Lab utilizes two methodologies for lung volumes. Plethysmography is the preferred method because it measures not only the ventilated area of the lung but also any trapped air in the lung. This methodology is more accurate in an individual with an obstructive disorder. Helium Dilution is the second method used when a subject is physically unable to get into the plethysmograph, is claustrophobic or has difficulty coordinating a VTG (Volume of Thoracic Gas) maneuver. 

The below measurements are obtained when ordering Lung Volumes:

Total lung capacity

Total lung capacity chart