How to read spirometry
Other platforms explain it with text and video. In VMS you practice it on the patient.
Spirometry shows how much air a patient can blow out and how fast. Reading it in a fixed order separates asthma and COPD from restrictive lung disease.
Step by step
Check test quality
Look for at least three good efforts with a fast start and a smooth curve. Poor effort makes every number unreliable. [1]
Look at the FEV1/FVC ratio
FEV1 is the air blown out in the first second and FVC is the total. A ratio below the lower limit of normal (often about 0.70 in adults) means obstruction. [2]
Check the FVC
A low FVC with a normal or high ratio suggests restriction. Confirm it with full lung volumes, because spirometry alone cannot prove it. [2]
Grade severity with FEV1
Compare FEV1 with the predicted value as a percent. The lower the percent, the more severe the disease. [2]
Read the bronchodilator response
Repeat the test after inhaled albuterol. A rise in FEV1 or FVC of more than 10 percent of the predicted value supports reversible disease such as asthma. [2]
Look at the flow-volume loop
A scooped, concave expiratory curve fits obstruction. A loop flattened on both sides can point to a fixed narrowing of the upper airway. [2]
Link to the patient
Match the pattern with symptoms, smoking history and the exam before you name a diagnosis. [1]
Common errors
- Reading FEV1 alone without the ratio.
- Calling restriction from a low FVC without lung volumes.
- Ignoring poor effort or a bad curve.
Common spirometry patterns (adults) [2]
| Pattern | FEV1/FVC | FVC |
|---|---|---|
| Normal | Normal | Normal |
| Obstructive | Low | Normal or low |
| Restrictive | Normal or high | Low |
| Mixed | Low | Low |
Practice it in VMS
In VMS you do this on the patient, not on paper: every step goes on the checklist with a score, and in Teach mode Blocky tells you what comes next.
VMS cases that train this skill
Sources
Facts and steps follow AAMC Core Entrustable Professional Activities (Core EPAs); NCCPA PANCE Content Blueprint. VMS is not affiliated with these organizations. Updated: 2026-10-11.