Spirometry principles - Grace

Bronchodilator response
• Spirometry is repeated after 15 min of the
administration of beta-agonist or 30 min after
ipratropium bromide
• An increase in 12-15% in the FEV1 represents a
significant response in an individual who has a
near normal spirometry
• With more severe obstructive disease the
magnitude of improvement should be at least 200
mL
• Because its large variability the improvement in
FEF 25-75 has to be of 30 to 40%.