Forced Expiratory Value in 1 second.
Volume of air that can forcibly be blown out in one
second, after full inspiration.
Average values for FEV1 in healthy people depend
mainly on sex and age.
FEV1 ≥ 15% increase following administration of
bronchodilator/trial of CS
FEV1 ≥ 15% decrease after 6 minutes of exercise
Peak Expiratory Flow Rate.
Measured with a small hand held device call Peak Flow
PEF is a person's maximum speed of expiration.
Patients need to record PEF after rising in the
morning and before retiring in the evening.
Asthma: >20% diurnal variation on ≥ 3 days in a week
for 2 weeks
Sometimes patients with symptoms are suggestive of
asthma have a normal lung function.
Challenge test is done to these type of patient
Administration of sequentially increasing of
concentration of either histamine, mannitol or
methacholine. Adenosine challenge test is more
Expressed as dose of either substance needed to
produce 20% decrease in the FEV1
Exercise challenge also can be done
Measurement of Allergic Status
Skin prick tests can demonstrate atopy
Measurement of total and allergen-specific IgE
Full blood picture may show peripheral blood
CXR is usually normal.
May shows hyperinflation of lungs fields
Lobar collapse if mucus occludes large bronchus
Flitting infiltrates if allergic bronchopulmonary
Assessment of eosinophilic airway inflammation.
Sputum differential eusinophil count greater than 2%
OR exhaled breath Nitric Oxide concentration