Assessment and Monitoring of Asthma
What the exam tests
Assessment runs on two tracks that questions love to blur: impairment (daytime symptoms, nighttime awakenings, SABA use, activity limitation, validated questionnaires) and risk (exacerbations, accelerating loss of lung function, SABA overuse, oral steroid courses, ED visits, ICU history). Severity is classified before treatment begins; control is classified while on treatment. Confusing those two is the most common trap in this domain.
Spirometry
Obstruction = reduced FEV1/FVC (below 0.70 in adults, roughly below 0.85 in children). Reversibility = an FEV1 increase of at least 12% AND at least 200 mL after a bronchodilator in adults (at least 12% in children). Normal spirometry between episodes does not exclude asthma.
Monitoring tools
ACT looks back over 4 weeks (20 or higher controlled, 16-19 not well controlled, 15 or lower very poorly controlled); C-ACT for ages 0-11 uses different cut points (20 or higher controlled, 13-19 not well, 12 or lower very poorly). Peak-flow zones use the patient's personal best: green 80% or more, yellow 50-79%, red below 50%. PEF variability above 10% in adults or 13% in children suggests inadequate control.
Worked example
Pre-bronchodilator FEV1 is 68% predicted and post-bronchodilator is 79% predicted in an adult with a 1.9 L baseline. The gain is 11 percentage points and about 210 mL; the percent change is 11%, below the 12% threshold, so this does not meet reversibility criteria even though the volume criterion was met.
Rule of thumb: severity is judged before treatment, control is judged on treatment.