Peak flow monitoring

Category: Lung & Breathing Tests · All lung & breathing tests

What it is

Peak flow monitoring uses a simple hand-held meter to measure your fastest breath out (peak expiratory flow). Recording it morning and evening for two to four weeks shows variability — the hallmark of asthma — and your personal best becomes a reference for action plans.

Why it is done

It helps diagnose asthma (looking for day-to-day variability), provides the basis for self-management plans, monitors occupational asthma (patterns across work and rest days), and tracks control in some asthma patients.

How to prepare

Your clinician or nurse will show you the technique and give you a diary or app. Use the same meter, at the same times, standing or sitting upright. Record the best of three blows each time.

What happens during the procedure

Blow into the meter as hard and fast as you can — a short, sharp blast after a full breath in, with a tight seal around the mouthpiece. Repeat three times and note the highest reading. Continue inhalers as prescribed unless your plan says otherwise.

Afterwards — recovery & results

There is no recovery period — it is a home measurement. Bring your diary to reviews; your team calculates variability and, once a personal best is established, sets traffic-light thresholds for your written asthma action plan.

Risks & considerations

There are no risks beyond brief light-headedness or coughing with repeated maximal blows. Poor technique gives misleading readings, so technique is rechecked at reviews.

Frequently asked questions

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