Peak Flow (PEFR): OSCE Station Checklist

Peak flow is the simplest device on the skills list and one of the easiest stations to underestimate. The measurement takes a minute. The marks are in the coaching, because PEFR is completely effort-dependent: the same lungs can produce 230 or 430 L/min depending on technique.

The sequence:

1. Explain the purpose: measuring how fast air leaves the lungs, used to track asthma control.
2. Hand hygiene, consent, and a clean single-use mouthpiece.
3. Position: standing if the patient safely can, otherwise sitting fully upright.
4. Zero the pointer. Grip clear of the scale so nothing blocks the slide.
5. Demonstrate first, then coach: deepest possible breath in, lips sealed tight around the mouthpiece, then one short sharp blast, as if blowing out candles in a single hit.
6. Read, zero, repeat. Three attempts, best recorded.
7. Interpret against personal best (preferred) or predicted values.
8. Document: value, position, time, and what you did with the result.

The scripted errors

The actor will usually blow badly on purpose: a long slow exhale, cheeks puffed with a loose seal, no full breath in first, or fingers on the scale. Each produces a low number. The marks are for catching the specific fault, correcting it without judgement, and repeating the attempt. “That blow was quite slow; peak flow wants one fast hard blast, like this” is a mark. Silently recording the bad number is the fail.

Making the number mean something

Reading PEFR against personal best, using the standard asthma action-plan zones:

Peak flow (% of personal best)	Zone	Meaning
80% or above	Green	Good control; continue usual treatment
50–79%	Amber	Worsening control; step up per action plan
Below 50%	Red	Severe; urgent treatment and escalation

A PEFR without a comparison is trivia. Personal best is the anchor when known; standard asthma action plans treat below 80% of best as slipping control and below 50% as severe, needing urgent response. The station’s scenario often hands you exactly this: a breathless patient, a known best, and today’s reading. Divide, say the percentage, and say what it triggers. The arithmetic is deliberately easy; the mark is for doing it unprompted.

The habits complete the station: mouthpiece disposed of, hand hygiene, and a record that includes the best value, the position used, and your action. If the pairing puts PEFR with blood glucose, you’ve got the exam’s two quickest procedures back to back, and the time pressure is lower than anywhere else; use it to be visibly thorough.

Five questions below, then oxygen therapy, where device choice carries the clinical weight.