Measuring Peak Expiratory Flow Rate (OSCE)

 What is peak flow?

🌬 A technique used to help diagnose or monitor asthma by establishing the speed with which you can blow air out of your lungs, to assess if your airways are narrowed.

🌬 Patients who have been previously diagnosed with asthma may be advised to regularly measure their peak flow, using a peak flow meter, for monitoring purposes.


Why measure PeFR?

🌬 It can indicate worsening of the patient’s condition 

🌬 It can help to identify asthma triggers

🌬 The patient may realise they are having an asthma attack

🌬 You can check if the patients treatment plan is successful 



  1. Greet the patient and introduce yourself 
  2. Using patient friendly language, briefly explain the procedure
  3. Gain patient consent
  4. Comfortably position the patient and check they are not in any pain or having any breathing difficulties
  5. Wash hands 


PeFR Measurement

  1. Set the meter to zero
  2. Stand up or sit with your back straight 
  3. Breathe in as deeply as possible
  4. Put your lips 👄 tightly around the mouthpiece of the peak flow meter, holding it horizontally
  5. Breathe out as powerfully as possible 
  6. Make a note of the reading on the peak flow meter 
  7. Repeat the previous steps two more times
  8. Take the highest of the three readings as your result


🌬 Now you should watch the patient performing the procedure alone, offering advice and feedback where necessary


Peak flow score 

🌬 This is the measurement on the meter, given in litres of air exhaled per minute (l/min)

🌬 A ‘normal score’ depends on factors such as gender, age and height

🌬 For diagnosis, the patient’s score should be compared with the normal range for individuals in the same categories

🌬 For monitoring, the patient’s score should be compared to their ‘best’ score




  1. Ask the patient if they have any queries ❓ or would like anything explained again
  2. Ask the patient to measure their peak flow each morning and night 🌙 and keep a record of their results to enable better management of their asthma
  3. Thank the patient
  4. Wash hands 


  1. Greet the patient and explain what you are going to do
  2. Measure the patient's peak flow
  3. Ask the patient to measure their own peak flow whilst you observe
  4. Compare the peak flow score to the normal range for individuals in the same category
  5. Ask the patient to measure their peak flow each morning and night and record it to manage their asthma more successfully

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