Peak Expiratory Flow Measurement

Peak Expiratoty flow Opener.jpeg

This module describes how to use peak expiratory flow measurement in asthma and COPD.




Always verify your patient’s identity and obtain informed consent before proceeding.

How do I explain this procedure?

“We need to measure how well your lungs are working. When your asthma is poorly controlled, the amount of air you can breathe into the tube is less, and when your asthma is well controlled, this volume goes up.”

What can my patient expect?

“This is a simple test that will not make you feel ill.”

What is my patient’s role?

“We will repeat the test several times today so that we can get an accurate value. We will write it down for you, and you will do it at home. Remember that the values vary during the day, so you need to use it at the same time

, and write the values down. Eventually, we want to get you to a

with which we can compare how your asthma is doing.”


Disinfect the measuring device mouthpiece with an alcohol swab before every demonstration.


Patients should sit or stand up straight for best effect.



I'm unsure how I should use these readings.

You can monitor the patient’s asthma control by comparing their PEF with the predicted mean from the graph below, according to the patient’s gender, age and height. The patient’s personal best is a better benchmark than these mean values, and once the patient’s treatment is optimised, you should attempt to record it.

For adults:

Peak expiratory flow Troubleshooting 1.jpeg

For children:

Peak Exiratory flow Troubleshooting 2.jpeg

I want my patient to adjust their treatment using their 'personal best'.

Patients should calculate the reading as a percentage of their personal best (new reading/personal best*100). Manage as follows:

80-100% of personal best: continue with current treatment

50-80% of personal best: initiate the

.

<50% of personal best: medical emergency. Initiate the home action plan and present for emergency care. Some patients may keep an emergency dose of oral corticosteroids, which they may take on the way to the hospital.