The peak expiratory flow rate or peak flow is a measurement of the maximum speed of expiration, starting from full lung inflation. It is a useful aid for assessing the degree of large airway obstruction.
Wash hands; Introduce self; ask Patient’s name, DOB and what they like to be called; Explain
Explain peak flow measures the maximum speed of expiration
Give patient specific details of what they should do:
Stand or sit upright
Set the meter dial to zero
Hold the meter horizontally and ensure they are not touching the dial
Take a deep breath in to full capacity
Place lips tightly around the cardboard tube to form a tight seal
Blow out as hard and as fast possible (it measures the first puff, so they do not need to expire fully)
Demonstrate for them with a different cardboard tube
Observe them doing it and comment on any mistakes
Ask patient to perform test three times at one minute intervals
Thank patient and ask if they have any questions
Bin the cardboard tube
Document in the notes the best of the three readings (in litres/minute)
Test your knowledge
What is the ‘expected’ peak flow based on?
How is the severity of an asthma exacerbation classified, based on peak flow results?