Don’t forget the PEF

Here’s our advice to keep the PEF on your radar…

While the PEF is not covered in the repeatability criteria, nor is it included in the GLI predicted values, it remains a crucial part of the acceptability criteria for spirometry.   

Acceptability of the PEF heavily depends not only on maximal effort and cooperation from the subject, but also depends on ‘how full’ the lungs are, and whether there is any pause, at the start of exhalation.  To judge if you have achieved an acceptable PEF, a good checklist to follow is:


☑️  Is there a steep rise at commencement of the expiratory trace?

☑️  Is there a sharp peak?

☑️  Was it achieved, without delay, from ‘full lungs’ (or TLC*)?

Once you have achieved 3 acceptable trials, it is good practice to always super-impose these flow volume curves to confirm they overlay.  You will likely start to notice that the PEFs can actually be repeatable!  So despite being absent from the repeatability criteria, we also suggest you add the following quality checks to the PEF checklist: 

☑️  Check if the PEF overlay

☑️  Aim for the two highest PEFs to match within 10%**

Why not download our free PEF CHECKLIST … so the PEF doesn’t fall off your radar.

* TLC is the total lung capacity and represents the total lung volume at position of maximal inhalation.

** Suggested as ‘useful criterion’ by European Thoracic Society 1993