The "personal best" peak expiratory flow (PEF) is the highest peak flow number you or your child can achieve over a two to three week period when asthma is under good control. Good control means you feel good and do not have any asthma symptoms.
Your personal best PEF is important because it is the number to which all of your other peak flow readings will be compared. Your asthma action plan, developed along with your healthcare professional, is based on this number.
You should always use the same peak flow meter and write your readings in your peak flow chart. Then, continue to take peak flow readings each morning. Daily readings will help you to recognise early drops in airflow and changes with asthma control.
FOOTNOTES:
[1] aaaai.org. Conditions-and-treatments/library/at-a-glance/peak-flow-meter. Accessed October 2017.
[2] Asthma.org.uk. All_about_asthma/controlling_your_asthma/resources_to_help_you/peak_flow_diary. Accessed Oct 2017.
[3] Webmd.com. Asthma/guide/peak-flow-meter. Accessed October 2017.