How to Measure Peak Expiratory Flow

Jan 10, 2024 - 3 min read

How to Measure Peak Expiratory Flow (PEF)

Peak expiratory flow (PEF) is a measure of how fast you can blow air out of your lungs. It is a simple and non-invasive test that can be used to monitor lung function and diagnose respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD).

PEF is measured using a peak flow meter, which is a small, handheld device. To measure your PEF, follow these steps:

Stand up straight with your feet shoulder-width apart and your chest out.
Hold the peak flow meter in one hand and place the mouthpiece in your mouth.
Take a deep breath and blow into the mouthpiece as hard and fast as you can for one second.
Record the number on the meter.
Repeat steps 2-4 two more times.

Your highest reading is your PEF.

Normal PEF values vary depending on your age, sex, and height. The following table provides average PEF values for healthy adults:

Age (years)	Sex	Height (cm)	PEF (L/min)
20-29	Male	175	550
20-29	Female	165	450
30-39	Male	175	525
30-39	Female	165	425
40-49	Male	175	500
40-49	Female	165	400
50-59	Male	175	475
50-59	Female	165	375
60-69	Male	175	450
60-69	Female	165	350

Factors that can affect PEF include:

Age: PEF decreases with age.
Sex: Men typically have higher PEF values than women.
Height: Taller people tend to have higher PEF values.
Smoking: Smoking can decrease PEF.
Exercise: Exercise can increase PEF.
Medications: Some medications, such as bronchodilators, can increase PEF.

PEF can be used to monitor lung function and diagnose respiratory conditions such as:

Asthma
COPD
Cystic fibrosis
Bronchitis
Emphysema

PEF monitoring can help you to track your lung function over time and identify changes that may indicate a worsening of your condition. It can also be used to assess the effectiveness of your treatment plan.

If you have a respiratory condition, your doctor may recommend that you monitor your PEF at home. Home PEF monitoring can help you to:

Track your lung function over time
Identify changes that may indicate a worsening of your condition
Assess the effectiveness of your treatment plan
Make adjustments to your treatment plan as needed

Home PEF monitoring is a simple and non-invasive way to track your lung function and manage your respiratory condition. Talk to your doctor if you are interested in monitoring your PEF at home.

Here are some additional tips for measuring PEF:

Make sure the peak flow meter is clean and dry.
Sit up straight and relax your shoulders.
Take a deep breath and blow into the mouthpiece as hard and fast as you can for one second.
Record the number on the meter.
Repeat steps 2-4 two more times.
Your highest reading is your PEF.

If you are having difficulty measuring your PEF, ask your doctor or a respiratory therapist for help.