Peak flow measurement

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The peak flow measurement is a simple lung function test that you can carry out yourself at home. You need a peak flow meter for this - a handy device that measures the maximum flow rate of the air you breathe when you exhale. Read here how to correctly carry out the peak flow measurement and how you can assess your values.

Peak flow measurement: how often is it necessary?

In order to get a good overview of the condition of their bronchi in obstructive airways diseases such as asthma or COPD, patients should take a peak flow measurement at least once a day. In certain cases, more frequent measurements are useful, namely in situations that can have a negative impact on the stability of the airways (e.g. great physical exertion, respiratory infections, contact with allergy-causing substances in asthma). Even if your own breathing situation worsens noticeably for an unknown cause, those affected should ideally measure the peak flow directly.

Peak Flow Measurement: How To Do It Right

You must carry out the measurement correctly so that you receive meaningful values during this self-test. Make sure that you always carry out the examination at around the same time of day - usually with a short interval between taking your bronchodilator medication. How to perform the measurement correctly:

First set the pointer on the peak flow meter to zero.
Stand up straight, hold the device horizontally in front of your mouth and breathe out once and then in again deeply.
After holding the inhaled air for a short moment, close the mouthpiece tightly with your lips.
Now exhale quickly with all your strength in a short breath through the measuring device. Make sure that no air escapes from the side of the mouthpiece!

Your breath moves the meter pointer (or digital display) to the value of the maximum flow rate. You can use this to derive information about the width of your airways in comparison with previous measurements. To compensate for individual fluctuations, you should take the measurement three times in a row. The highest measured value is valid. Enter this in your peak flow protocol (see below: Documentation).

Peak flow meter: normal values

Like all respiratory function values, the peak flow standard values also differ depending on the patient. Adults, for example, have a different normal range than children, as the values depend, among other things, on body size. Other influencing factors are the age and gender of the patient. The values you can (and should) achieve also depend on the underlying disease: People with pronounced asthma, for example, usually achieve lower values than their lungs-healthy peers, even with good drug treatment.

There is a corresponding peak flow table so that you do not have to calculate your peak flow normal values. The table that is right for you can be obtained from your doctor or found on the Internet.

Peak flow measurement: what do the measured values mean?

Basically, if your peak flow values remain at the level that you have discussed with your doctor over a long period of time or if they increase, you do not have to change anything in your therapy. The drugs you are given work well and keep your bronchi open. Under no circumstances should you stop taking the medication without consulting your doctor and do not reduce the prescribed dose, just because you may have fewer or no more symptoms!

If, on the other hand, the peak flow values decrease over time, this indicates a narrowing of the airways. In this case, your previous therapy is evidently insufficient. Then talk to your doctor about changing your medication as soon as possible.

Patients can learn more precise evaluation options for peak flow measurement in asthma training courses, for example the widespread traffic light system.

Peak flow measurement: documentation

Patients with chronic respiratory diseases such as asthma should regularly record their peak flow meter values, their complaints and important events such as stress or illness in an asthma diary. You should present these records when you visit a doctor. This makes it easier for the doctor to find out the reason for possible changes in lung function and helps him to quickly check the success of the therapy.

In your peak flow log, you should also note which medications (not just those for your respiratory disease!) You took before the peak flow measurement, as these can influence the condition of your bronchi.

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