Peak flow measurement: how often is it necessary?
To get a good overview of the condition of their bronchial tubes in obstructive airway 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 also advisable in situations that can have a negative impact on the stability of the airways (e.g. major physical exertion, respiratory infections, contact with allergenic substances in asthma). Even if your own breathing situation deteriorates noticeably for unknown reasons, it is best for those affected to measure their peak flow directly.
Peak flow measurement: how to do it correctly
In order to obtain meaningful values from this self-test, you must carry out the measurement correctly. Make sure that you always carry out the test at around the same time of day – usually a short time after taking your bronchodilator medication. How to carry out the measurement correctly:
- First set the pointer on the peak flow meter to zero.
- Stand upright, hold the device horizontally in front of your mouth and exhale once and then inhale deeply.
- After holding the inhaled air for a short moment, enclose the mouthpiece tightly with your lips.
Your breath moves the pointer of the measuring device (or the digital display) to the value of the maximum flow velocity. From this, you can derive information about the width of your airways in comparison with previous measurements. To compensate for individual fluctuations, you should carry out the measurement three times in succession. The highest measured value is valid. Enter this in your peak flow log (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 on body size, among other things. Other influencing factors are the patient’s age and gender. The values you can (and should) achieve also depend on the underlying disease: People with a pronounced asthma condition, for example, usually achieve lower values than their lung-healthy peers, even with good drug treatment.
There is a corresponding peak flow table so that you do not have to calculate your normal peak flow values separately. You can get the right table for you from your doctor or find it on the Internet.
Peak flow measurement: What do the measured values mean?
However, if the peak flow values fall over time, this indicates a narrowing of the airways. In this case, your current therapy is obviously not sufficient. Talk to your doctor as soon as possible about adjusting your medication.
Patients can learn more precise ways of evaluating the peak flow measurement in asthma training courses, for example the widely used traffic light system.
Peak flow measurement: documentation
Patients with chronic respiratory diseases such as asthma should regularly record their peak flow meter values, their symptoms and important events such as stress or illness in an asthma diary. They should present these records at doctor’s appointments. This makes it easier for the doctor to find out the reason for possible changes in lung function and helps them 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 were taking before the peak flow measurement, as these can affect the condition of your bronchial tubes.
