Peak Flow Meter is an inexpensive device that can be used by you to monitor your asthma at home. It is a mechanical device and does not require battery or power to run it. Peak Flow Meter is light, portable and easy to use with a little training.
Peak flow meter can measure your peak expiratory flow rate (PEFR) that indicates how easily air is moving out of your lungs. Note that during episodes of asthma, airways of lungs gradually begin to narrow down which in turn restricts smooth passage of airflow. Peak flow meter can help you as an early warning system to detect any narrowing in your airways even before you develop symptoms of asthma. The PEFR readings thus can help you decide if its time you need to take your medications. By taking your medications early, you may be able to stop the growing symptoms of your asthma and avoid any serious episode of asthma. Thus, Peak flow meters are used to check your asthma the way that blood pressure cuffs are used to check high blood pressure or home glucometers are used to keep track of your blood sugar.
All patients of age eight years and older who have moderate to severe asthma should think about using a peak flow meter. Some children as young as age five can also use it. Ask your doctor or nurse to show you how to use a peak flow meter. There are several types available. It is important, however, that you use the same peak flow meter every time for PEFR measurement. Its readings may be recorded on a peak flow chart.
Peak flow meter can help you and your doctor:
• Decide if it is asthma
If PEFR variability is over 20%, asthma is usually confirmed
• Talk about your asthma with more knowledge
• Assess severity of asthma
Your daily record of peak flow taken in the morning and at night can give an accurate assessment of asthma severity. Severity of asthma can be measured by two parameters of peak flow: i) reduction in PEFR and ii) increase in diurnal PEFR variability.
• Decide if your medicine plan is working well
• Decide when to stop, reduce or add medication
If you feel symptom free and your PEFR is within 10% of your personal best and your diurnal PEFR variability is less than 15% then your medication can be reduced or stopped. Medications are typically reduced in a step-wise manner, initially morning dose is reduced / stopped and subsequently if PEFR stays normal then the night dose is reduced / stopped. Similarly, medications can be added by looking at the symptoms and PEFR readings. (Note: consult your physician for above recommendations).
• Decide when to seek emergency care
• Identify triggers that cause your asthma symptoms to worsen
Lower than normal values of morning peak flow (PEFR) on any day generally suggest exposure to asthma triggers on the previous day. If you get low peak flow readings in the morning you should list in your asthma diary all suspected triggers that you might have encountered during your last 12 hours. You can periodically screen such a list of suspected triggers to identify common triggers. If any trigger, for example, is repeatedly occurring in your list then that trigger is your potential asthma trigger. Usually, multiple triggers are responsible for aggravation of asthma and an asthma diary prepared by you for past few months can help you identify most of them.
• Identify problem of under or over-sensing of asthma symptoms
Sometimes you may be tempted to stop your medications because you might perceive that you no longer have asthma symptoms (under-sensing). However, you may experience severe reductions in your PEFR that may indicate continuation of your asthma. In such situations, medications must be continued to protect airways from permanent damage, otherwise it could be fatal sometimes. Opposite to this example is a problem of the other extreme i.e. over-sensing asthma. You may belong to this group if you are rather oversensitive and you sense even slightest asthma symptom as grave emergency. You tend to visit emergency care frequently and often take more medication than needed. In such a case you are likely to be a victim of over-treatment. These problems can be solved by recording your PEFR regularly, which will assist you in adjusting your medication plan.