Overview of Peak Flow Rate Measurement
Peak expiratory flow (PEF) is a measure of how well a person’s lungs are working, and doctors often use it to understand how well they’re managing someone’s asthma. A peak flow meter is the device typically used to do this and it measures how much air a person can breathe out in one fast blast. This test involves a good deal of effort on behalf of the patient and is influenced by many things including the depth of the breath taken before the test, the size of the airway, the strength of the respiratory muscles, and the patient’s voluntary effort.
It is important that the patient follows the correct technique for the test to be accurate, so doctors usually watch their patients perform the test to ensure they are doing it right. One problem though is that not all peak flow meters are the same, and there is currently no good method to accurately compare the results from different meters. The International Organization for Standardization has published guidelines to determine the best peak flow meters, so it is recommended that doctors and patients pick those that meet these guidelines.
Once a patient’s best PEF is worked out (this is achieved by recording the highest reading out of a group of attempts), the doctor can put together a personalized plan to manage their asthma. Regularly measuring the PEF can help evaluate if the treatment is effective, alarm us to possible asthma flare-ups before symptoms appear and can also help in deciding treatment during asthma attacks. It’s particularly helpful for patients who find it tough to identify their asthma symptoms. PEF measurement is less frequently done during severe asthma attacks in young children.
As per their individual PEF values, the doctor is able to provide early intervention and the best continuous treatment, overall improving the management and outcomes for patients with asthma.
Why do People Need Peak Flow Rate Measurement
If you have asthma, using a tool called a Peak Expiratory Flow (PEF) meter can help you manage your symptoms. The PEF meter measures how well your lungs are working. By following a written plan that explains how to adjust your treatment based on your PEF meter readings and symptoms, you can both control your asthma and keep it from getting worse. Studies show that using a written plan like this can reduce the negative impact of asthma in both adults and children.
The PEF meter can be particularly useful if you find it hard to notice when your asthma symptoms are getting worse. It can also be used to see how severe an asthma attack is in adults and teenagers, and to check how your body is responding to treatment. It’s also a helpful tool to use at home to keep track of your asthma over time. It can be used to identify work-related asthma by taking readings at your job and comparing them to readings taken when you’re not at work. For children under 12, the PEF meter isn’t normally used to measure how severe an acute asthma attack is because it requires a significant amount of effort and specific technique to use.
Equipment used for Peak Flow Rate Measurement
Different types of peak flow meters are available for you to buy. A standard peak flow meter is easy to use. It’s a handheld, tube-shaped device with a piece you put your mouth on and an indicator that shows measurements along its body. You can use this device many times. Some electronic types can even record your readings and send them to your healthcare provider. You can even get handheld electronic spirometers for home use that can measure Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), and Peak Expiratory Flow (PEF). These terms represent how much air you can blow out of your lungs and how quickly you can do it, which are key points for lung health monitoring.
How is Peak Flow Rate Measurement performed
Peak flow meters come in different designs, but they all work in the same basic way. If you’re a patient using a peak flow meter, your healthcare provider will teach you how to do the process. Here’s a quick guide:
- Move the marker to 0.
- Stand or sit up straight.
- Take in a deep breath.
- Put the meter in your mouth and close your lips around the mouthpiece. Make sure your tongue isn’t blocking or inside the opening.
- As soon as your lips are closed, blow out as hard and fast as possible. Use your chest and stomach muscles. This shouldn’t take more than 2 seconds.
- Write down the result.
- Repeat the steps above 2 more times.
- Tell your healthcare provider about your highest result.
Your healthcare provider will watch you during your first try to help you adjust your technique. They’ll also go over the process during later visits to make sure you’re doing it right. It’s important to keep up with this technique because your peak flow rates can go down over time, likely due to a loss of skill or effort. This means you should relearn the technique during each follow-up visit, particularly when you’re also learning how to use an inhaler.
Every year, your healthcare provider should check your personal best peak flow rate. This can help measure growth in children and track how a disease is progressing.
What Else Should I Know About Peak Flow Rate Measurement?
When you’re feeling well, it’s ideal to determine your best peak flow rate. This means you should record the highest flow rate of air you can breathe out in a short burst, usually tracked for a period of two weeks. You need to track this two to four times every day. The highest measurement recorded during this time is considered your personal best.
Once your personal best is determined, your doctor will be able to help you create a plan in case your asthma symptoms become worse. This plan may help in improving the control of your asthma symptoms and your overall health.
However, it’s important not to just rely on peak flow measurements. Studies show that looking at these measurements alone doesn’t necessarily give a big advantage over just monitoring symptoms. Doctors are encouraged to consider both your reported symptoms and the objective data from the peak flow meter. This approach may decrease your visits to the doctor or hospital.
Peak flow meters, or devices that you blow into to measure your lung performance, usually have three zones to help you make sense of your measurements. Think of these zones like a traffic light.
The green zone is when your flow rates are 80% to 100% of your personal best. If you’re in this zone and not having symptoms, you just keep following your current treatment plan.
The yellow zone is when your rates are 50% to 80% of your personal best. If you’re in this zone, you follow the emergency steps of your treatment plan, which usually starts with medications to open up your airways.
The red zone is when your measurements are less than 50% of your personal best. If you’re in this zone, you should take your emergency medications and contact your doctor right away. This could indicate a severe problem with airflow to your lungs and should be considered a medical emergency.
In an emergency scenario at the hospital, these measurements can also guide treatment decisions. If your peak flow rate is less than 50% and not improving after aggressive treatment, you may need to be admitted to the hospital for closer monitoring and further treatment. In these cases, if you don’t know your personal best, there are tables of normal rates based on height and weight.
For children 5 years or older, the peak flow meter can be used reliably, but during an acute or severe flare up, the results may not be accurate. Children may struggle with the technique during an episode, so peak flow measurements aren’t routinely used during these times in children. In addition, it can be helpful to provide a second meter for the child to keep at school should any issues arise.
During pregnancy, peak flow rate and personal best numbers remain constant, regardless of changes to the body. If there are any changes in peak flow rates, it should be taken as a sign of worsening airflow until proven otherwise.
However, there are some limitations. An incorrect technique, chest wall disease, obesity, and muscle weakness can all cause inaccurately low readings. Also, people with severe asthma may find peak flow measurement underestimates how badly their airflow is limited. Furthermore, patients often find it hard to stick to long-term peak flow monitoring, so this test is most effective when done over shorter periods.