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Peak Flow Meter - Indications and Functioning

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The peak flow meter is used to track the working capacity of the lungs. Read the article below to learn about the uses and procedures of the peak flow meter.

Written byDr. Saberitha
Medically reviewed byDr. Kaushal Bhavsar
Published At October 18, 2022
Reviewed AtAugust 1, 2024

What Is a Peak Flow Meter?

The peak flow meter is a small, compact device used to measure the functional capacity of the lungs. It assesses the ability of the lungs to eliminate carbon dioxide. It is useful for both adults and children. Even children under five years old can easily use it. The small changes in the airways are reflected in the readings of the peak flow meter.

What Are the Uses of Peak Flow Meter?

Peak flow meters are used to assess various respiratory diseases. They are as follows;

  • It is used to track the severity of asthma and keep it under control with medications.

  • After the treatment, the working efficiency of the lungs can be analyzed using a peak flow meter.

  • It is used to recognize the signs of respiratory diseases at an earlier stage, even before the symptoms appear.

  • It helps the doctor to decide the mode of treatment for asthma flares.

  • Depending upon the results, the patient decides whether to take up normal treatment or emergency treatment.

How to Use a Peak Flow Meter?

The peak flow meter has a mouthpiece on one side. It has a reading to measure the force of expired air. The scale denotes air in liters per minute.

  • The marker must be at the bottom of the scale. If not, move it to the bottom of the reading.

  • Attach the mouthpiece to the peak flow meter.

  • Depending on the comfort, stand up or sit straight. Do not bend the back, as it interferes with forceful breathing.

  • Inhale a deep breath to fill the lungs with oxygen.

  • Place the mouth at one end of the mouthpiece. Both lips must be sealed over the mouthpiece to avoid air leakage.

  • Try to blow out the entire air in a single breath. Exhalation of air should be fast and forceful.

  • The marker moves to indicate the air pressure. Note the final reading. This reading is called the peak flow rate.

  • Repeat the above steps. Note down the reading three times. The highest marking out of the three times should be reported.

What Are the Instructions to Follow With Peak Flow Meter?

  • Though the peak flow meter can be bought without a prescription, the type of peak flow meter must be chosen on the doctor's advice.

  • Clean the peak flow meter after every use. Store it in a clean and dry place.

  • Handle the peak flow meter carefully for an accurate reading.

  • Charge the peak flow meter whenever necessary.

  • Practice exhaling forcefully many times before using the peak flow meter to get an accurate reading. Use it in front of the physician to check whether one is using it correctly.

  • Wash the peak flow meter with warm water and mild soap once a week to avoid contamination.

  • Dust particles trigger asthma patients. So, keep the mouthpiece free from dust.

  • The peak flow rate must be recorded for two to three weeks. Provide the measurement to the medical professional at the end of the third week. The highest reading obtained in these three weeks is known as personal best.

  • This personal best is used to manage the asthma treatment plan.

When Should the Peak Flow Meter Be Used?

  • Use the peak flow meter when the symptoms of asthma become severe.

  • If the asthma is not under control, then the peak flow rate must be recorded more than once a day.

  • Consult the medical professional about the frequency and duration of using the peak flow meter.

  • Few patients experience asthmatic attacks during sleep. The peak flow rate must be noted in such conditions.

  • If there are any symptoms during the day, like gasping for breath, the peak flow rate is recorded.

  • The peak flow rate should be noted even in respiratory diseases like cold, cough, or flu because these respiratory conditions influence breathing.

  • The peak flow rate must be noted before the use of medication. It is also used 20 to 30 minutes after medication.

What Are the Color Codes of the Peak Flow Zone?

Based on the peak flow rate and symptoms, the color codes are classified as green, yellow, and red.

  • Green Zone: The percentage of personal best is above 80 percent of the peak flow rate. This shows that there is no asthma. The person is normal because there are no signs and symptoms of asthma. But, medications can be taken as preventive measures without fail. The dosage of the medication is reduced if the person is in the green zone for a couple of months.

  • Yellow Zone: The range of peak flow rate is between 50 percent and 80 percent. It shows the poor management of asthma. The initial signs and symptoms of asthma are observed in the yellow zone. There may be signs of wheezing and coughing. In extreme cases, the patient experiences tightness in the chest area. Even before these symptoms appear, the peak flow meter shows decreased readings. The dosage of the drug must be improved. The doctor might change the medication if the symptoms do not subside.

  • Red Zone: It is the most dangerous zone compared to other zones. If the personal best rate is less than 50 %, the patient must be admitted to the emergency room. The patient has a severe cough and gasps for breath during inspiration. In case of wheezing, use bronchodilators because the bronchodilators can open the airways and help to breathe. The medical professional will prescribe a corticosteroid to prevent severe asthmatic attacks.

What Does a Peak Flow Meter State About the Lung Capacity?

Age, height, and sex will all affect the peak flow differently. Peak flow numbers are typically higher in taller or younger individuals. Adults may typically reach a peak flow of 400 to 700 L/m (liters per minute). A normal peak flow range in children can be anywhere between 150 and 450 L/m.

What Distinguishes a Peak Flow Meter From a Spirometer?

A device used to measure lung capacity is called a spirometer. This refers to how much air individuals can breathe in and out of their lungs. A peak flow meter determines how quickly they can expel air from their lungs.

Conclusion

Values obtained from peak flow meters and symptoms of asthma are used to determine the treatment plan. The healthcare professional gives instructions depending on the zone (yellow or red). Discuss the asthma action plan with the doctor and understand it completely. In case of any doubts, ask for an explanation from the medical professional. Record the information obtained from the peak flow meter in the asthmatic diary. Take the diary and peak flow meter to the physician on every follow-up. It helps the physician to analyze whether the patient is using the peak flow meter properly.

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Frequently Asked Questions

Peak flow meters are used to diagnose several respiratory conditions. The following are them:
- It is used to monitor the severity of asthma and manage it with medicines.
- A peak flow meter can assess the lung's functional effectiveness following treatment.
- It is used to identify lung disease symptoms early on, even before they become visible.
- It helps the physician in selecting the method of treating asthma flare-ups.
- Based on the test results, the patient decides whether to pursue regular or emergency treatment.
Yellow Zone: The peak flow rate ranges from 50 percent to 80 percent. Asthmatic symptoms and earliest warning indicators can be seen in the yellow zone. It demonstrates how asthma is poorly managed. Wheezing and coughing symptoms could be present. In rare instances, the patient feels stiffness in the chest region. The peak flow meter exhibits decreasing readings even before these symptoms emerge. It is necessary to increase the drug's dosage. The doctor can adjust the medicine if the symptoms do not go away.
Red Zone: Compared to other zones, the Red Zone is the most dangerous. The patient has to be hospitalized in the emergency room if their personal best rate is under 50 percent. During inspiration, the patient gasps for air and has a persistent cough. Use bronchodilators if the patient is wheezing because it widens the airways and makes breathing easier. A medical practitioner will prescribe a corticosteroid to prevent severe asthmatic attacks.
Low readings indicate that the lung's airways are becoming more constricted. If a patient experience asthma symptoms like wheezing or shortness of breath, a low peak flow measurement may be present.
An asthma diagnosis does not completely rely on a peak flow meter. It is part of the diagnosis where the peak flow meter reading gives an idea about the health of the lungs and how forcefully a patient can exhale. Peak flow measurements that are lower than normal indicate that the lungs may not function well and that asthma may worsen. The primary care physician will guide monitoring and managing low peak flow values.
On one side of the peak flow meter is a mouthpiece. The force of expired air is measured by reading it. Liters per minute of air are indicated on the scale.
- The marker needs to be at the scale's bottom.
- Connect the mouthpiece to the flow meter's peak.
- Stand up or sit upright, whichever is more comfortable for you. Avoid bending your back since it will prevent you from inhaling deeply.
- Take a long, deep breath to aerate the lungs.
- Set the mouth at the mouthpiece's one end. Both lips must be tightly closed over the mouthpiece to prevent air loss.
- Attempt to exhale all of the air at once. Air should be exhaled quickly and firmly.
- The marker moves and indicates the value. Take note of the conclusion. The reading is called the peak flow rate.
- Repeat the previous actions three times, and take down the reading. Out of the three instances, the highest value should be reported.
A portable gadget called a peak flow meter gauges how powerful your breath is. The patient only needs to breathe into one end of the device. The meter immediately displays a reading on a scale that indicates the lung capacity in standard terms of liters per minute.
Regular exercise has little impact on peak expiratory flow (PEF) variability in adults, but it improves asthma control as determined by the Asthma Control Test (ACT).
Various breathing exercises and, following timely prescriptions, taking medicine on time will improve the peak flow rate.
Reading in the yellow zone is between 250 and 400. In the yellow zone, asthmatic signs and symptoms are first noticed. There could be coughing and wheezing symptoms. In severe circumstances, the patient may feel constriction in their chest. The peak flow meter displays lower readings before the onset of these symptoms. The drug's dosage needs to be increased. The doctor may modify the medicine if the symptoms do not go away.
Breathing exercises help maintain or increase lung capacity. Increasing your physical activity can also aid in maintaining lung health. Diaphragmatic breathing, sometimes known as "belly breathing," is an efficient breathing technique that concentrates on your diaphragm, a muscle that helps expand your lungs and promotes proper oxygen exchange.
No, it is a helpful tool for identifying and tracking chronic obstructive pulmonary disease and its severity. The peak flow meter reading may decrease during chronic obstructive pulmonary disease exacerbation.
Peak flow meters do not need a prescription and are typically inexpensive.
With the aid of a spirometer, a medical professional can perform the simple test known as spirometry. The amount of air breathed and exhaled, lung capacity, and exhalation rate are all measured using this technique.
 
 On the other hand, a peak flow meter is a portable instrument. It monitors how forcefully a person exhales air from their lungs, indicating the exhaled capacity, and is largely limited to monitoring people living with asthma.
It depends on sex, age, and height to determine a person's normal peak flow value. Taller patients tend to have higher peak flow readings than women. After predicted rises through childhood and adolescence, the peak flow reading declines with aging starting around 30 to 40.
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Dr. Kaushal Bhavsar from iCliniq
Dr. Kaushal Bhavsar

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