What is Peak Expiratory Flow Rate (PEFR) test?
The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR), is a person’s maximum speed of expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person’s ability to breathe out air. It measures the airflow through the bronchi and thus the degree of obstruction in the airways.
The role of PEFR (peak expiratory flow rate)
Clinical evaluation, although useful, may underestimate the degree of airway obstruction in a child with bronchial asthma. There are more sensitive and objective measures. The most commonly used method is PEFR, which is the maximum rate of airflow during exertion after maximum inhalation.
This speed is easily measured with the use of a hand-held metering device and is not expensive. The strengths of PEFR include ease of implementation, low cost, and the ability to avoid changes during treatment. However, PEFR is dependent on exertion, and cannot be performed on newborns. In addition, PEFR measures function in medium or large airways, while most pathologies in bronchial asthma occur in medium and small airways; PEFR may therefore underestimate the severity of the disease.
Functions of PEFR index
These are principal functions of the PEFR which are listed below.
- Gives you options when to use inhaled asthma or other common asthma drugs. The use of asthma relief before the occurrence of asthma is of great benefit: to help quickly prevent the narrowing of the airway and avoid hospitalization for severe asthma.
- Warns the onset of the disease.
- Indicates the severity of asthma.
- Response to medications during asthma attacks.
- Helps to know if the asthma get worse
- Shows time to adjust drugs.
- When to go to emergency room.
- Helps you choose the right action plan
What is PEFR’s acceptable value?
The normal values depend on the age and height of the baby, as well as the severity of the disease that the child has. Therefore, the results should be expressed as a percentage of the predicted value or the percentage of the usual best value (if known).
- Minor illness when PEFR is at least 80% predicted
- On average 50-80%
- Severe when less than 50%.
- No minimum of 50% of the predicted value for an admission indication is achieved
The ‘best peak flow’ indicator helps to identify changes in asthma and to propose appropriate measures. For example, if the peak flow drops below 80% of the peak, you need to:
- Follow asthma treatment plan.
- Check peak traffic more frequently during the day.
- Seek immediate help before the symptoms worsen.
When does the patient need to use peak flow?
Out of an Asthma attack:
- Measure regularly every morning, before taking asthma drugs.
- Helps identify early ventilars and know if asthma is well controlled.
- Helps identify the natural improvement of the ‘best peak flow’ index as children grow.
In an asthma attack:
- Measure in asthma and after taking asthma drugs.
- Helps determine the effectiveness of short-term antipsychotics.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Review Date: June 19, 2017 | Last Modified: June 19, 2017
Daniel R Neuspiel, MD, MPH, FAAP, Peak Flow Rate Measurement. http://emedicine.medscape.com/article/1413347-overview. Accessed on April 13, 2017
Healthline, Peak Expiratory Flow Rate, http://www.healthline.com/health/peak-expiratory-flow-rate#overview1. Accessed on April 13, 2017