Peak Expiratory Flow Measurement - CE

Learn more about Clinical Skills today! Standardize education and management competency among nurses, therapists and other health professionals to ensure knowledge and skills are current and reflect best practices and the latest clinical guidelines.


Peak Expiratory Flow Measurement - CE


Do not further stress patients who are severely short of breath or who are hemodynamically unstable by having them use a peak flowmeter. Do not attempt a peak expiratory flow measurement with patients who have had recent eye surgery after which straining is contraindicated.

Most children age 5 or olderundefined#ref3">3 are capable of using a peak flowmeter (Figure 1)Figure 1 as part of their asthma management plan. Use a low-range peak flowmeter for small children (typically 8 years old or younger) and use a standard-range peak flowmeter for older children, teenagers, and adults.2

Anticipate predicted values for peak expiratory flow rate (PEFR) (Table 1)Table 1 to be approximately 10% lower for black and Hispanic patients than those shown in predicted peak flow tables.5

In children experiencing acute asthma exacerbations, PEFR correlates poorly with clinical appearance.1


Peak expiratory flow measurement is also known as peak flow or PEFR. PEFR is the maximal flow rate that a person can achieve during a short maximal expiratory effort, following a full inspiration.3,4

Increased bronchospasm or narrowing of the airways results in a decreased speed of air flow. PEFR measurement is used to assess respiratory function in obstructive airway diseases (especially asthma) and to evaluate the patient’s response to bronchodilator therapy. Peak flow is the most commonly used objective value that can be assessed at the bedside or at home; a declining value indicates the patient’s condition is deteriorating or not responding to therapy. Three PEFR measurements are obtained and only the highest is recorded.3

Ideally, peak expiratory flow should be measured before and after nebulizer treatments. The practitioner decides which scale meter to use in measuring PEFR; most commonly used are the European Union (EU) scale meter and the Wright scale meter. In addition, electronic peak flowmeters are available and can automatically record and track PEFR.


  • Emphasize the importance of establishing a normal baseline and a personal best value for PEFR.
    • Instruct the patient to measure and record three PEFRs two to four times daily for 2 to 3 weeks at home when the patient is feeling well and complying fully with his or her asthma therapy.4
    • Have the patient enter results and symptoms into a peak flow diary. The highest PEFR value recorded during the 2 to 3 weeks is the patient's personal best.4 The patient's normal PEFR range is 80% to 100% of the patient's personal best PEFR.4
  • Explain that peak expiratory flow numbers vary with sex, age, ethnicity, and height. Each person may have a personal best that is higher or lower than the average.
  • Instruct the patient to interpret peak flow measurements by using a zone scheme, similar to a traffic light system. Explain that:
    • Green is when the PEFR is more than 80% of the patient's personal best, indicating that the patient is doing well and can continue his or her usual maintenance regimen.2
    • Yellow is when the PEFR is between 50% and 80% of the patient's personal best, indicating that the patient is getting worse and should use caution.2 The patient should implement the asthma action plan (Figure 2)Figure 2 (starting by using the rescue inhaler) that the practitioner has established to reverse airway narrowing and regain control of the disease.
    • Red is when the PEFR is less than 50% of the patient's personal best.2 Warn the patient that this signals a medical alert, because airway narrowing and obstruction may be severe. Instruct the patient to initiate bronchodilator therapy and contact the practitioner immediately or call 911 for emergency medical assistance if the PEFR does not return to the yellow or green zones after bronchodilator therapy.4,6
  • Explain that in many cases the first sign of an “asthma attack” is a decrease in peak flow measurements, even in the absence of symptoms. Recognizing this change allows early medical intervention and can prevent severe symptoms. Instruct the patient that although the PEFR is useful for detecting changes in his or her asthma control, significant testing variability can occur. Advise the patient that the practitioner may select a more reliable test, such as spirometry, to confirm or exclude airflow limitation.5
  • Explain that peak flow measurements may be used to guide medication doses on the practitioner’s recommendation6 and that peak flow measurements may also be taken before and after exposure to potential triggers.
  • Instruct the patient to use the same meter for each measurement and to take the meter when being evaluated by the practitioner or emergency department (ED) practitioner because there can be variations between meters.6
  • Instruct the patient to report any increase in shortness of breath, faintness, or dizziness.
  • Teach the patient to keep the peak flowmeter clean to better ensure accurate measurements and to eliminate pathogens (such as cold contaminants) that may collect inside it. Instruct the patient to wash the peak flowmeter with mild detergent in hot water, rinse it, and allow it to air-dry.2
  • Teach the patient to measure and record his or her personal best PEFR at least once per year to account for changes in disease in all age groups, as well as to account for growth in children.4
  • Encourage questions and answer them as they arise.



  1. Perform hand hygiene before patient contact.
  2. Introduce yourself to the patient.
  3. Verify the correct patient using two identifiers.
  4. Determine the patient’s level of dyspnea.
  5. Obtain baseline vital signs and pulse oximetry reading.
  6. Obtain a thorough medical history, including history of previous intubation and the patient’s usual course of treatment.


  1. If the patient is able, have him or her stand to allow for full expansion of the lungs. If the patient is unable to stand, have him or her sit up straight with the shoulders back.1
  2. Ensure that the patient does not have any food, gum, or liquid in his or her mouth.
  3. Loosen any tight or restrictive clothing.
  4. Insert the disposable mouthpiece into the flowmeter.
  5. Reset the indicator to zero.


  1. Perform hand hygiene and don gloves.
  2. Verify the correct patient using two identifiers.
  3. Explain the procedure to the patient and ensure that he or she agrees to treatment.
  4. Provide the patient with instructions and guide him or her through the process of using the flowmeter.
    1. Have the patient stand if possible, or sit up straight, with no food, gum, or liquid in the mouth.
    2. Instruct the patient to hold the flowmeter in front with the mouthpiece toward the mouth and without blocking the openings or obstructing the scale.
    3. Instruct the patient to clear his or her airway by blowing out forcefully once without placing the mouth on the mouthpiece.
    4. Instruct the patient to inhale deeply until the lungs are full of air.
    5. Instruct the patient to hold his or her breath, place the mouth firmly around the mouthpiece, and seal the circumference with the lips. Instruct the patient to not block the mouthpiece with the tongue.3
    6. Instruct the patient to exhale through the mouth as forcefully as possible.
      If exhaled air leaks through the nose, use a nose clip or have the patient pinch his or her nose closed, because any leakage of air will yield an inaccurate reading.
  5. Read the line where the marker stops. Record this number as the PEFR measurement.
  6. Instruct the patient to take a few relaxed normal breaths.
  7. Repeat the procedure an additional two times and record each number.
  8. Document the best of the three readings. Do not average the numbers.
  9. Remove the disposable mouthpiece (if applicable) and discard it.
  10. Clean and disinfect the flowmeter or discard it (if applicable).
  11. Discard supplies, remove gloves, and perform hand hygiene.
  12. Document the procedure in the patient’s record.


  1. Assess for dyspnea, bronchospasm, and dizziness, and for the need to use a rescue inhaler if the patient is symptomatic after the procedure.
  2. Assess, treat, and reassess pain.
  3. Measure PEFR before and after bronchodilator treatments.


  • Accurate measurement of peak flow


  • Prolonged bronchospasm
  • Increased dyspnea
  • Dizziness
  • Complaints of near syncope
  • Inaccurate reading because of operator variability or poor effort by the patient


  • Highest value of the three measurements
  • Symptoms such as dyspnea or bronchospasm
  • Unexpected outcomes and related nursing interventions
  • Patient and family education


  • Peak flow measurements may be obtained in children as soon as they are able to understand the instructions to perform the test. This usually occurs at 5 years old.1,2,3 However, in children who are experiencing an acute asthma exacerbation, PEFR may not correlate well with the child’s clinical appearance.1,3
  • Pediatric normal measurements are based on the child’s height, regardless of age. (Table 1)Table 1.
  • Children should stand to do their peak flow reading if their condition permits.
  • Measurements are effort dependent. All users need to recognize the importance of taking a deep breath and exhaling forcefully. This is especially important to monitor with children.


  • If older adult patients are unable to stand to perform the test, have them sit up straight with their shoulders thrust back.5


  1. American Academy of Pediatrics (AAP). (2015). Peak flow meter. Retrieved January 28, 2019, from https://www.healthychildren.org/English/health-issues/conditions/allergies-asthma/Pages/Peak-Flow-Meter.aspx
  2. American Lung Association. (n.d.). Lung health & diseases: Measuring your peak flow rate. Retrieved January 28, 2019, from (Level VII)
  3. Dobra, R., Equi, A. (2018). How to use peak expiratory flow rate. Archives of Diseases in Childhood - Education and Practice, 103(3), 158-162. doi:10.1136/archdischild-2017-313178
  4. Gerald, L.B., Carr, T.F. (2018b). Patient education: How to use a peak flow meter (beyond the basics). Retrieved January 28, 2019, from http://www.uptodate.com
  5. Gerald, L.B., Carr, T.F. (2018a). Peak expiratory flow rate monitoring in asthma. Retrieved January 28, 2019, from http://www.uptodate.com
  6. National Heart, Lung, and Blood Institute (NHLBI), National Asthma Education and Prevention Program (NAEPP). (2007). Expert panel report 3: Guidelines for the diagnosis and management of asthma. Retrieved January 28, 2019, from (classic reference)* (Level VII)


Gorelick, M.H. and others. (2004). Difficulty in obtaining peak expiratory flow measurements in children with acute asthma. Pediatric Emergency Care, 20(1), 22-26. doi:10.1097/01.pec.0000106239.72265.16 (classic reference)*

U.S. National Library of Medicine, MedlinePlus. (2018). Peak flow meter use—series. Retrieved January 28, 2019, from

*In these skills, a “classic” reference is a widely cited, standard work of established excellence that significantly affects current practice and may also represent the foundational research for practice.

Elsevier Skills Levels of Evidence

  • Level I - Systematic review of all relevant randomized controlled trials
  • Level II - At least one well-designed randomized controlled trial
  • Level III - Well-designed controlled trials without randomization
  • Level IV - Well-designed case-controlled or cohort studies
  • Level V - Descriptive or qualitative studies
  • Level VI - Single descriptive or qualitative study
  • Level VII - Authority opinion or expert committee reports