INTRODUCTION — The management of asthma relies on a patient's ability to monitor their asthma regularly. Self-monitoring includes assessing the frequency and severity of symptoms (such as wheezing and shortness of breath) and measurement of lung function with tests such as a peak expiratory flow rate (PEFR). PEFR provides a number that correlates to how open the lung's airways are; as asthma worsens and the airways narrow, the PEFR decreases. Monitoring can help a patient and their healthcare provider determine the most appropriate asthma treatment plan. (See "Patient information: Overview of managing asthma").
ASTHMA MONITORING RECOMMENDATIONS — The National Asthma Education and Prevention Program (NAEPP) recommends that patients with moderate to severe persistent asthma have a peak flow meter at home and know how to use it [1]. The peak flow meter is small, inexpensive, and easy for most patients to use.
The NAEPP recommend that patients use a peak flow meter to: Provide a regular assessment of lung function and response to treatment over the short- and long-term Determine the severity of an asthma attack Assess response to treatment during an attack
Patients should use an asthma diary to record their daily peak flow meter readings, exposure to potential asthma triggers, asthma medication use, and asthma symptoms (show figure 1). This can help patients to see a cause-and-effect relationship between exposure to triggers and decreases in peak flow. The asthma diary can be reviewed with a healthcare provider to make decisions about asthma treatment. (See "Patient information: Trigger avoidance in asthma" and see "Patient information: Metered dose inhaler techniques").
HOW TO USE A PEAK FLOW METER — PEFR monitoring should be performed on a regular basis, even when asthma symptoms are not present. PEFR should also be checked if symptoms of coughing, wheezing, or shortness of breath develops. Patients should demonstrate PEFR measurement with their healthcare provider to verify that their technique is accurate.
Different brands of peak flow meters have unique features; however, these general instructions can be adapted to an individual's peak flow meter.
Getting the best readings — Several steps are important to make sure the peak flow meter records an accurate value: The peak flow meter should read zero or its lowest reading when not in use Use the peak flow meter while standing up straight Take in as deep a breath as possible Place the peak flow meter in the mouth, with the tongue under the mouthpiece Close the lips tightly around the mouthpiece Blow out as hard and fast as possible Breathe a few normal breaths and then repeat the process two more times. Write down the highest number obtained. Do not average the numbers.
Note: The test should be repeated if the tongue partially blocks the mouthpiece or if the patient coughs or spits during the test. Most peak flow meters need to be cleaned periodically; cleaning instructions should be available when the unit is purchased.
Establishing a baseline measurement — Unlike a blood pressure reading or a cholesterol test, there is no PEFR that is normal for everyone. For this reason, it is important to determine what PEFR value is normal for each individual.
To determine an individual patient's normal PEFR, they should measure their PEFR when they have no asthma symptoms. Three PEFR measurements should be done with the same peak flow meter two to four times daily for two to three weeks. For long term management, most clinicians will recommend testing once per day, usually in the morning.
The patient should note the highest PEFR measure achieved; this is the "personal best" PEFR. This number is used to determine if future PEFR readings are normal or low, and is also used to create a normal PEFR range (between 80 and 100 percent of the personal best PEFR).
Readings below the normal range are a sign of airway narrowing in the lungs. A low PEFR can occur before asthma symptoms such as wheezing or shortness of breath develop.
A personal best PEFR value should be remeasured each year to account for growth (in children) or changes in the disease (in both children and adults). In addition, home PEFR measurements should be verified with readings taken with equipment in a healthcare provider's office since this equipment is more sensitive.
The action plan — Once the normal range can been established, the healthcare provider will provide tailored guidelines (also called an action plan) to follow when the PEFR begins to decrease (show figure 2 and show figure 3).
Peak expiratory flow rates are divided into three zones, which are assigned colors similar to those of a traffic light. These zones can be used to make decisions about the need for treatment: GREEN (80 to 100 percent of personal best) signals that the lungs are functioning well. When readings are within this range and symptoms are not present, patients should continue their regular medicines and activities. YELLOW (50 to 80 percent of personal best) is a sign that the airways in the lungs are somewhat narrowed, making it difficult to move air in and out. A short-term change or increase in medication is generally required. Patients should change or increase their medication to reverse airway narrowing according to the treatment recommendations previously discussed with their provider. RED (below 50 percent of personal best) is a sign that the airways are significantly narrowed and requires immediate treatment. The "rescue" inhaler should be used according to the treatment recommendation previously discussed with the provider. PEFR should be rechecked 10 to 15 minutes after the rescue medication is used. If the PEFR improves, the patient should monitor their PEFR throughout the day. The healthcare provider should be contacted after the patient improves; daily medication may be changed or increased.
EMERGENCY CARE — Patients with asthma who fail to improve or worsen despite treatment require emergency medical services. Severe asthma attacks can be fatal if not treated promptly. In most areas of the United States, 911 can be called for emergency medical assistance. Patients should not attempt to drive to a hospital or clinician's office on their own.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Heart, Lung, and Blood Institute
(www.nhlbi.nih.gov/)
National Lung Health Education Program
(www.nlhep.org)
American Lung Association
(www.lungusa.org)
American Academy of Allergy, Asthma, and Immunology
(www.aaaai.org/patients.stm)
American College of Allergy, Asthma, and Immunology
(www.acaai.org/public/)
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Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. National Asthma Education Program Expert Panel. Guidelines for the diagnosis and management of asthma: Update on Selected Topics 2002. US Department of Health and Human Services, National Institutes of Health, Bethesda, (NIH Publication No. 02-5074) June 2003.
2. National Asthma Education Program Expert Panel. Guidelines for the diagnosis and management of asthma. US Department of Health and Human Services, National Institutes of Health, Bethesda, 1997.
3. Ignacio-Garcia, JM, Gonzalez-Santos, P. Asthma self-management education program by home monitoring of peak expiratory flow. Am J Respir Crit Care Med 1995; 151:353.
4. Jones, KP, Mullee, MA, Middleton, M, et al. Peak flow based asthma self-management: a randomised controlled study in general practice. British Thoracic Society Research Committee. Thorax 1995; 50:851.
5. Breathe Well, Live Well: An asthma management program for adults: The American Lung Association 2005.
6. National Asthma Education and Prevention Program. Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma Update on Selected Topics--2002. J Allergy Clin Immunol 2002; 110:S141.
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