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Peak flow meter


Related terms
Author information
How it works
Types of peak flow meters
How to use it
Determining personal best reading
Managing asthma

Related Terms
  • Antibodies, auto recessive, B-cells, bone marrow, bone marrow transplant, CBC, genetic disorder, immune system, immunodeficiency, inherited disorder, inherited immunodeficiency, leukocytes, leukemia, lymphoma, lymphocytes, malignancy, platelets, pneumonia, red blood cells, T-cells, thrombocytes, thrombocytopenia, tumor, WASP, white blood cells, Wiskott Aldrich syndrome, Wiskott-Aldrich syndrome protein, X-linked.

  • Wiskott-Aldrich syndrome (WAS) is an inherited, immunodeficiency disorder that occurs almost exclusively in males. The recessive genetic disorder is caused by a mutation in the WAS (Wiskott-Aldrich syndrome) gene, which is an X-linked trait. The gene mutation leads to abnormalities in B- and T-lymphocytes (white blood cells), as well as blood platelet cells. In a healthy individual, the T-cells provide protection against viral and fungal infection, the B cells produce antibodies, and platelets are responsible for blood clotting to prevent blood loss after a blood vessel injury.
  • Individuals diagnosed with WAS suffer from recurrent infections, eczema and thrombocytopenia (low levels of platelets).
  • Before 1935, patients only lived an average of eight months. Today, patients usually live an average of eight years, according to a recent case study. The cause of death is usually attributed to extensive blood loss. However, cancer (especially leukemia) is common and often fatal among WAS patients.
  • The only possible cure for WAS is a bone marrow transplant. However, if a patient's family member is not a possible match for a bone marrow donation, patients may have to wait years for a potential donor. Other aggressive treatments may also increase a patient's life expectancy. For instance, one study found that patients who underwent splenectomy (removal of the spleen) lived to be more than 25 years old. The spleen may harbor too many platelets, and cause a decrease in the number of platelets in circulation. Antibiotics, antivirals, antifungals, chemotherapeutic agents, immunoglobulins and corticosteroids have also been used to relieve symptoms and treat infections and cancer associated with WAS.
  • Researchers estimate that about four people per one million live male births develop the disease in the United States.
  • The syndrome is named after Dr. Robert Anderson Aldrich, an American pediatrician who described the disease in a family of Dutch-Americans in 1954, and Dr Alfred Wiskott, a German pediatrician who discovered the syndrome in 1937. Wiskott described three brothers with a similar disease, whose sisters were unaffected.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Binder V, Albert MH, Kabus M, et al. The genotype of the original Wiskott phenotype. N Engl J Med. 2006 Oct 26;355(17):1790-3.
  2. Jin Y, Mazza C, Christie JR, et al. Mutations of the Wiskott-Aldrich Syndrome Protein (WASP): hotspots, effect on transcription, and translation and phenotype/genotype correlation. Blood. 2004 Dec 15;104(13):4010-9. Epub 2004 Jul 29.
  3. Natural Standard: The Authority on Integrative Medicine. .
  4. St. Jude Children's Research Hospital. Inherited Immunodeficiencies: Wiskott-Aldrich Syndrome (WAS). .
  5. U.S. Immune Deficiency Foundation. The Wiskott Aldrich Syndrome. .

  • Pharmacia Diagnostics AB developed the allergen-specific IgE test, which was first marketed as RAST® in 1974. In 1989, Pharmacia Diagnostics AB replaced it with a superior test called the ImmunoCAP® specific IgE blood test, which is more sensitive and specific. The newer test is a cellulose polymer in a plastic reserve, which has a higher binding capacity of allergy proteins than the RAST® test. According to medical literature, the new test has replaced about 80% of the old RAST® tests in laboratories worldwide.
  • The newest version of ImmunoCap® is the only specific IgE assay to receive approval by the U.S. Food and Drug Administration (FDA).

How it works
  • A peak flow meter is made of a plastic tube with a mouthpiece on the end. A scale is located inside the device to measure the force of air that is expelled from the lungs and blown through the tube. This force, measured in liters per minute, is known as the peak expiratory flow (PEF).

Types of peak flow meters
  • Peak flow meters are most helpful for asthmatics who take asthma medication daily. Children as young as three years old have been able to use a peak flow meter safely and effectively.
  • There are several types of peak flow meters, which are available over-the-counter. A low-range peak flow meter is used for small children, and a standard-range meter is used for older children, teenagers and adults. A physician or pharmacist can help patients determine which type to use. Examples of peak flow meters include: ASSESS®, AsthmaCheck®, POCKETPEAK® and MicroPeak®.

How to use it
  • To use the device, first slide the pointer all the way down to the bottom of the scale. Then stand up, remove any gum or food from the mouth, and take a deep breath. Place the lips over the mouthpiece, making sure there are no gaps for air to escape. Do not put the tongue inside the hole. Blow as quickly and as forcefully as possible into the tube. Do not breathe out slowly or for a long period of time because the device is designed to measure how fast and hard the individual can expel air out of the lungs.
  • Once the air is expelled, take the meter of the mouth, and note the number next to the pointer. If the individual coughs or makes a mistake, the number is not considered an accurate reading. Repeat the procedure twice more, and then record the highest of the three readings. Do not calculate the average. It is recommended that individuals keep a chart, including the date and time of each peak flow reading.

Determining personal best reading
  • Individuals should determine their personal best peak flow reading. This is the highest number the individual can achieve when the asthma is under good control. Good control means that the patient feels healthy and is not experiencing asthma symptoms.
  • Take peak expiratory flow (PEF) readings at least twice a day for two to three weeks. It is recommended that individuals measure their peak flow in the morning and evening, after taking short-acting inhalers, when asthma symptoms occur and any other time the physician suggests. Record the readings when PEF is measured.
  • After two or three weeks, look at the recorded numbers and find the highest reading. This number is considered the personal best peak flow reading. Personal best readings vary among individuals, even if they are the same age, weight and height.
  • Three numbers are calculated from the personal best reading, and they are used to establish three separate "zones." These zones are based on percentages of the personal best reading and are merely guidelines.
  • Green zone: The green zone is more than 80% of the personal best reading. Readings in this zone signal that the asthma is under good control. Medications should be taken as usual.
  • Yellow zone: The yellow zone is 50-80% of the personal best reading. This zone indicates caution because there is some airway narrowing. Individuals are recommended to take a short-acting, quick-relief medication right away to prevent asthma symptoms. Individuals should also consult their healthcare providers to determine whether daily medicines should be altered.
  • Red zone: The red zone is less than 50% of the personal best reading. This signals a medical alert because there is significant narrowing of the airway passages. Individuals should take their quick-relief medication immediately (e.g., oral steroids), and call their physicians or go to the emergency department at the hospital to determine the best course of action.
  • If an individual's peak flow reading increases 20% or more after taking a short-acting inhaled quick-relief medicine, a qualified healthcare provider should be consulted to determine whether another medication or higher doses would help control the asthma symptoms.

Managing asthma
  • The muscles in the upper airways contract during an asthma attack, making it difficult for the lungs to take in and release air. However, this narrowing of the airways does not happen suddenly. In fact, the airway may start to narrow hours before the first symptoms of asthma arise.
  • The peak flow meter can help a patient determine when the airway begins to narrow, possibly before symptoms occur. A 20-30% decrease in an individual's PEF might indicate that asthma mediation is necessary to prevent an asthma attack. Taking medications before symptoms appear may help prevent severe exacerbations.
  • In addition, a peak flow meter can help patients and physicians learn what makes triggers the asthma (makes the asthma worse), decide whether the current treatment plan is working, decide when to add or stop medication(s), and decide whether emergency care is necessary.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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