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The Spirometer Versus the Peak Flow Meter

written by: Vasanth • edited by: Diana Cooper • updated: 1/23/2011

There are several diagnostic tools that assess how well the lungs function including a spirometer and peak flow meter. When comparing the spirometer versus peak flow meter, it is important to consider the size, cost, and function of each device.

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    Benefits of the Peak Flow Meter

    A peak flow meter is used to measure the speed at which air is expelled from the lungs. This value is known as the peak expiratory flow. By tracking the peak expiratory flow over a period of weeks or months, one can determine whether their specific lung condition is getting better or worse. In the case of asthma, the readings can be used to determine the severity of symptoms such as coughing and wheezing. For example, a reading that is 80-100% of an individual's maximum peak expiratory flow indicates that the lungs have not declined in function and are stable. A reading that is below 50% of an individual's maximum peak expiratory flow indicates that the lungs are not working well and immediate medical care is needed.

    A peak flow meter is small and easy to carry. It can be used frequently and most have a straightforward scale that is understandable. It is fairly inexpensive. Most are available for less than $40.

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    Limitations of the Peak Flow Meter

    A peak flow meter works when air is blown into it. For the results to be accurate, one must exhale as forcefully as possible. This may be difficult for individuals with reduced lung capacity. Shortness of breath and lightheadedness are temporary side effects of the test. Even with a normal peak flow meter reading, asthma attacks can still occur. It is important to consider environmental factors that may play a part in aggravating asthma or other lung conditions.

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    Benefits of the Spirometer

    When comparing a spirometer versus peak flow meter, it is important to look at what each one measures. The spirometer measures the total volume of air that is inhaled and exhaled. In addition, it measures the rate at which air is expelled from the lungs. These two measurements, known as the forced vital capacity (FVC) and forced expiratory volume (FEV-1), help to determine how well the lungs are performing. The data gathered from a spirometer is illustrated on a flow-volume graph. It can help diagnose diseases which affect the lungs, including asthma, bronchitis, and emphysema.

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    Limitations of the Spirometer

    A spirometer is larger than a peak flow meter, and it is not practical for individuals to carry them around. A high quality spirometer with multiple functions and convenient features, such as a touchscreen, will cost several hundred to several thousand dollars. The limitations of the spirometer versus peak flow meter are important to consider. Like the peak flow meter, normal readings on a spirometer don't completely rule out lung conditions. Usually, more tests are given to identify the cause of breathing problems, such as the bronchial challenge test.

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    Reference

    1. "Peak Flow Meter." Mayo Foundation for Medical Education and Research. http://www.mayoclinic.com/health/peak-flow-meter/MY01116/DSECTION=results

    2. "Spirometry." Mayo Foundation for Medical Education and Research. http://www.mayoclinic.com/health/spirometry/MY00413/DSECTION=results

    3. "Pulmonary Function Tests." Medline Plus. http://www.nlm.nih.gov/medlineplus/ency/article/003853.htm