Peak Flow Meter vs Spirometer

3 Min Read

Pulmonary Function Testing (PFT) is an area of respiratory care and diagnostics. This test is normally performed in a doctor's office. It requires you to blow into a tube and the doctor analyses the results. These results interpret two things: the power your lungs can generate and the volume of air your lungs can hold. Both are used to diagnose a patients condition. There are many devices used to monitor/diagnose lung health but peak flow meters and spirometers are the most common for people with asthma and or COPD. Smart spirometers and smart peak flow meters are now well established for use in clinical settings but also for use outside the clinic. Patients can now perform spirometry outside of the clinic and get clinical-grade results to be instantly shared with their care team (carer/doctor).

Peak Flow Meter

A peak flow meter is a straight forward device that measures a users Peak Expiratory Flow (PEF). This is a measure of the speed at which you can exhale air from your lungs. People with asthma use PEF monitoring to help manage their asthma. PEF testing can be performed as a means of early detection of potential asthma attacks, when they feel their symptoms are becoming worse or to help decide whether rescue medication is necessary. It is important that patients consult their doctor about what their personal best PEF is, or should be, to provide a point of reference for PEF tracking in disease management. The best way to set the baseline is to do a series of daily tests, for 2/3 weeks when you are feeling well. You can then use this baseline to judge for any irregularities in condition.

Benefits of a peak flow meter vs spirometer:

  • Easy to interpret results
  • Inexpensive and easily accessible

Related article: What Should My Peak Flow Be?


A spirometer is a more advanced device that measures a wider range of lung function metrics including PEF and also Forced Expiration Volume over 1 second (FEV1), Forced Vital Capacity (FVC), some also measure Inspiration Capacity (IC). Through the assessment of inspiratory and/or expiratory flows, a spirometer can help detect not only the type of respiratory disease (if any) present, but also the degree to which the disease has progressed. Spirometers are particularly useful in the diagnosis of diseases such as COPD where the disease remains largely asymptomatic until lung capacity has been irreversibly compromised.

These are the benefits of a spirometer vs peak flow meter:

  • Also measures PEF 
  • Much better diagnostic ability (much more data than a peak flow meter to identify and quantify defects in the respiratory system) than a peak flow meter

Related article: What is Spirometry?

Unfortunately, although these tools are beneficial for condition management there are drawbacks associated with them, results can be not representative of condition in many cases, such as:

  • Lack of proper technique
  • Lack of effort
  • Known or suspected respiratory infection
  • Nausea/Vomiting/Pain
  • Hypertension or pulmonary embolism

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