Peak flow is short hand for peak expiratory flow. It is also known as the peak expiratory flow rate.
What is peak flow exactly?
A quick peak flow definition that we can subsequently expand upon is that it is, simply put, a person’s highest speed of expiration. In other words peak flow is the maximum rate of flow of the air breathed out from a person’s lungs. Peak flow is often drastically below the normal in people who suffer from asthma and other associated breathing problems.
How to value peak flow?
Peak flow values are generally measured using a device called a peak flow meter. This is a small, portable unit that measures someone’s effectiveness at breathing out through their lungs. It works by measuring the airflow and can, therefore, identify any obstruction to the airway. So when a person is breathing well their peak flow readings will be high and if they have any obstructions to their airway the peak flow reading will be low. A low peak flow can be symptomatic of a number of breathing disorders including asthma.
Peak flow meter
Because of the high variation in readings other tests will be necessary in order to confirm a patient’s condition as being asthma. Of course many people with asthma do have regular peak flow tests, but this is alongside other monitoring and management procedures.
A peak flow meter is a piece of medical equipment that requires a trained user to interpret its readings. One reason for this is that there is a huge range of readings that may come from healthy individuals. The user needs to know what to look for depending on a number of factors about the individual including, for example, their age, height and lifestyle. Professionals will have access to charts showing the ranges of expected values. Overtime these readings can be used by healthcare professionals to assess the health of a person’s lungs. Results are recorded on what is known as a peak flow chart, this records results from the same patient using the same peak flow metre. The peak flow readings can be used by a doctor to aid in deciding on suitable treatment for patients breathing difficulties.
History of peak flow meter
Basil Wright invented the peak flow metre and gave his name to the original scale used to record peak flow values. Wright’s original was introduced in the 1950’s. It was immediately seen as a pioneering device with its ability to measure a patients breathing capacity. Wright developed the device and it has since gone through many updates to make it more efficient. Recently the measurement scale introduced by Wright has been updated to give more accurate and useful readings. This update is known as the European scale and is considered to be more accurate and was officially adopted by the UK in 2004. The predictive values shown on charts and tables that healthcare professionals have traditionally used have now all been updated and converted for the new European system.
The skillful interpretation of peak flow measurements has become a major tool in the diagnosis and ongoing monitoring of many patients breathing conditions.