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You are here:   Home  »  Public  »  Tests and Investigations  »  Lung Function Testing

Lung Function Testing

Spirometry the most common lung function test that looks at how well the lungs work.  Spriometry shows how much air an individual can breathe out and the time it takes to do so.  Breathing in and out can be affected by lung diseases such as chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis and cystic fibrosis. Spirometry therefore can help diagnose these various lung conditions.  Spirometry is also used to monitor the severity of lung conditions and their response to treatment. 

A spirometer is the device that is used to make the measurements.  An individual breathes in and forcefully exhales through a mouthpiece.  Spirometry measures the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled.  Spirometry measurements are compared to predicted values according to your age, gender, height and weight.


Measurements from spirometry:

1.    How much air an individual can breathe out in 1 second.  This is called FEV1 (forced expiratory  
      volume in 1 second).

2.    How much air an individual can breathe out in one breath.  This is called FVC (Forced Vital


The ratio between these two measurements will enable clinicians to see if an individual has abnormal lung function.

Patient undertaking Spirometry

Peak Expiratory Flow (PEF) s an objective measure of how well the lungs are functioning and can measure airway narrowing.  A peak flow meter is a small device that measures the fastest rate of air that a person can blow out of their lungs.  An increase in an individual’s PEF value reveals lung function has got better, and a decrease in PEF highlights that the lung function has got worse.  For example, for patients suffering from asthma, PEF readings are at their highest and do not vary from day to day when they are well controlled.  However, PEF readings may decline during an asthma attack.  Predicted or normal values help us to estimate what PEF could be expected according to a persons age, gender and height.