Hello and welcome to the zero to finals podcast.

My name is Tom and in this episode I'm going to be talking to you about lung function tests.

And you can find written notes on this topic at zero to finals.com slash lung function tests

or in the respiratory section of the second edition of the

Zero to Finals Medicine book. So let's get straight into it.

Lung function tests also called spirometry help to diagnose various lung conditions such as asthma,

chronic obstructive pulmonary disease, or COPD, and restrictive lung diseases. They can help to monitor the severity and the progression

of the disease and guide management. Let's talk about the outcome measures. Spirometry is the test used

to establish objective measures of lung function. This involves different breathing exercises

into a machine that measures the volumes of air and flow rates and produces a report.

Reverseability testing involves giving a bronchodilator, for example salbutamol,

before repeating the spirometry to see if this impacts the results.

Forced expiratory volume in one second, or FEV-, is the air a person can forcefully exhale in one second.

This measures how easily air can flow out of the lungs.

FEV1 is reduced with airflow obstruction.

Forced vital capacity, or FVC, is the total air a person can exhale after a full inhalation,

after a full breath in.

This measures the total volume of air that a person can take into their lungs.

FVC is reduced when there is restricted lung capacity.

Let's talk about obstructive disease.

Obstructive lung disease is diagnosed when the FV1 is less than 70% of the FVC,

meaning the FEV1 to FVC ratio is less than 70%.

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