Spirometry Basics for Nurses: How the Test Works and What Results Mean

Spirometry is the key test for diagnosing asthma and COPD. Nurses often carry it out, and the quality of the test depends on good coaching.

Imagine a patient labelled with COPD for years who has never had spirometry. When he finally does, the results suggest asthma instead, which changes his treatment.

What spirometry measures

• FEV1: the volume of air blown out in the first second
• FVC: the total volume of air blown out
• FEV1/FVC ratio: helps show whether airways are narrowed

Preparing the patient

• Check for reasons to delay, such as recent surgery or a recent heart attack
• Ask about inhaler use and follow local guidance on withholding
• Record height, age and sex for predicted values
• Explain the test and demonstrate

Coaching a good test

1. Breathe in fully
2. Seal lips around the mouthpiece
3. Blast out as hard and fast as possible
4. Keep blowing until no more air comes out
5. Repeat until you have at least three acceptable blows that agree closely

Understanding results

A reduced FEV1/FVC ratio suggests airflow obstruction, as in COPD or asthma. A low FVC with a normal ratio may suggest restriction. Results must be interpreted by a trained professional alongside the patient’s history.

Frequently asked questions

Do nurses need training?

Yes. Many countries have formal spirometry training and certification for performing and interpreting tests.

What is reversibility testing?

Repeating spirometry after a bronchodilator to see whether airflow improves, which can help diagnose asthma.

But the machine does the work

The machine records the results, but poor coaching gives poor results that can lead to the wrong diagnosis.

Sources: American Thoracic Society and European Respiratory Society spirometry standards (2019), Global Initiative for Chronic Obstructive Lung Disease (GOLD), Association for Respiratory Technology and Physiology (UK).