Lung function tests (infants)

This page explains about lung function tests for infants and what to expect when your child comes to Great Ormond Street Hospital (GOSH) to have this procedure.

Breathing tests can also be performed in babies and, just as in older children, they are done to assess how well the lungs are working.

These tests can help to monitor the growth and development of the lungs and the effectiveness of treatment (eg antibiotics).

Who does the infant tests?

Tests for babies and young children are only carried out by fully trained respiratory scientists, technicians and/or doctors.

What do the tests involve?

Breathing tests are very safe and painless, and will only be carried out when your baby is well and free from a cold, cough or wheeze. The tests are carried out while the baby sleeps. Young babies usually fall asleep after a feed but it is often necessary need to give older babies a spoonful of sedative syrup, called chloral, which helps them to sleep for about an hour while the test is carried out.

A small mask, connected to a meter (or sensor), is gently placed over the nose and mouth to monitor the baby’s breathing pattern which is displayed on a computer screen. The tests assess how well the lungs are working. For example, we assess:

  • how quickly the baby can remove waste gases (such as carbon dioxide) from his/her lungs
  • how much air is held at the end of each breath which allows us to calculate the size of the lungs
  • how fast the baby can “blow out” in order to find out if there is any narrowing of the air passages (or airways).
For more information, please see our information on lung function tests.

Throughout the tests, the baby’s oxygen saturation (the amount of oxygen in the blood) and heart rate will be monitored. Parents are welcome to stay with their baby at all times and ask questions. We also measure the baby’s weight and length.

How long do the tests take?

We can only record the baby’s breathing pattern during periods when he/she is sleeping quietly. It will take about 45 minutes to an hour to complete recordings for all the different assessments. In all - including the time spent asking a few questions (for example, family history of asthma) and waiting for the baby to fall asleep - most tests are completed within 2 hours.

When will we get the results?

The report will be forwarded to your consultant within three to five days. He/she will discuss your baby’s results with you in light of available clinical and other relevant details.

Compiled by:
Great Ormond Street Hospital
Last review date Jun