Breathing tests for babies

For many years, a team of doctors and nurses from Great Ormond Street Hospital (GOSH) have been measuring breathing patterns in babies in order to help prevent and treat chest problems in infants and young children. This page is designed to explain simply and clearly the work that we do – assessing the way babies’ lungs work.

Why do we need to measure babies’ lungs and breathing?

Breathing problems are very common in babies and young children, for example:

  • Some babies and young children are prone to chest infections or wheezy episodes which may continue through infancy and into adult life.

  • Premature and other small babies sometimes have under-developed lungs and they may need to be given oxygen or assisted ventilation. Occasionally, they continue to have breathing problems when they are older.

  • Very rarely, babies are born with serious lung problems such as diaphragmatic hernia or cystic fibrosis.

Breathing tests done soon after birth can help us to understand more about how these problems arise and how we can treat them.

To find out more about breathing problems in sick babies, we also measure breathing patterns in healthy infants.

What do breathing tests involve?

Breathing tests are carried out while your baby sleeps. We need to give babies a spoonful of sedative syrup that helps them to fall into a deep sleep for testing. We then gently place a small mask over their mouth and nose. This is attached to sensitive equipment which monitors your baby’s breathing, and the results are displayed on a computer screen.

We measure the amount of air that your baby breathes, how fast the air goes in and out, and how much effort your baby is making.

Important pieces of information that we need is how much air the lung holds at the end of each breath and how rapidly your baby can remove waste gases that the body produces (for example, carbon dioxide) from his/her lungs. We can do this by giving your baby a special air mixture to breathe for one to two minutes. This mixture has the same amount of oxygen that your baby normally breathes and is completely harmless. We then measure how quickly your baby is able to breathe this out again.

You may know that breathing tests in older children and adults involve taking a deep breath in, and then breathing out as fast as possible.

We obviously cannot ask a baby to do this, but we are able to do the same test by giving him/her some help. We encourage your baby to take a deep breath in by providing extra air through the facemask.

In order to help him/her to breathe out quickly, a small jacket (rather like a miniature life jacket) is secured around the chest and inflated when your baby has taken a breath in. This jacket inflation gives your babies chest a squeeze and encourages your baby to blow the air out. This is in no way painful or harmful for your baby.

This test has been performed many times by the team, and at other centres around the world. Babies usually stay sound asleep. For some tests, we may place your baby in a special cot with a Perspex hood, which looks rather like an incubator so that we can measure how big your baby’s lungs are.

What do we find out from these tests?

The lungs contain a huge network of branching tubes. The air can get in and out easily, if the airways are disease free. If a baby has evidence of disease they may have to work harder to breathe because this makes the airways narrower.

The infant lung function tests are used to measure how much effort your baby to breathe, and how big their lungs and breathing tubes (airways) are.

If a baby has narrow airways or stiff lungs, they have to work much harder to breathe.

Will the test hurt my baby?

The test does not involve any needles or painful procedures. We need your baby to be sleeping quietly before we can make any measurement, and so we try to make him/her as comfortable and relaxed as possible.

How long will the test take?

The duration of the test can be rather variable, depending upon when your baby falls asleep. We try to fit in around your normal routine as far as possible. If your baby wakes during the test, they can usually be soothed or comforted back to sleep. Testing will last approximately two to four hours.

Can I come and watch?

Yes. Parents are welcome to stay for the test duration and to be actively involved in the tests and to ask questions. You know your baby best, and so your help is very useful and appreciated. However, you can, if you are comfortable leave your baby in our care, the choice is yours.

What happens after the test?

After the test, we measure your baby’s length. Once your baby is awake, we ask that you give them something to eat and drink. After this you will be free to go home.

Compiled by:
The Cardiorespiratory Department in collaboration with the Child and Family Information Group.
Last review date:
August 2017