Lung function tests (infants)

Breathing tests are safe and painless procedures and will only be carried out when your baby is well and free from a cold, cough or wheeze. To perform the test, babies will need to be in a deep sleep. To help them fall into this type of sleep we will give them a prescribed dose of sedative syrup, called chloral. We try to book the test to fit into your child’s normal napping schedule to avoid disrupting their daily routine. It is important that your child does not eat or drink anything for a few hours before the sedation. This is called ‘fasting’ or ‘nil by mouth’. Fasting reduces the risk of stomach contents entering the lungs during and after the procedure. The team will give you the specific fasting times and answer any questions you have.

Throughout the tests, your 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 during testing and ask questions or can wait in the waiting rooms if preferred. On the day of testing we will also measure your baby’s weight and length.

Once your baby is asleep we will perform a test called the multiple breath washout. This test involves your child wearing a mask over their nose and mouth to allow them to breath in a special (harmless) gas mixture. The next stage of the test is to monitor your infant breathing out this gas mixture. The measurement outcome from this test is called ‘Lung Clearance Index (LCI)’ which gives a measurement of the efficiency of gas mixing within your infant’s lungs. It will take approximately 30 minutes to complete these measurements.

The total testing time, including completing a few questions (for example, family history of asthma), performing a clinical examination and waiting for your baby to fall asleep is usually within 2-3 hours. Once the test is ended we allow your child to wake naturally, they can then be offered a drink and snack.

The person accompanying your child for the test should have ‘Parental Responsibility’ for them. Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have Parental Responsibility, we may have to cancel the test.

The results for your test will be uploaded onto our electronic patient record system for your doctor to view, these will be discussed with you at your next clinic appointment.