Having a 24 hour impedance study

What is an impedance study?

An impedance study is a test which can be performed either awake on the ward or under general anaesthetic. It consists of a fine probe that measures the movement of liquid and air up and down the food pipe. Gastro-oesophageal reflux (GOR) occurs when stomach contents, whether acid or non-acid, comes back up from the stomach and into the food pipe (Oesophagus). The study is used to diagnose acid and non-acid reflux, or to see how well your child’s anti reflux medications are working.

What do I need to do in preparation for the test?

Your doctor should have already told you whether or not your child needs to stop their anti-reflux medications for the test. If you are unsure about whether or not you need to stop any medications please contact the gastro nurses at least two weeks before the study. If your child needs to stop reflux medication, it is important to follow the instructions below:

Protein pump inhibitors (PPI) should be stopped seven days before the test. PPI’s include:

• Omeprazole (Losec)
• Lansoprazole (Zoton)

Acid suppressants should should be stopped three days before the test and include:

• Cimetide
• Domperidone

Antacids should be stopped 24 hours before the test and include:

• Gaviscon
• Peptac

What happens before the test?

You can expect to receive written information before the test, stating the time, date and ward to attend. It is important that your child does not eat or drink anything two hours before the test, as this reduces the chance of them being sick during the investigation.

What does the test involve?

Before the test, the specialist nurse will talk through the procedure with you and your child. The tip of the probe will then be passed into your child’s nose and down the back of the throat into the lower part of the food pipe. This might make your child sneeze, cough or occasionally retch. The probe is held in place by a plaster on the side of the cheek and to make sure it is in the right position, you will be sent for a chest X-ray. Depending on the result of this, the probe may need to be pushed down or pulled back slightly.

The other end of the probe is attached to a small recording box in a bag. There will be four buttons on the recording box that you will need to press and a diary to keep for the duration of the test (24 hours). The specialist nurse will explain to you at the time of the test which buttons you need to press and when.

Are there any risks involved?

Sometimes there might be some bleeding from the nostril where the probe is inserted but this tends to happen if your child is prone to having nosebleeds or moves about a lot while the probe is being passed. There is also a small chance that the probe can be passed into a lung rather than into the food pipe. Your child will have an X-ray after the probe is passed to ensure that the probe is where it should be. Once the probe is in the correct position your child can eat and drink as normal.

Can my child go home or do we have to stay in the hospital?

In the majority of cases, your child should be able to go home and return to the hospital the following day to return the box and have the probe removed. If your child and you feel comfortable doing so you can remove the probe yourselves and simply return the box to the ward. In some circumstances for example if you live far away or your child has other health complications, it may be advised that you stay overnight on the ward. Sometimes, the probe can come out, if this happens and you are at home, don’t worry! Gently remove the probe completely from the cheek and write this down in the diary provided, noting the time and reason. If you are staying overnight, tell the nurse looking after you and they can re-pass the probe.

What happens after 24 hours?

After 24 hours the test is complete and you and your child should return to the ward and have the probe removed and return the recording box and diary. This should take only a few minutes and should not cause any pain. If comfortable doing so you can remove the probe at home and simply return the box. Once the probe is removed, you can go home and any medications that you stopped for the test can be re-started. The data from the recording box will be uploaded to a computer and analysed by a member of the gastroenterology team. Once analysed, you will be provided with the results at your next clinic outpatient appointment.