Gastroenterology - 24 Hour Ambulatory Impedance and pH Study

IMPORTANT!! Please read section 3 with regard to stopping medications (unless specified otherwise).

Introduction

Your doctor may want you to have an ambulatory impedance and pH study because you have symptoms such as frequent regurgitation of food or fluid, heartburn, cough, sore throat or chest pain. This test will help the doctor to understand the cause of the above symptoms.

What is an ambulatory impedance and pH study?

The 24 hour ambulatory impedance and pH study is a test that records how frequently the fluid and/or gas content from your stomach comes up into your gullet over a 24 hour period. This study is different from the previous 24 hour ambulatory pH study you may have had. The 24 hour ambulatory pH study detects only the acid refluxes. Occasionally, the reflux of fluid into the gullet can be non-acid and this is detected through the impedance and pH study.

The ambulatory pH catheter works by detecting the pH of the fluid that goes up into the gullet. The impedance pH catheter on the other hand detects the reflux of any type of fluid, whether it is acid, non-acid or gas, by detecting the changes in the electrical resistance around the probe. This test is usually undertaken prior to the consideration of surgery for reflux disease, and also as a diagnostic test for the evaluation of patients with unexplained cough thought to be due to reflux disease.

What does the study involve?

It is usually done following the oesophageal manometry study. You must have nothing to eat or drink (except for a glass of water) for 6 hours before the appointment time.

In the Gastrointestinal (GI) Physiology Unit you will be met by the doctor or the GI Physiologist who will check your personal details with you. As the test does not require any sedation you may drive home.

If you are taking any of the following medications, unless specified otherwise, you must stop taking them before the test as below

If you are on:

Omeprazole (Losec)
Lansoprazole (Zoton)
Pantoprazole (Protium)
Rabeprazole (Pariet)
Ondansetron (Zofran)
Esomeprazole (Nexium)
Stop 1 week before the test unless told otherwise

If you are on:

Ranitidine (Zantac)
Cimetidine (Tagamet)
Nizatidine (Axid)
Famotidine (Pepsid)
Cisapride
Domperidone (Motilium)
Metoclopramide (Maxalone)
Stop 3 days before the test unless told otherwise

If you are on antacids such as:

Gaviscon
Rennies
Gastrocote
Settlers
Algicon
Stop 24 hours before the test unless told otherwise:

You may take your other tablets as normal. If you are diabetic please continue with your tablet or injections, provided that you take your regular breakfast. You could obtain advice from your diabetic nurse or if in doubt contact a member of the staff at the GI Physiology Unit/Endoscopy Unit as given below.

What happens during the study?

After spraying your nostril with a local anaesthetic a fine tube will be passed up your nose, down the back of your throat and into your gullet. The tube will then be secured with tape onto your nose and face. It will be attached to a recording device carried in a pouch, which is then secured to your waist.

Using a micro-processor, the recording device is able to record reflux of any kind of fluid, both acid and non-acid, and also gas into your gullet, over a 24 hour period.

You will be given a diary sheet to record the times you eat and drink and the times you go to sleep and wake up and any symptoms you may develop during the 24 hour period. Before you leave the unit you will be given detailed instructions by the GI Physiologist , or the doctor doing the test, regarding food and fluid consumption during the test. As it can interfere with the test result you will be asked to avoid all acidic drinks like fruit juice, fizzy drinks, cordials, alcohol, fruit yoghurt etc during the study period.
 
You will then go home but return the following day for a few minutes, at the time specified on your diary sheet, to have the tube and recorder removed.

During the test, you are encouraged to continue with your normal activities. This is important so that the doctor can get an accurate picture of what is taking place in your oesophagus (gullet).

You should not remove the battery or get the unit wet (no shower) as this could interrupt or terminate the study. After the completion of the test, your doctor will study the data with the aid of a computer and the result of the test will be forwarded to your referring hospital consultant, or your GP, with appropriate comments and suggestions.

There are no major risks attached to the procedure. Some patients may experience minor discomfort in the throat, nose and occasionally develop nausea and vomiting but the vast majority are able to tolerate the procedure reasonably well.

Alternatives

No alternative tests are available for this purpose.

For any further information, advice and queries please contact GI Physiology Unit/ Endoscopy Suite, Rochdale Infirmary, Tel 01706 517547/517550/51422.