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Acid Reflux Test - Esophageal pH monitoring

Also called Esophageal acidity test.

Esophageal pH monitoring is a procedure for measuring the reflux (regurgitation or backwash) of acid from the stomach into the esophagus. It is useful when endoscopy has not detected damage to the mucous lining in the esophagus, but Acid Reflux symptoms are present. pH monitoring may be used when patients have not found relief from medicine or surgery.

How the Test is Done

Esophageal pH monitoring is performed by passing a thin plastic catheter a sixteenth of an inch in diameter through one nostril, down the back of the throat, and into the esophagus as the patient swallows. The tip of the catheter contains a sensor that senses acid. The sensor is positioned in the esophagus so that it is just above the lower esophageal sphincter, a specialized area of esophageal muscle that lies at the junction of the esophagus and stomach and prevents acid from refluxing back up into the esophagus. In this position the sensor records each reflux of acid. The catheter protruding from the nose is connected to a recorder that registers each reflux of acid. The patient is sent home with the catheter and recorder in place and returns the next day to have them removed. During the 24 hours that the catheter is in place, the patient goes about his or her usual activities, for example, eating, sleeping, and working. Meals, periods of sleep, and symptoms are recorded by the patient in a diary and/or by pushing buttons on the recorder. After the catheter is removed, the recorder is attached to a computer so that the data it has gathered can be downloaded into the computer where it is analyzed and put into graphic form.

The most recently-developed device for monitoring esophageal pH uses a large capsule. The capsule contains an acid sensing probe, a battery, and a transmitter. The probe monitors the acid in the esophagus and transmits the information to a recorder that is worn by the patient on a belt. The capsule is introduced into the esophagus on a catheter through the nose or mouth and is attached to the lining of the esophagus with a clip. The catheter then is detached from the capsule and removed. Thus, there is no catheter protruding from the nose. The capsule transmits for two days, and then the battery dies. Five to seven days later, the capsule falls off and is passed in the stool. (The capsule is not reusable.) The advantages of the capsule device are related to the absence of a catheter connecting the probe to the recorder. There is greater comfort without a catheter in the back of the throat, and patients are more likely to go to work and do more normal activities without feeling self-conscious about the appearance of the catheter to others. The disadvantages of the capsule are that it cannot be used in the pharynx (where it would be impossibly uncomfortable) and, so far, it has not been used in the stomach. More experience will be necessary to know if the information obtained with the capsule is comparable to the more standard catheter probe.

How to Prepare for the Test

Your health care provider will ask you to fast (no eating and drinking) and avoid smoking after midnight before the test.

Some drugs may change the test results, and your health care provider may ask you to not take those for 24 hours before the test. These substances may include:
• Antacids
• Anticholinergics
• Cholinergics
• Adrenergic blockers
• Alcohol
• Corticosteroids
• H2 blockers
• Proton pump inhibitors
Do not stop any medication unless told to do so by your health care provider.

How the Test Will Feel

You may experience a brief gagging sensation as the tube is passed through your throat.

Possible Risks and Complications from the Test

No significant risks have been reported with this test, but the following may occur rarely: You may experience a brief gagging sensation as the tube is passed through your throat. If the catheter induces severe gagging and vomiting results, there is a risk of aspirating (breathing in) some gastric contents.

Interpreting the Results

Normal values vary from person to person, and with different equipment and techniques. An increased frequency or duration of acid in the esophagus often correlates with Gastroesophageal reflux disease, Esophageal scarring and Barrett's esophagus

By Mortin - Copyright 2009
Last modification 31/12/2009

Acid Reflux Test - Esophageal pH monitoring References