Joy McCann Culverhouse Center for Swallowing Disorders

24-hour pH Study

Ambulatory esophageal pH monitoring is a test which measures the amount of acid or non-acid refluxing back into the esophagus.  The sensors placed in the esophagus measure hydrogen ion concentration based on a scale of 0-14.  A normal pH of the esophagus is between 5 and 7.  However, all of us "reflux" sometimes especially after large meals, so normal values have been established for these tests.

There are now several methods to perform esophageal pH testing:

Transnasal pH catheter: A small tube, the size of a spaghetti noodle, is placed into the esophagus through the nose after applying an anesthetic gel to decrease the discomfort.  You will be asked to sip water from a straw to help the tube advance down the esophagus.  Once in proper position, the tube is secured to the nose and face with small strips of tape.  The exposed end of the tube is connected to a small box known as a Digitrapper, worn on a belt, which records all acid reflux episodes over the 24 hour period.  Acid reflux is measured in both the upper and lower esophagus.  You are required to return to the Swallowing Center the next day to remove the catheter and download the Digitrapper. 

Impedance - pH testing: Similar to the transnasal pH catheter, this tube test measures both acid and non-acid (pH 4-7) reflux over 24 hours.  It is the only method to accurately measure reflux when taking PPI drugs like Prilosec, Prevacid, Nexium, Aciphex or Protonix.

Bravo 48 hour pH capsule:  This simple device attaches to the esophagus at the time of endoscopy.  Unlike the previous tests, a tube is not passed down your esophagus or hangs out your nose.  It allows much more normal activity, eating, sleeping and is not visible to others so you can go to work, out to eat, etc.  The pH capsule measures acid reflux for up to 48 hours.  A small pager like device is worn on a waist belt to collect the information.  Bravo pH capsule studies are only accurate when performed off PPIs or H2Ra such as Tagamet, Zantac or Pepcid.  The device is usually painless and passes out of your system in about 7 days.

Loose-fitting clothing (front, button up style preferred) should be worn to the examination and women are advised to wear a two-piece garment.  This will allow for ease of placement of an important sensor on the right chest wall, and for attachment of the Digitrapper.  A watch should be worn throughout the examination period to allow accurate recording in a food/event diary you will be given.  You must bring your watch to this appointment to accurately record time for diary entries.  For the Bravo pH test, a 24 hour clock will be provided. 

You will be advised as to whether or not you should stop any medications prior to the study.  You will not be allowed to take anything by mouth for at least 4 hours prior to the placement of the pH catheter and you will be instructed to continue your food/liquid intake (with minor restrictions) once the test has begun.

During the study your diet should not be altered.  You will be informed of which foods should be recorded in your diary as well as various daily events that should be recorded ( i.e. meals, time in bed, etc.) and any acid reflux symptoms you experience ( i.e. heartburn, acid regurgitation, chest pain, cough, etc.)

Caution regarding the pH equipment
Personal hygiene and bathing should be limited to a "sponge bath" only with the transnasal pH system. Showers and tub baths are not permitted during the study period. Water will severely damage the inner parts of the computer and the tube where it attaches, and all data entered to that point will be lost. The cost of replacement of the entire device is greater than $10,000.

Fortunately, the Bravo capsule offers unlimited activity and there are no restrictions for bathing or showering.  However, the recording box should be within 3-4 feet of the subject at all times, so it can be placed near the shower/tub in a dry place.

If you have any questions before the procedure please ask.  We will strive to answer all of your questions.