Esophageal pH Testing

Acid reflux into the esophagus has several manifestations. Most commonly, it results in heartburn but also contributes to some cases of asthma, laryngitis, chronic cough, dental erosions, chronic hoarseness, poor sleep, and recurrent pneumonia. Gastroesophageal reflux disease (GERD) is usually diagnosed by description of symptoms, response to treatment, and endoscopic examination of the upper GI tract. Measurement of the amount of acid exposure into the esophagus provides specific information especially in cases where the diagnosis is in question or needs objective verification.

There are two types of esophageal pH testing systems. A catheter approach has been in use for many years. A tube with a pH electrode attached to its tip is passed thru the nose into the lower esophagus. The electrode wire is attached directly to a data logger worn on a waist belt or shoulder strap. Every instance of acid reflux as well as its duration and pH is recorded, indicating gastric acid reflux over a 24-hour period after which the catheter is removed. This procedure often causes nasal and throat discomfort and limits the activities a patient can do.

More recently, a catheter-free, temporarily implanted device (Bravo pH monitoring System, Medtronic) is being used. One of the leading benefits of the new system is the ability of the patient to go about their daily activities without restriction since there are no catheters. In addition, the 48-hour study provides twice as much pH data compared to the 24-hour tube test.

The main components of the Bravo system are a Calibration Stand to standardize the system,  the pH Capsule attached to its delivery catheter, and the data receiver (about the size of a  pager), plus computer hardware link and software.

The pH capsule is small at 6 x 6.3 x 26 mm. and usually does not cause symptoms. Occasionally, patients notice a minor foreign body sensation that done not interfere with eating.   

To place the capsule, routine endoscopy is first performed and the distance from the teeth to the lower end of the esophagus is measured. After removing the scope, the delivery catheter is passed into the esophagus stopping at the pre-measured mark. Suction is applied to the delivery catheter for 30 seconds. This pulls a small piece of esophageal tissue into a chamber in the capsule. A plunger is then depressed, pushing a pin through the mucosa and anchoring the capsule to the esophageal wall. Suction is turned off and the catheter is gently twisted to remove it from the capsule before withdrawing. The capsule records pH levels for up to forty-eight hours and transmits them via radio frequency telemetry to a receiver worn on the patient's belt. Data from the recorder are uploaded to a computer for analysis. The capsule usually falls off after a few days and passes harmlessly in the stool. Patients are also asked to keep a daily diary of reflux symptoms. This diary, along with the transmitted data from the Bravo™ capsule, is then analyzed and a report is generated.

Indications for esophageal pH testing:

1. Documentation of abnormal acid exposure for patients being considered for surgical anti-reflux repair.

2. Evaluation of patients after anti-reflux surgery who are suspected to have ongoing abnormal reflux.

3. Evaluation of patients with either normal or equivocal endoscopic findings and reflux symptoms that do not respond to medications for reflux.

4. Evaluation of refractory reflux in patients with chest pain after negative cardiac evaluation.

5. Evaluation of suspected otolaryngologic manifestations of GERD (i.e. laryngitis, pharyngitis, chronic cough).

6. Evaluation of patient suspected of having acid reflux-induced asthma.