PH impedance
The esophagus is a muscular tube that connects your throat to your stomach. With each swallow, the esophagus muscle contracts and pushes food into the stomach. These rhythmic contractions are called as peristalsis. At the lower end of the esophagus, a valve (a special sphincter muscle) remains closed most of the time except when swallowed food or liquid is needed to move down in stomach or when you belch or vomit. The malfunction of this valve can cause acid and alkaline bile reflux and heartburn. Repeated such insults can lead esophageal injury, narrowing and carcinoma.
Esophageal pH monitoring is a test used to evaluate for the degree of acidity and frequency of acid backflow during a 24-hour period and to determine the effectiveness of medications that prevent acid reflux..
Who needs to undergo pH testing?
Esophageal pH testing is very effective in evaluating reflux symptoms. Number of symptoms results from reflux like heartburn, chest pain, difficulty in swallowing, and other non-gastrointestinal symptoms like chronic cough, sore throat, wheezing, hoarseness. PH studies also helpful in determining the success of treatment for acid reflux and surgical treatment of acid reflux into the esophagus.
Preparation
You should not eat or drink for eight hours prior to the procedure. You may be asked to stop certain medications that can affect the function of the esophagus. Your doctor may ask that you temporarily stop taking one or more medications before your test (Stop 7 days before the study – pantoprazole group of drugs, Stop 2 days before the study – ranitidine group of drugs). If you were asked to obtain the study on your current regimen then do not stop any of your medications. Also avoid tea, coffee, and alcohol prior to the test.
Procedure
There are two types of pH monitoring. Combined pH/impedance monitoring also allows detection of non-acid reflux. The nose is numbed for a short time. A thin wire-sized plastic catheter is passed into 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 addition, the catheter has other sensors (impedance rings) that measure flow across the esophagus – allowing the detection of non-acid reflux and determination of how far up the reflux goes (which may be important for atypical symptoms such as cough). Placing the probe takes approximately 5 to 10 minutes and no sedation is necessary. The other end of the small catheter comes out the nose and is connected to a small battery-powered recorder that is worn on a strap over the shoulder. During the 24 hours that the catheter is in place, the patient goes about his/her usual activities, for example, eating, sleeping, and working. Meals, periods of sleep, and symptoms are recorded by the patient in a diary and by pushing buttons on the recorder. The diary helps the doctor to interpret the results. The patient returns the next day for removal of the catheter. After the catheter is removed, the recorder is attached to a computer so that the data recorded can be downloaded into the computer where it is then analyzed. In order to determine the correct placement of the pH/impedance probe, it may be necessary to perform a short test called esophageal manometry
Side effects
There may be mild discomfort in the back of the throat while the catheter is in place. The vast majority of patients have no difficulty eating, sleeping, or going about their daily activities.
Alternative test/option
Other test to examine esophagus are barium study, endoscopy. But these cannot measure the acid changes in esophagus.
