Esophageal pH (a measure of the acidity or alkalinity of a solution) monitoring is a procedure for measuring the reflux (regurgitation or backwash) of acid from the stomach into the esophagus.
It is used to diagnose gastroesophageal reflux disease (GERD) effects, to determine if episodes of acidic reflux are causing episodes of chest pain, to determine the effectiveness of medications that are given to prevent acid reflux and to determine if acid is reaching the pharynx (lower throat) and is possibly responsible for such symptoms as a cough, hoarseness, and sore throat.
During the procedure, a thin plastic catheter a sixteenth of an inch in diameter is passed through one nostril, down the back of the throat, and into the esophagus as the patient swallows.
The sensor at the tip of the catheter 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.
The sensor in this position records each reflux of acid. The end of a catheter which is protruding from the nose is connected to a recorder that registers each reflux of acid.
Then, the patient is sent home with the catheter and recorder and he/she must do his/her usual activities, for example, eating, sleeping, and working and record in a diary or by pushing buttons on the recorder when he/she eat, sleep and having any kind of symptoms.
After 24 hours, the catheter is removed in the hospital and recorder is attached to the computer so that data can be downloaded and analyzed.
Most recently, a capsule is used for esophageal pH monitoring. The capsule contains an acid-sensing probe, a battery, and a transmitter which records information and it is worn by the patient on a belt.
The capsule is introduced into the esophagus on a catheter through the nose or mouth and transmits for two days or three days when the battery dies and five to seven days later it is passed in the stool as the capsule is not reusable.
The advantage of the capsule is greater comfort without a catheter in the back of the throat and patients can go to work and to more of their 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.
If there are abnormal amounts of acid reflux, it does not mean that symptoms are being caused by the reflux. Also, if a patient is having infrequent episodes of chest pain due to esophageal spasm (every few days or weeks), the symptoms may not occur during 24 hours monitoring session correlation will not be possible.
One attempt to get around the latter problem is to extend the monitoring to several days, but this extended monitoring is done infrequently.
The side effects of esophageal pH monitoring can be mild discomfort in the back of the throat while the catheter is in place but most patients have no difficulty eating, sleeping, or going about their daily activities but however, they prefer not to go to work because they feel self-conscious about the catheter protruding from their nose.
During swallowing, the capsule patient may feel discomfort in the chest and this may be due to food or the wave of esophageal contraction tugging on the capsule as it passes.
For now, there are no alternatives to esophageal pH monitoring.