Esophageal 24-Hour pH Metry

Esophageal pH monitoring is the current gold standard for diagnosis of gastroesophageal reflux disease (GERD). It provides direct physiologic measurement of acid in the esophagus and is the most objective method to document reflux disease, assess the severity of the disease and monitor the response of the disease to medical or surgical treatment. It can also be used in diagnosing laryngopharyngeal reflux.

Gastroesophageal Reflux Disease (GERD) is a common disease in western countries. In the United States, 7% of the population experiences heartburn daily and 44% at least once a month. Heartburn occurs when esophageal mucosa is exposed to the acidic gastric content, but the complaint of heartburn is not always a reliable guide to the presence of acid reflux in the esophagus. Further, only half of the patients with increased esophageal acid exposure will have esophagitis. Therefore, the diagnosis of gastroesophageal reflux disease (GERD) on the basis of symptoms or endoscopic findings is problematic.

Ambulatory esophageal pH monitoring is now the gold standard for the diagnosis of gastroesophageal reflux disease.

Esophageal pH monitoring is currently performed using one of the following techniques: Single and dual sensor pH monitoring using a pH catheter. The duration of the test is 24 hours.

Esophageal 24-Hour pH Metry Tracings


What is an esophageal pH test?

An esophageal pH test measures and records the pH in your esophagus to determine if you have gastroesophageal reflux disease (GERD). The test can also be done to determine the effectiveness of medications or surgical treatment for GERD.

What happens during esophageal reflux?

Esophageal reflux is a condition in which stomach acid refluxes or moves back into the esophagus.

A specialized muscle, called the lower esophageal sphincter, is located where the esophagus meets the stomach. This sphincter opens to allow food and liquid to pass into the stomach, then closes. When the sphincter does not close tightly, food particles, stomach acid and other digestive juices can splash back up into the esophagus. When this happens, the condition is called gastroesophageal reflux. When reflux occurs on a regular basis, it can cause permanent damage to the esophagus. The esophageal pH test measures how often stomach contents reflux into the lower esophagus and how much acid the reflux contains.

How does the esophageal pH test work?

A thin, small tube with an acid sensing device on the tip is gently passed through your nose, down the esophagus. In assessment of distal esophageal pH, the sensor is placed 5 cm above upper border of the lower esophageal sphincter (LES) determined by esophageal manometry. To measure proximal esophageal acid exposure the second sensor is placed 1-5 below the lower border of the upper esophageal sphincter (UES).The tube is secured to the side of your face with clear tape. The end of the tube exiting from your nose is attached to a portable recorder that is worn on your belt or over your shoulder. The recorder has several buttons on it that you will press to mark certain events. A nurse will review the monitoring instructions with you.

How do I prepare for the 24-hour esophageal pH test?

Seven days before the monitoring period, do not take proton pump inhibitors: omeprazole, lansoprazole, rabeprazole, pantoprazole, or esomeprazole.
Two days (48 hours) before the monitoring period, do not take the H2 blockers: ranitidine, cimetidine, famotidine, nizatidine; or the promotility drug metoclopramide or gastroperidone.
Six hours before the monitoring period, do not take antacids.
Four to 6 hours before your appointment do not eat or drink
Please note: Occasionally, your doctor may want you to continue taking a certain medication during the monitoring period to determine if it is effective.

Once the test has begun, what do I need to know and do?

Activity: Follow your usual daily routine. Do not reduce or change your activities during the monitoring period. Doing so can make the monitoring results less useful.
Note: do not take a tub bath or shower; the equipment can’t get wet.
Eating: Eat your regular meals at the usual times. If you do not eat during the monitoring period, your stomach will not produce acid as usual, and the test results will not be accurate. Eat at least 2 meals a day. Eat foods that tend to increase your symptoms (without making yourself miserable). Avoid snacking. Do not suck on hard candy or lozenges and do not chew gum during the monitoring period.
Lying down: Remain upright throughout the day. Do not lie down until you go to bed (unless napping or lying down during the day is part of your daily routine).
Medications: Continue to follow your doctor’s advice regarding medications to avoid during the monitoring period.
Recording symptoms: Press the appropriate button on your recorder when symptoms occur (as discussed with the nurse).
Recording events: Record the time you start and stop eating and drinking (anything other than plain water). Record the time you lie down (even if just resting) and when you get back up. The nurse will explain this.
Unusual symptoms or side effects. If you think you may be experiencing any unusual symptoms or side effects, call your doctor.
You will return the next day to have the tube removed. The information on the recorder will be downloaded to a computer and the results will be analyzed.

A reflux episode is defined as esophageal pH drop below four. Esophageal pH monitoring is performed for 24 hours and at the end of recording, patients tracing is analyzed and the results are expressed using six standard components. Of these 6 parameters a pH score called Composite pH Score or DeMeester Score has been calculated, which is a global measure of esophageal acid exposure. A Demeester score > 14.72 indicates reflux.

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