Ambulatory 24-hour Esophageal pH Monitoring

Ambulatory 24-hour esophageal pH monitoring is a diagnostic test used to measure the amount of acid refluxing into the esophagus over a 24-hour period.

Indications

• Diagnostics of gastroesophageal reflux disease (GERD)
• Evaluation of symptoms such as heartburn, regurgitation, and dysphagia
• Assessment of the effectiveness of treatment for GERD
• Predominantly used in patients with atypical symptoms or when endoscopy is normal but symptoms persist

Procedure

The procedure involves inserting a thin, flexible tube (catheter) through the nose and into the esophagus. The catheter has a sensor on the tip that measures the pH levels in the esophagus.

• A local anesthetic may be used to numb the throat before insertion
• The catheter is usually inserted by a healthcare professional in an outpatient setting
• Once in place, the catheter is secured to the nose or cheek with tape
• The patient is then sent home and goes about their normal activities while wearing the device

Data Collection and Analysis

The sensor on the catheter transmits data to a small recorder that the patient wears on their belt. The recorder captures pH readings at regular intervals (usually every 4-6 seconds) over the 24-hour period.

• The patient is asked to keep a diary of symptoms, meals, and activities during the monitoring period
• After 24 hours, the catheter is removed and the data from the recorder is downloaded and analyzed by a computer
• The analysis provides information on the frequency, duration, and pattern of acid reflux episodes, as well as the correlation between symptoms and reflux events

Interpretation of Results

The results are compared to normal values to determine if there is an abnormal amount of acid in the esophagus.

• A DeMeester score is often used to quantify the severity of acid reflux, with higher scores indicating more severe disease
• Symptom association analysis can help identify correlations between symptoms and reflux events

Risks and Complications

As with any invasive procedure, there are potential risks and complications associated with ambulatory 24-hour esophageal pH monitoring.

• Nosebleeds or discomfort during insertion
• Coughing or gagging during the procedure
• Infection (rare)
• Temporary throat irritation or hoarseness after removal of the catheter

Conclusion

Ambulatory 24-hour esophageal pH monitoring is a valuable diagnostic tool for evaluating patients with suspected GERD, particularly those with atypical symptoms or normal endoscopy results. The test provides detailed information on acid reflux patterns and symptom correlation, helping guide treatment decisions.