From the Guidelines
Esophageal impedance-pH testing is a diagnostic procedure that measures both acid and non-acid reflux in the esophagus by combining two technologies: multichannel intraluminal impedance (MII) and pH monitoring. This test involves placing a thin catheter through the nose into the esophagus, where it remains for 24-48 hours while the patient goes about normal daily activities. The impedance component detects all types of reflux (liquid, gas, or mixed) regardless of acidity by measuring changes in electrical resistance, while the pH sensor specifically identifies acid reflux episodes (pH < 4) 1.
Key Components of Esophageal Impedance-pH Testing
- The test is particularly valuable for evaluating patients with persistent symptoms despite acid-suppressive therapy, atypical reflux symptoms, or when considering anti-reflux surgery 2.
- Before testing, patients usually need to discontinue proton pump inhibitors for 7 days and H2 blockers for 3 days, though sometimes testing is performed while on medication to assess treatment efficacy 3.
- The procedure is generally well-tolerated with minimal discomfort beyond initial catheter placement, and it provides comprehensive data about reflux patterns that cannot be obtained through other methods like endoscopy or barium studies 4.
Clinical Applications
- Esophageal impedance-pH testing is recommended for patients with symptoms suspected to be due to gastro-oesophageal reflux disease but not responsive to a proton pump inhibitor, before antireflux surgery to confirm excess oesophageal acid exposure and/or an association between symptoms and acid or non-acid reflux episodes 4.
- The test can help determine the mechanism of persisting esophageal symptoms despite therapy, and can be used to assess treatment efficacy 2.
Interpretation and Limitations
- The test results should be interpreted in the context of the patient's symptoms and medical history, and should be used in conjunction with other diagnostic tests and clinical evaluation 1.
- The test has limitations, including the need for careful patient selection and the potential for false negative results 4.
From the Research
Definition of Esophageal Impedance-pH Testing
- Esophageal impedance-pH testing is a diagnostic tool used to assess gastroesophageal reflux disease (GERD) 5.
- It combines impedance monitoring with traditional pH monitoring to detect both acid and nonacid reflux episodes 6, 5, 7.
- This testing is considered the gold standard to assess whether symptoms in patients with GERD are due to persistent acid reflux despite treatment with proton-pump inhibitors (PPIs) 8.
How Esophageal Impedance-pH Testing Works
- The test involves the placement of a catheter in the esophagus to measure impedance and pH levels 5, 7.
- Impedance monitoring detects changes in electrical resistance in the esophagus, allowing for the detection of reflux episodes regardless of their acidity 5, 7.
- pH monitoring measures the acidity of the refluxate, distinguishing between acid and nonacid reflux episodes 6, 5, 7.
Clinical Applications of Esophageal Impedance-pH Testing
- The test is useful in patients with persistent symptoms despite PPI treatment, to determine if symptoms are due to acid or nonacid reflux 8, 5, 7.
- It can also be used to assess patients with atypical reflux symptoms, such as cough or regurgitation 7.
- Esophageal impedance-pH testing can guide clinicians in managing GERD, particularly in patients who do not respond to initial treatment 8, 5, 7.