Esophageal pH Monitoring (cont.)
Charles Patrick Davis, MD, PhD
Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
In this Article
How is esophageal pH monitoring used?
Almost everyone has some acidic reflux, but the amount of reflux is small and rarely causes inflammation of the esophagus (esophagitis). As the amount of acid reflux increases above the normal range, so does the probability of developing esophagitis and its symptoms. In patients with symptoms that suggest acid reflux, a diagnosis of reflux can be made by demonstrating an acid pH in the esophagus for a greater than normal amount of time.
A common alternative method to diagnose reflux is to treat patients with medications that reduce reflux. If the patient's symptoms stop, then the symptoms are likely to be due to acid reflux. Another way of diagnosing acid reflux as the cause of symptoms is to demonstrate that episodes of acid reflux recorded by esophageal pH monitoring occur at exactly the same time as esophageal pain.
Esophageal pH monitoring also can be used to determine why treatment for reflux is not working. For example, a patient treated for acidic reflux may continue to have symptoms. If so, then the question must be asked as to why the symptoms are continuing. Is it because the medication is not adequate or is it because the symptoms are not due to reflux and, therefore, are not responding to treatment for reflux? If the pH monitoring study performed while the patient takes his or her medication for reflux shows abnormal amounts of reflux, then treatment is inadequate and needs to be changed. If the amount of acid reflux is within the normal range, then it is likely that the symptoms are not being caused by acid reflux, and other potential problems need to be considered as the cause of the symptoms.
What are the limitations of esophageal pH monitoring?
The demonstration of abnormal amounts of acid reflux does not mean that symptoms are being caused by the reflux. Only treatment with medications that treat reflux coupled with a marked reduction of symptoms can be used to substantiate reflux as the cause of the symptoms. Nevertheless, it is important to remember that treatment is associated with a placebo response. For instance, 10% to 20% of patients without acid reflux report an improvement in symptoms with anti-reflux medications. Therefore, even a good response to treatment does not definitely prove that reflux is the cause of symptoms.
Some of the strongest evidence that episodic chest pain is being caused by acid reflux is provided by demonstrating that the painful episodes coincides with an episode of acid reflux. If there are very frequent episodes of reflux, however, it may not be possible to separate a true association between a symptom and reflux from a chance association due to the great frequency of episodes of reflux. Conversely, if a symptom occurs infrequently, for example, once every few days, it is unlikely that the symptom will occur during a routine 24 hour monitoring session, and therefore, a 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.