Esophageal pH
The
esophagus is the muscular tube that carries food and liquid from the
throat to the stomach. However, it is not a rigid tube. The muscles
in the wall of the esophagus automatically contract when a person
swallows. This type of contraction, called peristalsis, occurs as a
sweeping wave down the esophagus. It literally squeezes the food or
liquid along from the mouth to the stomach.
Another important part of the esophagus is the Lower Esophageal
Sphincter (LES). It is a strong muscular ring located where the
esophagus enters the stomach. This specialized muscle remains tightly
closed most of the time. It is supposed to open only to allow food
and liquid to enter the stomach. Occasionally the LES opens at the
wrong time, allowing caustic stomach acid and bile to splash up into
the esophagus. This is called acid reflux. It is reflux that is
responsible for the discomfort of heartburn. Almost everyone has
experienced heartburn occasionally, and it is nothing to be concerned
about. However, when it happens on a regular basis, it can lead to
damage and scarring in the esophagus.
pH is a measure of acidity or alkalinity. Most people are familiar
with pH tests done on soil or swimming pools. An esophageal pH test
measures how often stomach acid flows into the lower esophagus and
the degree of acidity during a 12-24 hour period.
Equipment
The equipment for esophageal pH consists of a small, thin probe at
the end of tubing. This probe measures acidity. The tubing is gently
inserted through the nose, down to the end of the esophagus. It is
attached to a portable recorder that is carried at the waist. Over 12
to 24 hours, the acidity in the lower esophagus is recorded on a
paper tape. When the patient experiences reflux or other symptoms,
he/she presses a button on the recorder. This marks the time so as to
see how it relates to the acidity levels measured by the probe. The
recording is then analyzed, and a full report is sent back to the
physician.
Reason for the Exam
There are a number of symptoms that originate in the esophagus,
including heartburn, difficulty swallowing food or liquid, and chest
pain. A measurement of esophageal pH is of great importance in
evaluating these symptoms and allowing the physician to treat
problems of acid reflux. Additionally, measurement of pH may be
helpful in determining the success of treatment for acid reflux. So,
this exam is often done before and after medical and especially
surgical treatment of acid reflux into the esophagus.
X-ray examination (known as upper GI series or barium swallow),
and endoscopy are other diagnostic tests often used when these
symptoms are present in the esophagus. Endoscopy is a visual
examination of the esophagus and stomach with a thin, lighted,
flexible tube.
Preparation
The preparation for esophageal pH measurement is very simple. The
patient should take no food or liquid for about 8 hours before the
exam. In most cases, the physician will want to study the esophagus
in its natural state. In other words, there should not be any
medicine in the body that can affect the function of the esophagus.
Patients should review all medications they are taking with their
physicians, so they can be advised which they should and should not
be taking before the test. Generally, the following list of drugs may
affect how much acid flows into the esophagus. They usually need to
be discontinued at least 48 hours before the test. However, do not
stop taking any medication without consulting the physician.
- Caffeine (coffee, tea, cola, chocolate)
- Alcohol
- Reglan (generic: metoclopramide)
- Urecholine (generic: bethanechol)
- Erythromycin (E-Mycin, and others)
- Nitroglycerin (Isordil, and others)
- Calcium channel blockers, (Procardia, Adalat, Calan, Cardizem,
and others)
- Beta blockers (Corgard, Inderal, Lopressor, and others)
- Donnatol
- Librax
- Levsin
- Tagamet (generic: cimetidine)
- Zantac (generic: ranitidine)
- Pepcid
- Axid
- Prilosec
- Prevacid
The Procedure
It takes about 10-15 minutes to insert and place the pH probe. While
the patient is seated in a chair or lying on his/her side, a thin
soft tubing is gently passed through the nose, or occasionally the
mouth. Upon swallowing, the tip of the tube enters the esophagus and
the medical technician or nurse then quickly passes it down to the
desired level. There is usually some slight gagging at this point,
but it is easily controlled by following instructions. The tubing is
then attached to the waist recorder, and the patient is sent on to
his or her regular daily activities.
Results
Normally there are several mechanisms that keep acid out of the
esophagus. The first is swallowed saliva which helps neutralize
stomach acid. Second are the sweeping muscle contractions that act to
cleanse the lower esophagus of acid reflux. Third is the protective
contraction of the LES. Generally, the esophageal pH test will show a
small amount of acid seeping into the esophagus at various times
during the day and night. This is normal for almost everyone, and the
patient may not even be aware of symptoms. However, if the above
protective actions of the esophagus do not function properly, the
test will show a greater degree and duration of stomach acid in the
esophagus.
Benefits and Alternatives
The primary benefit of the exam is that the physician has clear
documentation of the degree and duration of acidity in the esophagus.
With this information a specific treatment program can be outlined,
or reassurance can be provided if the exam is normal.
While there are other examinations used to study the esophagus,
such as upper GI series and endoscopy, nothing really takes the place
of esophageal pH measurement. Esophageal pH is often done in
association with a pressure recording of the esophagus, known as
Esophageal Manometry.
Side Effects and Complications
Generally, there are no serious problems associated with the
esophageal pH test. Once the tube is in place, it is usually easily
tolerated.
Summary
Esophageal pH is a valuable method of determining the severity of
acid reflux into the esophagus. With this information, the physician
can usually develop effective treatment for most patients who have
acid disorders in the lower esophagus.
Related Diseases
GERD
| Barrett's
Esophagus
Related Procedures
Esophageal
Manometry | Correction
of Acid Reflux by Laparoscopy
This material does not cover all information and is
not intended as a subsitute for professional care. Please consult
with your physician on any matters regarding your health.
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Chek Med Systems®, Inc., All Rights Reserved.