Gastroesophageal reflux (GER), defined as the passage of gastric
contents into the esophagus, occurs on a daily basis as a normal
process in infants, children, and adults. Most episodes of physiologic
reflux are transient, asymptomatic, and reach only the distal esophagus.
Gastroesophageal reflux disease (GERD) is distinguished by reflux
into the esophagus resulting in well-defined symptoms or medical
problems (see Chapter 12). When children present with atypical complaints or
extraesophageal symptoms, testing may be necessary to document the
presence or absence of pathologic reflux, or the association between
reflux events and specific symptoms.1
While endoscopy can be helpful in documenting acid damage to
the esophageal mucosa in the form of erosions or ulcers, the majority
of patients with symptoms of GERD do not have endoscopic or pathologic
evidence of esophagitis.2 Tests designed to detect the
presence of GER have been developed.
The first test utilized was esophageal pH monitoring, in which
an electrode designed to detect changes in pH is used to assess
the frequency and duration of acidic reflux present in the distal esophagus.
Over the years the advantages, disadvantages, and limitations of
traditional, catheter-based esophageal pH monitoring have become
better defined, with a subsequent evolution of newer diagnostic
techniques. Wireless methods to detect acidic contents in the esophagus
have now become available (Bravo capsule). Additionally, we have
seen the development of the technical possibility of measuring both
acidic and non-acidic reflux with multichannel intraluminal impedance
(MII). In the present chapter we will review the current techniques
that are being used for the dynamic detection of reflux episodes.
Esophageal pH monitoring, which quantifies the frequency and
duration of acidic reflux episodes, can be used to confirm abnormal
esophageal acid exposure and/or correlate symptoms with
acidic reflux episodes. Testing may be especially helpful in patients
who present with atypical symptoms, patients with persistent symptoms
despite pharmacologic treatment, or patients without evidence of
mucosal damage on endoscopy. Other diagnostic approaches, such as
barium contrast upper GI series or nuclear scintigraphy, have had
variable sensitivity and specificity when compared to esophageal
pH monitoring.1 Unacceptably high false-positive and false-negative
rates seen with these radiographic tests have made esophageal pH
monitoring preferable over barium contrast and scintigraphy studies
for the diagnosis of reflux.
Over the years, the methodology of esophageal pH monitoring in
children has become relatively standardized as evidenced by the
publication of professional practice guidelines.1,3 In
addition to a catheter-based pH sensor, a portable data logger that
records intraesophageal pH as well as events during the study such
as symptoms, meals, position changes, and activity is required.
As technology has improved and as electronic devices have become
smaller, pH monitoring is now conducted on an ambulatory basis,
even for pediatric patients.
The catheter-based pH electrode is placed through the nose into
the distal esophagus....