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The Laryngoscope
V
C
2013 The American Laryngological,
Rhinological and Otological Society, Inc.
The Role of Impedance Monitoring in Patients With
Extraesophageal Symptoms
Robert T. Kavitt, MD, MPH; Elif Saritas Yuksel, MD; James C. Slaughter, DrPH; C. Gaelyn Garrett, MD;
David Hagaman, MD; Tina Higginbotham, MPA; Michael F. Vaezi, MD, PhD, MSc (Epi)
Objectives/Hypothesis:
Ambulatory esophageal impedance monitoring is commonly employed to assess for nonacid
reflux in patients with extraesophageal reflux. We aimed to determine if
on
therapy impedance data can be predicted from
off
therapy upper endoscopy, manometry, or pH parameters.
Study Design:
Prospective Cohort Study.
Methods:
Patients with extraesophageal reflux symptoms and either partial- or nonresponders to twice-daily PPI under-
went impedance monitoring
on
twice-daily PPI, as well as manometry, upper endoscopy, and 48-hour wireless pH monitoring
off
acid-suppressive medications for 1 week. Percent time pH
<
4 and number of reflux episodes were obtained. Multivariable
linear regression was used to determine association between the impedance data
on
therapy and upper endoscopy, manome-
try, and pH parameters measured
off
therapy.
Results:
Seventy-five patients (77% female, median BMI 29, 38% with hiatal hernia, and 19% with esophagitis) were
studied both
on
and
off
therapy. Thirty-five percent had abnormal impedance monitoring
on
therapy and 84% had abnormal
pH testing
off
therapy. There was no significant (
P
¼
0.184) overall correlation between total number of impedance events
and the baseline physiologic parameters of hiatal hernia, degree of acid reflux, or manometric findings, with only weak corre-
lation (r
¼
0.54,
P
¼
0.045) with % time pH
<
4 among patients with esophagitis.
Conclusions:
In patients with suspected extraesophageal reflux refractory to PPI therapy, impedance measures
on
ther-
apy cannot be predicted from traditional baseline esophageal physiologic parameters. We recommend caution regarding over-
interpretation of impedance data.
Laryngoscope, 000:000–000, 2013
Key Words:
Impedance, GERD, refractory reflux.
Level of Evidence:
2b.
Laryngoscope,
123:2463–2468, 2013
INTRODUCTION
Gastroesophageal reflux disease (GERD) is a com-
mon disorder with increasing prevalence in the Western
world.
1
Approximately 40% of adults frequently com-
plain of heartburn,
2
and GERD remains the leading
outpatient physician diagnosis for gastrointestinal disor-
ders in the United States.
3
Extraesophageal reflux (EER) is widely implicated
in the etiology of laryngeal, pharyngeal, and pulmonary
symptoms, and controversy exists regarding the diagno-
sis and management of this condition.
4
Currently, most
patients with signs and symptoms attributed to EER are
empirically treated with proton pump inhibitors (PPIs).
However, symptomatic improvement on PPIs is not as
consistent compared to those with classic GERD.
5
Patients with presumed EER refractory to initial empiric
medical therapy are often referred for further testing.
Current guidelines recommend diagnostic testing, which
can include the use of upper endoscopy and pH and/or
impedance monitoring.
6
Combined impedance-pH monitoring can detect var-
ious types of esophageal refluxate: gas, liquid, acid, or
nonacid, and is used to clarify the mechanisms of PPI-re-
fractory symptoms.
7–11
Multicenter studies utilizing
impedance-pH testing in patients with PPI-refractory
symptoms suggest that approximately one-third of
patients exhibit weakly acid or nonacid reflux. In the
background of potent acid suppression, the clinical
significance of these findings currently remains contro-
versial. While some advocate for the clinical utility of
impedance-pH monitoring in assessing the impact of
weakly acidic material on patients’ persistent symptoms,
others are not as enthusiastic. Studies have suggested
that 40% to 50% of patients with persistent symptoms
on acid-suppressive therapy have no temporal correla-
tion between their symptoms and any type of reflux.
12,13
While there is no doubt that impedance-pH testing
is currently the most accurate and detailed method for
detecting reflux of all kinds, the clinical indications for
its use are still evolving. Its role in the management of
GERD patients awaits further definition, mainly due to
From the Division of Gastroenterology, Hepatology and Nutrition
(
R
.
T
.
K
.,
E
.
S
.
Y
.,
T
.
H
.,
M
.
F
.
V
.), the Department of Biostatistics (
J
.
C
.
S
.), the
Vanderbilt Voice Center; Department of Otolaryngology (
C
.
G
.
G
.), and the
Allergy, Sinus and Asthma Program (
D
.
H
.), Vanderbilt University Medical
Center, Nashville, Tennessee, U.S.A.
Editor’s Note: This Manuscript was accepted for publication
August 22, 2012.
The authors have no funding, financial relationships, or conflicts
of interest to disclose.
Send correspondence to Michael F. Vaezi, MD, PhD, MSc (Epi),
Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt Uni-
versity Medical Center, 1660 TVC, 1301 22nd Ave. South, Nashville, TN
37232-5280. E-mail:
Michael.vaezi@vanderbilt.eduDOI: 10.1002/lary.23734
Laryngoscope 123: October 2013
Kavitt et al.: The Role of Impedance Monitoring in Extraesophageal Symptoms
Reprinted by permission of Laryngoscope. 2013; 123(10):2463-2468.
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