Reflux characteristics in patients with suspected laryngopharyngeal reflux; a prospective study using ambulatory pH/impedance measurements

Laryngopharyngeal reflux (LPR) is movement of gastric content into the
laryngopharyngeal cavity where damage to vocal cords and pharynx can occur. The
upper part of the esophagus is anatomically connected to the laryngopharyngeal
cavity and divided by the upper esophageal sphincter (UES) which prevents
movement of gastric content out of the esophagus into the laryngopharyngeal
cavity. Therefore, LPR can only occur during relaxation of the upper esophageal
sphincter. Symptoms ascribed to LPR are dysphonia or hoarseness, cough, globus
pharyngeus, throat clearing and dysphagia.
Current diagnostic tools that are routinely used in the diagnosis of LPR are
laryngoscopy and a clinical symptom questionnaire. When diagnosed with clinical
symptoms and laryngoscopy, PPI response can not be predicted, as 50% of
suspected LPR patients responds to PPI therapy(1).
Dual probe pH-metry has also been used as a tentative diagnostic tool in
suspected LPR. using dual probe pH monitoring, it has been demonstrated that
there is increased proximal reflux in patients suffering from RL compared to
GERD patients and healthy subjects (2). The rate of proximal reflux measured by
dual probe pH has not been shown to be a prognostic marker for PPI response(1).
However, in this study only 6 PPI responsive patients were included. Both
studies demonstrate that there is a PPI responsive and a PPI unresponsive
subgroup of patients with suspected LPR, which appear equally divided among LPR
suspected patients. However, to make this differentiation current diagnostic
tools are insufficient.
A relatively new diagnostic tool is esophageal impedance measurement(2).
Compared to conventional single probe pH-metry, impedance measurement has the
advantage of accurately measuring proximal extent of reflux. It can also detect
non-acidic reflux and gas reflux and is able to differentiate pure fluid reflux
from gas-liquid reflux, the so called mixed reflux. The ability to detect mixed
reflux is of particular importance in LPR as demonstrated by Babaei et al, who
observed that UES relaxation was the predominant response during reflux events
with air in the reflux in healthy subjects (92%)(3). This is important in LPR
patients since relaxation of the upper esophageal sphincter is necessary to
allow movement of gastric content into the laryngopharyngeal necessary for
LPR.
Two studies have used impedance measurements in LPR suspected patients.
Kawamura et al measured 10 patients with reflux characteristics in patients
with suspected LPR using impedance located inside the UES and a dual probe
pH-metry(4). The authors found that the number of total reflux events in the
proximal esophagus was higher in the LPR group than in the GERD group as well
as the ratio of distal esophageal reflux events reaching the proximal
esophagus(4). Khan et al measured reflux events in LPR patients unresponsive to
PPI therapy and in patients with typical reflux symptoms and found no
significant differences between these two groups. However, methodological
concerns have been raised for both studies limiting their value since the
studies are limited by small sample size. Furthermore, the study population of
the study by Khan et al is subject to selection bias as only patients that are
unresponsive to PPI therapy(5) and both studies using impedance measurements
did not use impedance measurement as a prognostic tool for PPI response.
We hypothesize that in patients with clinically suspected LPR there are more
proximal mixed gaseous liquid reflux events compared to healthy controls.
Furthermore, we hypothesize that in patients with suspected LPR, PPI response
correlates with number of proximal mixed gaseous-liquid reflux events.

We aim to investigate the reflux characteristics in patients with LPR and
healthy controls using pH/impedance measurements. A second analysis will be to
compare total number of proximal reflux events in PPI responders and
non-responders.

A prospective study using ambulatory pH/impedance measurements

Patients have to stop PPI or medication influencing GI-motility and have to
travel to the AMC. There are no known risks associated with the investigations