Simultaneous Laryngopharyngeal and Conventional Esophageal pH Monitoring

Summary

Laryngopharyngeal pH monitoring has been specifically designed to measure acid exposure above the upper esophageal sphincter and complements diagnostic evaluation in patients that present with mainly extraesophageal reflux symptoms. Patients with suspected laryngopharyngeal reflux (LPR) were evaluated using distal esophageal and laryngopharyngeal pH testing simultaneously.

Abstract

In addition to typical reflux symptoms, many patients with gastroesophageal reflux disease (GERD) present with extraesophageal symptoms such as cough, hoarseness or asthma, which can be caused by laryngopharyngeal reflux (LPR). Due to their multifactorial origin, those symptoms can be a great diagnostic and therapeutic challenge. Esophageal pH-monitoring is commonly used to determine abnormal esophageal acid exposure and confirm the diagnosis of GERD. However, for better evaluation of acid exposure above the upper esophageal sphincter, a new laryngopharyngeal pH measurement system is now available and may lead to more reliable results in patients with predominantly extraesophageal symptoms. This article aims to present a standardized protocol for simultaneous pH measurement using esophageal and laryngopharyngeal pH probes in order to obtain acid exposure scores from both measurements.

Introduction

Gastroesophageal reflux disease (GERD) is one of the most common benign diseases affecting up to 20% of people in western countries¹. In addition to typical symptoms such as heartburn or regurgitation, some patients may suffer from atypical symptoms such as cough, hoarseness, or asthma^2,3. Despite the agreement that chronic cough, chronic laryngitis, and asthma can have a reflux related origin and are significantly associated with laryngopharyngeal reflux (LPR), the exact pathomechanism still remains unclear. As these symptoms are usually part of a multifactorial process, they depict a great diagnostic and therapeutic challenge⁴.

Distal esophageal pH monitoring 5 cm above the lower esophageal sphincter is commonly used to determine abnormal esophageal acid exposure in patients with suspected GERD². In an attempt to use the same technique, proximal conventional pH monitoring was introduced in the late 1990s as a diagnostic device to measure abnormal acid exposure at the upper esophageal sphincter (UES) as the probe is placed at or slightly above the UES. However, this method does not always provide valid and accurate results as the probe is not designed for an oropharyngeal environment leading to the measurement of invalid artifacts such as pseudoreflux events caused by drying out of the probe^5,6.

Lately, laryngopharyngeal pH monitoring was introduced as a new diagnostic device specifically designed to measure acid exposure in the oropharynx, as the probe is placed above the UES slightly lateral to the uvula (Figure 1). Since previous research has shown it to have a positive predictive value of 80% for a successful outcome after antireflux surgery in patients with primarily atypical symptoms, this new tool has been a valuable addition to the diagnostic pathway in selected patients. Its tear drop sensor is equipped with an antimony technology that detects liquid and aerosolized acid and does not need direct mucosal contact to measure valid results. In addition, the sensor can, in contrast to proximal pH monitoring, resist drying out which may lead to more reliable results^7,8.

Current literature on the correlation of concomitant conventional esophageal and laryngopharyngeal pH measurement is sparse. Previous studies either included only a small number of patients or did not perform both measurements simultaneously^9,10,11. We recently published data on the correlation between both pH measurements in a large cohort of 101 patients with suspected GERD. We concluded that laryngopharyngeal and esophageal pH measurement do not necessarily need to correspond due to the existence of a variety of different reflux scenarios¹². We furthermore developed a human reflux model with patients following esophagectomy and reconstruction with a gastric interposition showing 100% correlation between both pH monitoring methods in volume-refluxers¹³.

Here, we aim to provide instructions for simultaneous pH measurement using distal esophageal and laryngopharyngeal pH monitoring. In addition, guidance on analysis of composite acid exposure scores and correlation between results obtained by both methods is given. We furthermore present the newest data of a large patient cohort evaluated using simultaneous esophageal and laryngopharyngeal pH monitoring.

Protocol

The following study protocol was reviewed and approved by the Ethics Committee of the Medical Faculty of the University of Cologne.

NOTE: Ensure that the patient arrives NPO for the following gastrointestinal function testing. Perform a high-resolution manometry to determine the exact location of the lower esophageal sphincter (LES) and to rule out esophageal dysmotility disorders such as achalasia. The patient should be off antisecretory medication for at least 7 days prior to ensure a valid pH measurement.

1. Setting up the esophageal pH monitoring system

1. Insert batteries into the esophageal monitoring system.
2. Connect the esophageal pH catheter to the device.
3. Start the device. Make sure date and time is accurate. Select Start study.
4. Calibrate the catheter in solutions with pH 4 and 7 and rinse the probe in water. Set the probe aside for insertion.

2. Setting up laryngopharyngeal pH monitoring system by first formatting the SD card with patient’s data.

1. Insert the SD card into the computer and open the software for laryngopharyngeal pH monitoring (e.g., DataView 4). Add a new patient by clicking on New and typing in all details about the patient. Click Save to save the data to the SD card. Eject the SD card and insert it into the recorder.
2. Insert batteries into the transmitter using the supplied screwdriver to remove the cover of the transmitter case and install a new CR1632 lithium coin battery.
3. Insert two AA batteries into the recorder.
4. Turn the recorder on. Use the up/down keys to select Setup. Press any round key to select the Setup mode. Modify the time and date if needed by using the up/down keys to change the digits and any round key to select the respective value. If time and date is correct, select Yes and continue.
5. Select No when the Recorder asks “Tst PSG Adapter?”.
6. Select Study in the main menu.
7. The transmitter is now detected automatically. Confirm that the correct transmitter is detected and press any round key for confirmation. The transmitter displays the serial number that is paired with the recorder.
8. Attach the probe to the transmitter.
   NOTE: When connected to the transmitter, the red light-emitting diode (LED) at the probe tip will flash once per second. The LED stops flashing after four hours to conserve battery life.
9. Select Hydrate for the calibration process. Hydrate the probe with the provided clear water solution by placing the probe tip in the clear water solution and agitating briefly. Press any round key to start the hydration process.
   NOTE: The Recorder will display “Hydrating” and will count down from “300 seconds” to zero or will transition to 15 seconds countdown when the recorder detects that the probe is hydrated. Set the probe aside for insertion.

3. Placing the esophageal pH catheter first

1. Ensure that the patient is sitting upright, looks straight and swallows periodically. Provide a small glass of water with a straw to assist swallowing.
2. Ask the patient which side of their nose is clearer and easier to breathe through.
3. Apply a topical gel that contains a local anesthetic to the probe shaft for ease of insertion.
4. Insert the Probe through the patient’s nose, straight in and not up. A measuring scale on the probe shaft helps to determine the correct position.
   NOTE: The correct position is 5 cm above the LES as previously determined by high resolution manometry.

4. Securing the esophageal pH catheter

1. Secure the probe as closely to the nares as possible to ensure that it does not move during the study using surgical tape.
2. Attach the probe to the cheek, near the nose.
3. Loop the probe over the ear and use tape to affix the probe to the neck, behind and below the ear.

5. Placing the laryngopharyngeal pH catheter

1. Ensure that the patient is sitting upright, looks straight and swallows periodically.
2. Apply a topical gel that contains a local anesthetic to the distal end of the probe shaft for ease of insertion.
   Caution: DO NOT apply topical gel to the probe tip where the sensor is located.
3. Insert the probe through the patient’s opposite nostril of the esophageal catheter, straight posteriorly and not up.
   NOTE: The round probe tip will help it curve around and through the velopharyngeal port into the oropharynx. The distance from the patient’s nares to the oropharynx can often be estimated by using the distance from the nares to the earlobe.
4. Confirm that the red light is clearly visible, lateral to or slightly below the uvula. Use a tongue depressor for clear visibility if needed.
   NOTE: If the patient’s gag reflex is triggered, retract the probe to a higher position in the oropharynx.

6. Securing the probe and transmitter

1. Secure the probe as closely to the nares as possible to ensure that it does not move during the study using surgical tape.
2. Attach the probe to the cheek, near the nose.
3. Loop the probe over the ear and use tape to affix the probe to the neck, behind and below the ear.
4. Attach the transmitter to the patient’s clothing with the clip-on transmitter carrying case.

7. Ensuring that simultaneous pH measurements are performed

1. Make sure the internal clocks of both pH measurement devices are synchronized. Manually adjust the times if needed.
2. Start esophageal and laryngopharyngeal pH studies concurrently. Select a 24-hour study for the laryngopharyngeal pH measuring device.

8. Patient diary and instructions

1. Ask the patient to fill out a detailed diary that includes mealtimes, exact time of supine periods and symptoms they experience during the time of the study.
2. Provide the following instructions for the 24-hour measurement period to the patient to ensure a successful data recording:
   Three mealtimes on day 1 of the study, one mealtime on day 2 of the study.
   No supine periods before 9pm.
   Eat, drink, and behave as usual (daily activities can be done).
   Caution: Devices are NOT waterproof.

9. Removing the esophageal and laryngopharyngeal probe after the 24-hour study period is completed

1. Concurrently end the study on both devices.
   1. End the esophageal pH study by pressing the two buttons located in the middle simultaneously until “upload later” appears on the display.
   2. End the laryngopharyngeal pH study by simultaneously pressing the cough, ESC and heartburn button until “complete” appears on the display.
2. Remove tape and gently pull out both catheters.

10. Interpreting the results obtained by the esophageal pH study

1. Connect the device to a computer. Open the software used for analyzing results obtained from the esophageal pH measuring device and upload the patient’s study.
2. Manually type in the patient’s data and the information obtained by the patient’s diary, such as mealtimes, upright and supine periods and symptoms experienced during the study period. Delete any button presses that might have accidentally been performed by the patient during the study period.
3. Exclude mealtimes from the data analysis.
4. On the report, look at important parameters and thresholds provided to determine an abnormal esophageal acid exposure such as the composite score, the total % pH below baseline (upright and supine) and total number of events.
5. Calculate a composite score (DeMeester score) for the study period using % time pH < 4 total, upright and supine, total number of events, number of events lasting longer than 5 minutes and the duration of the longest event¹⁴. Make sure the report shows the composite score.
   NOTE: A DeMeester score > 14.72 displays an abnormal esophageal acid exposure.

11. Interpreting results obtained by laryngopharyngeal pH monitoring

1. Insert the SD card into the computer and open the software used for analyzation of results obtained by the laryngopharyngeal pH measuring system. To upload the study, click on Retrieve.
2. Manually add the information obtained by the patient’s diary, such as mealtimes, upright and supine periods and symptoms experienced during the study period. Left click on the graph and drag and highlight the area on which you want to add the event and choose the respective event. Delete any button presses that might have accidentally been performed by the patient during the study period.
3. Exclude mealtimes from the data analysis.
4. Click on Report to see a graph displaying acid exposure in the oropharynx during the study period, including supine period, symptoms and mealtimes as well as a study summary.
5. On the report, look at important parameters and thresholds to determine an abnormal oropharyngeal acid exposure such as the composite score, the total % pH below baseline (pH < 5.5 upright and pH < 5 supine) and total number of events.
6. Calculate a composite score (RYAN Score) for both the upright and supine period using the % time pH below 5.5 upright and 5 supine, total number of events and the duration of the longest event⁸. Make sure, a composite score for the upright and supine period is shown in the report.
   NOTE: A RYAN Score of > 9.4 upright and > 6.8 supine shows a severely abnormal oropharyngeal acid exposure.

Results

A total of 181 patients were evaluated using the previously described standardized protocol. Results of the first 101 patients have been previously published¹². The following data depicts an extension of the previously published cohort, however, evaluated using the new software for analyzation of results obtained by laryngopharyngeal pH testing¹⁵. Demographic data is depicted in Table 1. All patients presented with atypical symptoms including chronic cough,...

Discussion

Esophageal pH monitoring is commonly used to confirm the diagnosis of GERD in patients with typical reflux symptoms. However, many patients present, in addition to typical reflux symptoms, with atypical reflux symptoms such as cough or hoarseness most likely related to LPR. Current guidelines suggest an empiric trial with PPIs to proof a reflux related origin of those symptoms and a standardized objective measurement is lacking². Laryngopharyngeal pH testing, due to its location above the upper es...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
AA Battery	-	-	-
Calibration Solutions pH 4 and 7	Medtronic		part of the Digitrapper Reflux Testing system
CR 1632 Lithium coin cell battery	-	-	-
Digitrapper pH & Impedance catheter	Medtronic
Digitrapper Recorder	Medtronic
Gelicain	PUREN		topical gel
Hydration vials with clear water	Respiratory Technology Corporation		part of the Restech Dx pH system
Leukoplast	BSN medical GmbH		surgical tape
Restech Dx pH probe	Respiratory Technology Corporation		part of the Restech Dx pH system
Restech Recorder	Respiratory Technology Corporation		part of the Restech Dx pH system
Restech Transmitter	Respiratory Technology Corporation		part of the Restech Dx pH system
Screwdriver	Respiratory Technology Corporation		part of the Restech Dx pH system
SD Card plus Adapter	Respiratory Technology Corporation		part of the Restech Dx pH system
tongue depressor	NOBAMED		wooden