Exhaled Breath Condensate pH in Patients With Cough Caused by Gastroesophageal Reflux

Study Overview
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Brief Summary
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Cough is the most common complaint for which patients seek medical attention in the United States, accounting for approximately 1 billion dollars in health care expenses annually. Gastroesophageal reflux disease (GERD) is the sole cause of chronic cough in up to 20-40% of all cases. The majority of these patients with GERD-induced cough have no classic heartburn symptoms, so this important cause of cough can thus be difficult to detect. Our hypothesis is that changes in exhaled breath condensate (EBC) pH can be used as a sensitive and non-invasive marker to identify subjects with cough caused by acid reflux.

Detailed Description
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Gastroesophageal reflux disease (GERD) is the sole cause of chronic cough in up to 20-40% of all cases, and majority of these patients with GERD-induced cough have no classic heartburn symptoms. This important cause of cough can thus be difficult to detect. Non-invasive radiologic tests for GERD such as barium swallow is imperfectly sensitive in subjects with GERD-induced cough. The 24 hour pH probe, which continuously monitors esophageal pH and can correlate cough events with reflux events, is considered to be the gold standard test. However, this test is expensive, invasive, and not universally available. The goal of the current study is to compare simultaneous measurements of esophageal pH with exhaled breath condensate pH after cough episodes, in patients with symptomatic cough. The cause of cough will be determined by a standard protocol, which includes 24 hour pH probe studies, and assessment for asthma, upper airway causes and sinus disease, and medication effects. All subjects will undergo 24 hour pH monitoring. During this monitoring period, they press an event button on the pH recording device to indicate a cough episode. After six such events, they will immediately perform an EBC collection, and EBC pH will subsequently be analyzed. Differences between pH changes in the group with cough cause by GERD will be compared to pH measurements in the group with cough but no GERD, to determine the sensitivity and specificity of pH changes for discriminating between the two groups, and optimal threshold values for pH changes in EBC.

Official Title
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Exhaled Breath Condensate pH in Patients With Cough Caused by Gastroesophageal Reflux

Conditions
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Cough, Gastroesophageal Reflux

Intervention / Treatment
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* Device: RTube Exhaled Breath Condensate Collection System


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age > 18 years old able to speak and read English chronic cough Exclusion Criteria: Cigarette smoking within the past 6 months, or greater than 10 pack year history of prior smoking Any self-reported or clinically diagnosed form of active lung disease, including asthma and emphysema Symptoms of persistent rhinitis within the past three months Dysphagia Symptoms of acute viral upper respiratory tract infection or sinusitis within one month of entry into the study Pregnancy - based on self report Abnormal chest radiograph

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 1<br>Chronic cough caused by GERD | Device: RTube Exhaled Breath Condensate Collection System<br>* Subjects breath through the device to collect exhaled breath condensate<br>|
| 2<br>Chronic cough without GERD | Device: RTube Exhaled Breath Condensate Collection System<br>* Subjects breath through the device to collect exhaled breath condensate<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity of esophageal PH changes | Determine the sensitivity of esophageal PH changes between the group with GERD and the group without GERD. | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cough, Gastroesophageal reflux, Exhaled breath condensate