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