Thomas V. K. Herregods; Ans Pauwels; Jafar Jafari; Daniel Sifrim; Albert J. Bredenoord; Jan Tack; and André J. P. M. Smout

Gut 2017 March 15

Abstract available at: https://www.ncbi.nlm.nih.gov/pubmed/28298354

It is well known by gastroenterologists that cough does not respond well to acid suppression with proton-pump inhibitors (PPIs), especially in patients who do not have typical GERD symptoms of heartburn or regurgitation. This is one of the most common referrals we receive.

To identify determinants of cough in GERD, researchers in Europe evaluated 24-hour esophageal pH impedance pressure monitoring results (off PPIs) in 49 patients identified with reflux-induced cough. They compared characteristics of reflux episodes with and without an accompanying cough burst (≥2 rapid simultaneous pressure peaks within 3 seconds). A reflux episode was defined as an orally progressing sequential drop in impedance to <50% of baseline value and was considered acidic if pH was <4 for at least 4 seconds.

Of 2,270 reflux episodes identified, 395 included cough bursts. Factors significantly associated with cough burst were a higher proximal extent of the refluxate and longer volume clearance time, but not pH drop or acid clearance time. The percentage of reflux episodes that were acidic was similar with or without cough. Among the 49 patients, 19 had no typical GERD symptoms (heartburn, regurgitation, or both).

Comment: Acid doesn’t seem to be a determinant of cough. The fact that some reflux episodes reaching only the distal esophagus included cough events suggests a neurogenic esophagobronchial reflex in some, rather than frank aspiration. Clearly, impedance pH monitoring in patients with GERD-related cough is helpful to guide therapies and expectations for successful response.