Intrapharyngeal distribution of gastric acid refluxate

Determination of intrapharyngeal distribution of gastric acid refluxate is needed to better understand the pathogenesis of reflux-attributed aerodigestive tract disorders. The aims of the study were to determine intrapharyngeal distribution of gastric acid refluxate and to determine whether this distribution can better differentiate patients from control subjects compared with data obtained from a single hypopharyngeal site.

We prospectively studied 10 healthy volunteers, 12 patients with reflux laryngitis, and 15 patients with vasomotor rhinitis using a concurrent dual pharyngeal/dual esophageal pH recording technique. We determined the hypopharyngeal and oropharyngeal pH profile, including number, duration, and distribution of reflux events irrespective of and in correlation with intraesophageal pH profile using four different pH thresholds.

Few drops in pharyngeal pH were found to be true reflux events based on their correlation with esophageal pH events. For the pharyngeal pH threshold criterion of a drop to 4.0 or less, 6 of 12 patients with reflux laryngitis, 5 of 15 patients with vasomotor rhinitis, and 2 of 10 normal control subjects exhibited a total of 25 (range, 1-5) distal pharyngeal acid reflux events. Overall, 34% of these events reached the oropharyngeal pH recording site. Between-group comparison for all levels of pH threshold criteria did not show any significant difference of reflux parameters in the hypopharyngeal or in the oropharyngeal sites among the studied groups.

Reflux of gastric acid into the pharynx may extend to the region of the oropharynx in both patients and control subjects. Overall distribution of acid refluxate to the oropharynx is low but as groups is similar between healthy individuals and patients with reflux laryngitis and those with vasomotor rhinitis. Parameters of oropharyngeal acid reflux such as number and duration do not differentiate patients from control subjects.