Effect of acid, pepsin, and bile acid on the stenotic progression of traumatized subglottis.

Background And Aims: Gastroesophageal reflux disease is related to various laryngeal sequelae. However, there is a lack of established reflux animal models covering longer observation periods. We evaluated the effects of acid, pepsin, and bile acid on healing of the traumatized subglottis in a simulated reflux model.

Methods: In the first experiment, 48 rabbits were inflicted with a posterior subglottic injury using a diode laser, and there were 10 unwounded controls. After catheter insertion under transoral endoscopic guidance, animals were randomly assigned to one of the four groups: acid reflux (pepsin 0.3 mg/mL+taurodeoxycholic acid 0.155 mg/mL+acid pH 2); nonacid reflux (pepsin+taurodeoxycholic acid+pH 6); saline reflux; and unwounded control. Animals received catheter irrigation with 3 mL of a mixed solution or saline, twice daily for 6 wk. In the second experiment, 36 animals were inflicted with a subglottic injury followed by acid or saline reflux treatment and were sacrificed after 1, 2, and 4 wk for time-serial observations. Gross and histological findings were compared among the different groups.

Results: Catheter-related problems were minor. Most animals received laryngopharyngeal irrigation with the solutions well, and 19 were excluded. Inflammation scores, fibrosis, thickening, and luminal stenosis were greatest in the acid reflux group (p<0.005). Values were not different between the nonacid reflux and saline reflux groups (p>0.1).

Conclusions: Our data suggest that subglottic wound healing is significantly affected by pepsin and bile acid only under acidic conditions. This implies that acid-suppressive therapy can prevent further subglottic inflammation and stenosis by laryngeal reflux.