EFFECTS OF SIMULATED GASTROESOPHAGEAL REFLUX ON THE UNTRAUMATIZED RABBIT LARYNX

Objective: Gastroesophageal reflux (GER) has been shown, clinically an d experimentally, to cause inflammation of traumatized laryngeal mucos a. This study was performed to determine if GER causes inflammation of untraumatized laryngeal mucosa. Method: Sixteen adult New Zealand whi te rabbits underwent tube pharyngostomy under general anaesthesia with out endotracheal intubation. After 7 days recovery, 1 mL/kg of normal saline or HCl (pH 1.5) with pepsin (0.3 mg/ml) was infused into the pi riform sinus while the rabbit was under mild sedation: once, twice, or three times per day, for 14 consecutive days. Results: Rabbits that r eceived HCl and pepsin exhibited various degrees of apnea and coughing . Eventually, most developed biphasic strider on exertion. Histologica lly, the degree of laryngeal inflammation was greatest when GER was si mulated three times per day. Glottic inflammation was greatest in one rabbit, which responded to GER simulation with paroxysmal coughing. Co nclusion: The mechanism of injury in GER laryngitis is postulated to b e a combination of chemical trauma (due to HCl and pepsin) and mechani cal trauma (due to an individually variable laryngeal chemoreflex). Fu rther study of GER laryngitis in this new animal model is warranted.