A pilot study of pepsin in tracheal and oral secretions.

Background: Because reflux of gastric juice into the oropharynx must precede its aspiration into the lungs, it is reasonable to hypothesize that the detection of pepsin (the major gastric enzyme in gastric juice) in oral secretions may provide a relatively noninvasive method of predicting risk for aspiration.

Objective: To describe the incidence of pepsin in oral and tracheal secretions collected concurrently from a sample of 50 gastric-fed patients undergoing mechanical ventilation.

Methods: An exploratory descriptive design with a convenience sample from 4 medical and surgical intensive care units. An oral secretion and a tracheal secretion were collected concurrently from each patient (yielding a sample of 50 oral and 50 tracheal secretions). The tracheal secretions were obtained via the inline suction system with an attached sputum trap; oral secretions were obtained via a Yankauer suction tip with an attached sputum trap. All specimens were assayed for pepsin by the Western blot method.

Results: Oral secretions from 10 patients (20%) and tracheal secretions from 2 patients (4%) were pepsin-positive. Both patients with pepsin-positive tracheal secretions also had pepsin-positive oral secretions. Pepsin was not found in the tracheal secretions from the remaining 8 patients with pepsin-positive oral secretions.

Conclusions: Although reflux of gastric juice into the oropharynx must precede its aspiration into the lungs, individual reflux events do not necessarily lead to aspiration. Thus, it is reasonable that we found pepsin 5 times more often in oral secretions than in tracheal secretions.