Assessment of a new method to distinguish esophageal from tracheal intubation by measuring the endotracheal cuff pressure in a porcine model

Abstract

Study objectives: Timely assessment of proper endotracheal tube placement is necessary to avoid serious morbidity and mortality. Various methods are used to verify tracheal intubation and to detect esophageal intubation. Many of these methods fail under certain circumstances. With the knowledge of differences of anatomic structure and resistance against certain volume between trachea and esophagus, we conduct an animal study to evaluate the usefulness of the endotracheal cuff pressures in endotracheal and esophageal intubation to detect esophageal intubation. Methods: Six swine were anesthetized and intubated with regular 7.5-mm endotracheal tube (Mallincrodt Medical Intermediate Hi-Lo). After confirmation of tracheal intubation by fiberoptic bronchoscopy, a second endotracheal tube (also 7.5 mm) was placed in the esophagus of each swine, and the cuffs were not inflated. Both tubes extended the same distance from the mouth. Each pilot balloon of both tubes was connected to a 10-mL syringe and a manometer by a 3-way stopcock. The cuff pressure was measured after incremental 1-mL filling volume of air. The data of cuff pressure caused by variable volume in both endotracheal and esophageal intubations were compared. The pressure-volume relationships in both intubations were also measured. Results: The endotracheal cuff pressures (mean±SD) increased significantly in esophageal intubations compared with endotracheal intubation (115±12.4 versus 53±9.8 cm H₂O, at 10-mL inflation of air, <i>P</i><.05). The pressure and the rate of increase in cuff pressure were also significantly higher (<i>P</i><.05) in the esophageal intubation during the inflation of the cuff in the study. Conclusion: In this animal study, the cuff pressure of esophageal intubation was significantly higher than that of endotracheal intubation under the same inflated volume. It may provide an adjunctive, simple, rapid, and reliable method to verify endotracheal intubation and detect the occurrence of esophageal intubation by measuring the endotracheal cuff pressure.