Distinguishing esophageal from endotracheal intubation by measuring endotracheal tube cuff pressure

Background: It is unknown whether measuring endotracheal tube cuff pressure can accurately confirm tracheal intubation. Animal and human cadaveric studies show conflicting results. In anesthetized patients, we tested the hypothesis that the pressurevolume characteristics of the cuff located in the trachea would differ from that measured in the esophagus potentially making cuff pressure a useful tool to distinguish esophageal from tracheal intubation. Methods: Thirty-four female and 35 male patients undergoing general anesthesia were intubated under direct laryngoscopy with 7.0 mm and 8.0 mm cuffed tubes, respectively, first in the esophagus and next in the trachea. Cuff pressures at each site were recorded during sequential one mL inflation volumes up to 10 mL or when cuff pressure exceeded 250 mmHg and compared using the Wilcoxon signed rank test. Results: In females, tracheal cuff pressure significantly exceeded esophageal cuff pressure at all volumes between 3 and 10 mL (p<0.05) but with a large degree of interpatient variability. In contrast, male esophageal cuff pressure exceeded tracheal cuff pressure at volumes less than 3 mL and did not differ between the two sites at higher cuff volumes. Conclusions: In female patients, greater cuff pressures in the tracheal than esophageal location are attributed to the influence of less compliant cartilaginous rings. These findings were not replicated in male patients. However, the large degree of variability precludes the clinical application of this technique for accurate identification of cuff location in the trachea.