Documenting the Hypopharyngeal Environment of Patients Undergoing General Endotracheal Tube Anesthesia: A First Look at Intraoperative pH Characteristics

Abstract

Objectives: While laryngeal injuries are important and not infrequent following both short and extended endotracheal tube exposure, little detailed information is available regarding the hypopharyngeal environment during intubation. The objective of this pilot study was to explore a simple method of accurately documenting hypopharyngeal pH values in surgical patients undergoing endotracheal tube anesthesia and to report the findings. Methods: Twenty volunteers were continuously monitored intra-operatively using a commercially available hypopharyngeal pH monitoring system. Demographics, pre- and postoperative voice and reflux self reported survey data were also collected. Results: No complications associated with the pH monitoring system occurred. Median pH was 6.5 (range 6.0-7.0); median recorded time in minutes was 183.9 (range 130.7 – 323.5). 13/20 patients had pH>5.0 ≤ 5.5 events, for up to 113 minutes of monitored time; 2/20 patients had pH>4.0 ≤ 5.0 events, for up to 8 minutes of monitored time; 2/20 patients had pH ≤ 4.0 events, for up to 61 minutes of monitored time. Conclusions: The hypopharyngeal pH test was used successfully to intra-operatively record hypopharyngeal pH variations. Extended pharyngeal exposures to low pH environments were commonly documented. No associations were found with patient survey scores. Future research appears warranted to expand this study, identify “at-risk” populations and to rigorously evaluate an expanded set of voice-related and lower airway clinical outcomes measures.