Background and Goal of Study: An unobserved esophageal intubation causes significant hypoxemia. To auscultate patient's breathing and gastric sound using stethoscope is the essential method for confirming the endotracheal tube (ETT) position after tracheal intubation, but it can frequently be inaccurate.
We have tried to invent a new technology for changing the breathing sounds signals into a visual form. We could visualize breathing sounds in a three-dimensional (3-D) color visual form, continuously in the previous study. We improved the Visual Stethoscope (VisiStetho) to visualize two sounds simultaneously. We applied this new dual channel VisiStetho to detect esophageal intubation.
Materials and Methods: Fifty patients who were scheduled to undergo general anaesthesia were involved in this study. Routine monitoring and standard anesthesia induction was performed.
One stethoscope sensor of VisiStetho was placed on the right side of the chest, at the lateral axillary line and another sensor placed over the epigastrium. The trachea was intubated by an anesthesia intern attended by a skilled anesthesiologist. During tracheal intubation, an observer monitored both breathing and gastric sound continuously and simultaneously by the dual channel VisiStetho. Esophageal intubation was judged when the large gastric sound synchoronizing with bag compression was visualized, but the representative breathing sound was not visualized. Within 5 breathes after intubation was performed, the observer was requested to judge whether the ETT was inserted into the trachea or esophagus.
Results and Discussions: Four accidental esophageal intubations occurred (4/50), and the observer identified all the tracheal and esophageal intubations using the dual channel VisiSthetho.
Objective evaluation of the breathing and gastric sound using traditional stethoscope is difficult because it is conducted by a single attending doctor and traditional stethoscope can not evaluate both sounds at once. Using dual channels VisiStetho, it solved these problems.
Conclusion: Dual channel VisiStetho may be an effective tool for detection of accidental esophageal intubation under scheduled general anesthesia.