Background and Goal of Study: Gum elastic bougie placement (GEB) into trachea has been confirmed by subjective methods. Tesla meter can measure magnetic flux density of magnets. Magnetic flux density of the magnet depends on the distance from the magnet. This pilot study was undertaken to determine whether the measurement of magnetic flux density of magnet attached to the tip of GEB could be used to distinguish endotracheal from esophageal insertion of the GEB.
Materials and Methods: Nineteen adult patients (56 ± 19 yr) scheduled for an elective surgery under general anesthesia were included in this study. Routine monitoring was performed and a standard anesthesia protocol was followed. Anaesthesia was induced with 1.5-2 mg/kg propofol and 1-2 μg/kg fentanyl, followed paralysis with 1 mg/kg vecronium. A GEB with a small magnet on its tip was inserted first into the esophagus, and next into the trachea before tracheal intubation. During GEB insertion, magnetic flux density on the skin of the cricoid cartilage was measured and continuously recorded with Tesla meter.
Results and Discussions: Peak magnetic flux density during the GEB insertion into the trachea or esophagus ranged between 11.75 and 1.54 mT, or between 0.26 and 1.02 mT, respectively. These ranges did not overlap each other.
Conclusion: Combination of Handheld Tesla meter and GEB with a small magnet was reliable in distinguishing tracheal from esophageal insertion of the GEB.