Evaluation of transmitted glow point at chosen depth (1 cm below vocal cords) for lightwand intubation: a prospective observational study

Objective When performing lightwand intubation, an improper transmitted glow position before tube advancement can cause intubation failure or laryngeal injury. This study was performed to explore the transmitted glow point corresponding to a priori chosen depth for lightwand intubation. Methods Before lightwand intubation, we marked the transmitted glow point from a bronchoscope on the neck when it reached 1 cm below the vocal cords. Lightwand intubation was then performed using this marking point. The distances from the mark to the upper border of the thyroid cartilage, upper border of the cricoid cartilage, and suprasternal notch were measured. Results In total, 107 patients were enrolled. The success rate of lightwand intubation using the mark was 93.5% (95% confidence interval, 88.7%–99.2%) at the first attempt. The marking point was placed 12.0 mm (95% confidence interval, 10.6–13.4 mm) below the upper border of the cricoid cartilage. Conclusion Anaesthesiologists should be aware of the appropriate point of the transmitted glow on the patient’s neck when performing lightwand intubation. We suggest that this point is approximately 1 cm below the upper border of the cricoid cartilage. Trial registration: ClinicalTrials.gov NCT0348003