Retromolar laryngoscopy: a randomized crossover vocal cords visualization study.

BACKGROUND

Vocal cords visualization is a major determinant for successful tracheal intubation. The aim of our study was to compare vocal cord visualization by using conventional direct laryngoscopy with retromolar direct laryngoscopy in patients with an existing retromolar gap at the right mandible.

METHODS

We enrolled 100 adults needing endotracheal intubation for elective surgery. In each patient, the vocal cords were visualized and scored according to Cormack and Lehane with a Macintosh blade #3 for conventional technique and with a Miller blade #4 for the retromolar technique in a randomized sequence. Finally, tracheal intubation was performed primarily by conventional laryngoscopy and in the case of failing retromolar laryngoscopy was used as the rescue method.

RESULTS

Overall 100 laryngoscopies with the conventional method and 100 laryngoscopies with the retromolar method were scored according to Cormack and Lehane. The retromolar technique achieved significant (P=0.000003) lower Cormack and Lehane scores compared to the conventional technique. In eleven patients, intubation by conventional laryngoscopy failed and seven of those patients were successfully intubated by the retromolar technique. A BURP-maneuver significantly improved vocal cord visualization during both methods.

CONCLUSIONS

In summary, laryngoscopy via the retromolar method by using a Miller blade #4 lead to a significantly better vocal cord visualization compared to the conventional method performed with a Macintosh blade #3 in patients with an existing retromolar gap on the right side.