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Vocalization Assessed by Electrolaryngography Is Unaffected by Topical Lidocaine Anesthesia: A Prospective, Crossover, Randomized, Double-Blind Placebo-Controlled Study

BACKGROUND: Topical anesthesia of the upper airway is often recommended when difficulty in airway management is anticipated. There are published reports, however, of administration of topical anesthesia resulting in complete loss of airway control. Adverse effects are mostly attributed to interference with involuntary protective airway reflexes, while gross motor function itself generally is thought to be preserved. We hypothesized that if motor control is affected, measurable quantitative changes in vocalization should follow the use of topical anesthesia. METHODS: A prospective, crossover, randomized, double-blind study was conducted, in which 24 healthy volunteers each performed 2 vocal exercises, while having their glottic appearance recorded digitally via fiberoptic nasendoscopy. Subjects gargled with 3 test solutions on separate occasions (placebo, 2% lidocaine, and 4% lidocaine) and repeated the vocal exercises and nasendoscopy. The angle between the vocal cords was measured using MB-Ruler®, and the Laryngograph Speech Studio® software was used for vocal parameter analysis. RESULTS: The only significant changes in voice quality occurred between the control and test groups (P = 0.014). No difference could be found between the placebo and lidocaine groups. CONCLUSIONS: Although gargling with local anesthetic affected vocalization, no pharmacological effect attributable to local anesthetic was observed.