Dynamics of lidocaine in topical anesthesia for office-based laryngeal procedures: A pilot study.

OBJECTIVES:To study topical lidocaine for office-based laryngeal procedures recording onset, duration, and subjective experience of topical anesthesia. STUDY DESIGN:Nine healthy volunteers were anesthetized with 4 % lidocaine endoscopically. Laryngeal sensitivity prior to and during anesthesia was recorded until normal sensation returned measured by air-puff sensory testing. Subjective experience of the process was recorded. METHODS:Questionnaires regarding subjective experience were completed prior to, during, and after anesthesia. Laryngeal sensitivity via air-pulse trigger of the laryngeal adductor reflex (LAR) prior to and after 3 mL shower of 4 % lidocaine was recorded at 30 second intervals until the larynx was insensate with no LAR at 10 mmHg. Time to anesthesia was recorded and post-endoscopy questionnaire was given. Upon subjective change in sensation, sensitivity via air-pulse trigger of the LAR was recorded until baseline sensation returned. A post-anesthesia questionnaire recorded the subjective experience. RESULTS:Average time to full anesthesia was 110 s (±31.2). Subjective return of sensation was noted at 10 min (±2.5), however time to return to normal LAR was 22 min (±5.8). Based on three standard deviations, 99.7 % of the population will be anesthetized at 3.4 min, report subjective change at 18.2 min and regain full sensation at 40 min. CONCLUSIONS:Office-based laryngeal procedures should be performed at least 2 min following topical 4 % lidocaine with a window for manipulation of at least 16 min. Oral intake should be delayed for over 45 min to ensure complete return of sensation. The laryngeal shower of lidocaine is subjectively tolerated. LEVEL OF EVIDENCE:2C Outcomes Research.