A double blind study of 111 consecutive elective upper gastrointestinal endoscopies performed with a flexible fiberoptic esophagogastroduodenoscope was made to determine the efficacy of topical pharyngeal anesthesia with lidocaine as an adjunct to intramuscular meperidine, intramuscular atropine, and intravenous diazepam. Patients who received lidocaine rated the over-all endoscopy and passage of the endoscope significantly easier than did those receiving placebo. The endoscopist found that patients who received lidocaine tolerated endoscopy significantly better, although gagging was not affected. © 1976, The Williams & Wilkins Co.. All rights reserved.
Gordon, M. J., Mayes, G. R., & Meyer, G. W. (1976). Topical Lidocaine in Preendoscopic Medication. Gastroenterology, 71(4), 564–569. https://doi.org/10.1016/S0016-5085(76)80542-2