Is oropharyngeal anaesthesia with topical lignocaine useful in upper gastrointestinal endoscopy?

The aim of this study was to determine whether patients' tolerance of upper gastrointestinal endoscopy is related to the dose of lignocaine spray used for oropharyngeal anaesthesia and to measure plasma concentrations at these doses. Sixty consecutive patients undergoing routine upper gastrointestinal endoscopy with sedation were randomized to receive lignocaine spray 50 mg (Group A), 100 mg (Group B) or 200 mg (Group C). Patient, endoscopist and endoscopy nurse were unaware of the variation in dose used. Each patient's tolerance of the intubation and of the remainder of the gastroscopy was assessed independently by the patient, endoscopy nurse, and endoscopist using a visual analogue scale. Plasma lignocaine concentration was measured at 20, 40, 60 and 80 min after administration of the spray. Fifty (83%) patients were unable to recall either the intubation, or the procedure. On the endoscopy nurse's assessment, the patients in Group B tolerated the intubation better than those in Group A, and Groups B and C tolerated the remainder of the gastroscopy better than those in Group A. On the endoscopist's assessment, Groups B and C tolerated the remainder of the gastroscopy better than Group A. There were fewer gags per min in Groups B and C compared to Group A. Mean plasma lignocaine concentrations showed a dose-dependent absorption of the spray, but none exceeded the potentially toxic level of 5 mg/L.