Background: Submucosal resection is accompanied by significant post-operative pain and discomfort. The aim of this randomized, double-blinded clinical trial was to study the efficacy of a local block anaesthetic, delivered after induction of general anaesthesia, in reducing post-operative pain.

Methods: Patients aged 16 years and over who were scheduled for elective submucosal resection were randomly assigned to receive either standardized general anaesthesia, general anaesthesia with local anaesthetic infiltration or general anaesthesia with placebo infiltration. Haemodynamic stability, intra-operative blood loss, post-operative pain (over a seven day follow-up period), analgesics consumption, hospital stay, and the patient's and surgeon's levels of satisfaction were assessed.

Results: We found significantly lower results for pack removal pain score, volume of intra-operative blood loss, number of patients suffering from headache, altered dental sensation or nasal pain, number of patients who consumed analgesics, and length of hospital stay, comparing the infiltration group with the general anaesthesia and placebo groups (p<0.05).

Conclusion: This clinical trial showed that infiltration with the local anaesthetics fentanyl and clonidine substantially reduced post-operative pain and shortened patients' hospital stay.