The effect of local injection of bupivacaine with and without fentanyl at the operative site in mandibular open reduction on acute pain intensity and opioid requirement: a randomized clinical trial.

PURPOSE: The aim of this study is to investigate the effects of bupivacaine local injection with and without fentanyl at the operative site in mandibular open reduction surgeries on the severity of acute pain and the need for opioids.

METHODS: This randomized clinical trial, age-sex-matched double-blind study included 44 patients with isolated mandibular fractures who would be candidates for open reduction. They were divided into two groups (intervention using fentanyl and control not using fentanyl). In both groups, the amount of opioid used, hemodynamic indices, oxygen saturation, and pain intensity were collected based on the Visual Analogue Scale (VAS) every 4 h for 24 h.

RESULTS: As for basic and demographic variables such as gender, age, ASA class, and duration of surgery (P > 0.05), there was neither a significant difference between the two groups nor was there any difference in nausea and vomiting and subsequent anti-nausea medication (P > 0.05). The need for a post-operative opioid in the bupivacaine + fentanyl group (13.6%) was significantly less than in those who received only bupivacaine (45.5%) (P < 0.05). Changes in pain scores over time were significantly different in the two groups, and bupivacaine + fentanyl reduced pain more than bupivacaine (P < 0.05). However, over time, there was no significant difference between the two groups in terms of changes in oxygen saturation, heart rate, systolic blood pressure, and diastolic blood pressure (P > 0.05).

CONCLUSION: The addition of fentanyl to bupivacaine for supraperiosteal injection in the open reduction surgery site reduces post-operative pain in the first 24 h and reduces the need for opioids without causing complications such as nausea and vomiting.