Role of ultralow dose of naloxone as an adjuvant to fentanyl–bupivacaine in thoracic paravertebral block analgesia after modified radical mastectomy: Randomized controlled trial

Abstract

Objective: We evaluated the effect of the addition of 100 ng of naloxone to fentanyl–bupivacaine mixture used in thoracic paravertebral block (PVB) on the duration and the quality of post-mastectomy analgesia.Design: A randomized double-blinded trial.Setting: Oncology surgery unit.Patients and participants: This study included 135 patients, aged 40-60 years of either sex presented for elective unilateral-modified radical mastectomy. Interventions: Patients were divided randomly into three groups: group I, received 0.3 mL/kg of 0.25 percent bupivacaine; group II, received 0.3 mL/kg of 0.25 percent bupivacaine, fentanyl 50 μg, and naloxone 100 ng; group III, received 0.3 mL/kg of 0.25 percent bupivacaine and fentanyl 50 μg.Main outcome measure(s): The visual analog scale was assessed immediately post-operative, every 2 hours till 12 hours, and then every 6 hours for 24 hours; the time of first and total amount of rescue analgesia and side effects during the first 24 hours were recorded.Results: Group II showed a significant prolonged analgesia with a delayed first request of rescue analgesia and lower amount of morphine (592.1 ± 14.9 minutes and 7.28 ± 7.81 mg, respectively) than groups I (127.7 ± 35.1 minutes and 19.84 ± 2.56 mg, respectively) and III (232.2 ± 9.27 minutes and 13.52 ± 1.74 mg, respectively) as p 0.001.Conclusion: Using naloxone as additives in PVB has been promising and effective in controlling post-mastectomy pain.