Combined intrathecal fentanyl and neostigmine:: Therapy for postoperative abdominal hysterectomy pain relief

Abstract

Study Objective: To evaluate the analgesic action of spinal neostigmine as part of a multimodal analgesic therapy approach including spinal neostigmine and spinal fentanyl for postoperative pain relief. Design: Randomized, prospective study. Setting: Teaching hospital. Patients: 50 ASA physical status I and II patients undergoing abdominal hysterectomy. Interventions: Patients were assigned to one of five groups (n = 10) to receive 15 mg bupivacaine plus 1 ml of the test drug intrathecally. The control group (CG) received saline as the test drug, the fentanyl group (FG) received 25 μg fentanyl; the neostigmine group (NG) received 25 μg neostigmine; the fentanyl-neostigmine 10 μg group (FNG10) was given 10 μg fentanyl plus 10 μg neostigmine; and the fentanyl-neostigmine 25 μg group (FNG25) received 25 μg fentanyl plus 25 μg neostigmine. Pain and nausea were evaluated using a 10-cm visual analog scale (VAS). Main Results: The analgesic consumption, in 24 hours was greatest in CG, next highest in NG, FG, and FNG10 where consumption was the same in the three groups; and least in FNG25 (p < 0.05). The time to first rescue analgesic medication was greatest for FNG25 compared with the other groups (>5 hours compared with 2 to 3 hours; p < 0.05). VAS showed no statistically significant differences for pain impression, intraoperative and postoperative nausea, or occurrence of vomiting (p > 0.05). Conclusion: The combination of 25 μg neostigmine with 25 μg fentanyl given intrathecally with 15 mg of hyperbaric bupivacaine delayed postoperative pain and lowered the number of rescue analgesics. Because the better quality of analgesia was obtained with an increased (although not statistically significant difference) incidence of untoward side effects, larger samples should be studied before its routine use is recommended.