Efficacy of Intrathecally Administered Dexmedetomidine Versus Dexmedetomidine With Fentanyl in Patients Undergoing Major Abdominal Cancer Surgery

Abstract

Background: Most of the clinical experience gained in the use of intrathecal α2- adrenoceptor agonists has been described with clonidine. Human studies using a combination of intrathecal dexmedetomidine and local anesthetics are lacking. Objectives: A safety investigation and comparison of the analgesic efficacy of intrathecally administered dexmedetomidine or dexmedetomidine combined with fentanyl in patients undergoing major abdominal cancer surgery. Study Design: A randomized, double-blind trial. Setting: Academic medical center. Methods: Ninety patients were randomly assigned to receive intrathecally either 10 mg bupivacaine 0.5% (control group, n = 30), or 10 mg bupivacaine 0.5% plus 5 µg dexmedetomidine (dexmedetomidine group, n = 30), or 10 mg bupivacaine 0.5% plus 5 µg dexmedetomidine and 25µg fentanyl (dexmedetomidine+ group, n = 30). Assessment parameters included hemodynamics, sedation score, pain severity, time of first analgesics request, total analgesic consumption, and side effects in the first 24 hours. Results: The mean intraoperative heart rate was significantly reduced in the dexmedetomidine group (P < 0.05) and the dexmedetomidine+ group (P < 0.05) compared with the control group. Also, there was a significant reduction in mean intraoperative systolic and diastolic blood pressure in the dexmedetomidine group (P < 0.05) and the dexmedetomidine+ group (P < 0.05) compared with the control group, with no significant differences in postoperative hemodynamics or sedation scores among all the study groups. The mean visual analog scale scores showed a significant reduction immediately and at 12 hours postoperatively in both the dexmedetomidine and dexmedetomidine+ groups compared to the control group. The mean time of the first analgesic request was significantly prolonged in the dexmedetomidine group (3.30 ± 0.87 hours, P < 0.01) and the dexmedetomidine+ group (5.41 ± 1.23 hours, P < 0.01) compared with the control group (0.23 ± 0.11 hours). Moreover, postoperative tramadol consumption was significantly reduced in the dexmedetomidine (142.85 ± 13.04 mg, P < 0.01) and the dexmedetomidine+ (131.25 ± 11.96 mg, P < 0.01) groups, compared with the control group (310.0 ± 12.08 mg). No significant serious adverse effects were recorded during the study. Limitations: This study is limited by its sample size. Conclusion: Dexmedetomidine 5 µg given intrathecally improves the quality and the duration of postoperative analgesia and also provides an analgesic sparing effect in patients undergoing major abdominal cancer surgery. Furthermore, the addition of intrathecal fentanyl 25 µg has no valuable clinical effect. Key words: dexmedetomidine, fentanyl, intrathecal, postoperative pain