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

Background: Most of the clinical experience gained in the use of intrathecal α2- adrenoceptoragonists has been described with clonidine. Human studies using a combination of intrathecaldexmedetomidine and local anesthetics are lacking.Objectives: A safety investigation and comparison of the analgesic efficacy of intrathecallyadministered dexmedetomidine or dexmedetomidine combined with fentanyl in patientsundergoing 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 mgbupivacaine 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 and25µg fentanyl (dexmedetomidine+ group, n = 30). Assessment parameters included hemodynamics,sedation score, pain severity, time of first analgesics request, total analgesic consumption, and sideeffects in the first 24 hours.Results: The mean intraoperative heart rate was significantly reduced in the dexmedetomidinegroup (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 pressurein the dexmedetomidine group (P < 0.05) and the dexmedetomidine+ group (P < 0.05) comparedwith the control group, with no significant differences in postoperative hemodynamics or sedationscores among all the study groups.The mean visual analog scale scores showed a significant reduction immediately and at 12 hourspostoperatively in both the dexmedetomidine and dexmedetomidine+ groups compared to thecontrol group.The mean time of the first analgesic request was significantly prolonged in the dexmedetomidinegroup (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 tramadolconsumption 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 controlgroup (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 ofpostoperative analgesia and also provides an analgesic sparing effect in patients undergoing majorabdominal cancer surgery. Furthermore, the addition of intrathecal fentanyl 25 µg has no valuableclinical effect.Key words: dexmedetomidine, fentanyl, intrathecal, postoperative pain