Post-operative Analgesic Characteristics of Intrathecal Adjuvant AgentsIncluding Ketamine, Fentanyl, Sufentanyl, Neostigmine, Dexmedetomidine, Midazolame and Droperidole and their Effects on Spinal Anesthesia

Aim: This study was designed to compare the intraoperative, postoperative analgesic characteristics and adverse effects of intrathecal combinations of several adjuvant agents combined with hyperbaric bupivacaine in the cases who underwent spinal anaesthesia. Materials and methods: 180 cases were randomized to 9 groups of 20 cases (n=20). 15 mg of 0.5% hyperbaric bupivacaine and 0.5 ml of serum physiological were administrated to the control group (group-0). In the other groups, instead of serum physiological: Group-1 (2.5 mg hyperbaric bupivacaine), Group-2 (12.5 mg ketamine), Group-3 (25 μgr Fentanyl), Group-4 (2.5 μg sufentanyl), Group-5 (2 μg dexmedetomidine), Group-6 (250 μg neostigmine), Group-7 (500 μg midazolame), Group-8 (1.25 mg Droperidole) were combined with hyperbaric bupivacaine. Total spinal drug volume was 3.5 ml. Intraoperative and postoperative side effects, time to the first pain, and the characteristics of spinal anaesthesia were recorded. Results: Intrathecal adjuvant agents had no effects on the characteristics of the spinal anaesthesia (p>0.05). Time to the first pain was similar between the groups (p>0.05). The most common side effect was pruritus in Group-3 and Group-4 (p>0.05), nausea-vomiting in Group-6 (p>0.05), urinary retention in Group-2 and Group-4 (p>0.05), and PSBA in Group-1 and Group-3 (p>0.05). Discussion: No differences in the time to the first pain were found between intrathecal adjuvant agents. Their effects on the characteristics of spinal anaesthesia were similar. Each adjuvant agent causes specific side effects. However, postoperative analgesic requirement was not considered in our study, and dose-finding studies (which are performed to determine the adjuvant agent doses that cause minimal and maximal side effects) were not performed. Further studies should be performed to evaluate those factors.