The effects of 2 µg and 4 µg doses of dexmedetomidine in combination with intrathecal hyperbaric bupivacaine on spinal anesthesia and its postoperative analgesic characteristics.

OBJECTIVE: To compare the postoperative analgesic characteristics and side effects of two different doses of intrathecal dexmedetomidine in combination with hyperbaric bupivacaine, and to evaluate the effects of these combinations on spinal anesthesia.

METHODS: After obtaining approval from the local ethics committee, 60 male patients who were undergoing inguinal surgery and were classified as American Society of Anesthesiologists physical status class I were included in the study. The present study was conducted in 2003 in a military hospital with a capacity of 100 beds. The patients were randomly assigned to three groups of 20 patients: group 1, 0.5 mL saline added to 3 mL (15 mg) hyperbaric bupivacaine; and groups 2 and 3, 2 µg dexmedetomidine and 4 µg dexmedetomidine added to 3 mL (15 mg) hyperbaric bupivacaine, respectively. Medications were administered by intrathecal injection in a total volume of 3.5 mL. The postoperative analgesic characteristics, effects on spinal anesthesia and side effects were recorded.

RESULTS: Demographic characteristics were similar among the groups. The mean (±SD) time to onset of pain was 220.75±112.7 min in group 1, 371.5±223.5 min in group 2 and 1042.50±366.78 min in group 3. Time to first pain sensation in group 3 was significantly longer than that in groups 1 and 2 (P<0.001).

CONCLUSION: Two different doses of dexmedetomidine, an α2-adrenoceptor agonist with analgesic effects, resulted in an increased duration of analgesia and efficacy, decreased postoperative analgesic use and was associated with no notable adverse effects.