Dexmedetomidine (DEX) has been reported to have synergistic action with local anesthetics. This prospective, randomized, double-blind clinical study was designed to observe the efficacy of intravenous DEX without loading dose on spinal blockade duration, postoperative sedation, patient-controlled analgesia and its morphine-sparing effect in lower limb surgeries.
Seventy-five patients, scheduled for lower limb surgery under spinal anesthesia, were randomly allocated into 2 groups: group BS (received 15 mg of 0.5% of bupivacaine for subarachnoid anesthesia and continuous intravenous infusion of saline in Ringer solution) and BD group (received 15 mg of 0.5% of bupivacaine for subarachnoid anesthesia and continuous intravenous infusion of DEX in Ringer solution at a rate of 0.25 μg/kg/h). Intravenous infusion started 15 minutes before spinal anesthesia.
The onset time of sensory and motor blockade was shorten, the duration of sensory and motor blockade was significantly prolonged in BD patients when compared to BS patients. The Ramsay sedation score measured immediately after surgery was greater in BD group than BS group. BD patients also shown increased time to the first request of postoperative morphine and decreased total morphine consumption as compared with BS patients.
Collectively, intravenous administration of DEX without loading dose promoted the efficacy of spinal bupivacaine anesthesia and postoperative analgesia in patients undergoing lower limb surgery.