BACKGROUND AND OBJECTIVES: Clonidine is an imidazolynic compound which exhibits partial alpha2-receptor agonist action, with anxiolytic and hypnotic properties. When spinally administered, it produces selective effects in pain modulation and may prolong surgical anesthesia and motor block. This study aimed at evaluating the effects of combined clonidine and 0.5% hyperbaric bupivacaine on spinal anesthesia. METHODS: Thirth ASA I or II patients off both genders, aged between 16 and 57 years and scheduled to undergo surgical inguinal hernia repair were randomly divided into three groups in this prospective double blind study. After monitoring, patients were sedated with 2 mg venous midazolam 10 minutes before surgery, followed by paramedian spinal puncture (L3-L4) in the left lateral position with a 25G Quincke needle. After CSF confirmation, 1 ml of one of the proposed solutions were injected with 15 mg hyperbaric bupivacaine: Group I - 150 µg clonidine; Group II - 75 µg clonidine + 0.5 ml bi-distilled water; and Group III - 1 ml bi-distilled water. The following parameters were evaluated: sensory block level at 5, 20 and 30 minutes, time for two metamers regression, sedation scores through a 0 to 3 scale, motor block by a modified Bromage’s scale, postoperative pain and analgesics requirement. RESULTS: Demographics and maximum sensory level (mode) were similar for all groups. Anesthesia regression and muscle relaxation were longer for Group I. There were no difference in sedation and hemodynamic parameters between groups. Group I had a prolonged analgesia as compared to other groups, what was confirmed by the less need for analgesics as a function of time. CONCLUSIONS: Clonidine has not changed cephalad spread and hemodynamic effects of spinal anesthesia with 0.5% hyperbaric bupivacaine. However, it has promoted better analgesia during the four hours observed after blockade and a prolonged anesthesia.
Analgesics; ANESTHETICS, Local; ANESTHETIC TECHNIQUES, Regional
