EFFECTS OF INTRATHECAL CLONIDINE ON DURATION OF BUPIVACAINE SPINAL-ANESTHESIA, HEMODYNAMICS, AND POSTOPERATIVE ANALGESIA IN PATIENTS UNDERGOING KNEE ARTHROSCOPY

Clonidine, an alpha-2-adrenergic agonist, may have a clinically releva nt analgesic action but also a hypotensive action, when administered s pinally. In this study, therefore, the analgesic and circulatory effec ts of intrathecal clonidine were studied in patients undergoing knee a rthroscopy under spinal anaesthesia. Forty ASA I-II patients were rand omly divided to two groups. One group received clonidine 3 mu g . kg(- 1) mixed with 15 mg 0.5% bupivacaine and the other group an identical saline volume mixed with bupivacaine as above, in a double-blind fashi on. Sensory analgesia, blood pressure, heart rate and sedation were fo llowed during and after the operation. Oxycodone 0.14 mg . kg(-1) i.m. or ketoprofen 100 mg p.o. was administered when needed. The duration of sensory analgesia (until regression of the block to L2) was longer in the clonidine group (mean 217 min) than in the control group (mean 160 min) (P<0.05). Duration of motor blockade was also longer in the c lonidine group (mean 215 min) compared to the control group (161 min) (P<0.05). Mean arterial pressure and heart rate were significantly low er in the clonidine group compared to the control group. The clonidine patients needed fewer supplemental doses of oxycodone (8 doses) than those in the control group (16 doses) (P<0.05). More patients in the c lonidine group were sedated 3-6 h after the injection (P<0.05). Additi on of clonidine prolonged the bupivacaine spinal block. However, marke d haemodynamic changes and sedation may limit the usefulness of intrat hecal clonidine.