Comparison of spinal hypobaric ropivacaine and bupivacaine in arthroscopic knee surgery

1VIII-SUMMARYThe aim of this study is to investigate equipotent doses of hypobaric ropivacaine andbupivacaine arthroscopic knee surgery under spinal anesthesia.Sixty ASA I, II patients were included in the study. Patients were positioned in lateraldecubitus position with operated sides uppermost. Spinal anesthesia was performed at L3-4intervertebral space to apply hypobaric bupivacaine 8 mg and hypobaric ropivacaine 8, 10 and12 mg. Patients were kept in 15 minutes both lateral and supine position. Heart rate, meanarterial blood pressure were recorded during and after the operation. Onset, duration of motorand sensory blocks; micturation time; first analgesic requirement time; patient and surgeonsatisfaction were evaluated.Hypobaric bupivacaine 8 mg and ropivacaine 12 mg were comparable with respect toonset and recovery time of motor and sensory blocks, time to first analgesic requirement; timefor first micturation; rates of patient and the surgeon satisfaction. Hypobaric ropivacaine 8 mgdid not provide adequate surgical anesthesia for every patient. The sensory and motor blockonset, duration and regression times were similar in bupivacaine 8 mg, ropivacaine 10 mg andropivacaine 12 mg; the quality of surgical anesthesia achieved with ropivacaine 10 mg waslower than that of bupivacaine 8 mg and ropivacaine 12 mg.In conclusion, during arthroscopic knee surgeries, hypobaric intrathecal bupivacaine 8mg and ropivacaine 12 mg behaved as equipotent in terms of sensory and motor blockcharacteristics but hypobaric ropivacaine 8 mg was insufficient in every aspect and hypobaricropivacaine 10 mg provided unreliable surgical anesthetic conditions in unilateral spinalanesthesia.