Does oral clonidine premedication prolong spinal anaesthesia duration?

The aim of this study was to investigate the effect of oral clonidine on the duration and level of spinal anaesthesia with bupivacaine. After obtaining approval from local ethical committee, we studied 30 ASA I class patients, that were randomly divided into two equal groups. The patients of clonidine group received 150 μg clonidine orally 90 minutes before spinal anaesthesia while the control group did not receive any premedication. Three mililiters of 0.5 % hyperbaric bupivacaine was given to all patients through L3-4 interspace for spinal anaesthesia. The onset time and duration of sensory block at T10 level were evaluated with pinprick test; the onset and resolution of grade 4 motor block with bromage scale. Heart rate, blood pressure and SpO2 were recorded. There weren't any difference between the two groups with respect to the onset time and the level of sensory and motor block, but the duration of sensory and motor block were longer in clonidine group (p<0.05). Significant decreases were also detected in heart rate, blood pressure and SpO2 in clonidine group compared to control. We concluded that oral clonidine premedication prolongs the duration of sensory and motor block in bupivacaine spinal anaesthesia, although the decrease in heart rate, blood pressure and SpO2 should be monitored more closely, even they had no clinical importance