the effect of trendelenburg posture on sensory block level in spinal anesthesia with intrathecal hyperbaric bupivacaine for hernia repair

background: obtaining a good sensory and motor block is the goal of performing spinal anesthesia for surgeries. the aim of this study is to compare the effect of trendelenburg position on sensory block level after spinal anesthesia with intrathecal hyperbaric bupivacine. methods: we enrolled 80 men, classified as asa i, scheduled for elective hernia repair under spinal anesthesia. participants were randomly allocated equally to one of the two groups, horizontal or trendelenburg position. spinal anesthesia was performed in the sitting position using 15 mg of 0.5% hyperbaric bupivacaine. then the patients were turned to supine position. in trendelenburg position group, a 20 degree head tilt position was performed for 40 seconds, then the patients were returned to horizontal position and 30 mg ephedrine was administered intramuscularly. sensory block level and incidence of hypotension were recorded in the two groups. results: there were significant effects of trendelenburg position on sensory block heights during the study period (10.61 ± 0.32segments blocked above the injection point versus 7.24 ± 0.51 in horizontal group).  no episodes of severe hypotension were seen among the patients. six patients in horizontal group experienced intraoperative discomfort or pain, versus no patient in trendelenburg group. (p=0001). conclusion : a higher level of sensory block can be obtained with performing a short time head down position after intrathecal injection.