RESUMEN

BACKGROUND AND AIMS: We aimed to evaluate and compare the block characteristics and duration of analgesia of intrathecal isobaric ropivacaine-fentanyl and bupivacaine-fentanyl combination in adult patients undergoing lower limb orthopedic surgery. MATERIAL AND METHODS: Seventy-four American Society of Anesthesiologists' I and II adult patients undergoing lower limb orthopedic surgery under subarachnoid block were randomized to receive either 3 ml 0.5% isobaric ropivacaine and 25 mcg fentanyl (Group R) or 3 ml 0.5% isobaric bupivacaine and 25 mcg fentanyl (Group B). The hemodynamic profiles, maximum upper level of sensory block height, time to reach peak block height, two dermatome regression time, and duration of motor block were recorded. RESULTS: There was no statistically significant difference regarding the hemodynamic parameters between the groups. The median (range) peak sensory block height was T7 (T4-T9) in Group R and T7 (T4-T10) in Group B. Time to reach peak block height (13.2 ± 2.3 min in Group R vs. 13.7 ± 2.2 min in Group B; P = 0.385) was similar between the groups. Two dermatome regression time in sensory block (median 120 min vs. 85 min; P < 0.001) and duration of motor block (median 245 min vs. 150 min; P < 0.001) was significantly higher in Group B. The duration of analgesia (median 360 min vs. 245 min; P < 0.001) was significantly higher in the bupivacaine group. CONCLUSION: Intrathecal isobaric bupivacaine-fentanyl combination produces a significantly longer duration of analgesia, sensory block and motor block than isobaric ropivacaine-fentanyl combination. As ropivacaine has a shorter duration of sensory and motor block, it may be preferred in day care surgery.