ED50 and ED95 of Intrathecal Isobaric Levobupivacaine Coadministered with Fentanyl for Transurethral Resections: Randomized, Double-blind Trial

Background: Levobupivacaine use is progressively increased for intrathecal anesthesia in transurethral resections. The aim was to determine ED50 and ED95 of intrathecal isobaric levobupivacaine by addition of 25mcg fentanyl for patients undergoing transurethral resections. Methods: A total of 100 patients undergoing transurethral resections with ASA I-III, were randomized to groups receiving intrathecal 0.5% isobaric levobupivacaine in doses of 6, 8, 10, 12 or 14mg in equal volumes with 25mcg intrathecal fentanyl addition. Sensorial block level was determined by pinprick and motor block by Bromage scale. Results: Mean onset time of sensorial block in 6mg group was significantly longer than that of sensorial block in 10mg, 12mg and 14mg groups (p<0.01), 8mg was longer than 12mg and 14mg (p<0.01), and 10mg onset time of sensorial block was significantly longer than 12mg and 14mg (p<0.01). Mean onset time of T10 sensory level in 6mg group was significantly longer than mean onset time of T10 sensory level in 10mg, 12mg and 14mg (p<0.01), the mean onset time of T10 sensory level in 8mg group was also significantly longer than that of 12mg, 14mg groups (p<0.01). ED50 and ED95 of levobupivacaine coadministered with 25 mcg fentanyl were 7.32mg and 10.88mg, respectively. Conclusion: Levobupivacaine with opioid co-administration can be used in doses considerably lower than doses proposed for routine use as it is a safe drug depending on its hemodynamic effects, side effects.