A comparative evaluation of equipotent doses of isobaric Levobupivacaine and Ropivacaine with neuraxial adjuvant Fentanyl for lower abdominal and lower extremity surgery

Introduction: Hyperbaric preparation of local anaesthetics have been used in subarachnoid block till now. Levobupivacaine and Ropivacaine, newly introduced S-enantiomer related to bupivacaine, have low cardio-neurotoxicity profile. In this study isobaric form of Levobupivacaine and Ropivacaine with Fentanyl were evaluated in terms of clinical efficacy as well as block characteristics. Materials and Methods: In this prospective, single blind study, sixty patients of ASA grade I or II, 20-65yrs of age, of either sex, posted for lower abdominal or lower extremity surgery, were randomly administered either 3 ml Levobupivacaine (0.5%) or Ropivacaine (0.75%) with Fentanyl (25µg). Intra and postoperative block characteristic, hemodynamic parameters as well as side effects were recorded. Results: Time to reach T10 sensory level and bromage 1 was earlier in group LF compared to group RF (p value =0.001). Peak sensory level was T6-T8 in group LF and T8-T10 in group RF. Significantly longer duration of sensory and motor block was produced in group LF (271.5 ± 5.06 and 252.16 ± 4.69 min) compared to group RF (228 ± 4.16 and 195.33 ± 3.54 min). The time to first rescue analgesia was also significantly prolonged in group LF (292.83 ± 5.28 min) compared to group RF (258 ± 4.32 min) (p value =0.001). Conclusion: Equipotent doses of isobaric Levobupivacaine and Ropivacaine with Fentanyl (25µg) offered satisfactory anaesthesia with minimal haemodynamic variability. Levobupivacaine produced rapid onset and prolonged anaesthesia while Ropivacaine provided rapid recovery of sensory and motor block and early mobility, suitable for day care surgery.