Intrathecal 0.75% Isobaric Ropivacaine Versus 0.5% Heavy Bupivacaine for Elective Cesarean Delivery: A Randomized Controlled Trial

OBJECTIVE: Ropivacaine, a local anesthetic with duration of action of 2-3 hours, has shown greater selectivity for sensory blockade along with lower systemic toxicity as compared to bupivacaine when used for spinal anesthesia. This study was aimed to compare the intrathecal efficacy and safety of 0.75% isobaric ropivacaine for cesarean delivery with 0.5% heavy bupivacaine in parturients. MATERIALS AND METHODS: We enrolled 46 parturients of ASA (American Society of Anesthesiologists) grade I-II scheduled for elective cesarean delivery under spinal anesthesia for this prospective randomized control trial. The patients were randomized to receive either 12.5 mg of 0.5% hyperbaric bupivacaine or 24 mg of 0.75% isobaric ropivacaine intrathecally. Intraoperative hemodynamic parameters, characteristics of sensory and motor nerve block, neonatal outcome and maternal adverse effect (such as hypotension, bradycardia, nausea, vomiting, shivering or pruritis) were evaluated. RESULTS: Baseline demographic variables were similar in the 2 groups (p-value>0.05). Neonatal outcomes were also similar in both the groups. The time to achieve sensory block to T10 (3.2 ± 1.5 vs 2.5 ± 1.3 minutes) or to the maximal level (9.8 ± 3.1 vs 7.9 ± 2.3 minutes) was longer in the ropivacaine group (p-value 0.048) but the median maximal level of sensory block was similar between the two groups (p-value>0.05). Duration of sensory block was shorter in the ropivacaine group (160.5± 22.2 vs 182.3± 30.5 minutes) (p-value 0.03). Duration of motor block was also significantly shorter than bupivacaine group (112.5 ± 45 vs 165.3 ± 26) (p-value 0.004). CONCLUSION: Spinal anesthesia for elective cesarean delivery with intrathecal 24 mg of 0.75% isobaric ropivacaine provided clinically effective surgical anesthesia of shorter duration without compromising neonatal outcome and can be used as an effective and safe alternative to bupivacaine. Conflicting Interest: None Declared This article has been peer reviewed. Article Submitted on: 18 th January 2012 Article Accepted on: 25 th March 2012 Funding Sources: None Declared Correspondence to: Dr. Manish Jain Address: Department of Anaesthesiology & Critical Care, NSCB Subharti Medical College, Meerut (UP), India Email: jainmanish45@ya hoo.com INTRODUCTION Cesarean delivery is usually conducted under spinal anesthesia with bupivacaine. Ropivacaine, which blocks sensory nerve fibers more readily than motor fibers, is now gaining popularity due to its reduced cardiac toxicity with overdose [1]. Recent studies with intrathecal ropivacaine have demonstrated low cardiovascular and neurotoxic effects, good tolerability and efficacy [2]. The aim of this randomized controlled trial was to compare the efficacy and safety of intrathecal 0.75% isobaric ropivacaine (24 mg) with 0.5% heavy bupivacaine (12.5 mg) for elective cesarean delivery [3]. We selected the ropivacaine dose based on the dose-response study by Khaw et al, which estimated the 95% effective dose (ED 95) of intrathecal ropivacaine