ROPIVACAINE 7.5 MG/ML FOR EPIDURAL ANESTHESIA IN ELECTIVE CESAREAN SECTION

Abstract

S361 INTRODUCTION: Ropivacaine is a new local anesthetic agent belonging to the same homologue series of compounds as bupivacaine. Because of cardiotoxicity bupivacaine 7.5 mg/ml has been unavailable to obstetric anesthesiologists for more than a decade [1]. The new agent ropivacaine has been shown to have a lower cardiovascular and cerebral toxicity than bupivacaine [2,3] thus allowing the clinical use of higher concentrations in obstetric anaesthesia [4]. METHOD: With Institutional Ethics Committee approval and informed written consent. 120 patients for elective Cesarean section were enrolled in a prospective, single-center, randomized, double-blind study. Patients were randomized to receive either ropivacaine 7.5 mg/ml or bupivacaine 5 mg/ml epidurally. After receiving a main dose of 20 ml over 5 minutes the patients could, if required for adequate anesthesia, receive a blinded administration of two 5 ml top-up doses. The first top-up dose in the ropivacaine group was active drug, while the second dose was normal saline. In the bupivacaine group both top-up doses were active drug. STATISTICAL METHODS: The treatment groups were compared using Wilcoxon (mid) rank tests. A p-value <0.05 was considered statistically significant. Where there are missing data the actual number of patients is shown (/n). RESULTS: 60 patients were randomized to receive ropivacaine (Group R) and 60 patients bupivacaine (Group B), and all were valid for safety analysis. Three patients in Group R and 1 in Group B were judged to have been technical failures and were removed from the efficacy analysis. The remaining 57 Group R patients and 59 Group B were valid for safety and efficacy analysis. However 5 patients in group R and 7 patients in group B are not included in the analysis of motor block since they received additional analgesia before the assessments. Both treatment groups were similar with regard to concomitant diseases and demographic variables, except for weight, where the ropivacaine group had a mean weight of 5.3 kg greater than the bupivacaine group. In Group R, 7 patients received 187.5 mg of study drug and the remaining 53 received 150 mg. In Group B, 5 patients received 150 mg, 5 patients 125 mg and 50 patients received 100 mg. The median time to T6 block was 4 and 5 minutes after the end of the main dose in Groups R and B respectively. The maximum upper spread of sensory block varied between T6 and C3 in Group R and between T10 and C3 in Group B. 26/52 Group R patients (50%) and 15/52 Group B patients (29%) had grade 3 motor block at the assessments after surgery, according to the modified Bromage scale (no statistical difference). Pain at delivery was experienced by 15/57 (26%) Group R patients compared to 17/59 (29%) Group B patients. Quality of analgesia was excellent in 43/57 (75%) Group R patients compared to 38/59 (64%) Group B patients (nsd). The median value of the maximum drop in maternal systolic blood pressure as a percentage of baseline was -40% in Group R compared to -38% in Group B (nsd). The Apgar score obtained in neonates 5 minutes after delivery was 10 in all Group R patients and either 9 or 10 in Group B. The median Neurologic and Adaptive Capacity Score (NACS) 2 hours after delivery were 37 in both groups, and 24 hours after delivery, 39 in both groups. CONCLUSIONS: The present study shows that ropivacaine 7.5 mg/ml can be safely administered epidurally in doses up to 150 - 187 5 mg and provides excellent anesthesia for elective Cesarean section.