Epidural administration of ropivacaine and its effects on the pharmacodynamics of rocuronium: Randomized controlled trial. Interaction between ropivacaine and rocuronium

BACKGROUND: Potentiation of neuromuscular blocking agents by local anesthetics has been described in various clinical and experimental studies. This study assessed the influence of epidural ropivacaine on pharmacodynamic characteristics of rocuronium. DESIGN: This was a prospective randomized clinical trial at the women's hospital, an university tertiary hospital in Brazil. Sixty-two patients underwent elective abdominal surgeries requiring general anesthesia. INTERVENTION: Patients were distributed into two groups: Group 1 (general anesthesia and epidural anesthesia) and Group 2 (general anesthesia). In Group 1, 0.2% ropivacaine at a dose of 40 mg (20 ml) was associated with 2 mg (2 ml) of morphine in a single epidural injection. The following parameters were assessed: clinical duration (DC(25)) and time for recovery of the train-of-four (TOF) 0.9 ratio (T4/T1 = 90%) after an initial 0.6 mg/kg dose of rocuronium. The primary outcomes were DC(25) and TOF 0.9 ratio (T4/T1 = 90%). Secondary outcomes were total propofol and remifentanil consumption. RESULTS: Values were presented as median and interquartile range. The results for DC(25) and TOF 0.9 of rocuronium were, respectively, 41.5 35.0–55.0 (25.0–63.0) in Group 1 and 44.0 37.0-51.0 (20.0–67.0) in Group 2 (P = 0.88); 88.0 67.0–99.0 (43.0–137.0) in Group 1; and 80.0 71.0-86.0 (38.0–155.0) in Group 2 (P = 0.83). There was no significant difference between the groups, in terms of pharmacodynamic characteristics of rocuronium. Propofol consumption did not show any difference between the groups. However, remifentanil consumption was significantly lower in Group 1 (P < 0.01). CONCLUSION: Epidural ropivacaine, in the dose studied, did not prolong the duration of rocuronium-induced neuromuscular blockade. TRIAL REGISTRY NUMBER: ReBEC (ref: RBR-7cyp6t).