The effect of warmed ropivacaine to body temperature on epidural sensory block characteristics

Study Objective: To determine whether warmed (body temperature) ropivacaine increases the speed of onset of sensory block of epidural anesthesia. Study Design: Prospective, randomized, double-blind study. Setting: University hospital. Patients: 180 ASA physical status I and II patients, aged 18 to 64 years, undergoing elective anal surgery. Interventions: Patients were randomly divided into 6 groups defined by ropivacaine temperature [room temperature (RT) or body temperature (BT)] and concentration (0.5%, 0.75%, or 1.0%). Measurements: Sensory block was evaluated by pinprick at the T10, T12, L3, and the perianal region (S4, S5) dermatomes. pH values and adverse events were also recorded. Main Results: There were no differences in baseline demographics, pH, or upper sensory level between groups. Mean onset time of T12 and L3 sensory block was significantly faster for each BT than RT ropivacaine concentration. Anal region (S4, S5) sensory block was significantly faster after BT 0.75% versus RT 0.75% ropivacaine. Conclusions: Warmed ropivacaine shortens the onset of sensory block of epidural anesthesia.