Spinal anesthesia with ropivacaine: a double-blind study on the efficacy and safety of 0.5% and 0.75% solutions in patients undergoing minor lower limb surgery.

Abstract

The purpose of this study was to determine the clinical efficacy and safety of ropivacaine as a local anesthetic for spinal anesthesia. Forty patients between the ages of 18 and 75 yr, scheduled for minor lower limb surgery, were studied. They were randomly allocated to receive either 3 mL glucose-free 0.5% (15 mg) or 0.75% (22.5 mg) ropivacaine in a double-blind fashion. The subarachnoid puncture was performed with a 26-gauge Quincke-point needle at the L3-4 interspace with the patients in the sitting position. The onset of analgesia to pinprick was similar with both concentrations. The median (range) upper level of analgesia obtained with the 0.5% solution was T11 (L4-T5) and was T10-11 (L4-T4) with the 0.75% solution. The duration of analgesia at T12 (P < 0.01) and the total duration of analgesia (P < 0.002) were longer in the 0.75% group. In addition, the area under the number of blocked segments versus time curve was larger with the 0.75% ropivacaine solution (P < 0.001). The incidence of complete motor block of the lower limbs was higher (P < 0.02) and the total duration of motor block longer (P < 0.002) in the 0.75% group. No unexpected adverse events were registered. We conclude that subarachnoid injection of glucose-free ropivacaine solutions results in a variable spread of analgesia, mostly accompanied by a good quality of motor block, in particular with the 0.75% solution.