[Intradural ropivacaine for cesarean section: choosing the appropriate dose]

The trend in spinal administration of local anesthetics is to use small doses. The aim of this study was to compare 2 minimum doses of ropivacaine administered by intradural infusion for cesarean section.

After the study was approved by the ethics committee, 64 women scheduled for cesarean delivery were enrolled. The patients were randomly allocated to 2 groups: a group of 32 women received 7.5 mg of 0.75% ropivacaine (ROP 0.75%) and another group of 32 received 10 mg of the anesthetic at a concentration of 1% (ROP 1%). Both groups received 25 microg of fentanyl. Parameters assessed were time until the block reached T6, time until the highest point was reached, hemodynamic changes, incidence rates of hypertension and bradycardia, ephedrine and atropine requirements, time until recovery of motor function, duration of analgesia, time until regression of block to T10, degree of muscle relaxation, patient satisfaction, and incidence of adverse side effects.

No patients were excluded from the study. It was necessary to provide a rescue dose in 16% of the cases in the ROP 0.75% group (P<0.05). The incidence of hypotension was higher in the ROP 1% group than in the lower-dose group (60% vs 28%) and ephedrine requirements were greater (16.56 [SD, 18.85] vs 7.96 [15.44] mg; P<0.05 in both cases). There were no significant differences in other parameters.

There was greater need for a supplementary dose of local anesthetic and a lower incidence of hypotension in the ROP 0.75% group. The level of anesthesia was satisfactory for all patients in the ROP 1% group but the incidence of hypotension was higher.