Spinal anaesthesia with ropivacaine 5 mg ml(-1) in glucose 10 mg ml(-1) or 50 mg ml(-1)

Forty patients undergoing spinal anaesthesia for a variety of surgical procedures were randomly allocated to receive 3 ml of ropivacaine 5 mg ml(-1) in glucose 10 mg ml(-1) or 50 mg ml(-1). Onset of sensory block to T10 was significantly faster (P=0.03) with the glucose 50 mg ml(-1) solution (median 5 min, range 2-20 min) than with the 10 mg ml(-1) solution (median 10 min, range 2-25 min). Maximum extent of cephalad spread was virtually the same in both groups (10 mg ml(-1) median T6/7, range T3-T10; 50 mg ml(-1) median T6, range T3-T10) with similar times to regression beyond S2 (10 mg ml(-1) median 210 min, range 150-330 min; 50 mg ml(-1) median 210 min, range 150-330 min). Complete motor block was produced in the majority of patients (10 mg ml(-1) 90%; 50 mg ml(-1) 85%) and the time to complete regression was the same in both groups (median 120 min, range 90-210 min). A block adequate for the projected surgery was achieved in all patients.