Comparison of hyperbaric and plain ropivacaine 15 mg in spinal anaesthesia for lower limb surgery

Previously, plain ropivacaine 15 mg given intrathecally has been shown to be feasible for ambulatory surgery of lower-extremities. Hypothetically, hyperbaric solution could improve and shorten the block.

This prospective, randomized, double-blind study included 56 patients undergoing surgery of lower extremities. They received intrathecally either 1.5 ml of ropivacaine 10 mg ml(-1) and 0.5 ml of glucose 300 mg ml(-1) (HYP) or 2 ml of ropivacaine 7.5 mg ml(-1) (PL).

All patients in Group HYP achieved T(10) dermatome analgesia but only 64% (18/28) of Group PL. T(10) analgesia was reached in 5 min (median, range 5-20 min) in the HYP group vs 10 min (5-45 min) in the PL group (P=0.022), and full motor block in 10 min (5-45 min) vs 20 min (5-60 min) (P=0.003), respectively. Group HYP had a longer duration of analgesia at T(10); 83 min (5-145 min) vs 33 min (0-140 min) (P=0.004). Duration of sensory block from injection of the anesthetic to complete recovery was shorter in Group HYP than in Group PL, 210 min (120-270 min) vs 270 min (210-360 min) (P<0.001), as was duration of motor block, 120 min (5-150 min) vs 210 min (120-330 min) (P<0.001). Patients of Group HYP attained discharge criteria earlier than those of Group PL (P=0.009).

In comparison with the plain solution, 15 mg of intrathecal hyperbaric ropivacaine produced a faster onset, greater success rate of analgesia at the level of T(10) dermatome, and faster recovery of the block.