Background: 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.
Methods: 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).
Results: 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).
Conclusion: 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.