Orbicular muscle akinesia in regional ophthalmic anaesthesia with pH-adjusted bupivacaine: effects of hyaluronidase and epinephrine.

The success rate and duration of lid akinesia after adding hyaluronidase and/or epinephrine to pH-adjusted bupivacaine was examined in a double-blind fashion in patients undergoing cataract surgery under local anaesthesia. A two-injection-site technique was used. For globe akinesia all patients (n = 120) received an inferolateral intraconal injection (3 ml) of pH-adjusted bupivacaine 0.75% and hyaluronidase. Lid akinesia was obtained with a medial extraconal injection (3.5 ml) of alkalinized bupivacaine with or without an adjunct. The patients were randomized to four groups as follows: a medial injection of plain bupivacaine (n = 31), with added hyaluronidase (n = 30), with added epinephrine (n = 29) or with both epinephrine and hyaluronidase (n = 30). The final solutions had a pH of 6.7. Lid akinesia was supplemented with periosteal injections if needed. The degree of akinesia from clinical assessment was graded from 0-2 and also measured with electromyography at ten minute intervals for 30 min after surgery, and three hours after the block. The least satisfactory result (P < 0.01) and shortest duration of the lid block (P < 0.05) was obtained with plain pH-adjusted bupivacaine. No differences in the success rate or duration of the block among the other groups were seen. The duration of the block was longer in the epinephrine groups than in the two other groups (P < 0.01) and longer in the epinephrine and hyaluronidase group than in the group receiving only hyaluronidase (P < 0.05). We conclude that the best initial results and longest duration of blocks were shown in the groups receiving epinephrine or epinephrine and hyaluronidase.