Comparison between Morphine and Hyaluronidase Added to Local Anesthetic in Sonar Guided Supraclavicular Brachial Plexus Block; Randomized Double Blinded Controlled Study

Background: Huge volumes of local anaesthetics used in conventional blocks may be associated with complications. Hyaluronidase is an enzyme that hydrolyses hyaluronic acid in the tissue. It has been shown to aid the spread of local anaesthetics (LA) through tissue. The aim of this study was to compare between the addition of morphine or hyaluronidase to local anaesthetic in sonar guided supraclavicular brachial plexus block regarding the onset and duration of the block, postoperative analgesia and the total analgesic requirements in the first 24 hours.

Patient and methods: Seventy-five patients of American Society of Anaesthesiologists (ASA) physical status I & II, aged 18-60 years, scheduled to acute or elective elbow, forearm or hand surgery under sonar guided supraclavicular brachial plexus block at Tanta University Hospital were randomly allocated into three equal groups; Group I (Control group) received 20 ml containing 9 ml bupivacaine 0.5% and 9 ml lidocaine 2% plus 2 ml normal saline, group II (Morphine group) received 20 ml containing 9 ml bupivacaine 0.5% and 9 ml lidocaine 2% plus 5 mg morphine in 2 ml normal saline and group III (Hyaluronidase group) received 20 ml containing 9 ml bupivacaine 0.5% and 9 ml lidocaine 2% plus 1500 units of hyaluronidase in 2 ml normal saline. The onset of sensory and motor block, duration of sensory and motor block, postoperative VAS, time to first rescue analgesia, total morphine consumption and possible side effects were recorded.

Results: Onset of the sensory block and motor block was significantly shorter in the hyaluronidase group than control group and morphine group. Duration of the sensory block and motor block was significantly prolonged in morphine group than hyaluronidase group & control group. VAS started to increase at 6 hours in the control group, at 10 hours in morphine group and at 8 hours in hyaluronidase group. Time to first rescue analgesia was significantly prolonged in morphine group than control group and hyaluronidase group. Total analgesic consumption of morphine was significantly lower in morphine group than control group and hyaluronidase group.

Conclusion: Morphine was superior to hyaluronidase as regarding to improving the post-operative pain. The incidence of complications was nil and self-limited in the three groups.