Comparison of Magnesium Sulfate and Dexmedetomidine as an Adjuvant to 0.5% Ropivacaine in Infraclavicular Brachial Plexus Block.

Background: Magnesium sulfate and dexmedetomidine were used as adjuvants to local anesthesia to improve the quality of regional anesthesia.

Aims: The aim of this study is to evaluate and compare the effects of magnesium sulfate and dexmedetomidine when added to ropivacaine on the quality of infraclavicular brachial plexus block (BPB).

Settings and Design: This was a prospective randomized double-blinded controlled study.

Patients and Methods: A total of 105 adult patients undergoing surgery in hands, wrist, and forearm using infraclavicular BPB were randomly assigned into three groups. Ultrasound-guided infraclavicular BPB was performed using 35 ml ropivacaine 0.5% diluted with 4 ml normal saline 0.9%. Magnesium sulfate 150 mg and dexmedetomidine 100 μg were added in the magnesium sulfate group and dexmedetomidine group, respectively. Duration of analgesia, onset times and durations of sensory block (SB) and motor block (MB), patient's satisfaction, and complications were recorded.

Statistical Analysis: Statistical software SPSS 16 was used for statistical analysis.

Results: Dexmedetomidine and magnesium sulfate provided longer duration of analgesia and lesser consumption of postoperative rescue analgesia than the control group ( P = 0. 000); dexmedetomidine provided the longest duration of analgesia versus control and magnesium sulfate groups ( P = 0.000). Dexmedetomidine provided the quickest onset times and the longest durations of both SB and MB than control and magnesium sulfate groups ( P = 0.000). Dexmedetomidine group had higher incidences of bradycardia and hypotension.

Conclusions: Magnesium sulfate or dexmedetomidine is a useful adjuvant to ropivacaine for infraclavicular BPB in lengthening the duration of analgesia. Dexmedetomidine provided quicker onset and longer duration of both SB and MB and longer duration of analgesia with lesser consumption of postoperative rescue analgesia; however, it showed a higher incidence of intraoperative hypotension and bradycardia than magnesium sulfate.