Magnesium Sulphate in the Ultrasound-guided Supraclavicular Brachial Plexus Block

The supraclavicular approach to the brachial plexus provides more consistent and effective regional anesthesia to the upper extremity than other approaches to brachial plexus blockade. However, the fear of pneumothorax is often cited by anesthetists as a reason to avoid this approach. With increasing affirmation on patient safety and better patient outcomes, ultrasound guided regional anesthesia (UGRA) is becoming more widely popular. Ultrasound provides clinicians with a real time image suitable for visualizing anatomical structures, needle placement, and local anesthetic spread. Ultrasound-guidance to supraclavicular brachial plexus block has shown to increase success rates, reduce the volume of local anesthetic (LA) used and has the potential to minimize the risk of complications.

Although there are many treatment choices for postoperative pain, a gold standard has not been established. Prolonging the duration of peripheral nerve blocks using long-acting Local Anesthesia or perineural catheters can be used. However, perineural catheters are more time-consuming, costly, has possible higher complication rates (e.g. Infection), and needs more postoperative care.

Several adjuvants such as fentanyl, alpha-2 adrenergic agonists (clonidine or dexmedetomidine), tramadol, and magnesium have been used to extend the duration of peripheral nerve blocks. 5-7 Magnesium has antinociceptive effects in animal and human models, principally related to blocking the N-methyl-D-aspartate (NMDA) receptors and regulation of calcium influx into cells. Calcium influx leads to a sequence of central sensitization such as windup phenomenon and long term potentiation which are crucial mechanisms that determine the duration and intensity of post-operative pain. Magnesium prevents central sensitization triggered by peripheral nociceptive stimulation in response to painful stimuli.

The investigators designed this study to evaluate the effect of adding magnesium sulphate to bupivacaine in the ultrasound-guided supraclavicular brachial plexus block anesthesia. The sensory and motor block durations were evaluated as primary endpoints and the postoperative analgesic effects as a secondary endpoint.

Inclusion criteria

• - ASA physical status I to II,
• - Patients listed for elective forearm or hand surgery using supraclavicular brachial plexus block anesthesia

Exclusion criteria

1 - evidence of severe cardiovascular, renal, or hepatic diseases, preexisting neurological or psychiatric illnesses.

2- patients have allergy to the study drugs. 3 - patients who have any contraindications to brachial plexus block anesthesia.

4- pregnant or lactating women, or 5- if the BMI was > 35 kg/m2.