Comparison between Perineural and Intravenous Dexamethasone on Duration of Analgesia in Supraclavicular Brachial Plexus Block - An Observational Study.

BACKGROUND

A disadvantage of regional blocks is their limited period of efficacy. One of the medications that has been found to have the ability to extend the duration of effect is dexamethasone. For the purpose of determining the duration of analgesia after administration of 4 mg of dexamethasone via the intravenous and perineural routes following an ultrasound (USG)-guided supraclavicular brachial plexus block.

OBJECTIVE

To compare the duration of analgesia between perineurial and intravenous dexamethasone when giving supraclavicular USG-guided brachial plexus block, time of administering rescue analgesia, and any adverse events like postoperative nausea and vomiting (PONV).

METHODS

This comparative observational study involved 100 adults, aged 18-70 years, with ASA physical status between I and III, who were scheduled to undergo elective procedures of the upper limb under USG-guided supraclavicular brachial plexus block, and were assigned to either the perineural group or intravenous group. Patients in the perineural group ( n = 50) were given 10 mL of 0.5% bupivacaine hydrochloride, 10 mL of 2% lidocaine hydrochloride with adrenaline 1:200,000 (5 μg/mL), and 4 mg of dexamethasone. Patients in the intravenous group ( n = 50) were given an additional 4 mg of dexamethasone intravenously just before giving the local anesthetic mixture into the brachial plexus. The extent of analgesia, pain, adverse effects like PONV, and rescue analgesia required were recorded.

RESULTS

Up to 24 h after the procedure, a greater segment of patients in the perineural group reported analgesia (72% vs. 24%; P = 0.001) and a reduction in pain (76% vs. 36%; P = 0.001). Adverse effects like PONV were minimal and comparable. Patients in the intravenous group received rescue analgesia with paracetamol 1 g intravenous repeated every 6 h when VAS score is 3 or more. Patients with VAS score of 1 or 2 did not receive any rescue analgesics. Second rescue analgesic is injection diclofenac 75 mg intramuscular repeated every 6 h if paracetamol fails.

CONCLUSION

When compared to the intravenous route, the perineural route of dexamethasone was shown to be beneficial in extending the duration of anesthesia for up to 24 h, which resulted in prolonged pain-free and a reduced need for rescue analgesia. Furthermore, enhanced recovery was noted in patients when dexamethasone was given via the perineural route due to the extended duration of pain relief.