Comparison of ultrasound-guided intermediate vs subcutaneous cervical plexus block for postoperative analgesia in patients undergoing total thyroidectomy: A randomised double-blind trial

BACKGROUND AND AIMS: Intermediate cervical plexus block (CPB) is a new procedure whose analgesic efficacy compared to superficial cervical plexus block is yet to be established. We compared the analgesic efficacy of superficial vs intermediate CPB for post-operative analgesia after thyroid surgery. METHODS: Forty-five patients with American Society of Anaesthesiologists' physical status 1 or 2 undergoing total thyroidectomy were recruited. Forty-four patients in superficial/subcutaneous CPB group (n = 22) and intermediate CPB (n = 22) received 20 mL 0.25% bupivacaine with adrenaline 100 μg bilaterally in ultrasound-guided superficial and intermediate cervical plexus block before induction of general anaesthesia., respectively. The primary outcome measure was the postoperative visual analogue scale (VAS) scores at 0, 2, 4, 6, 12 and 24. Secondary outcome measures included the total dose of rescue analgesic required, duration of postoperative analgesia and patient's satisfaction score. Statistical analysis was with the Mann-Whitney U test and independent t-test. RESULTS: The post-operative VAS scores were lower in intermediate CPB group compared to superficial CPB group at 2, 4, 6, 12, 18 and 24 h [P < 0.05]. Time tofirst rescue analgesic demand was prolonged 10.06 ± 3.62 h in intermediate group compared to 7.94 ± 3.62 h in superficial group [P = 0.017] and total analgesic consumption were lower in intermediate group (71.25 ± 16.70 μg) than the superficial group (101.25 ± 50.31 μg) [P = 0.011]. CONCLUSION: Ultrasound-guided intermediate CPB reduces post-operative pain scores, prolongs duration of analgesia and decreases demands for rescue analgesia compared to superficial CPB.