Analgesic efficacy of bilateral superficial cervical plexus block administered before thyroid surgery under general anaesthesia

Background. The use of regional anaesthesia in thyroid surgery remains controversial. This double-blind, randomized controlled study was conducted to evaluate the analgesic efficacy of bilateral superficial cervical plexus block (BSCPB) performed under general anaesthesia in patients undergoing total thyroidectomy. Methods. Eighty-seven consecutive consenting patients were randomized to receive a BSCPB with saline (Group P n=29), ropivacaine 0.487% (Group R, n=29), or ropivacaine 0.487% plus clonidine 5 mu g ml(-1) (Group RC, n=29). Sufentanil was given during the intraoperative period for a 20% increase in arterial mean pressure or heart rate in a patient with a bispectral index between 40 and 60. All patients received 4 g of acetaminophen during the first 24 h after operation. The pain score was checked every 4 h and nefopam was given for pain score > 4 on a numeric pain scale. Results. During surgery, the median sufentanil requirements were significantly reduced in Group RC compared with Groups R and P (0.32 vs 0.47 and 0.62 mu g kg(-1); P < 0.0001). After surgery, the number of patients requiring nefopam within 24 h of surgery was significantly lower in Groups R and RC than in Group P (16 and 19 vs 25; P=0.03). At post-anaesthetic care unit admission, median (range) pain scores were significantly lower in Groups R [3 (0-10)] and RC [3 (0-8)] than in Group P [5 (0-8), P=0.03]. No major complications of BSCPB occurred during study. Conclusions. BSCPB with ropivacaine and clonidine improved intraoperative analgesia. BSCPB with ropivacaine or ropivaciane and clonidine was effective in reducing analgesic requirements after thyroid surgery.