Cervical plexus blocks (CPB) have been widely used to provide effective anesthesia and analgesia during various head and neck procedures. The ICPB was considered a good alternative to the deep CPB with an easier technique and fewer adverse events such as intravascular, epidural, subarachnoid injection, and phrenic nerve palsy. A recent randomized trial investigated the analgesic efficacy of superficial vs intermediate CPB combined with GA during total thyroidectomy. Authors used 10 ml bupivacaine 0.25% bilaterally, and they revealed a lower pain score and prolonged duration of analgesia with ICPB compared to superficial CPB; however, the authors did not assess the influence of this bupivacaine concentration on the diaphragmatic motion. [5] This randomized comparative trial is designed to investigate the analgesic efficacy of ICPB combined GA using two bupivacaine concentrations in patients undergoing neck surgeries (total thyroidectomy or total laryngectomy). We hypothesize that a smaller concentration of bupivacaine (0.185%) could provide an equivalent analgesic effect to a larger concentration (0.25%) with less impact on the diaphragmatic motion. The primary endpoint is the duration of postoperative analgesia. The secondary endpoints are the intraoperative hemodynamics, the postoperative pain score, total postoperative opioid consumption over 24 hours, diaphragmatic motions, and hemi-diaphragmic paresis.

Inclusion Criteria:

• ASA physical status I-III,
• scheduled for total thyroidectomy or total laryngectomy

Exclusion Criteria:

• Heart failure,
• A history of arrhythmias or treatment with antiarrhythmic drugs,
• Impaired pulmonary, liver or kidney functions,
• Neck infection or rash