Background and Aims Thyroid surgery maybe associated with mild-moderate pain, with 66-90% patients requiring opioids on the first postoperatively. This study compared superficial cervical plexus block (SCPB) [USG subcutaneous local anaesthetic (LA) injection at Erb’s point] and intermediate CPB (IMCPB) [USG LA injection below posterior SCM border] for thyroid surgery under general anaesthesia. Primary outcome was 24-hr postoperative fentanyl requirement; secondary outcomes included time to first analgesic, 24-hr pain at rest and swallowing, pre and 20 min post block diaphragmatic excursions (normal, deep breathing, sniffing), diaphragmatic thickening fraction (TFdi), PFT (phrenic nerve function), hoarseness (RLN nerve function), Horner’s syndrome and dermatomes blocked.
Methods Following ethics committee approval, 57 consenting ASA I-II, 18-75-year patients undergoing thyroidectomy were randomly allocated to IMCPB (n=28) or SCPB (n=29) groups. Ropivacaine 10ml, 0.375% was injected bilaterally, pre-induction in both groups.
Results C2-C4 dermatomes were blocked in both groups. 24-hr postoperative fentanyl requirement was significantly lower and time to first rescue analgesic was shorter in the IMCPB group. (table 1) VAS on rest and swallowing was significantly lower in the IMCPB group for 2-hrs and at 24-hrs. (figure 1) 53% IMCPB patients developed a sympathetic haemodynamic response 5min post-block that lasted for 30-45min. Diaphragmatic excursions on deep breathing and PEFR were significantly reduced in the IMCPB group. Incidence of hoarseness, ear lobe numbness, Horner’s syndrome was significantly higher in the IMCPB group. (table 2)
Conclusions IMCPB resulted in better analgesia but more adverse effects. Further studies need to ascertain optimal LA dose for IMCPB in patients undergoing thyroid surgery.
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