Evaluation of Analgesic Efficacy of Preoperative Bilateral Superficial Cervical Plexus Block in Patients Undergoing Thyroidectomy under General Anaesthesia: A Study of 60 Cases

The aim of the study was to prospectively evaluate the analgesic efficacy of preoperative bilateral superficial cervical plexus block in patients undergoing thyroidectomy under general anaesthesia. This study included 60 eligible patients who were divided into two groups, 30 in each. Study Group received bilateral superficial cervical plexus block with Bupivacaine 0.25% 10ml on each side, Control Group received bilateral superficial cervical plexus block with normal saline 10 ml on each side. Block was performed 20 mins prior to induction using landmark technique. After waiting for onset time of around 10 – 15 minutes the blockade was assessed by pin prick by a separate assistant, General Anaesthesia was given to all patients. Anaesthesia was standardized for all patients. Intraoperative monitoring was done using multipara monitor which includes pulse rate, saturation, bloodpressure, end tidal carbon dioxide and electrocardiography.If mean arterial pressure or heart rate rises by more than 20% above basal values addition fentanyl citrate dose of 0.5 μg /kg was given. At end of the surgery residual neuromuscular blockade was reversed and patients were extubated. After extubation, laryngoscopy was done to evaluate the vocal cord movements and then patient transferred to post anaesthetic care unit. In post anaesthetic care unit, post-operative pain assessment was done by using visual analogue scale score (VAS score) when patient was able to communicate (H0),then after every 3 hours for the first 12 hrs (H3, H6, H9, H12) and every 6hrs until 24 hrs(H18,H24). Patients stayed for 2 hours in PACU, then shifted to Surgical Intensive Care Unit (SICU). If VAS ≥ 40mm, Morphine 1 – 2 mg given IV, then patients were assessed every 10 minutes until VAS score becomes <40mm. Observations: Complications of the procedure like vascular puncture, hematomas etc. if occurred were noted down.Only successful blocks were considered for study group. Demographic details were comparable in both groups. Base line hemodynamic variables were also comparable in both groups. In the intraoperative period, the total dose of intraoperative opioid used was noted. In the postoperative period number of patients having VAS ≥ 40mm at H0, morphine requirement in PACU and patients requiring morphine in SICU and its dosage were recorded. Post operatively patients were monitored for any episodes of bradycardia, hypotension, nausea, vomiting, excessive sedation and respiratory depression - respiratory rate and oxygen saturation was monitored. Of the two groups intraoperative fentanyl requirement in study group was 79.7 ± 8.7μg and in control group was 132.5 ± 14.2μg which was significant (p value = 0.0001). Study group had a morphine requirement of 0.83 ± 1.93 mg ,1.97 ± 2.37 mg and 2.8 ± 3.6 mg in post anaesthetic care unit , surgical intensive care unit and in the first 24hour postoperative period respectively while control group had 6.13 ± 3.59 mg, 5.07 ± 1.74 mg and 11.2 ± 4.1 mg in post anaesthetic care unit, surgical intensive care unit and in the first 24 hour postoperative period respectively which was statistically significant (p value= 0.0001). Overall 93.3% patients in the control group required morphineat any time during first 24 hours postoperatively compared 43.3% patients in study group which was statistically significant (p value 0.0001). 70% patients in control group had VAS score of > 40mm in immediate post-operative period (H0) compared to 16.7% in study group which was significant statistically (p value 0.0001). Five patients in study group and Eight patients in control group had post-operative vomiting. Even though control group had higher incidence, it was not statistically significant (‘p’ value 0.5308). In study group, maximum Ramsay sedation score was two. Even though 13.3% patients in control group had sedation score of three, it was not statistically significant (‘p’ value 0.0562). There was no incidence of bradycardia, vascular puncture, hypotension, respiratory depression, and fall in oxygen saturation, phrenic nerve palsy, epidural or intrathecal injection or local anaesthetic toxicity in both the groups. CONCLUSION: In conclusion, the data and the statistical analysis suggest that “Bilateral superficial cervical plexus block”is an effective and safe peripheral nerve blockade technique which reduces opioid requirements both intra operatively and post operatively and also reduces pain intensity score in post-operative period without any serious complications for patients undergoing thyroid surgeries under general anaesthesia