Bilateral superficial cervical plexus block with conscious sedation for thyroid surgery

Thyroid surgery is the commonest endocrine surgical procedure being carried out throughout the globe.1 General anaesthesia (GA) is commonly used for thyroid surgery. Bilateral superficial cervical plexus block (BSCPB) is adequate to produce anaesthesia for procedures on anterolateral aspect of neck. The advantages of regional anaesthesia (LA) with monitored anaesthesia care (MAC) are faster post-anaesthesia recovery, no throat or vocal cord irritation and potential avoidance of the adverse effects of GA2. Bilaterally superficial cervical plexus block (BSCPB) consists of a bilateral injection of local | Original | Article |


Introduction
Thyroid surgery is the commonest endocrine surgical procedure being carried out throughout the globe. 1 General anaesthesia (GA) is commonly used for thyroid surgery. Bilateral superficial cervical plexus block (BSCPB) is adequate to produce anaesthesia for procedures on anterolateral aspect of neck. The advantages of regional anaesthesia (LA) with monitored anaesthesia care (MAC) are faster post-anaesthesia recovery, no throat or vocal cord irritation and potential avoidance of the adverse effects of GA 2 . Bilaterally superficial cervical plexus block (BSCPB) consists of a bilateral injection of local | Original | Article | Bilateral superficial cervical plexus block with conscious sedation for thyroid surgery Total thyroidectomy can safely be performed by bilateral superficial cervical plexus blockade which is a regional anesthetic technique to anaesthetize superficial branches of the anterior primary rami of cervical 3-5 spinal nerves. Conscious sedation with this anesthetic technique enhance safe and faster recovery compared to general anesthesia (GA) with endotracheal intubation which is traditionally employed technique for thyroidectomy. This randomized active control trial was conducted in the department of Anaesthesia, Analgesia and Intensive care medicine, Bangabandhu Sheikh Mujib Medical University from January to December 2018 to compare perioperative outcome between bilateral superficial cervical plexus blockade and GA technique during total thyroidectomy. Total 60 patients of American Society of Anesthesiologists Classification grade I and II who were selected for thyroidectomy were randomly divided into Group-A(n=30) and Group-B (n=30). Group A received with 0.5% bupivacaine and 1% lignocaine; and group B received general anesthesia during total thyroidectomy. Heart rate, systolic blood pressure, diastolic blood pressure mean arterial blood pressure , oxygen saturation (SPO2) were recorded and compared between the groups. Operative site bleeding, surgeon's satisfaction & post operative pain were measured with Boezaart Scoring system, Likert scale & visual analogue scale repectively; and compared between two groups. During induction, systolic and diastolic blood pressure were high in group B and reduced in group A which were statistically significant. Systolic and diastolic blood pressure was significantly reduced in Group-A in comparison to Group-B after 5 minutes, 30 minutes, 45 minutes and at the end of operation. Bilateral superficial cervical plexus blockade reduced pain more effectively than GA group & it was statistically significant. Mean value of bleeding score were also statistically significant in Group-A. Regarding surgeons' satisfaction, there was no statistically significant difference between the groups. Bilateral superficial cervical plexus block with conscious sedation provided better outcome in terms of perioperative hemodynamics, pain and surgical site bleeding compared to general anaesthesia.
anesthetic behind the lateral border of the sternocleidomastoid muscle producing surface anaesthesia of the neck. 3 The patient is maintained in a state of conscious sedation. Conscious sedation can be achieved via increments of midazolam or a Target controlled infusion (TCI) of Propofol. 4 Research work also recommended that close monitoring of haemodynamics, respiratory rate and level blockade is required 5 Paul Lo Gerfo was a notable pioneer of the use of cervical plexus block in thyroid and parathyroid surgeries. 3 In this study the effectiveness of bilateral cervical plexus block with conscious sedation was observed in comparison to general anaesthesia.

Methods
This randomized active control trial were conducted in the department of Anaesthesia Analgesia and Intensive care medicine, Bangabandhu Sheikh Mujib Medical University from January 2018 to December 2018. A total of sixty (N=60) patients who were selected for thyroidectomy were included. The patients were divided into two groups (Group-A and Group-B), each group consist of thirty (30) patients.
Group A received bilateral superficial cervical plexus block with 0.5% bupivacaine and 1% lignocaine. Conscious sedation was maintained by propofol 1% at the dose of 2mg/kg/hr and fentanyl 2mgm/kg mixed with 0.9% normal saline drip. Conscious sedation was maintained at a constant level by using Ramsay sedation scale 7 level 6. All the patients were administered oxygen 5 l/min through nasal cannula. Effectiveness of superficial cervical plexus block was assessed by mechanical, touch and pinprick after performing the bilateral superficial cervical plexus block. 8 Group B received general anaesthesia using thiopental sodium and fentanyl as induction agents; & intubated by succinylcholine. General anaesthesia was maintained by halothane, nitrous oxide, oxygen and vecuronium bromide. For superficial cervical plexus block, midpoint of the posterior border of the sternocleidomastoid was identified. From this point, 12-15ml of the local anesthetic (a mixture of 20ml 0.5% bupivacaine + 10ml 1% lignocaine) was infiltrated along the border of the muscle 3cm cephalad and caudal. A further 3-5ml of the solution was also infiltrated superficially above the muscle to block the transverse cervical branch of the plexus. The block was performed on both sides of the neck using a size 21-gauge hypodermic needle.
Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) were monitored at 5 minutes interval by using sphygmomanometer and pulse oximeter. Data were recorded at 5 minutes interval for statistical analysis. Operative site bleeding was measured with Boezaart Scoring system. 9 The Boezaart scoring system is a scale assigning a numerical value from 0 to 5. Surgeon's satisfaction was measured by using Likert scale. 10 A 5-point likert scale was used to assess surgeons' satisfaction. Postoperative pain was assessed by visual analogue scale (VAS). 10

Results
The groups were similar with respect to age, gender, height, weight, body mass index, American Society of Anesthesiology physical status, heart rate, duration of anesthesia, and procedure, mean arterial pressure and end-tidal carbon dioxide. Total study population (N=60) were divided into two groups. Both groups were almost similar in respect to age, weight, height, BMI. Mean age of the patients in group-A was 27.9 3.90 and group-B was 28.1 3.85. Among them maximum age was 37 years and minimum age was 22 years in group-A and 35 years and 22 years in group-B respectively. Age distribution had no clinical impact on the outcome.
The maximum weight was 68kg and minimum weight was 58 kg in group-A and group-B. BMIof the study population between the two groups were not statistically significant(p=1.000) ( Table-I The mean value of baseline systolic blood pressure (SBP) was 118.7±6.8 in group A and 118.3±6.3 in group B, baseline diastolic blood pressure (DBP) was 78.8±3.0 in group A and 78.8±3.0 in group B, and baseline mean arterial blood pressure Chi-square was performed to see the association between two groups, ns = not significant, Unpaired student t-test was performed to compare mean age between two groups, ns = not significant.

Variables
Group   Table-II    Other adverse effect 2 5 Among group A we found 3.23±1.65 and4.13±1.47 in group B. This change was statistically significant(p=0.030). (Table -IV) Regarding surgeon's satisfaction both groups showed same score. That means in both group surgeon was satisfied. This result was not significant (p= 1.00) ( Table -V).

Comparison of recovery status between two group
Recovery status was measured by three parameters Modified Aldrete Score , Recall of any pain, pressure or noise and others adverse effect. Regarding the Modified Aldrete Score 25 patients scored 10 out of 10 and only 5 patients scored 9 out of 10 in group A. In group B 21 patients scored 8, 9 patients scored 9 out of 10. In group A only 3 patients recalled about pressure and noise during operation. In group B 2 patients recalled about pain during operation time. There was no other adverse effect observed during operation in both groups. (TableVI)

Discussion
Thyroid surgery is commonest endocrine surgical procedure being carried out throught the throughout the globe. 1 General anaesthesia is commonly used for thyroid surgery, Bilateral superficial cervical plexus block(BSCPB) is adequate to produce anaesthesia for procedures on anterolateral aspect of the neck.The advantage of regional anaesthesia (LA) with monitored anaesthesia care(MAC) are faster post operative recovery and potential avoidance of adverse effect of GA.
In this study total population (N=60) selected for thyroidectomy was divided into two groups. Group A: received bilateral superficial cervical plexus block with conscious sedation and group Group B: received general anaesthesia. General anaesthesia is commonly used for thyroidectomy. But now a days bilateral superficial cervical plexus block is being accepted in many parts of the world 3 . William B. Inabnet et al also used local/ regional anaesthesia with conscious sedation for thyroid surgery. 11

Table-V
Data were expressed as frequency and percentage and mean±SD Unpaired student t-test was performed to compare between two groups *significant, ns = not significant to group B. In group A 50% patient showed mild bleeding 1, 33% patient showed mild bleeding 2 and 12% patient showed mild bleeding 3. On the contrary 66.7% patient showed mild bleeding 3 and 15% patient showed moderate bleeding during operation in group B. This changes were statistically significant. So bilateral superficial cervical plexus block reduces blood loss and provide better surgical condition in comparison to general anaesthesia. Guay J found similar observation. 13 Regarding for post-operative pain assessment by VAS (Visual Analogue Scale) 6 this study showed VAS score was 1 in 80% cases of group A. On the other hand, VAS score was 5 in 80% cases of group B. This indicate bilateral superficial cervical plexus block reduces post-operative pain more effectively than general anaesthesia as this change was statistically significant where p value was<0.013.Comparisom with other study showed that Shukla V K et al observed in their study the post-operative requirement of analgesic was much less in the local anaesthesia group than general anaesthesia. 14

Conclusion
It was concluded that bilateral superficial cervical plexus block with conscious sedation provide better outcome in terms of peroperative haemodynamics, surgeons satisfaction, reduce per operative surgical site bleeding for thyroidectomy patients in comparison to general anaesthesia

Conflict of interest:
Authors declared no conflict of interest.