MATERIAL & METHODS

â–ª         Study Settings:The study will be conducted in Department of Anesthesiology, King George’s Medical University, Lucknow.

â–ª         Study design: Randomized controlled study

â–ª         Study duration: 1.5 years

Sample size: 20 in each group

The sample size formulae used are as follows: (Bernard, 5th edition) [10]

                                      n=

n= (0.76.6²+58.9²)/1(1.645+0.84)²

54.2²

n= (5867.56+3469.21)/1(6.18)

2937.64

       n= (9336.77) (6.18) = 57701.2386 = 19.687≈20 in each group

                                               2937.64              2937.64

n= Sample size

σ₁ = Estimated Standard Deviation cases [=76.6]

σ_{2 =} Estimated Standard Deviation control [=58.9]

∆ = Difference of means [=54.2]

κ= Ratio [=1]

Z_1-α/2= Two-sided Z value [=1.645]

Z_1-β= Power [=0.84]

Assuming a dropout of 5%, we will consider total sample size of 48.

  Inclusion criteria:

â–ª         Patients of age above 18 years of either gender.

â–ª         Patients with ASA grade I and II.

â–ª         Patients undergoing total thyroidectomy surgery under TIVA.

â–ª         Patients who give consent form.

Exclusion criteria:

●       Patients with a history of allergies to local anaesthesia.

●       Contraindication to regional anaesthesia (like patients on anticoagulants)

●       Coagulopathy, chronic use of opioid analgesia or opioid analgesic, analgesic intolerance.

●       Patients with huge goitre.

STUDY PROTOCOL

Ethical clearance and Written and Informed consent will be taken.

The study will be done at King George Medical University, Lucknow.  A total number of 48 patients who are planned for total thyroidectomy will be enrolled in the study and will be randomly allocated to one of the two groups.

After establishing a standard monitoring procedure for general anaesthesia, all patients will be preoxygenated with 100% O2 (O2 flow at 10 litres/minute) for 3 to 5 minutes. Thereafter all patients will be induced with 1.5 mcg/kg of fentanyl and 1.5 to 2.5 mg/kg of propofol and injection vecuronium (0.1 mg/kg). After 3 minutes of controlled  bag and mask ventilation,   the patient will be intubated with endotracheal tube of appropriate size. The patients will be administered TIVA (Propofol at a rate of 50-100 mcg/kg/min) and injection vecuronium for maintenance.

Maintenance of anaesthesia will be by oxygen, air, propofol infusion (at a rate of 50 -100 mccg/kg/min) and fentanyl will be used as per requirements. After completion of surgery propofol infusion will be stopped and patient will be taken on 100% O2 and will be reverted with injection neostigmine (0.04 to 0.08 mg/kg)  and glycopyrrolate (0.005 to 0.01 mg/kg) after return of spontaneous circulation  and will be extubated on eye opening.

After inducing general anaesthesia, the anesthesiologist will administer ultrasound-guided bilateral superficial cervical plexus blocks prior to making the incision by the surgeon. In this technique, the patient is positioned supine with head turned towards contralateral side. The high-frequency linear probe (6Hz to 13Hz) is placed in a transverse orientation for an in-plane approach (parallel to the probe axis). This is done at a location over the midpoint of the posterior border of the sternocleidomastoid muscle. This also approximates the level of C4 and the notch of the thyroid process. The probe marker is pointed medially towards the thyroid cartilage. Skin is prepared using chlorhexidine or an iodine-based solution and the local parts are draped. The needle (usually 25 to 27 gauge, 1 ½ inch length) is inserted in lateral to medial direction 1 cm to 2 cm directly under the posterior border of the sternocleidomastoid muscle. The needle should enter at the level of the thyroid cartilage (located halfway between the clavicle and mastoid bone). The needle tip is placed in a position to inject the local anesthetic just deep to the posterolateral tapering sternocleidomastoid muscle and superior to the levator scapula as this thick fascial layer is the location of the cervical plexus. The needle tip should not be further than 2 cm deep to prevent inadvertent injection into underlying structures. While directly visualizing the needle tip to prevent inadvertent intravascular injection, inject approximately 10 mL of local anesthetic. 15 minutes before completion of the surgery, all patients will receive intravenous paracetamol injection 1gm and thereafter it will be repeated every 6 hourly. In this study, patients will not be aware of, in which study group they are enrolled, and the observer who collects the data during intraoperative and postoperative period will also be blinded about the study group in which the patients are enrolled.

All post-operative patients will be transported to the PACU.  We will record incidences of postoperative pain (including VAS scores), nausea, and vomiting. If a patient’s pain on the VAS (where 0 means no pain and 10 is the worst agony imaginable) is greater than 3, tramadol hydrochloride (1 mg.kg1) will be administered. Ondansetron is administered to patients who experience nausea or vomiting. The VAS scores of patients will be evaluated at 0 hour (immediately after extubation), 1 hour, 2 hour, 6 hour, 12 hour, 24 hour, and 48 hours. Each patient’s total tramadol hydrochloride consumption and ondansetron dosage will be documented. We will also record intraoperative fentanyl, propofol and vecuronium consumption. Intraoperative and postoperative vitals will be recorded and any incidence of hypotension or bradycardia will be reported.

Statistical Analysis:

Data will be entered in Microsoft Excel and analyzed using statistical software SPSS version 26.0 (Chicago, IL, USA). The continuous variables will be evaluated by mean (standard deviation) or range value when required. The dichotomous variables will be presented in number/frequency and will be analyzed using Chi-square or Fisher Extract test. For comparison of the means between the two groups, analysis by Student t-test, Mann-Whitney U test, and Spearman correlation with 95% confidence interval will be used. A p-value of < 0.05 will be regarded as significant.

REVIEW OF LITERATURE

Eti Z et al., (2006) [9] evaluated and compared the analgesic efficacy of bilateral superficial cervical plexus block and local anesthetic wound infiltration after thyroid surgery. Forty-five patients were assigned to 3 groups. After general anesthesia induction, bilateral superficial cervical plexus block with 0.25% bupivacaine 15 mL in each side was performed in Group I, and local anesthetic wound infiltration with 0.25% bupivacaine 20 mL was performed in Group II. In Group III (control) no regional block was administered. Intravenous patient-controlled analgesia was used to evaluate postoperative analgesic requirement. Neither visual analog scale scores nor total patient-controlled analgesia doses were different among groups. We concluded that bilateral superficial cervical plexus block or local anesthetic wound infiltration with 0.25% bupivacaine did not decrease analgesic requirement after thyroid surgery.

Sardar K et al., (2013) [10] evaluated the analgesic efficacy of bilateral superficial cervical plexus block after thyroid surgery. Sixty patients were assigned to two groups. General anesthesia was induced with 2mg/kg propofol, 0.1mg/kg vecuronium and 1.5μg fentanyl IV for both group. After endotracheal intubation, bilateral superficial cervical plexus block with 0.25% bupivacaine 15ml in each side was performed in Group I. In Group II (control) no regional block was administered. Intravenous on demand analgesic was used to evaluate postoperative analgesic requirement. Neither visual analog scale scores nor intravenous analgesics doses were different between the groups. The first analgesic requirement time in Group I was significantly longer than for the control group. The incidence of nausea and vomiting was significantly lower in Group I than Group II. We concluded that bilateral superficial cervical plexus block with 0.25% bupivacaine did not decrease analgesic requirement after thyroid surgery.

Hassan AH et al., (2021) [11] aimed to evaluate the analgesic effect, onset time of sensory block, duration time, postoperative visual analogue score (VAS) and complications of adding dexmedetomidine versus dexamethasone to levobupivacaine for cervical plexus block. A prospective, randomised clinical trial conducted between April 2018 and March 2020 at Sohag University. Fifty patients with (ASA) Class I or II, ages 30 to 60, who were scheduled for euthyroid procedures (including thyroid adenoma, Hashimoto’s goitre, and nodosity thyroiditis) were included in the study. The addition of dexmedetomidine to levobupivacaine (group D) decreased the onset time of sensory block compared to the addition of dexamethasone to levobupivacaine (group S; p<0.05). The duration of analgesia from cervical plexus block was significantly prolonged in group (D) than in group (S) (p<0.05; 232.34 versus 303.55 minutes). (p<0.05) The HR level in group (D) was significantly lower than that in group (S). The addition of 1 μg kg^-1 dexmedetomidine to levobupivacaine for cervical plexus block (BSCPB) decreased the sensory block onset time, enhanced the duration and quality of analgesia, and was superior to the addition of dexamethasone.

Karakış A et al. (2019) [12] investigated the intraoperative and postoperative analgesic efficacy of bilateral superficial cervical plexus blocks. Patients undergoing thyroidectomy (n = 46) were randomly divided into 2 groups: general anaesthesia (GA; n = 23) and general anaesthesia plus BSCPB (GS; n = 23). The intraoperative analgesic requirement (remifentanil) and VAS score at numerous postoperative time points (after extubation, at 15, 30, 1, 2, 6, 12, 24, and 48 hours) were evaluated. The total amount of tramadol, paracetamol, and ondansetron consumption was recorded. Significantly less intraoperative remifentanil was required in the GS group than in the GA group (p = 0.009). 15 (p<0.01), 30 (p<0.01), 1 (p<0.01), 2 (p<0.01), 6 (p<0.01), 12 (p<0.01), and 24 (p = 0.03) hours postoperatively, the GS Group had significantly reduced pain scores than the GA Group. The GS Group required substantially less tramadol following surgery than the GA Group (p = 0.04). Significantly fewer patients utilised ondansetron in the GS group compared to the GA group (p = 0.004). They concluded that BSCPB with 0.25 percent bupivacaine decreases postoperative pain intensity and opioid dependence in patients undergoing thyroid surgery.

Tang C et al. (2017) [13] discusses the evidence supporting the preoperative, intraoperative, and postoperative efficacy of dexmedetomidine as an adjuvant, as well as the efficacy of intravenous, spinal canal, and nerve block analgesia with dexmedetomidine for the treatment of perioperative acute pain. Dexmedetomidine is appropriate for use as an adjuvant analgesic at all perioperative stages, despite the absence of large-scale clinical trials. However, there are potential adverse effects, such as hypotension and bradycardia,that clinicians must take into account.

Santosh BS et al. (2016) [14] examined the impact of dexmedetomidine on the duration and quality of analgesia generated by BSCPB with 0.5% ropivacaine in thyroid surgery patients. In this prospective, double-blind study, 60 adults undergoing thyroid surgery were randomly assigned to receive BSCPB with either 20 ml 0.5% ropivacaine (Group A) or 20 ml 0.5% ropivacaine with 0.5 µg/kg dexmedetomidine (Group B) after induction of anaesthetic. VAS was used to assess postoperative analgesia at 0, 2, 4, 6, 12 and 24 hours and patient satisfaction at 24 hours. Intraoperatively, hemodynamics were documented. VAS and sedation scores were analysed using the Wilcoxon signed-rank and Mann–Whitney U tests, respectively. Age, weight, duration of surgery, and duration of postoperative analgesia were evaluated using the unpaired t test. Significantly prolonged analgesia duration (1696.2±100.2 vs. 967.8±81.6 min; P<0.001) and greater patient satisfaction at 24 hours were observed in Group B (7 [7–9] vs. 5 [4–6]; P<0.001). While VAS scores for pain were comparable up to 6 h, at 12 h (0 [0–1] vs. 2 [1–2]; P 0.001) and 24 h (2 [2–2] vs. 5 [5–6]; P<0.001) they were lower in Group B. The scores for haemodynamic stability and sedation were comparable between groups. There were no side effects. However, respiratory discomfort persisted in both groups. In patients undergoing thyroidectomy, the combination of 0.5% ropivacaine and dexmedetomidine for BSCPB substantially improved postoperative analgesia and patient satisfaction compared to 0.5% ropivacaine alone.

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