The study consists of enrollment period until 74 participants acquired (37 will be in each arm), a treatment period (day of surgery), and a 2 week follow up period.
A web-based randomizer (https://randomizer.org/) will be used to randomly assign participants into Group A (bilateral superficial cervical plexus blocks + local wound infiltration) and Group B (placebo + local wound infiltration). Numbered envelopes with respective assignments and medications sealed within will be prepared by a research assistant separate from the surgical team and brought to the operating theater together with subjects. Participants and surgeons will both be blinded to the intervention.
Induction of anesthesia will occur prior to performing a block. All participants will be closely monitored by anesthesia, including BP, HR, SpO2, tidal volumes, peak pressures, CO2.
Participants who are randomized to the bilateral superficial cervical plexus blocks + local wound infiltration (Group A) will have 10mL of 0.25% Bupivacaine injected bilaterally (total 20mL) at Erb's point, which is located at the mid-point between the mastoid process and the posterior border of the clavicular head of the sternocleidomastoid muscle (SCM). The injection is just below the lateral border of the SCM, which produces surface level anesthesia of the neck, targeting superficial nerves of the cervical plexus (1). Injections will be aimed at just below the dermis. Then 10mL of 0.25% Bupivacaine will be injected at the planned neck incision (local wound infiltration). The participants randomized to the placebo+local wound infiltration group will have 10mL of 0.25% Bupivacaine injected at the planned neck incision, with 10mL of normal saline injected at bilateral Erb's point (total 20mL). All injections will be performed by the same team of two surgeons and with 22 gauge needles to standardize the technique. Surgery will be performed according to standard clinical care, also by the same group of surgeons, standardizing the surgical technique.
As is our standard practice following thyroid surgery, participants will be observed for at least 4 hours in the post anesthesia care unit for postoperative complications, adequate pain control, neck hematoma, and possible complications from the BSCPB. These rare complications can include CNS toxicity, partial brachial plexus palsy, Horner's syndrome, or recurrent laryngeal nerve block. All participants will be assessed at 3-5 hours after surgery to ensure their post operative pain is acceptable on oral medications and they do not have any of the above complications. They will either stay overnight or be discharged home with standardized discharge instructions and pain medication regimen, which will include taking Tylenol every 6 hours, alternated with ibuprofen. This pain regimen will be used for participants unless changed for clinical contraindications as determined by the attending surgeon. If participants request additional medication, they will be prescribed with a few pills of 5mg oxycodone, which they can take up to every 4 hours.
A primary outcome will be postoperative pain. Neck pain intensity will be quantified using the numeric rating scale (visual analog score 0-10, VAS) at 3-5 hours (in post anesthesia care unit), post operative day 2, via telephone call, and 2 weeks +/- 3 days postoperatively (at their follow up video visit). In addition, comparisons between groups will be made for 48-hour opioid usage by participants self-reporting at the post operative day 2 follow up phone call.
Another primary outcome is the 15-item quality of recovery questionnaire score at post operative day 2 and two weeks postoperative.
Incidence of nausea, vomiting, dysphagia or hoarseness in the first 2 days after surgery will also be measured (roughly the first 48 hours after surgery).
The planned data analysis for quality of recovery scores will be done using independent t test, with 95% confidence interval and two-tailed p values reported. Significance levels will be set at p=0.05. The investigators plan to analyze pain scores across the 3 periods with linear regression, with output the difference between the groups across all periods (95% CI and p=0.05) and the difference between the groups in each period (95% CI and p=0.05). The 48-hour opioid usage will be likely analyzed by using independent t test with 95% confidence intervals and two-tailed p values reported (p=0.05). Nausea, vomiting, hoarseness, dysphagia will be recorded as categorical variables and the investigators plan to analyze them using the Pearson chi-squared test.
