Participants
This study was approved by the Ethics Committee of the Anqing Affiliated Hospital of Anhui Medical University.The study was prospective registered in the Chinese Clinical Trial Registry on November 4,2019 (ChiCTR1900027185).Before surgery,each patient signed an informed consent. The study conducted at the Anqing Affiliated Hospital of Anhui Medical University from November 2019 to October 2020.
Female or male patients aged 18-and 65-years-old,of American Society of Anesthesiologists (ASA) physical status Ⅱ-Ⅲ,scheduled to undergo total parathyroidectomy were eligible.Patients were excluded if they had platelet abnormality, coagulation abnormalities, anticoagulation,serious cardiovascular and cerebrovascular diseases, hypertension(predialysis diastolic blood pressure, DBP > 110mmHg), hyperkalemia, amino-amide local anesthetic allergy, local sepsis, or diaphragmatic motion abnormality and refusal to participate .
All eligible participants were randomised to the BSCPB group and the CON Group with a 1:1 allocation using computer-generated random number. Group assignments were kept in sealed envelopes, and only the nurse responsible for preparing the local anesthetic was allowed to open the envelope and the assigned drug. The assigned drugs according to group assignments in syringes which had no difference in appearance. The patients, data collectors (anesthesiologist) did not know the drugs used for bilateral superficial cervical plexus block. All of the patients were NPO since approximately 6 hour before surgery.
Study Protocol
All surgeries were performed by three experienced surgeons.The patients were not given any preoperative medication. A dialysis was performed routinely within 24 hours before surgery. The arteriovenous fistula of long-term dialysis patient should be protected by medical staff during surgery. Noninvasive blood pressure (NBP), heart rate (HR), electrocardiogram (ECG) and peripheral pulse oximeter (SPO2) values were monitored by using a multiparameter monitor (Philips MX500, Boeblingen, Germany).Intravenous catheter was inserted into the forearm without arteriovenous fistula, and ringer's solution was intravenously administered through the catheter at the rate of 3ml/kg/h.
As described by Tran et al.[14] all bilateral blocks were performed by the attending anesthesiologist who experienced in techniques including ultrasound and nerve block before the induction of anesthesia.Patients were lying supine, and their heads were rotated to the opposite side of the block. The ultrasound probe and the skin of the blocked area were routinely sterilized.The high-frequency linear ultrasonic probe was placed on the posterior margin of sternocleidomastoid(SCM) muscle at the level of C4.At the posterior corner of the SCM muscle, the superfcial cervical plexus was visualized as a hypoechoic structure. The 22-gauge needle was inserted under the SCM muscle with the in-plane technique.The needle position and location were confirmed by injecting 0.5-1ml of solution after negative aspiration of no blood and air, 7.5 ml ropivacaine 0.5% was administered on each side in the BSCPB group,while equal amount of normal saline was administered in the CON group. After being administered, no block-related side effects such as anesthetic toxicity, epidural block anesthesia, total spinal block anesthesia, recurrent laryngeal nerve blocked, phrenic nerve blocked, or Horner's syndrome were confirmed, then the induction of general anesthesia was performed.
General anesthesia was induced with midazolam (0.02mg/kg), propofol (2.0mg/kg), sufentanil (0.3µg/kg) and cisatracurium (0.15mg/kg), and anesthesia was maintained with propofol (50–80 µg/kg/min) and remifentanil (0.15–0.2µg/kg/min). Tracheal intubation was performed after adequate muscle relaxation. All of the patients were ventilated with an Aspire view anesthetic machine (GE Healthcare, Madison, WI, USA)in volume control mode. In two groups, the tidal volume (VT) was maintained at 8-10ml/kg, the respiratory rate (RR) was fixed at 10–12 breaths/min, the inspiratory to expiratory time ratio (I: E) was 1:2 and the inspired oxygen fraction (FiO2) was 0.5 (balanced with air) throughout the anesthesia period. To maintain a controlled ventilation, cisatracurium was intermittently used for muscle relaxation. The depth of anesthesia was maintained with an infusion rate of propofol and remifentanil, according to the Bispectral Index values (BIS) and the hemodynamic parameters within 20% of the baseline. To prevent the occurrence of intraoperative awareness, the BIS values were kept between 45 and 60 in the both groups during surgery. Experienced surgeons preserved the anatomical integrity of motor nerves by visual identification and exposure both of the external branch of the superior laryngeal nerve and the recurrent laryngeal nerve, and the recurrent laryngeal nerve was prevented injury by intraoperative neuromonitoring during parathyroidectomy. All patients were retained the endotracheal tube and transferred to post anesthesia care unit (PACU).The endotracheal tube was removed after full recovery of consciousness and spontaneous ventilation,and the train-of-four (TOF) ratio at least 0.9. If the Steward recovery score was > 4 points, patient was escorted back to the ward from PACU.The administration of postoperative routine analgesia was IV infusion of parecoxib sodium 40mg at the end of surgery, followed by a IV infusion of parecoxib sodium 40mg every 12h for the next 24h. If the visual analogue scale (VAS) score at least 3 or patient requested for analgesia, IV infusion of tramadol 50mg was given as a rescue analgesic.
Data Collection
Demographic and clinical characteristics including gender, age, height, weight, ASA physical status, RBC (red blood cell count), HGB(hemoglobin), PLT (platelet), APTT (activated partial thromboplastin time), PT(prothrombin time), TT (thrombin time), Fib (fibrinogen) were recorded.Preoperative and postoperative serum K+ (potassium)concentration, serum Ca2+ (calcium ion)concentration, serum phosphate concentration,and PTH level were recorded. Intraoperative fluid input and intraoperative blood loss were recorded. Each patient was assessed using the global QoR-40 score on the day before surgery, and POD1.QoR-40 includes five dimensions: emotional state(9 items), physical comfort (12 items), physical independence (5 items), psychological support (7 items), and pain(7 items). Each item is assessed using a 5-point numerical rating scale.The score of QoR-40 ranges from 40 to 200.The recovery state is proportional to the score (40 = extremely poor recovery, 200 = all excellent recovery)[15].The first time to require rescue analgesia,the numbers of patient requiring rescue analgesia,and total consumption of tramadol during the first 24h after surgery were recorded. The total consumption of propofol and remifentanil was recorded. The incidence of PONV was recorded. The VAS score at 2, 4, 8,12and 24h after surgery was rated using a 10cm visual analogue scale (VAS: 0 = no pain, 10 = the most imaginable pain).
Statistical analysis
Calculation of sample size was based on the global QoR-40 scores.A change of 10-point or more for QoR-40 signify a clinically important difference. In our pilot study, an overall standard deviation of 13 points was estimated and an α of 0.05, 37 patients would be required in each group (assuming a power of 80%). Anticipating a study drop-out rate of 10%, we included 41 patients per group.
Data analysis was performed using SPSS version 23.0 (SPSS Inc, Chicago, IL). Continuous variables were presented as Means(standard deviations,SD).Normally distributed variables were compared using the Student’s t-test.The VAS scores were analysed using linear mixed model with a Bonferroni correction. Non-normally distributed variables were compared using the Mann– Whitney U test.The qualitative data were presented as number or percentage, and compared using the Chi-square test. P values of less than 0.05 were considered to be statistically significant.