INTRODUCTION:
After thyroid diseases, hyperparathyroidism is one of the most common endocrine surgical disease [1]. It occurs either from a disorder within the parathyroid glands (primary hyperparathyroidism) or disorder outside the parathyroid glands (secondary or tertiary hyperparathyroidism) [2]. In recent years, since described by Kocher in the late 1980’s, treatment of hyperparathyroidism was the surgical removal of 4 parathyroid glands with transcervical incision [2-4]. After, realisation of that a single adenoma is the cause of hyperparathyroidism in most of the patients (80-85%), surgical management was changed significantly [2]. With preoperative imaging tools (ultrasound and technetium-99m sestamibi scintigraphy) for localisation of the adenoma and intraoperative parathyroid hormone level measurements for confirmation, surgical excision of the offending parathyroid adenoma is still accepted as the main treatment of primary hyperparathyroidism[1,2,5].
The increasing diagnosis of thyroid pathologies in early stages and a societal emphasis on physical appearances, especially in young women, have been led to development of new surgical techniques alternative to conventional transcervical incision consistently [3,6]. Over the last two decades, so many techniques such as Open Minimally Invasive Parathyroidectomies (OMIP), Minimally Invasive Video-Assisted Parathyroidectomy (MIVAP) and pure Endoscopic Minimally Invasive Parathyroidectomy (EMIP) and recently transoral endoscopic parathyroidectomy vestibular approach (TOEPVA) have been developed [3,7].
Here, we describe our anaesthesia experience for parathyroidectomy with Transoral Endoscopic Parathyroidectomy by Vestibular Approach (TOEPVA). According to our knowledge, this is the first report that explain anaesthesia management in TOEPVA.
Methods: Seven patients undergo TOEPVA at the Health Sciences University Izmir Bozyaka Training and Research Hospital between November 2018 and April 2019. All patients were diagnosed with primary hyperparathyroidism due to a solitary parathyroid adenoma, and were managed by the same anaesthetist and by the same experienced surgeon on minimally invasive and endocrine surgery. Demographic data, drugs used for anesthesia management (induction, maintenance and extubation), hemodynamic parameters, end tidal carbondioxide and pulse-oximeter values, additional agents used preoperatively in anesthesia management and preoperative and peroperative measurements of PTH levels were recorded prospectively and evaluated retrospectively.
Preoperative setting: After informed consent of patient was approved for anaesthesia, all patients received preoperative anaesthesia evaluation, including laboratory tests and imaging studies (chest radiography, focused ultrasound for parathyroid adenoma mapping). Also preoperative PTH levels were obtained to compare intraoperative rapid parathormone levels. All patients received amoxicillin-clavulanic acid (1.2 gr) 30 minutes before the incision as antibiotic prophylaxis.
Anaesthesia management: After routine monitorization (Non-invasive blood pressure, electrocardiogram, end tidal carbondioxide and pulse-oximeter), anaesthesia was induced with propofol (2mg/kg), remifentanil infusion (0.01-0.5 mcgr/kg/min) and rocuronium (0.6mg/kg) was administered to facilitate the tracheal intubation. Airway patency was achieved by nasal intubation with an inner diameter of 6.5 mm spiral endotracheal tube in six patients and with an inner diameter of 6.0 mm spiral endotracheal tube in one patient. Eyes were carefully closed to keep them closed peroperatively and to prevent contact with the solution (chlorhexidine and povidone iodine) used to clean the vestibular area. Dexametazone (8mg) and H2 blocker (50 mg) were applied to all cases after anesthesia induction as routine clinical practice. Anaesthesia was maintained with desflurane 5% to 6% concentration in a gas mixture consisting of 45 % oxygen in air. All patients were ventilated on
volume control ventilation mode with 5-7 mL / kg tidal volume and respiratory rate was modified to keep the end tidal carbondioxide within the normal values. Pulse-oximeter values were changed between 96-100% in all patients peroperatively. Neuromuscular blocker dose was repeated every 30 minutes routinely and also administered as rescue bolus dose if the view of surgical field was worsened. After removal of parathyroid adenoma, which was verified by histopathological examination and by blood PTH level decrease, we administered contramal as 0.3 mg/kg intravenously for postoperative analgesia. At the end of the operation, sugammadex (2-4 mg/kg) was administered to reverse the neuromuscular block. All patients transferred to Post Anaesthesia Care Unit (PACU) at the end of the operation and to their ward one hour after PACU stay, uneventfully.
Surgical management: All patients were operated by the same principles of TOEPVA which was described by Anuwong at al (8). In detail, the patient is placed in a supine position with slighlty neck extention. After a proper surgical preparation, a 10-11 mm transverse incision is made at the center of the oral vestibule just below the vermilion border. Once the periosteum is approached and identified by electrocautery and blunt dissection through the central incision the neck area is injected with 20 to 40 mL diluated epinephrine (0,5 mg epinephrine in 500 mL saline) by a Veress needle. About 2,5 cm distance from this central incision two additional 5mm vertical incisions are made on both sides, above and as lateral as possible to the canine teeth to avoid mental nerve injury. These lateral trocar sides are also prepared by injection with the same diluated epinephrine solution of 5 to 10 mL. Then, one central 10-11mm and two lateral 5mm trocars are inserted and CO2 insufflation is began at a maximum pressure of 6 mmHg with a flow rate of 6 L/min to create an air pocket to perform parathyroidectomy with ordinary laparoscopic instruments.
Results: The patients characteristics, preoperative, operative and postoperative details are shown in Table 1. Two patients (Case 1 (Heart rate: 43/min) and Case 5 (Heart rate: 41/min)) required atropine (0.5 mg) and one patient (Case 2) (Blood pressure: 60/40 mmHg) required ephedrine (10 mg) administration during insufflation. While all patients require lower dose remifenantil infusion during drapping and preparation for surgery after induction of anaesthesia; required higher doses remifentanil during hyrodissection. Except insufflation and hyrodissection phases of surgery, patients hemodynamic parameters were stable (changed ±20% from baseline) during the operation time. Changes in mean arterial pressure and heart rate in cases by the operation time were shown on Figure 1 and Figure 2 respectively. No conversion to conventional open surgery was necessary. In all patients, intraoperative parathyroid hormone level decrease was confirmed by laboratory test.