Thyroid & Parathyroid Surgery Flashcards
Discuss purpose of intraoperative neuromonitoring for thyroid and parathyroid surgery
- Helps surgeon to identify neural structures close to thyroid and parathyroid glands
- Can map the external branch of SLN, RLN and vagus nerve using direct elective nerve stimulation to:
o Detect anatomical variations
o Check and clarify the mechanisms of potential nerve injury
o Predict outcome of vocal cord movements - Integrated surface electrodes are placed between vocalis muscles to record RLN function.
- EMG feedback from vocal muscles monitors function of the nerves during IONM
How does unilateral RLN injury present?
Alterations in phonation, swallowing, and breathing with varying degrees of impairment
How does bilateral RLN injury present?
Respiratory distress
How does injury to the EBSLN present?
Vocal fatigue and alterations in vocal range and pitch
How do NMBD affect IONM?
NMBDs reduce EMG-evoke response and amplitude, and increase risk of nerve injury.
Rocuronium is commonly used due to its rapid onset, titratable duration and reversal.
Using 1mg/kg Sugammadex after 0.6mg/kg Rocuronium induces less bucking than 2mg/kg
How does your choice of maintenance anaesthetic agent affect IONM?
Depression of IONM signals is greater with halogenated agents than with TIVA
What strategies could you employ to reduce the incidence of coughing intraoperatively and for extubation?
Lidocaine may help suppress coughing, bucking and swallowing during anaesthesia and may help reduce misposition of electrodes.
(1.5mg/kg loading dose followed by 1.5mg/kg/hr infusion)
Dexmedetomidine
0.5mcg/kg followed by 0.4mcg/kg/hr infusion
Using Remifentanil with TIVA or volatiles can prevent coughing at emergence
What is the incidence of difficult airways n patients for thyroid/parathyroid surgery?
10%
What are the risk factors for difficult airways in thyroid and parathyroid surgery?
Male Sex
BMI > 30kg/m2
Goitre
Signs and symptoms of tracheal compression
Tracheal Deviation
Mallampati Score >3
Interincisor gap < 4.4cm
Thyromental distance <6.5cm
Neck circumference >40cm
NC/TMD ratio > 5
How would you evaluate the airway preoperatively?
Fibreoptic visualisation is recommended to:
- Determine preoperative vocal cord palsy
- Visualise anatomical alteration/deviation
Presence of thyroid pathologies is a predictor of difficult tracheal intubation or FMV
How would you intubate a patient with anticipated difficult airway?
Awake tracheal intubation is used in patients with anticipated difficult airway due to tracheal compression (both flexible bronchoscope and video-laryngoscopy)
Consider intubation in seated or semi-recumbant position (30 degrees)
Manage sedation, topicalization, oxygenation and performance
How would you manage the airway if the patient had an obstructed or narrowed airway?
- Minimise sedation
- Consider lower Lidocaine concentrations
- Use HFNO
- Experienced practitioners
How would you plan for an unsuccessful Awake Tracheal intubation?
- Stop and Think
- FONA Access or
- High risk GA
Consider in patients with short neck, goitre, and indistinct anatomical landmarks may lead to difficulties in ATI-FONA
For high-risk GA
1. A-D strategy as per 2015 DAS guidelines
2. NMB, first airway approach using VL and presence of most skilled clinician
What are the perioperative challenges or considerations in thyroid surgery?
- Thyrotoxicosis (with or without hyperthyroidism)
- Hyperthyroidism, Hypothyroidism(i) Plasmapharesis is an option to reduce thyroid blood levels
(ii) Emergency surgery for patients with severe hypothyroidism - Risk of impaired diastolic dysfunction - Cardiac evaluation for patients with symptoms of heart failure.
How might severe hypothyroidism present?
Myxoedema coma
Altered mentation
Pericardial effusions
Heart Failure
How would you manage severe hypothyroidism / myxoedema coma?
Give loading dose of IV Levothyroxine 200-500mcg + 20-100mcg daily
IV Liothyronine should only be considered in myxoedema coma
Glucocorticoids in patients with adrenal insufficiency
How would you perform preoperative assessment for goitre surgery?
o Clinical Assessment
(i) Dyspnoea, dysphagia, SVC compression, Nerve compression (Horner’s – RLN injury), (ii) Pemberton’s sign – facial congestion with cyanosis after arm elevation because of ‘thyroid cork effect’
o Airway assessment
(i) Predictors of difficult airway, intubation or both
o TFTs, including serum Calcium
o Imaging (CT, Xray or MRI or CT with 3D reconstruction from multi-sliced CT)
What is you intraoperative airway management plan for a patient with goitre?
- Preserve spontaneous ventilation in patients with obstructive signs and symptoms (ATI technique)
- IONM technique if increase risk of RLN injury
- Anaesthesia with NMB during surgery
- Extubation strategy – with DAS algorithm, consider LMA, surgical tracheostomy
What are the post operative risks after goitre surgery?
- High risk of postoperative bleeding
- High risk of postoperative hypocalcaemia
- High risk of post-thyroidectomy tracheomalacia
High risk among patients with goitre for > 5 years, RLN preoperative palsy, preoperative tracheal deviation, retrosternal and retrotracheal extension, thyroid malignancy, anticipated difficult intubation
Which patients are prioritized for parathyroid surgery?
- Guidelines – Perform parathyroidectomy in cases with normal serum Ca2+ concentrations
- Priority for
o Patients with primary hyperparathyroidism and adjusted calcium >3mmol/l despite medical treatment
o Pregnant patients
o Patients with recurrent renal stones associated with sepsis in primary hyperparathyroidism
What are the risks associated with suboptimal preoperative serum calcium concentrations?
Patients with hypercalcaemia preop may develop hypercalcaemia crisis
How would you manage a hypercalcaemia crisis?
- Essential to rehydrate patients with IV fluids
- Arrange urgent endocrinology consultation
- Medical management
o Drugs – Denosumab, Cinacalcet, Calcitonin, Bisphosphonates - Use quantitative NM monitoring
- Risk of CV collapse – alteration in QTc length, dysrhythmias, and rapid decrease in serum calcium after parathyroid removal
Emergencies
How would you manage an immediate postoperative B/L RLN palsy?
- May develop respiratory distress and require reintubation – call for help, use DAS guidelines
- Consider immediate revision surgery to improve patency and post op voice quality
- Admit to ICU until protected airway is established
What are the risk factors for bleeding after thyroid and parathyroid surgery?
Male sex, increasing age,
Revision surgery, Retrosternal goitre, Thyroid surgery, neck dissection
Low surgeon volume, duration of surgery (>2 hours)
Excision of parathyroid glands
Grave’s disease, DM, Perioperative use of anticoagulants/antiplatelets
What are the criteria to perform day case endocrine neck operations?
- Low risk of post operative haemorrhage
- Necessary informed consent
- Verbal and written instructions about post operative bleeding protocols
- Easy access to healthcare facilities
How would you evaluate a post op haematoma?
6 Triggers
(DESATS)
- Difficulty swallowing
- EWS - increase
- Swelling
- Anxiety
- Tachypnoea
- Stridor or difficulty breathing
How would you manage a post op neck haematoma?
Oxygenate + Evaluate, Evacuate + Intubate
6 triggers – difficulty swallowing, increase in EWS, swelling, anxiety, tachypnoea or difficulty in breathing and stridor
Before signs of airway compromise:
1. SCOOP
Skin exposure, cut sutures, open skin, open muscles, pack wound
- Then consider tracheal intubation
How does acute postoperative hypocalcaemia manifest?
Neurological impairment with perioral paraesthesia
Restlessness
Altered NM activity
Chvostek sign
Trousseau sign
Cardiac Sx - prolonged QTc, Torsades de pointes
What are the risk factors for acute post operative hypocalcaemia?
Surgery related
- B/L thyroid procedures
- Central neck dissection
- Low volume thyroid surgery
- Simultaneous thyroidectomy and parathyroidectomy
Patient related
- Prior gastric bypass, malabsorptive state
- Substernal goitre
- Prior central neck surgery
- AI thyroid disease
What is your pre- operative pain management plan for thryroid and parathyroid sugery?
Paracetamol 15 mg/kg IV
Ibuprofen 800 mg IV OR
Eterocoxib 120 mg PO
Gabapentin 1200 mg
Identify patient with opioid-related
postoperative risk
and consider OFA
What is your intraoperative pain management plan for thyroid and parathyroid surgery?
Adequate tracheal tube
Local anaesthetics
Superficial cervical plexus
Lidocaine 1-1.5 mg/kg IV
Dexamethasone 4-8 mg IV
Remifentanil infusion (hyperalgesia risk)
Dexmedetomidine infusion 1.2 mg/kg/h
Ketamine bolus 0.25-1 mg/kg (consider infusion)
Paracetamol 15 mg/kg IV AND ketorolac 15-30 mg IV
What is your post-operative pain management plan for thyroid and parathyroid surgery?
Paracetamol mg/kg IV
COX 1/2 inhibitors IV or oral
Patient-directed opioids
Restrict opioid prescription
<75 mg morphine equivalents
The endocrine surgery section of the American Head and Neck Society (AHNS-ES), with a view to reduce the use of opioids for pain management during endocrine neck surgery, recommends opioid administration only in case of contraindications or failure of first-line non-opioid drugs
