Examiners lamented 'general' answers to a question on thyroid surgery in the September 2018 SAQ (47% pass rate), providing correspondingly generic feedback in turn.
This had seemingly been taken on board by the time of the March 2020 CRQ on thyroid disease and thyroid surgery (91% pass rate).
A further CRQ on thyroidectomy in September 2022 (68% pass rate) was "reassuringly...answered well".
This page is primarily concerned with the perioperative conduct of thyroid surgery, regardless of aetiology/indication.
Relevant reading from elsewhere within the FRCA curriculum include pages on:
Thyroid gland anatomy and function
Thyroid hormones
Drugs used in the treatment of thyroid disease
Hyperthyroidism
Hypothyroidism
Perioperative management of the patient undergoing thyroid surgery
History
Duration of goitre
Rapid onset suggests malignancy
Insidious onset increases risk of tracheomalacia
Ask about symptoms that may indicate degree of goitre and difficulties with induction when lying supine:
Positional dyspnoea or stridor
Ability to lie flat
Dyspnoea in general
Stridor
Dysphonia
Dysphagia
History of coalescent autoimmune disorders
Examination
Airway
Check to assess degree of difficulty in airway management
Check for tracheal deviation
Is it possible to palpate below the thyroid gland? A 'no' may indicate retrosternal extension
Cardiovascular
Exclude tachycardia and AF, which may be associated with hyperthyroidism
Check for SVC obstruction;
Distended neck veins not changing with respiration
Pemberton's sign; raising arms in the air causes venous congestion of the face
Investigations
Bloods: FBC, U&E, LFT, TFT's and calcium levels
Patients should be clinically and ideally biochemically euthyroid prior to surgery
ECG for AF/tachyarrhythmias
CXR may detect tracheal deviation or narrowing
CT neck and chest; assess presence and degree of tracheal compression, deviation or retrosternal extension of goitre
Spirometry
May demonstrate fixed upper airway obstruction
Such obstruction was present in 33% of patients in one case series; it was unrelated to type or size of thyroid goitre
Nasendoscopy may demonstrate laryngeal deviation or pre-existing vocal cord dysfunction (useful medicolegally)
Airway management
Airway management strategy should be informed by pre-operative assessment and discussion with surgeon
Options include:
Straightforward direct/video laryngoscopy and intubation
Awake tracheal intubation
Awake tracheostomy, acknowledging the difficulty caused by an enlarged thyroid gland
Ventilation via rigid bronchoscope in extreme cases
Intubation is typically straightforward, though a smaller-than-anticipated tube may be required
There is a risk of difficult intubation (∽6%) in patients with a goitre due to tracheal compression or deviation; difficult airway equipment should be available
If CICO due to large goitre, then obstruction is likely to be below the level of a cricothyroidotomy and rigid bronchoscopy may be necessary
Armoured/reinforced ETTs are typically used, sometimes with in-built electrodes (EMG endotracheal tube) to help identify the recurrent laryngeal nerve during surgery
North-facing polar tubes are another option
Induction
Induction in ramped or sitting position may be necessary if positional dyspnoea is present
There's the possibility of slower and/or difficult intubation, so adequate preoxygenation with HFNO should take place
Typically IV induction, although theoretically inhalational induction with sevoflurane can be done
Those with significant airway obstruction ± dysphagia may benefit from anti-sialogogue pre-medication and (at least theoretically) Heliox
If NMBA are used, quantitative monitoring must be in place to ensure paralysis worn off prior to dissection close to the recurrent laryngeal nerve
Maintenance
IV and inhalational maintenance are viable
Theoretically increased MAC in hyperthyroidism/decreased MAC in hypothyroidism although patients should be euthyroid at the time of surgery anyway
Remifentanil TCI is popular as it:
Obtunds laryngeal reflexes without need for repeated doses of NMBA
Provides intra-operative analgesia
Provides bradycardia and hypotension, contributing to the 'hypotensive anaesthetic' necessary for a bloodless field
May need vasopressors or Valsalva towards the end of the case to maintain normal MAP and check adequate haemostasis
Positioning
Position head-up 25° to aid venous drainage
Neck extended by using a sand bag between shoulder blades
Head supported in a head ring
Eyes padded especially if exophthalmos
Analgesia
Superficial and deep cervical plexus blocks have been described but aren't routinely used
Regular simple analgesia and opioids as part of a multi-modal approach
Surgical infiltration with LA + adrenaline reduces bleeding and provides a degree of perioperative analgesia
Care bundle
Temperature management as long surgery and existing disease may make patients more intolerant of cold/heat
Multi-modal anti-emesis including dexamethasone for its anti-emetic and anti-oedematous properties
Suitable antiobiotic prophylaxis
Suitable VTE prophylaxis
Extubation
Vocal cord assessment may be required prior to wakening, with direct or fibreoptic laryngoscopy
Ensure cuff leak prior to extubation to assess for tracheomalacia
Ensure reversal of NMBA to ToF >0.9(5)
Avoid coughing during extubation e.g. sufficient analgesia, deep extubation, topic anaesthesia to vocal cords, short-acting opioids, swap to SAD
Extubate sitting up
Can be performed as a day case although typically inpatient
Minimum 6hrs monitoring post-operatively for day case patients
Ongoing analgesia, anti-emesis and DrEaMing
Must maintain vigilance for complications (see below)
This potentially life-threatening complication is given its own section, especially in view of the recent Association guideline on the topic
The incidence of bleeding is reportedly 0.45 - 4.2%
Subsequent haematoma formation and airway compromise necessitating bedside interventions occurs in up to 25% of these patients
50% occur within 6hrs of surgery, and most occur within 24hrs of surgery
Prevention
Pharyngeal oedema and haematoma may result from poor venous drainage, so keeping patients sat-up with appropriate analgesia helps
Post-operative monitoring for early detection includes:
Wound inspection
NEWS scoring
Awareness of subtle signs including anxiety, agitation, discomfort or dyspnoea
Other signs include dysphagia/odynophagia, neck swelling and stridor
Post-thyroid emergency box should be at the bedside of all patients who've undergone thyroid surgery, and e-FONA kit available on the ward
Management
Initial management involves:
Calling for help
Sitting the patient upright
Applying oxygen
Continuous monitoring
Evaluating the degree of airway compromise
Administration of adjuncts e.g. IV TXA and IV dexamethasone
If signs of deterioration or airway compromise e.g. hypoxia, respiratory distress, stridor, profound tachypnoea, then immediate evacuation is required:
Skin exposure (from dressings and whatnot)
Cut sutures
Open skin
Open neck muscles (superficial and deep)
Pack wound, presumably after removing clot causing airway compression
If deteriorating despite this then emergency re-intubation should be considered, with use of VL, a smaller ETT and possibly ATI
This should facilitate definitive surgical management and subsequent disposition to a higher care area
Hypocalcaemia
May occur due to unintentional parathyroidectomy (11%)
Hypocalcaemia occurs in up to 20% but is rarely (only ∽3%) permanent
Check serum calcium at 6hr and 24hr post-op.
Treated with either calcium given either orally (Ca2+ ≥2mmol/L) or IV (Ca2+ <2mmol/L)
Recurrent laryngeal nerve injury
Mechanisms include ischaemia, contusion, traction, oedema, entrapment and frank transection
Commonly arises due to laryngeal oedema rather than nerve injury
Risk reduced by using an EMG tube intra-operatively and checking vocal cord function prior to wakening
Incidence of unilateral palsy is 4% (temporary) or <1% (permanent); risk is greater in surgery for malignant disease or secondary operations
Perhaps counter-intuitively, partial paralysis of the nerve is worse than total paralysis
Partial paralysis of the nerve leads to relatively greater ABductor (posterior cricoarytenoid) weakness than ADductor (lateral cricoarytenoid and intra-arytenoid) weakness
The vocal cord on the affected side therefore lies in, or cross, the midline leading to impediment of airflow
Symptoms include:
Hoarse voice
Breathlessness
Ineffective cough
Aspiration
Conversely, total paralysis of the nerve leads to the vocal cord lying open
Bilateral recurrent laryngeal nerve injury is less common but can result in life-threatning airway obstruction, stridor or respiratory distress
Tracheomalacia
Rare but may follow long-standing goitre
Can be life-threatening, requiring re-intubation ± tracheostomy ± tracheal support
Laryngeal oedema
Rare, but if present may require humidified oxygen and steroids
May occur alongside venous congestion from haematoma
Others
Laryngospasm
Pneumothorax from dissection of retrosternal goitre