Anaesthetic Aspects of Thyroid and Parathyroid Surgery

Mireille Berthoud

2014

Thyroid disease

Reasons why patients may come to surgery

• Grave’s Disease

• Thyroid nodule

• Thyroid cancer

• Multinodular goitre

• Other more rare conditions

Parathyroid disease

Reasons why patients may come to surgery

• Primary parathyroid disease

• Tertiary parathyroid disease

Physiology of thyroid hormones Hypothalamus

TRH

Pituitary Gland TSH

Thyroid Gland FT4 FT3

Peripheral Tissues T4 T3

T4 and T3

T4 and T3

-

- +

+

What is meant by subclinical disease?

Serum TSH High Low

Hypothyroidism ? Hyperthyroidism?

Free T4 and Free T3 Free T4 and Free T3

High Low Normal Normal

Sub-clinical Hypothyroidism

Sub-clinical Hyperthyroidism

Hypothyroidism Hyperthyroidism

The normal for TSH is 0.27 to 4.2 mIU/l, for adults in STH

Grave’s disease

What is it?

• Autoimmune thyroiditis

• Immunoglobulins cause false TSH

stimulation

• Diffuse goitre

• Associated eye disease

• 8x more common in women

• Up to 2% of the population

Grave’s disease

What treatments are available? Why operate?

• Medical management

• Radioiodine

• Surgical management – Less relapse

– Airway obstruction

– Thyroid eye disease

– Pregnancy

– Patient choice

Euthyroid for surgery

• Anti-thyroid drugs

Carbimazole

Propylthiouracil

• B blockers

• Lugol’s iodine

• Steroids

Famous folk with thyroid eye disease

Thyrotoxic crisis

• I have never seen it

• Saba has seen it twice, in a medical context

• Peri-operative crises are rare now days

• Diagnosis is clinical

• Needs to be managed on ITU, with respiratory and CVS support available.

Thyrotoxic crisis: Treatment

• Treat electrolyte imbalance (iv glucose is useful as patient has a hypermetabolic state)

• Treat hypercalcaemia

• Treat arrhythmias (B blockers, e.g. Esmolol, propranalol for IV)

• Control hyperthermia (dantroline)

• Correct hyperthyroid sate (propylthiouracil, Leugol’s iodine, glucocorticoids)

• Plasmapheresis

Thyroid nodules and thyroid cancer

• 10% of patients who have surgically removed thyroid nodules return to theatre for completion thyroidectomy

• Thyroid cancer is increasing in incidence

• It (mostly) carries an excellent prognosis, depending on the type

• Surgery for cancer is more complex, takes longer and is more prone to RLN damage

• Difficult airways occur more frequently in thyroid cancer patients, than from goitres of other causes

Types of thyroid cancer

• Papillary cancer: (78%) 10 year survival of 90%. Spreads locally and to the lymph nodes. May invade the trachea.

• Follicular cancer: (17%) More aggressive than papillary, but still 80% 10 year survival. Spreads to lungs, bone liver and brain. Metastasis concentrate radio iodine.

• Medullary cancer: (4%) 5 year survival is 80%. Sporadic or familial when it is associated with MEN 2A and 2B.

• Anaplastic cancer: very poor prognosis. Surgery usually only palliative.

Monitoring the recurrent laryngeal nerve.

• Some centres do this for all thyroid operations.

• In Sheffield we do it in patients with cancer, in patients having recurrent surgery, and in patients where we already know one of the nerves is damaged.

• It involves a special endotracheal tube with electrodes in contact with the vocal cords, and an anaesthetic technique without muscle relaxation.

Red to Right

The difficult airway

• All patients should be intubated, preferably with an armoured ET.

• All patients should have indirect laryngoscopy to assess cord function pre-op.

• In practice most elective patients are straight forward, even with quite narrowed or deviated tracheas, if not cancer. Size of goitre is not predictive.

• The books quote 6% of cases are difficult. Anaplastic cancer is the worst.

• The warning signs are just the same for any potential obstructed airway: dysphagia, stridor, dyspnoea when lying flat, choking.

The difficult airway

• In my time, we have never employed flow volume loops in Sheffield.

• Imaging is very helpful, but symptoms are more important.

• The method of choice for most papers is an awake fibre-optic intubation, and a small armoured ET though the nose.

• Gas induction is still an option. • Tracheostomy may not be possible because of the

overlying tumour. • Case reports for extra-corporial oxygenation in the

literature all start with intubated patients.

The difficult airway

Multinodular goitre

• The most common reason for operating on patients with a multinodular goitre is to relieve or prevent obstructive symptoms.

• Cosmesis may be a reason for surgery.

• They can be toxic or hypothyroid

• They can have a difficult airway, though this is less common than in thyroid cancer, even for big goitres, and quite narrowed tracheas.

Retro-sternal goitre

Primary Hyperparathyroidism

Symptoms of hyperparathyroidism

ORGAN SYSTEM SYMPTOM/SIGN

Skeletal, articular Osteopenia, gout and pseudo gout

Neuropsychiatric Depression, anxiety, lethargy, fatigueability

Cardiovascular Hypertension, vascular calcification

Gastroentestinal Peptic ulcer disease, pancreatitis, impaired glucose tollerance

Renal Stones of all types, 30% have a reduced GFR.

Haematological Anaemia

Primary Hyperparathyroidism

• Pre-op preparation is to optimise the general medical condition of the patient.

• Avoid thiazides and lithium.

• Control the hypercalcaemia. In practice Martin and I will not be too anxious in any patient with a corrected calcium at or below 3mmol/mol.

Medical Treatment of Hypercalcaemia

• Only hope for cure is surgery

• Correction of vitamin D deficiency

• Do not dehydrate

• Acutely, fluids and sometimes loop diuretics

• Biphosphonates (don’t lower calcium)

• Calcimimetics

Finding the adenoma.

• Pre-operatively

– Ultrasound

– CT/MRI

– Radionuclide isotope scanning

• Focal surgery

Finding the adenoma.

• Per-operatively

– Methylene blue

– Gamma probe

– Intra-operative PTH

– Frozen section

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retchingDVT prophylaxis • DVT prophylaxis

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Bilateral superficial cervical blocks

Images for the New York School of Regional Anaesthesia web site at http://www.nysora.com

Bilateral superficial cervical blocks

Conduct of anaesthesia for thyroid and parathyroid surgery

• Need to protect the airway • Need to minimise bleeding • Need to provide good positioning for surgical access • May need un-paralysed patient • May be a long procedure • Need to allow for haemostasis at the end of the

surgery • Need smooth emergence • Need good post-operative analgesia and to minimise

coughing and straining and retching • DVT prophylaxis

Postoperative complications • Haematoma

• Recurrent Laryngeal Nerve Damage

• Tracheomalacia

• Laryngeal oedema

• Hypocalcaemia