What are the anesthesia considerations for a patient with hyperthyroidism undergoing surgery?

Anesthesia Considerations for Hyperthyroidism

For hyperthyroid patients undergoing surgery, proceed with thyroidectomy even in the hyperthyroid state when cardiovascular stability is achieved, as recent evidence demonstrates safe outcomes without requiring biochemical euthyroidism, though preoperative preparation with beta-blockers and antithyroid drugs remains essential for cardiovascular optimization. 1

Preoperative Assessment and Optimization

Thyroid Function Evaluation

• Obtain thyroid function tests (TSH, FT4, T3) to quantify the degree of hyperthyroidism 2
• Assess cardiovascular stability as the primary determinant of surgical readiness, since cardiovascular effects represent the most clinically significant manifestation of hyperthyroidism 1
• Coordinate evaluation between anesthesiologist, surgeon, and endocrinologist for patients with uncontrolled disease 1

Airway Assessment

• Conduct thorough evaluation of thyroid anatomy during pre-anesthetic assessment to identify potential difficult airway from enlarged thyroid gland, goiter, or abnormal laryngeal structures 2
• Document baseline vocal cord function, as recurrent laryngeal nerve (RLN) injury risk is 3-3.4%, making preoperative laryngeal examination standard of care 3
• Prepare for difficult airway management with fiberoptic intubation equipment and difficult airway cart availability 2

Medical Optimization Strategy

Combination therapy targeting thyroid hormone synthesis, secretion, and peripheral effects should include: 1

• Thionamides (methimazole or propylthiouracil) to block hormone synthesis 1
• Beta-blockers to control cardiovascular manifestations and block peripheral conversion of T4 to T3 1, 4
• Additional agents for refractory cases: iodine preparations, corticosteroids, cholestyramine, lithium carbonate, or therapeutic plasma exchange 1, 4

Critical caveat: While achieving euthyroid state is ideal, delaying surgery until biochemical euthyroidism is no longer considered mandatory if cardiovascular stability is achieved, as thyroid storm risk exists regardless of biochemical thyroid status 1

Intraoperative Management

Anesthetic Technique

• Use general anesthesia with endotracheal intubation as the standard approach for thyroidectomy 2
• Avoid long-acting neuromuscular blocking agents if intraoperative nerve monitoring is planned—these are absolutely contraindicated 2
• Consider total intravenous anesthesia (TIVA) as a preferred technique for thyroid surgery 5

Communication and Planning

• Establish preoperative communication between surgeon and anesthesiologist regarding nerve monitoring requirements, which directly affects muscle relaxant selection 2
• Utilize pre-procedural checklist to improve team communication and decrease errors 2

Thyroid Storm Prevention

Monitor for thyroid storm throughout the perioperative period, recognizing that: 1, 6

• Preoperative antithyroid treatment does not guarantee prevention of thyroid storm
• Storm can occur intraoperatively or postoperatively in both euthyroid and hyperthyroid patients
• Experienced anesthesiologists and surgeons can safely perform thyroidectomy during hyperthyroid phase without precipitating storm 1

Special Populations and Comorbidities

Patients on Chronic Corticosteroids

Provide stress-dose steroid coverage: 7

• Hydrocortisone 100 mg IV at induction
• Followed by continuous infusion of 200 mg/24 hours
• Continue hydrocortisone 200 mg/24 hours IV while nil by mouth postoperatively

Critically Ill Patients

• For patients with amiodarone-induced thyrotoxicosis who are critically ill with cardiac disease, total thyroidectomy under local anesthesia may be the safest option to avoid general anesthesia risks 8
• These patients present a paradox: requiring amiodarone for life-threatening arrhythmias while the drug precipitates hyperthyroidism that worsens their cardiac status 8

Postoperative Monitoring and Complications

Immediate Postoperative Period

• Monitor patients at least hourly for the first 6 hours postoperatively, as approximately 50% of hematomas occur within this timeframe 2
• Assess voice function immediately postoperatively 2
• After 6 hours, adjust observation frequency based on individual patient risk 2

Airway Compromise Recognition

Use the DESATS protocol for early identification of complications: 3

• Difficulty swallowing
• EWS (Early Warning Score) elevation
• Swelling
• Anxiety
• Tachypnoea
• Stridor

Any DESATS findings require immediate senior review 3

Hematoma Management

If suspected hematoma with airway compromise develops, use the SCOOP approach at bedside: 7

• Skin exposure
• Cut sutures (subcuticular)
• Open skin to expose strap muscles
• Open muscles to expose trachea
• Pack wound

Local anesthetic infiltration is not required when opening the wound emergently 7

Additional Postoperative Complications to Monitor

• Laryngeal edema (can cause clinical deterioration even with small hemorrhage) 2
• Recurrent laryngeal nerve palsy 6
• Tracheomalacia (especially with large goiters requiring potential re-intubation) 2, 6
• Hypocalcemic tetany 6
• Pneumothorax 6

Discharge Planning

• Avoid same-day discharge if any postoperative concerns arise 2
• Reevaluate suitability for ambulatory discharge based on individual patient course 2
• Do not underestimate risk of clinical deterioration from postoperative hemorrhage, particularly in context of laryngeal edema 2