How is thyroid storm managed intraoperatively in an adult patient with a history of hyperthyroidism, likely due to Graves' disease or toxic multinodular goiter?

Intraoperative Management of Thyroid Storm

If thyroid storm develops intraoperatively, immediately administer propylthiouracil (PTU) as the first-line agent because it uniquely blocks both thyroid hormone synthesis AND peripheral conversion of T4 to T3, making it superior to methimazole during this life-threatening crisis. 1, 2

Immediate Intraoperative Protocol

Step 1: Block Thyroid Hormone Synthesis

• Administer PTU loading dose followed by maintenance dosing every 4-6 hours 1
• PTU is preferred over methimazole intraoperatively because it inhibits peripheral T4 to T3 conversion in addition to blocking synthesis 1, 2
• Alternative: Methimazole 20 mg every 4-6 hours if PTU is unavailable, though it lacks the peripheral conversion blocking effect 1

Step 2: Block Thyroid Hormone Release (Critical Timing)

• Administer saturated potassium iodide solution (SSKI) 5 drops every 6 hours OR sodium iodide 500-1000 mg IV every 8 hours 1, 3
• Never give iodine before thionamides—wait at least 1-2 hours after starting PTU/methimazole, as premature iodine administration will worsen thyrotoxicosis 1, 3, 4

Step 3: Control Cardiovascular Manifestations

• Propranolol 60-80 mg orally every 4-6 hours is first-line because it provides dual benefit: controls adrenergic symptoms AND blocks peripheral T4 to T3 conversion 1, 3
• For hemodynamically unstable patients requiring vasopressor support: Use esmolol with loading dose of 500 mcg/kg IV over 1 minute, then maintenance infusion starting at 50 mcg/kg/min 1
• Non-dihydropyridine calcium channel blockers are an alternative if beta-blockers are contraindicated 3

Step 4: Corticosteroid Administration

• Administer dexamethasone or hydrocortisone to reduce peripheral T4 to T3 conversion and treat potential relative adrenal insufficiency 1, 3, 4

Essential Supportive Measures

Respiratory Support

• Provide supplemental oxygen immediately 1
• Position patient head-up to improve respiratory function 1

Temperature Control

• Administer antipyretics for fever control (avoid aspirin as it increases free thyroid hormone levels) 1, 3

Monitoring Requirements

• Monitor for cardiac complications including heart failure and arrhythmias 1, 3, 4
• Establish large-bore IV access for fluid resuscitation and medication administration 4
• Monitor coagulation parameters including PT, aPTT, and fibrinogen 4

Critical Decision Points

When to Escalate Treatment

• Escalate treatment if worsening confusion, seizures, or progression to stupor/coma develops 1
• Consider therapeutic plasma exchange or emergency thyroidectomy if medical therapy fails 5

Surgical Considerations

• Reduce PTU dosage when heart rate normalizes to <90-100 bpm 1
• The mortality rate can rise to 75% with treatment delays, so never wait for laboratory confirmation before initiating therapy 1, 3, 6

Common Pitfalls to Avoid

• Delaying treatment while awaiting laboratory confirmation—mortality rises significantly with delays 1, 3, 6
• Administering iodine before thionamides—this worsens thyrotoxicosis 1, 3, 4
• Using aspirin for fever control—it increases free thyroid hormone levels 1
• Failing to recognize that thyroid hormone levels do not differ between uncomplicated thyrotoxicosis and thyroid storm; diagnosis is entirely clinical 6, 5

Post-Crisis Management

• Switch from PTU to methimazole after storm resolution due to PTU's significant hepatotoxicity risk with prolonged use 1
• Monitor thyroid function every 2-3 weeks after initial stabilization 1, 4
• Plan definitive treatment (continued medical therapy, thyroidectomy, or radioactive iodine ablation) after the acute crisis is controlled 3
• All patients with adrenal insufficiency should obtain and carry a medical alert bracelet 7

Special Population: Pregnancy

• Treatment protocol is identical to non-pregnant patients, as maternal mortality risk outweighs fetal concerns 1, 3
• PTU is preferred over methimazole in first trimester 1
• Avoid delivery during thyroid storm unless absolutely necessary due to extremely high maternal and fetal mortality risk 1, 3