2025 PACUPrep BCCCP Preparatory Course Thyroid Emergencies: Thyroid Storm & Myxedema Coma Supportive Care and Complication Monitoring in Thyroid Emergencies
Supportive Care in Thyroid Emergencies

Supportive Care and Complication Monitoring in Thyroid Emergencies

Objectives Icon A clipboard with a checkmark, symbolizing learning objectives and care plans.

Objective

Recommend supportive care and complication monitoring strategies to optimize outcomes in thyroid storm and myxedema coma.

Learning Points

  • Recognize indications for airway protection and mechanical ventilation in thyroid emergencies.
  • Apply lung-protective ventilation and sedation strategies tailored to storm and coma.
  • Initiate fluid and vasopressor support based on high-output failure in storm vs. low-output state in coma.
  • Implement temperature control: active cooling in storm, passive rewarming in coma.
  • Employ ICU prophylaxis against VTE, stress ulcers, and infections.
  • Monitor for treatment-related complications: agranulocytosis, hepatotoxicity, arrhythmias.

1. Airway and Respiratory Support

Airway compromise in thyroid emergencies can arise acutely from altered mentation, central hypoventilation, or significant soft-tissue edema of the tongue and pharynx. Early intubation and implementation of a lung-protective ventilation strategy are associated with reduced mortality.

Indications for Intubation

  • Altered Mental Status: Glasgow Coma Scale (GCS) score ≤8.
  • Respiratory Failure: Apnea or significant hypoventilation (PaCO₂ >50 mm Hg).
  • Airway Obstruction: Stridor or visible edema compromising the airway.
  • Refractory Hypoxemia: SpO₂ <90% despite high-flow noninvasive support.

Ventilator and Sedation Strategy

A lung-protective approach is crucial. Initial settings should include a tidal volume of 6 mL/kg of predicted body weight, PEEP of 5–10 cm H₂O, and maintaining a plateau pressure below 30 cm H₂O. For sedation, a propofol infusion allows for rapid titration and neurologic assessments. Benzodiazepines should be minimized, particularly in myxedema coma, due to their prolonged clearance and risk of accumulating.

Pearl Icon A lightbulb icon, indicating a clinical pearl. Clinical Pearl: Hyperthermia and CO₂ Production

In thyroid storm, severe hyperthermia dramatically increases metabolic rate and carbon dioxide (CO₂) production. Clinicians must anticipate this by increasing the patient’s minute ventilation on the ventilator to prevent hypercapnic acidosis. Additionally, shivering during active cooling must be aggressively managed with sedation and analgesia, as it can increase oxygen consumption by up to 400%.

2. Hemodynamic Management

Hemodynamic profiles differ starkly between the two emergencies. Thyroid storm typically causes a high-output cardiac failure state with vasodilation and tachyarrhythmias, whereas myxedema coma leads to a low-output state with bradycardia, vasoconstriction, and pericardial effusion. Therapy must be tailored accordingly.

Hemodynamic Management Flowchart A flowchart showing the divergent hemodynamic management strategies for thyroid storm (high-output failure) and myxedema coma (low-output state). Thyroid storm requires norepinephrine and beta-blockers, while myxedema coma requires cautious fluids and potential vasopressors. Assess Hemodynamic Profile MAP < 65 mmHg or signs of shock Thyroid Storm (High-Output Failure) • Cautious Fluids (10-20 mL/kg) • Norepinephrine (1st Line Vasopressor) • Add β-Blocker for rate/arrhythmia • Dobutamine if LV dysfunction persists • Avoid pure α-agonists (phenylephrine) Myxedema Coma (Low-Output State) • Very Cautious Fluids (risk of edema) • Norepinephrine for hypotension • Consider Dobutamine for bradycardia • Await thyroid hormone effect • POCUS for pericardial effusion
Figure 1: Hemodynamic Management Strategies. Therapeutic choices diverge based on the underlying pathophysiology. Thyroid storm requires managing vasodilation and tachycardia, while myxedema coma requires supporting a failing, bradycardic heart.

3. Temperature Management

Core temperature dysregulation is a hallmark of thyroid emergencies. Active, aggressive cooling is necessary to reduce metabolic stress in thyroid storm, while controlled, gradual rewarming is essential to avoid cardiovascular collapse in myxedema coma.

  • Thyroid Storm (Hyperthermia): Initiate active cooling with surface methods like cooling blankets, fans, and evaporative cooling. Administer acetaminophen (650 mg PO/IV every 4 hours) to reset the hypothalamic set point. Avoid ice-cold IV fluids, which can induce shivering and paradoxical vasoconstriction.
  • Myxedema Coma (Hypothermia): Begin passive rewarming with blankets in a warm room. The target rate of rewarming is slow and steady: 0.25–0.5 °C per hour. Rapid rewarming with forced-air devices can cause peripheral vasodilation and profound hypotension.
Pearl Icon A lightbulb icon, indicating a clinical pearl. Clinical Pearl: Lukewarm Fluids in Myxedema Coma

While avoiding overheated fluids is critical, administering standard room-temperature IV fluids can contribute to heat loss. Using a fluid warmer to deliver crystalloids at a lukewarm temperature (37–38 °C) can support the gradual rewarming process in myxedema coma without triggering dangerous vasodilation.

4. ICU-Specific Prophylaxis

Critically ill patients with thyroid emergencies are at high risk for common ICU-acquired complications. Prophylaxis against venous thromboembolism (VTE), stress-related mucosal disease, and infections is a standard component of supportive care.

  • VTE Prophylaxis: Use pharmacologic prophylaxis unless a major contraindication exists. Enoxaparin (40 mg SC daily) is preferred for patients with adequate renal function (CrCl >30 mL/min). For those with renal impairment or high bleeding risk, unfractionated heparin (5,000 units SC every 8–12 hours) is a suitable alternative. Intermittent pneumatic compression devices should be added for all, and used alone if anticoagulation is contraindicated.
  • Stress Ulcer Prophylaxis: Indicated for patients on mechanical ventilation or those receiving high-dose glucocorticoids. A proton pump inhibitor (e.g., pantoprazole 40 mg IV daily) is the first-line agent.
  • Infection Control: Maintain strict hand hygiene. Obtain blood, urine, and sputum cultures early, especially if an infectious trigger is suspected. Initiate empiric broad-spectrum antibiotics promptly and de-escalate based on culture results and clinical response, in line with antimicrobial stewardship principles.

5. Monitoring for Iatrogenic Complications

The therapies used to treat thyroid emergencies, particularly thionamides, carry risks of serious adverse effects. Targeted laboratory and telemetry monitoring is essential for early detection and management of drug-related toxicity.

Monitoring for Key Treatment-Related Complications
Complication Key Indicator Monitoring Action Threshold
Agranulocytosis Absolute Neutrophil Count (ANC) Baseline CBC. Repeat urgently if fever or sore throat develops. Discontinue thionamide if ANC <1,000/mm³.
Hepatotoxicity (PTU) AST / ALT Baseline LFTs. Monitor weekly for first month, then monthly. Discontinue PTU if transaminases >3x upper limit of normal.
Arrhythmias / QTc QTc Interval, Electrolytes Continuous telemetry. Daily EKG and electrolyte panel (K⁺, Mg²⁺, Ca²⁺). Pause/change agent if QTc >500 ms or increases by >60 ms.
Pearl Icon A lightbulb icon, indicating a clinical pearl. Clinical Pearl: Neutropenic Fever on Thionamides

The development of fever and pharyngitis in a patient recently started on propylthiouracil (PTU) or methimazole is a medical emergency. It should be considered agranulocytosis until proven otherwise. The thionamide must be stopped immediately, a STAT complete blood count with differential should be drawn, and a full sepsis workup with empiric broad-spectrum antibiotics should be initiated.

6. Multidisciplinary Goals of Care

Thyroid emergencies carry high morbidity and mortality, and treatments can be invasive and high-risk. Early and ongoing shared decision-making, facilitated by a multidisciplinary team, is crucial to ensure that care aligns with the patient’s values and prognosis.

  • Team Engagement: Actively involve consultants from endocrinology, critical care, pharmacy, and nursing. For complex ethical situations, palliative care and ethics teams provide invaluable support.
  • Goals-of-Care Discussions: Proactively discuss prognosis, code status, and patient preferences with the patient or their surrogate decision-maker. These conversations should be revisited as the clinical situation evolves.
  • Advanced Therapies: For refractory cases, consider advanced therapies like plasmapheresis, ECMO, or emergent thyroidectomy. These decisions require a careful weighing of risks, benefits, and resource allocation by the entire team.
  • Family Involvement: Conduct structured family meetings using clear, lay language to explain the patient’s condition and treatment plan. Ensure all decisions are documented and reflect informed consent.

References

  1. Wall CR. Myxedema Coma: Diagnosis and Treatment. Am Fam Physician. 2000;62(11):2485–2490.
  2. Leung AM. Thyroid Emergencies. J Infus Nurs. 2016;39(5):281–286.
  3. Bahn RS, Burch HB, Cooper DS, et al. Hyperthyroidism and other causes of thyrotoxicosis: Management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists. Thyroid. 2011;21(6):593–646.
  4. Cooper DS. Antithyroid drugs. N Engl J Med. 2005;352(9):905–917.
  5. Rivkees SA, Mattison DR. Propylthiouracil hepatotoxicity in children and recommendations for discontinuation of use. Int J Pediatr Endocrinol. 2009;2009:132041.
  6. U.S. Food and Drug Administration. Propylthiouracil-Induced Liver Failure Safety Communication. 2009.
  7. Lee SY, Modzelewski KL, Law AC, et al. Comparison of propylthiouracil vs methimazole for thyroid storm in critically ill patients. JAMA Netw Open. 2023;6(4):e238655.
  8. Muller C, Perrin P, Faller B, et al. Role of plasma exchange in the thyroid storm. Ther Apher Dial. 2011;15(6):522–531.
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