Hyperthyroidism

Elevated T3, T4, decreased TSH

Secondary to Graves' disease, toxic multinodular goiter, thyroid adenomas, TSH-secreting tumor (rare), or overdose of thyroid hormone

Symptoms

Fatigue, sweating, intolerance to heat

Increased appetite, weight loss, or gain

A-fib, palpitations are usually the first symptoms, and CHF

Increased BP, HR, pulse pressure

Increased thyroid levels

Thyroid goiter

Exophthalmos (antibodies to eye orbital muscles)

Nervousness, agitation

Thyroid Storm

Life-threatening exacerbation of hyperthyroidism during periods of stress. It can be mistaken intraop for malignant hyperthermia, sepsis, anaphylaxis, or other hypermetabolic reactions

Symptoms

Hyperthermia >40 degrees C

Tachycardia

Widened pulse pressure

Anxiety

Altered mental status leading to psychosis, coma, and myopathy

Treatment

Increase FIO₂

Fluid resuscitation

Electrolyte replacement/correction (Increased Ca⁺⁺)

Cooling blankets

Acetaminophen

Maintain diuresis

Treat precipitating events (infection, CHF, DKA, pregnancy)

Specific treatment

Propylthiouracil (block synthesis)

Sodium Iodide (block release)

Steroids (unclear mechanism)

Beta-blockers (caution reactive airway, CHF)

NOTE:  Block synthesis BEFORE (1 hour is adequate) giving iodides to block release

• Otherwise, "iodine escape" will occur later, and thyroid hormones will be produced

Anesthetic considerations

Ensure euthyroid state

• Check temp, HR, pulse pressure, and reflexes

Tracheal compression from large goiters can cause tracheal deviation, stridor

Increased BMR causes increased VO₂ (oxygen uptake) and rapid desaturation on induction

Beta-blocker therapy for increased HR

Generous sedation due to nervousness

Avoid agents that stimulate the sympathetic nervous system

• Ketamine, pancuronium, meperidine

Visualize vocal cords function before extubation

The ability to phonate "e" implies continued vocal cord function

Emergence

Risk of airway obstruction

• Secondary to recurrent laryngeal nerve damage
  • Bilateral: the patient is unable to speak and requires reintubation
  • Unilateral: hoarseness

Tracheomalacia (weakness and floppiness of tracheal cartilage) or hematoma

• Rapid intubation may be lifesaving
• If hematoma, then reopen the incision and drain the blood

Acute hypo parathyroid state (hypocalcemia)

• Can present as laryngeal stridor 24-48 hr postop
• It may start with tingling of fingertips and lips, which, untreated, can progress to tetany and seizures
  • Give 1 amp of Ca⁺⁺ gluconate iv over 20 min will usually alleviate symptoms