Abstract
In this chapter discusses the relevant perioperative anesthetic concerns related to thyroidectomy surgery. Reviewed is Graves’ disease, electrolyte and anatomic considerations of thyroid surgery as well as the timeframe and pathophysiology in relation to surgery.
An 11-year-old female presents for subtotal thyroidectomy for Graves’ disease. She has been treated with methimazole for the past three months and has a visibly enlarged anterior neck mass.
What Is Graves’ Disease?
Graves’ disease is the most common cause of hyperthyroidism in children. It is more common in females and often presents during the teenage years. It is an autoimmune disease in which thyroid-stimulating hormone (TSH)-receptor antibodies cause overproduction of TSH that activates the thyroid gland causing thyroid growth (goiter) and high levels of thyroid hormones. Common symptoms include tachycardia, tremors, weight loss, muscle weakness, heat intolerance, and insomnia. Some patients may demonstrate exophthalmos, an outward bulging of the eyes caused by periorbital inflammation, but this is less common in children. Medical management includes administration of antithyroid drugs, such as methimazole, radioactive iodine, or subtotal thyroidectomy when medical management fails or when the thyroid is large and unsightly. Surgical cure must be accompanied by lifetime administration of exogenous thyroid hormones. Beta blockers may be used to suppress palpitations, tachycardia, and tremors. In our patient, it is likely that her surgical intervention is mainly cosmetic and has been scheduled following a course of methimazole to ensure that her thyroid function is closer to normal at the time of surgery.
What Preoperative Laboratory Studies Are Indicated in This Patient?
Adequate thyroid suppression is evidenced by low or normal levels of circulating total T3 and free T4 as well as resolution of symptoms. A complete blood count should be obtained because of the rare occurrence of pancytopenia with antithyroid therapy.
Is a Cardiac Evaluation Warranted?
Depending on the duration of symptoms, Graves’ disease patients are at risk for developing tachycardia-induced cardiomyopathy, but this is extremely rare in the pediatric population. Prolonged duration of untreated symptoms of tachycardia resulting from excessive circulating thyroid hormone can lead to dilated heart failure. Often, symptoms of heart failure can be identified by history. Chest radiograph can reveal an enlarged heart although in severe and prolonged cases, transthoracic echocardiography may be beneficial in identifying cardiac pathology prior to anesthesia.
How Is the Airway Evaluated in the Setting of a Large Thyroid Mass?
Patients should be questioned regarding their ability to lie supine and presence of dyspnea or dysphagia, which may reveal posterior compression of the airway and esophagus (Figure 34.1). A CT scan is helpful to assess upper airway compression. If significant airway compression exists, especially in the setting of dyspnea while supine, it may be prudent to perform tracheal intubation while the patient is breathing spontaneously (see Chapter 19). This is exceedingly rare in the pediatric population.
