RT Book, Section A1 Albright, Brooke A2 Atchabahian, Arthur A2 Gupta, Ruchir SR Print(0) ID 57261450 T1 Chapter 74. Endocrine Surgery T2 The Anesthesia Guide YR 2013 FD 2013 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-176049-2 LK accessanesthesiology.mhmedical.com/content.aspx?aid=57261450 RD 2024/03/28 AB HyperthyroidismCausesExcess release of thyroid hormone as seen in Graves’ disease, multinodular goiter, toxic adenoma, thyroiditis, pituitary thyrotropin (rare), iodine induced (amiodarone or angiographic contrast media), pregnancy inducedSigns and symptomsGoiterSweatingTachycardia, nervousnessBowel or menstrual problemsEye symptoms (ophthalmopathy)DermopathySkeletal muscle weaknessVasodilationHeat intolerancePreoperativeTreat with anti-thyroid drugs, surgery, or radiation to reduce thyroid tissuePropylthiouracil (PTU), methimazole, and carbimazole can be used to inhibit organification of iodide and synthesis of hormoneAt least 6–8 weeks are required to regulate thyroid levels in most hyperthyroid patientsOptimal duration of anti-thyroid drug therapy for Graves’ disease is 12–18 months with low dose therapy to prevent relapseBeta-blockers should be used in all hyperthyroid patients to attenuate excessive sympathetic activity unless contraindicated. Goal is HR < 90 bpmPropranolol also impairs the peripheral conversion of T4 to T3 over 1–2 weeksPotassium iodide can be used prior to surgery to reduce circulating thyroid hormone and cardiovascular symptomsGlucocorticoids (dexamethasone 8–12 mg/day) can be used in severe thyrotoxicosis to reduce hormone secretion and peripheral conversion of T4 to T3Thorough airway exam is necessary in anticipation of a difficult airway in those patients with goiters, especially substernal goiters. It may be necessary to perform an awake fiberoptic intubation or an inhalation inductionIntraoperativeAll anti-thyroid medications should be continued through morning of surgeryGeneral anesthesia with tracheal intubation and muscle relaxation is the most popular anaesthetic technique for thyroidectomy. A small reinforced tracheal tube may be needed if there is some degree of tracheal compression presentThe incidence of temporary unilateral vocal cord paralysis resulting from damage to the recurrent laryngeal nerve (RLN) is 3–4%. Intraoperative electro-physiological monitoring of the RLN can be done with the use of a tracheal tube with integrated EMG electrodes positioned at the level of the vocal cords. When the RLN has been identified, the nerve is stimulated until an EMG response is obtainedAnesthetic goal is to keep patient deep enough to avoid exaggerated sympathetic response to surgical stimuliHyperthyroidism does NOT increase MAC requirementsAvoid medications that may stimulate the nervous system, such as pancuronium and ketamineAvoid histamine releasing drugs as well, such as atracurium and vancomycinTreat hypotension with direct-acting vasopressors, rather than those that indirectly release catecholaminesMay need to use reduced dose of muscle relaxant initially, and use a nerve stimulator to guide subsequent muscle relaxant dosesSome surgeons perform thyroid surgery under MAC and cervical plexus block. Typically, a superficial cervical plexus block will be performed on the side with the smaller goiter or nodule, and both a deep and superficial cervical plexus block on the larger side. Avoid bilateral deep blocks, as this would block the phrenic nerve bilaterallyPostoperativeComplications of thyroidectomy include recurrent laryngeal nerve damage, tracheal compression due to hematoma or tracheomalacia, and hypoparathyroidismIatrogenic hypoparathyroidism may result in hypocalcemia manifesting as laryngeal stridor progressing to laryngospasm within the first 24–96 hours post opTo assess recurrent laryngeal nerve damage, ask the patient to phonate before and after surgery by saying “ee”. Bilateral recurrent laryngeal nerve damage causes aphonia and requires immediate reintubation. Unilateral damage causes hoarseness and is usually transientALERTThyroid storm: Possible life-threatening exacerbation of hyperthyroidism. Manifestations include ...