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Hyperthyroidism. Co-existing diseases: The Endocrine System Boston Medical Center Dept. of Anesthesiology Gerardo Rodriguez, MD. Outline. Case sample Medical disease background Preoperative evaluation & preparation Intraoperative management Postoperative management
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Hyperthyroidism Co-existing diseases: The Endocrine System Boston Medical Center Dept. of Anesthesiology Gerardo Rodriguez, MD
Outline • Case sample • Medical disease background • Preoperative evaluation & preparation • Intraoperative management • Postoperative management • Highlight airway issues.
Case Sample • 62y.o. Albania female w/ goiter x 20yrs, moved to U.S. 4mos ago. Refused surgery, very anxious. Now w/ worsening SOB when supine and dysphagia. • PMhx: HTN, Afib, Thyroid storm? • PEx: • VS: T98.7, 160/80, 113, 20, 100% RA • Airway: MP2 • HEENT: Large goiter • CT imaging: R-deviated trachea w/o compression.
Background • Hyperthyroidism is a condition caused by the effects of too much thyroid hormone. • Hyperthyroidism: usu. excess synthesis and secretion of thyroid hormone by the thyroid gland, also known as thyrotoxicosis. • free thyroxine (T4), free triiodothyronine (T3), or both. • Most common of thyrotoxicosis: • diffuse toxic goiter (Graves disease, ~50-60%) • toxic multinodular goiter (Plummer disease, 15-20%) • toxic adenoma (3-5%).
Epidemiology • U.S. • Graves’ • Annual incidence: ~0.5 cases in 1000 persons. • Peak age occurrence: 20-40yrs. • diffuse toxic goiter (Graves’ disease, ~50-60%) • toxic multinodular goiter (Plummer disease, 15-20%) • toxic adenoma (3-5%). • International • Frequency of Graves’ and toxic multinodular goiter vary by iodide intake. • E.g. US has I- intake incid of Graves’ > toxic goiter
Epidemiology http://www.scielosp.org/scielo.php
Epidemiology • Gender • Women>men (Graves’, female-to-male: 1 to 5-10.) • Age • Graves: 20-40yrs • Toxic multinodular goiter: >50yrs • Race • Graves: Caucasians/Asians/Hispanics >> Black population
Evaluating Hoarseness: Keeping Your Patient's Voice Healthy - June 1998 - American Academy of Family Physicians; http://www.aafp.org/afp/980600ap/rosen.html
Evaluating Hoarseness: Keeping Your Patient's Voice Healthy - June 1998 - American Academy of Family Physicians; http://www.aafp.org/afp/980600ap/rosen.html
Review the laryngeal innervation. Evaluating Hoarseness: Keeping Your Patient's Voice Healthy - June 1998 - American Academy of Family Physicians; http://www.aafp.org/afp/980600ap/rosen.html
T3 / T4 • T3 ~10x more potent than T4: T3 T4 • Peak Onset 24hrs 10 days • Effect Lasts 2-3 days 2-3 weeks
Mitochondrial effects: • mRNA transcription • Na-K-ATPase synthesis • BMR • Cellular energy use: • GLC absorption • Glycolysis • Gluconeogenesis • Insulin secretion • Cellular-GLC uptake • Lipolysis • Lipids metabolism • Chol to bile serum Chol/ TG/PL.
[Thyroid hormone] oxidative phosphorylation uncoupling (i.e. short circuits the coupling between the electron transport chain and ATP synthesis) heat production/ inefficient energy conversion. heat
HR, contractility CO O2 consumption, CO2 production Vt, RR / PTH levels bone turnover (i.e. formation/ catabolism) Vasodilation Blood flow
Systems Signs/Sx • Constitutional • Sweating, warm/moist skin, muscle weakness, wt loss, appetite • CV • HR, high-output CHF, cardiomegaly, pulm/periph edema, MVP, Afib, heart block, dysrhythmias • Resistant to digitalis/ cardiac glycosides. • ‘apathetic’ (i.e. blunted signs/sx) hyperthyroidism in pts age>60, cardiac manifestations predominate, e.g AFib. • Pulm • RR, min vent
Systems Signs/Sx • Neuro • Anxiety, confusion, tremor, seizures • GI • Secretory diarrhea, alk phos • Heme • Wbc, Hb, Plts • Renal • K excretion, Na excretion.
Systems Signs/Sx • Ocular • Exophthalmus • Derm • Vitiligo, hyperpigmentation. • Psych • Emotional instability, insomnia
Thyroid storm • Acute, severe, exacerbation of thyrotoxicosis due to acute serum T3/T4. • Causes: stressors • DKA, infection, acute I- tx withdrawal, trauma, thyroid gland manipulation, radioactive I-, surgery, ether anesthesia. • Onset: sudden. For surgical pts at risk, it may occur: • Intraop • Postop: 6-18hrs. • Signs • T, HR, CHF, confusion, Glc, shock, death.
Preoperative Preparation • Medical Therapy: Thyrotoxicosis • Goal: euthyroid. Resting HR best sign of acceptable tx. • Traditional pre-op tx: Antithyroid meds >2 mos before surgery, then may be stopped post-op. • Propylthiouracil or methimazole • Saturated KI sol • Li-carbonate (if I- allergy) • More recent preop tx: Treat x 7-14days w/ • Saturated KI sol • Propanolol or nadolol: ß-blockers postop >7days.
Preoperative Preparation • Medical Therapy: Thyroid storm • Immediate tx • Cooled IV fluids • Propylthiouracil: T4 synthesis + peripheral T4-to-T3 conversion • Methimazole (PO/NG) • Followup tx • Propylthiouracil (PO Q8) • Na I- (IV Q8) • Saturated KI sol (PO QD): T4 synth/secretion (Wolf-Chaikoff effect) • Propanolol (IV, max 10mg, titrate to HR<90, then PO) • Hydrocortisone (IV Q8)
Preoperative Preparation • Airway assessment tools • CXR/ CT imaging • Tracheal deviation? • Airway obstruction/ compression? • Pulmonary Function Testing (PFT) • Non-invasive • Flow-volume loops
Preoperative Preparation • Normal Flow-Volume Loop • Used to eval airway obstruction. • Can determine the extent + location of airway obstruction. • Intrathoracic (variable) • Extrathoracic (variable) • Fixed
Preoperative Preparation • How to produce a Flow-Volume Loop? • (1): Inhale to TLC. • (1 to 2): Exhale to RV. • (2 to 3): Inhale to TLC. • How might loops change w/ various obstructions? 1 2 3
Anesthetic Management A review of cases performed at the University of California, San Francisco, from 1968 to 1982 revealed that virtually all anesthetic drugs and techniques have been used without adverse effects even being remotely attributable to the drug or technique. Roizen MF, Becker CE: Thyroid storm: A review of cases at University of California, San Francisco. Calif Med 115:5, 1971. No controlled study has demonstrated clinical advantages of any anesthetic drug over another for surgical patients who are hyperthyroid. Miller’s Anesthesia, 6th Ed.; www.anesthesiatext.com
Anesthetic Management • Preinduction preparation: • Airway obstruction assessment • Airway exam: Large Goiter/ airway obstruction Difficult Airway? • CXR/ CT imaging • PFTs • Airway devices: difficult intubation cart?, AFOI?, re-inforced ETT? • Premeds: minimize sedation?
Anesthetic Management • Intraoperative management: • GA/Induction: • Thiopental: antithyroid activity. • Ketamine: avoid, sympath activity. • Muscle relaxants: avoid agents w/ cardiac effects. • Maintenance: • MAC requirement • narcotics?: to blunt sympath stim. • Muscle relaxants: caution, possible prolonged effects if preop muscle weakness. • PaCO2: avoid, sympath stim. • Temp monitoring • Exophthalmus: corneal injury susceptibility.
Anesthetic Management • Postoperative management: • Monitor for postop complications: • Tracheomalacia • Thyroid storm • Bilateral recurrent laryngeal nerve injury • Unopposed ad-duction of vocal cords: stridor, aphonia, airway obstruction. • Unopposed ab-duction of vocal cords: aspiration risk. • Hypocalcemic tetany • Postop Hematoma