Hyperthyroidism

Co-existing diseases: The Endocrine System

Boston Medical Center

Dept. of AnesthesiologyGerardo 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

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

www.medscape.com; http://ae.medseek.com/

• T3 ~10x more potent than T4:

T3 T4• Peak Onset 24hrs 10

days• Effect Lasts 2-3 days 2-3

weeks

T3 / T4

• 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

• 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.

Thyroid storm

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 requirementnarcotics?: 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