anesthetic aspects of endocrine surgery

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Anesthetic Aspects of Endocrine SurgeryLawrence T. Kim, M.D.Professor of SurgeryUniversity of North Carolina

Anesthetic Aspects of Endocrine SurgeryThyroid cancerAirway management in goiterIntraoperative nerve monitoringPheochromocytoma and ParagangliomaChanging approaches for hyperparathyroidism

Differentiated Thyroid Cancers (DTC)Fastest rising incidence of all cancersEstimated 64,300 U.S. cases 201663,000 U.S. cases 201437,200 U.S. cases 2009Almost the entire increase is papillaryDisproportionate increase in small tumors

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Thyroid Cancer Incidence

Davies and Welch, JAMA OtolaryngologyHead & Neck Surgery Published online February 20, 2014

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Davies, L. et al. JAMA 2006;295:2164-2167.Trends in Incidence of Thyroid Cancer (1973-2002) and Papillary Tumors by Size (1988-2002) in the United States

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Clinically Silent Thyroid CancerVery CommonIn autopsy series papillary ca found in up to 1/3 of specimensHarach HR et al., Cancer 1985;56(3):531538.Recent meta-analysis 7.6%12% if including only studies that examined the entire glandValle and Kloos, J Clin Endocrinol Metab 96: E109E113, 2011

Vaccarella S et al. N Engl J Med 2016;375:614-617.

Observed versus Expected Changes in Age-Specific Incidence of Thyroid Cancer per 100,000 Women, 19882007.Reported in NY Times, Aug. 23, 2016

11Observed versus Expected Changes in Age-Specific Incidence of Thyroid Cancer per 100,000 Women, 19882007.The observed rates were derived from Cancer Incidence in Five Continents, International Agency for Research on Cancer (available at http://ci5.iarc.fr/CI5I-X). The expected rates were based on the observation that before the introduction of ultrasonography and other novel diagnostic techniques, thyroid-cancer incidence increased exponentially with age in all countries with available long-term data, in keeping with the multistage model of carcinogenesis described by Armitage and Doll (rate proportional to agek, where the exponent k is to be estimated from incidence data). For each 5-year period, the expected age-specific rates were obtained by hypothesizing that the disease would have retained the historical age curve described by the multistage model. Since thyroid-cancer incidence varied only minimally across periods among people 80 to 84 years of age, we added a constraint that sets as equal the expected and observed incidence rates for this age group. We hypothesized that the progressive departure of the observed rates from the multistage model was attributable to the increased detection of asymptomatic, nonlethal disease that is, overdiagnosis.

Cancer patients 2.5 times more likely to declare bankruptcyThyroid cancer patients second highest (3X risk)

Health Aff (Millwood). 2013 June; 32(6): 1143-1152

Age of patientSexPresence of metastasesTumor sizeLocal invasionDeterminants of Prognosis

TNM stagingPapillary or follicular (differentiated) thyroid cancer in patients younger than 45Stage I (any T, any N, M0)Stage II (any T, any N, M1)Papillary or follicular (differentiated) thyroid cancer in patients 45 years and olderStage I (T1, N0, M0)Stage II (T2, N0, M0)Stage III:T3, N0, M0T1 to T3, N1a, M0Stage IVA: T4a, any N, M0T1 to T3, N1b, M0Stage IVB (T4b, any N, M0)Stage IVC (any T, any N, M1)

T categories for thyroid cancer (other than anaplastic thyroid cancer)TX: Primary tumor cannot be assessed.T0: No evidence of primary tumor.T1: The tumor is 2 cm (slightly less than an inch) across or smaller and has not grown out of the thyroid.T1a: The tumor is 1 cm (less than half an inch) across or smaller and has not grown outside the thyroid.T1b: The tumor is larger than 1 cm but not larger than 2 cm across and has not grown outside of the thyroid.T2: The tumor is between 2 cm and 4 cm (slightly less than 2 inches) across and has not grown out of the thyroid.T3: The tumor is larger than 4 cm or it has begun to grow a small amount into nearby tissues outside the thyroid.T4a: The tumor is any size and has grown extensively beyond the thyroid gland into nearby tissues of the neck, such as the larynx (voice box), trachea (windpipe), esophagus (tube connecting the throat to the stomach), or the nerve to the larynx. This is also called moderately advanced disease.T4b: A tumor of any size that has grown either back toward the spine or into nearby large blood vessels. This is also called very advanced disease.N categories for thyroid cancerNX: Regional (nearby) lymph nodes cannot be assessed.N0: No spread to nearby lymph nodes.N1: The cancer has spread to nearby lymph nodes. N1a: Spread to lymph nodes around the thyroid in the neck (called pretracheal, paratracheal, and prelaryngeal lymph nodes). N1b: Spread to other lymph nodes in the neck (called cervical) or to lymph nodes behind the throat (retropharyngeal) or in the upper chest (superior mediastinal).

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Surgical TreatmentMainstay of thyroid cancer treatmentBecame more aggressive over last 20 yearsPendulum now swinging towards less aggressive surgerySelected patients may be followed without surgery

Surgical optionsLobectomyTotal thyroidectomyTotal thyroidectomy plus lymph node dissectionIpsilateral or bilateral central compartmentsLateral compartments

Surgical RisksRecurrent laryngeal nerve injuryUnilateral, hoarseness, globus sensation. Seldom causes airway issueHypoparathyroidismPermanent approx. 1%Temporary very common

HypoparathyroidismHigh dose calciumCalcitriol. 1,25 OH Vitamin DOften given to prevent temporary hypocalcemia after thyroidectomyLow PTH post-operatively can predict hypocalcemia


Airway Management in GoiterThyroid nodules can cause airway symptomsNodule size not well correlated with symptomsTracheal deviationTracheal compression

Pt. presentation72 y.o. F5 yr. history of goiter, observation recommendedHx of CADPresented to outside ER because of dyspneaTransferred by air to UNCOn arrival, stridorous but in no acute distress

Awake fiberoptic oral intubation attempted. Failed because couldnt turn corner into tracheaAttempted awake direct laryngoscopy without successFiberoptic nasotracheal intubation successfully completedNo operative complicationsPt. discharged POD 1

4572 pts in database, 919 with retrosternal goiter133 pts further analyzed32 identified as likely difficult airway

Retrosternal Goiter17 pts had awake fiberoptic intubation. In two pts attempt abandoned and had IV induction11 pts had inhalational induction. Two converted to IV inductionWe found no good evidence that thyroid surgery patients with retrosternal goitre, with or without symptoms and signs of tracheal compression, present the experienced anaesthetist with an airway that cannot be managed using conventional techniques.

Personal ObservationsFiberoptic laryngoscopy must be mastered under easy conditions before being used in the most difficult casesCoughing, gagging, aspiration, airway irritation and trauma are common with awake intubationsOrotracheal awake intubations are particularly difficult


Intraoperative Nerve MonitoringRecurrent Laryngeal NerveInnervates all but one of the muscles of the larynxInjury to the nerve results in paralysis of the vocal cord on that side.

Goals of Intraoperative Nerve MonitoringPrevent Nerve InjuryWarn when nerve is stressedAnatomical identification of nerve

Outcomes of Nerve MonitoringDoes not prevent injury to recurrent nerveMay help confirm that a nerve is functionally intact prior to proceeding to the other sideMay help the surgeon improve nerve handlingCan have both false-positive and false-negative signals


Pheochromocytoma and Paraganglioma Pheochromocytoma: Catecholamine secreting adrenal tumor arising from chromaffin cells of adrenal medullaChromaffin cells derive from the neural crest.They contain granules which stain with oxidizing agents.Paraganglioma: Extra-adrenal pheo

Prevalence Affects approximately 0.2% of hypertensivesPeak incidence 4th/5th decades3-9% of Incidentalomas (Incidental finding on CT Scan)

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Adrenal MedullaStored catecholamines80% stored as epinephrine, 20% as norepinephrinesAll are derived from tyrosine

Activity of catecholamines:Increase glycogenolysisIncrease gluconeogenesisIncrease glucagon secretionDecrease glucose uptake

Clearance: by urine, peripheral enzymatic degradation, uptake at nerve endings

b1Chronotrope, inotrope, lipolysis, sweat releaseTachycardia, diaphoresisb2Smooth muscle relaxation, vasodilation, glycogenolysis, gluconeogenesis, insulin secretionHypotension, hyperglycemiaa1Smooth muscle contraction, glycogenolysis, gluconeogenesis, sodium reabsorption, sweat releaseHypertension, hyperglycemia, diaphoresisa2Inhibits release of norepinephrine, vasoconstriction, stimulates cognitionPallor

Pheochromocytoma: the 10 % TumorBilateralMalignantMultifocalExtra adrenalChildrenFamilial

Presentation of Pheochromocytoma Signs:

HypertensionTachycardia

Symptoms:

Headaches DiaphoresisNausea/vomitingAnxiety

Diagnosis of PheochromocytomaSigns and symptomsFrequently asymptomatic or subclinically symptomaticIncidental finding on CT ScanSporadic versus FamilialConfirmation by biochemical testing and localization studies

Biochemical Testing for PheochromocytomaPlasma Metanephrines24 hr urine catecholamines (norepi, epinephrine, dopamine) and metabolites (metanephrine, normetanephrine, vanillylmandelic acid)Elevations will be dramatic in pheochromocytomaElevated serum epinephrine suggests pheochromocytoma at adrenal medulla or at the organ of Zuckerkandl because phenylethanolamine N methylating enzyme is found at these sites

Perioperative ManagementGoals:Treat hypertension: adequate alpha blockade

Volume expansion: vasoconstricted and intravascularly depeleted

Control cardiac arrhythmia: addition of beta blockade

Alpha blockade

Phenoxybenzamine: Alpha adrenergic antagonist Initiate 1-3 weeks before resectionTitrate dose to mild orthostasisExpensive and difficult to findDoxazosin: Alpha 1 antagonistMay be as effective as PhenoxybenzamineMay reduce intra and post-op hypotension

Once adequately alpha blocked:Adequate alpha blockade: fluid retention leading to weight gain; orthostatic hypotensionMay initiate beta blockade for arrhythmiasNever initiate blockade with beta antagonistsUnopposed alpha effect of catecholamine will worsen vasoconstriction and precipitate hypertensive crisis or pulmonary edema

Intraoperative monitoringAvoid anesthetics which precipitate catecholamine secretionLeast cardiac depressant: isoflurane, enflurane,nitroprusside, phentolamine A line: blood pressureNitroprussideLabetolol

Treatment during Pregnancy 1st trimester: initiate medical therapy and resect in 2nd trimesterIf noted late in pregnancy: elective c section at term, avoid vaginal delivery- may percipitate hypertensive crisis


Parathyroid GlandComposed primarily of Chief cellsSecrete PTHProminent GolgiContain secretory granulesOxyphil cellsBegin to appear at pubertyDo not secrete PTHFunction not knownFatIncreases to about 30% by age 25, remains constant

Parathyroid Hormone84 amino acid polypeptideSecreted from parathyroid cells in response to low calciumLithium increases PTH secretion and decreases cell sensitivity to Ca++ 1,25 (OH)2 D decreases PTH secretion

Effects of PTHIncreases activity of osteoclasts causing release of calcium from boneIncreases calcium reabsorption from urine in the kidneyIncreases urinary phosphate excretionIncreases renal production of 1,25 (OH)2 DWhich causes increased GI absorption of calcium

Primary HyperparathyroidismIncidence approximately 21 per 100,000 per yearIncidence slowly decliningPeak age early 50sFemale: male 3:1Most common cause of hypercalcemia in outpatients

Primary HyperparathyroidismApproximately 85% caused by single adenomaApproximately 10% diffuse hyperplasiaApproximately 5% multiple adenomas

Signs/SymptomsStones, Bones, Groans, MoansRenalSkeletalAbdominalCardiovascularPsychiatric and neuromuscular

Signs/SymptomsNeuropsychiatric ManifestationsEasy fatiguabilityDepressionInability to concentrateMemory problems Proximal myopathy

ManagementSurgery the only cureBisphosphonates can lower calcium but do not lower and may increase PTHCinacalcet lowers calcium but only modestly lowers PTH. Does not decrease calcium excretion.Does everyone need surgery?

ManagementSurgery vs. observation in asymptomatic pts.*Consensus conferences 1990, 2002, 2008, 20131990200220082013Age

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