Anesthesia for Endocrine Surgery Flashcards
1
Q
The thyroid gland is formed by two lateral lobes connected by the _________ at about the second tracheal ring
A
Thyroid Isthmus
Thyroid Isthmus is ANTERIOR to the trachea
2
Q
What sensory nerves innervate above the vocal cords?
A
Internal Laryngeal Branch of Superior Laryngeal Nerve
3
Q
What sensory nerves innervate below the vocal cords?
A
Recurrent Laryngeal Nerve
4
Q
Motor innervation to most of the intrinsic muscles of the larynx is supplied by which nerve?
This nerve does not innervate which structure of the larynx?
A
- Recurrent Laryngeal Nerve
- Cricothyroid Muscle
5
Q
What nerve supplies motor innervation to the cricothyroid muscle?
A
External Laryngeal Branch of Superior Laryngeal Nerve
6
Q
Colloid-filled follicles store what substance?
A
Thyroglobulin
7
Q
Parafollicular cells produce what substance?
A
Calcitonin
8
Q
What mineral fuels the production of thyroid hormones?
A
Iodine
9
Q
What are the peripheral effects of Thyroid Hormone?
A
- Heat generation
- Stimulates ATP formation
- Influences flux of ions
- Stimulates metabolic processes ( Basal metabolic rate, protein synthesis, regulation macro metabolism)
10
Q
What are the cardiac effects of Thyroid Hormone?
A
- ↑ LV contractility
- ↑ LV EF
- Tachycardia
- ↑ SBP and ↓ DBP
- Chronic hyperthyroidism can lead to Heart Failure, AF, Dysrhythmias
11
Q
Parasympathetic innervation of the thyroid comes from which nerve?
A
Vagus Nerve
12
Q
Sympathetic innervation of the thyroid comes from which nerve?
A
Superior, Middle, and Inferior Ganglia of the Sympathetic Trunk
13
Q
Sympathetic nerve fibers will run through the thyroid via what plexus?
A
- Cardiac periarterial plexus
- Superior and inferior thyroid plexus
14
Q
What hormone regulates thyroid gland secretion?
Where does this hormone come from?
A
- TSH
- Anterior Pituitary Gland
15
Q
What are the three sources of blood supply to the thyroid gland?
A
- Superior thyroid artery (branch of ext carotid)
- Inferior thyroid artery (branch of subclavian)
- Thyroid ima
16
Q
Venous drainage location of the thyroid gland.
A
- Superior thyroid vein (IJ)
- Middle thyroid vein (IJ)
- Inferior thyroid vein (brachiocephalic)
17
Q
What is the normal level of TSH?
A
0.4-5.0 milliunits/L
18
Q
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Hyperthyroidism
T4:
T3:
TSH:
A
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Hyperthyroidism
T4: Elevated
T3: Elevated
TSH: Normal/Low
19
Q
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Primary Hypothyroidism
T4:
T3:
TSH:
A
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Primary Hypothyroidism
T4: Decrease
T3: Decrease/Normal
TSH: Increase
20
Q
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Secondary Hypothyroidism
T4:
T3:
TSH:
A
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Secondary Hypothyroidism
T4: Decreased
T3: Decreased
TSH: Decreased
21
Q
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Pregnancy
T4:
T3:
TSH:
A
Give the anticipated lab values for the following thyroid disease/condition.
Dx: Pregnancy
T4: Elevated
T3: Normal
TSH: Normal
22
Q
What type of cancer has the fastest rising incidence?
A
Thyroid cancer
23
Q
What factors determine the prognosis of thyroid cancer?
A
- Age of patient
- Sex
- Presence of metastases
- Tumor size
- Local invasion
24
Q
What is the mainstay of thyroid cancer?
A
Surgical Treatment
25
Surgical options for thyroid cancer
* Lobectomy
* Total thyroidectomy
* Total thyroidectomy plus lymph node dissection
26
What are the risks of thyroid surgery?
* RLN injury (biggest risk)
* Hypoparathyroidism (mostly temporary)
* Bleeding
## Footnote
Unilateral RLN - hoarseness, global sensation, temporary
Bilateral RLN - AIRWAY issue
27
A syndrome caused by excessive secretion of TH when there is an overactive thyroid gland.
HYPERTHYROIDISM
28
Clinical Manifestation of Hyperthyroidism
Thyrotoxicosis
29
Cause of Hyperthyroidism
* Graves disease (most common)
* Thyroid adenoma
* Thyroid carcinoma
* TSH pituitary adenomas
* Iatrogenic
30
Symptoms of Hyperthyroidism
* Tachycardia/ Palpitations
* Nervousness
* Heat intolerance/ ↑ Sweating
* Fatigue and weakness
* ↑ Metabolism/ Weight loss
* Hyperdefication
31
Signs of Hyperthyroidism
* Thyroid enlargement
* Tachycardia
* Atrial fibrillation
* Systolic hypertension ( wide pulse pressure)
* Eye signs (exophthalmos)
32
Which gender is more prone to hyperthyroidism?
Female (age 20-40)
33
Possible treatments for hyperthyroidism
* Anti-thyroid Drugs
* β-blockers
* Steroid/ Glucocorticoids
* Radiation
* Surgery
34
Normal T4 level
60-120 nmole/L
35
Factors that increase T4 level
* Hyperthyroidism
* Thyroditis
* Early hepatitis
* Pregnancy
* Oestrogen therapy
* Exogenous T4
36
Factors that decrease T4 level
* Hypothyroidism
* Androgens
* Salicylates
* Sulphonamides
37
Normal T3 level
0.92-3 nmole/L
38
Factors that increase T3 level
Hyperthyroidism
39
Factors that decrease T3 level
* Hypothyroidism
* Cirrhosis
* Uremia
* Malnutrition
40
What condition will increase TSH level?
Primary Hypothyroidism
41
What condition will decrease TSH level?
Hyperthyroidism
42
Give examples of Anti-thyroid drugs.
MOA.
* PTU
* Methimazole
* Carbimazole
* MOA: Inhibition of synthesis of TH by blocking the action of peroxidase, also inhibits the T4 → T3 conversion
43
MOA of how glucocorticoids treat hyperthyroidism
* Decreases Release of hormone
* Inhibits conversion T4 → T3
44
MOA of how radioactive iodine treats hyperthyroidism
* Destroys follicular cells
* Remission Rate: 80% +
* 40% - 70% hypothyroid within ten years
45
What is the last resort for hyperthyroidism treatment?
* SURGERY
* Remission 95%
* 10% - 30% hypothyroid w/i 20 yrs
46
Indications for Thyroid Surgery
* Large goiter
* Compressive symptoms
* Kids
* CA pt or suspicious nodules
* Allergy to anti-thyroid drugs
* Pregnant and those with a desire to conceive soon
* Moderate to severe ophthalmopathy
* Cosmetic desire of the patient
47
Pre-op assessment for patients undergoing thyroid surgery
* Assessment of upper airway & tracheal deviation
* Thoracic inlet X-ray, CT scan
* Patient must be EUTHYROID
* Use anti-thyroid drugs and β-blockers
* Resting pulse rate 85-90 bpm
48
What drugs should you avoid during thyroid surgery?
* Atropine
* Pancuronium
* Halothane
* Ketamine
## Footnote
These drugs may activate the SNS
49
Drug of choice for induction of a hyperthyroid patient.
* Etomidate
* Propofol
* Barbituates
50
Choice of muscle relaxant for hyperthyroidism
* Atracurium
* Vecuronium
## Footnote
*Cardio stability*
51
Choice of VA for hyperthyroid patient
Isoflurane
## Footnote
*Cardio Protective*
52
What type of infusion will typically be started on thyroid patients to keep HR in check?
Esmolol infusion 50-150 mcg/kg/min
53
What is a postoperative concern for thyroid surgery patients?
Thyroid storm/ crisis
## Footnote
An acute exacerbation of hyperthyroidism with excessive release of thyroid hormone
54
When will the patient experience a thyroid storm/ crisis?
Onset can be intraoperative or 6-24 hours after surgery
55
Signs and Sx of Thyroid Storm
* Hyperpyrexia,
* Tachycardia or atrial fibrillation
* Hypotension
* Vomiting/ Dehydration,
* Tachypnea
* Acute abdominal pain
* Agitation/ psychosis
## Footnote
Need to R/O: MH, Pheochromocytoma, or Light Anesthesia
56
How will Thyroid Storm be managed?
* PTU
* Carbimazole
* Sodium Iodide/ Potassium Iodide
* Steroids
* Receptor blockade (propanolol)
* Tx Cardiac failure (diuretics, dig, O2)
* Tx Hyperpyrexia
* Tx Dehydration (IV fluids)
57
What is the triad of concerns for patients undergoing thyroid surgery?
* Airway obstruction
* Tetany
* RLN Injury
58
What are the possible causes of airway obstruction in a hyperthyroid patient?
* Neck hematoma w/tracheal compression
* Tracheomalacia
* Incomplete reversal of NDMR
* CNS depression
59
Clinical Manifestation of Tetany
* Circumoral tingling
* Paraesthesia
* Laryngeal spasm,
* Chvostek & Troussau signs
60
Tetany can result in what type of acid-base imbalance?
Respiratory Alkalolsis
61
Management for Tetany
* Calcium Replacement
* Slow injection of 10% calcium gluconate 10 mL IV
62
Clinical Manifestation of Unilateral RLN Injury
* Weak and horse voice croaking
* Coughing when drinking
* Aspiration
* Usually no O2 desaturation
63
Management of Unilateral RLN Iinjury
* Reintubation & observe for 6-12 minutes
* If the normal function of cords is not returned within 6- 12 minutes Teflon injection
* Speech therapy
64
Clinical Manifestation of Bilateral RLN Injury
* Usually manifests immediately after extubation.
* Laryngeal stridor
* Acute respiratory distress
* Phonation lost
* O2 desaturation
65
Management of Bilateral RLN Iinjury
* Reintubation/ muscle paralysis
* Hydrocortisone 100 mg TID
* If extubation fails after 48 hrs, Tracheostomy is warranted
66
What is Hypoparathyroidism?
Condition when the body tissues are exposed to decreased circulating concentration of thyroid hormones
67
Causes of Hypoparathyroidism
* Destruction of the thyroid gland
* CNS dysfunction
68
Management of Hypoparathyroidism
* High dose calcium
* Calcitriol
* Vitamin D
* These are often given to prevent hypocalcemia during thyroidectomy
69
What lab value can be used to predict hypocalcemia?
Decrease PTH
70
Signs and Sx of hypothyroidism
* ↓ Metabolic activity
* Cold intolerance
* Lethargy
* ↓ CO up to 40%
* Prolonged circulation time
* Narrow pulse pressure
* ↑ PVR to decrease heat loss
71
What medication is given to treat hypothyroidism?
Levothyroxine
72
Severe form of hypothyroidism
Myxedema
73
Clinical manifestation of Myxedema
* Stupor
* Coma
* Hypoventilation
* Hypotension
* Hypothermia
* Hypernatremia
74
Myxedema is a medical emergency with a mortality rate of ________%
25-50%
75
What induction agents will be used for Myxedema?
* Ketamine is a preferable induction agent
* If no severe CVS depression, propofol can be used
* When using relaxants keep in mind that there is a coexisted skeletal muscle weakness, decrease the dose
76
Myxedema Anesthetic Management
* Hydrocortisone 100mg IV followed by 25 mg IV QID
* Fluid and Lytes Supplementation
* Avoid Hypothermia
* Awake Extubation
* Consider Ketorolac
* Regional Anesthesia preferred over GA
77
What is the NMBD of choice for Myxedema?
Pancuronium
## Footnote
Pancuronium can precipitate catecholamine release
78
Factors that cause delayed emergence for myxedema patients
* Hypothermia
* Respiratory Depression
* Slow Drug Biotransformation
79
What is the best plan to establish an airway if a patient presents with a goiter?
Order or study imagining to determine an airway plan
80
Which nerve is usually monitored during intraoperative endocrine surgery?
RLN
81
What type of ETT is used for nerve monitoring for endocrine surgery?
Neural Integrity Monitor (NIM) ETT
82
Goals of Intraoperative Nerve Monitoring
* Prevent Nerve Injury
* Warn when the nerve is stressed
* Anatomical identification of nerve
83
Outcomes of Nerve Monitoring
* Does not prevent injury to RLN
* Help confirm that a nerve is functionally intact prior to proceeding to the other side
* Help the surgeon improve nerve handling
* Can have both false-positive and false-negative signals
84
Catecholamine-secreting adrenal tumors arising from chromaffin cells of the adrenal medulla
Pheochromocytoma
## Footnote
Mass on the kidney
85
What is a paraganglioma?
Extra-adrenal pheochromocytoma
86
The adrenal medulla stores what hormone?
* Catecholamines
* 80% as epinephrine
* 20% as norepinephrine
87
Catecholamines (Epi/NE) are derived from which amino acid?
Tyrosine
88
Effects of Catecholamines
* Increase glycogenolysis
* Increase gluconeogenesis
* Increase glucagon secretion
* Decrease glucose uptake
89
How are catecholamines cleared from the body?
* Urine
* Peripheral enzymatic degradation
* Uptake at nerve endings
90
Receptor: β1
Activity:
Symptoms:
Receptor: β1
Activity: Chronotrope, Inotrope, Lipolysis, Sweat Release
Symptoms: Tachycardia, Diaphoresis
91
Receptor: β2
Activity:
Symptoms:
Receptor: β2
Activity: SM relaxation, vasodilation, glycogenolysis, gluconeogenesis, insulin secretion
Symptoms: Hypotension, Hyperglycemia
92
Receptor: α1
Activity:
Symptoms:
Receptor: α1
Activity: SM contraction, glycogenolysis, gluconeogenesis, Na+ reabsorption, sweat release.
Symptoms: Hypertension, Hyperglycemia, Diaphoresis
93
Receptor: α2
Activity:
Symptoms:
Receptor: α2
Activity: Inhibit the release of NE, vasoconstriction, stimulates cognition
Symptoms: Pallor
94
Signs and Sx of Pheochromocytoma
* HTN
* Tachycardia
* HA
* Diaphoresis
* N/V
* Anxiety
## Footnote
*Pretty much the feeling you get during your first day at clinical*
95
Dx of Pheochromocytoma
* Frequently asymptomatic
* Incidental CT Scan
* Confirmed by biochemical testing
96
What are the Biochemical studies for Pheochromocytoma?
* Plasma Metanephrines
* 24 hour catecholamines
* Elevated serum epinephrine
97
What substance will be measured in the 24-hour urine catecholamines test?
* NE
* EPI
* Dopamine
* Metabolites (Metanephrine, Normetanephrine, Vanillylmandelic Acid)
## Footnote
Board Question
98
Where can Phenylethanolamine N Methylating Enzyme be found?
* Adrenal Medulla
* Organ of Zuckerkandl
99
Perioperative Management Goal of Pheochromocytoma
* Treat hypertension w/ α-blockade
* Volume expansion
* Control cardiac arrhythmia w/ β-blockade
100
What two main drugs are used for α-blockade for pheochromocytoma?
* Phenoxybenzamine
* Doxazosin
101
When will Phenoxybenzamine be initiated before resection of the pheochromocytoma?
1-3 weeks before resection
102
What S/E may the pheochromocytoma patient experience once they are adequately α blocked?
* Fluid Retention
* Weight Gain
* Orthostatic Hypotension
103
When should β-blockade be initiated for pheochromocytoma patients?
AFTER α-blockade
## Footnote
If beta blockers are given first, it would block the beta receptors of the vascular smooth muscle repsonsible for vasodilation. This will cause a net effect of vasoconstriction which can worsen hypertension or pulmonary edema.
104
What anesthetic drugs should be avoided in pheochromocytoma patients b/c they can precipitate catecholamine release?
* Ketamine
* Pancuronium
105
Which anesthetic agents are the least cardiac depressant?
* Isoflurane
* Enflurane
* Nitroprusside
* Phentolamine
106
During which trimester will a pheochromocytoma be resected in a pregnant patient?
During the 2nd trimester
107
If pheochromocytoma is noted late into pregnancy, what should be the delivery method?
* C-section
* Vaginal delivery may precipitate a hypertensive crisis
108
What cells make up the parathyroid gland?
* Chief Cells (majority of parathyroid gland)
* Oxyphil Cells
* Fat Cells
109
What does the Chief Cell secrete?
PTH
110
When do Oxyphil cells begin to appear?
Puberty
111
How many amino acids make up the PTH?
84 amino acids
112
When will PTH be secreted?
PTH will be secreted from the parathyroid gland increase to low calcium levels.
113
Maintenance of Ca2+, Phos, and Mag homeostasis is under the influence of which two polypeptide hormones:
* Parathyroid hormone(PTH)
* Calcitonin
114
Which hormone acts directly on the bones and kidneys and indirectly on the intestine. Its production is regulated by the concentration of serum-ionized calcium.
PTH
115
Which hormone is released by the “C” cells (Para follicular cells in the thyroid gland) in response to small increases in plasma ionic calcium. It acts on the kidneys and bones to restore the level of calcium to just below a normal set point, which, in turn, inhibits the secretion of the hormone.
Calcitonin
116
Effects of PTH
* ↑ Activity of osteoclasts causing the release of Ca from bone
* ↑ Ca reabsorption from urine in the kidney
* ↑ Urinary phosphate excretion
* ↑ renal production of Vitamin D3 (calcitriol)
* ↑ GI absorption of calcium
117
What is the most common cause of hypercalcemia in outpatients?
Primary Hyperparathyroidism
118
Which gender is more likely to have hyperparathyroidism?
Females are 3x more likely
119
Causes of Primary Hyperparathyroidism?
* 85% caused by single adenoma
* 10% diffuse hyperplasia
* 5% multiple adenomas
120
Signs and Sx of Primary Hyperparathyroidism?
* Renal
* Skeletal
* Abdominal
* Cardiovascular
* Psychiatric and neuromuscular
## Footnote
*Stones, Bones, Groans, Moans*
121
Neuropsychiatric Manifestations
of Primary Hyperparathyroidism.
* Easy fatiguability
* Depression
* Inability to concentrate
* Memory problems
* Proximal myopathy
122
What is the only cure for Primary Hyperparathyroidism?
Surgery
123
Effects of Bisphosphonates on Hyperparathyroidism
* Bisphosphonates can lower calcium
* May increase PTH
124
Effects of Cinacalcet on Hyperparathyroidism
* Cinacalcet lowers calcium
* Modestly lowers PTH.
125
Why is surgery to most optimal route for most hyperparathyroidism?
* When end-organ damage occurs, it is irreversible
* Neuropsychiatric symptoms are common and often subtle
* The operation is very effective and has minimal morbidity
126
What is involved in the surgical treatment for Hyperparathyroidism
* Removal of all affected glands (one or more adenomas)
* For diffuse hyperplasia, removal of all but approximately 50-70 mg of parathyroid tissue
127
Which hyperparathyroidism surgery has a 100% success rate?
* Directed parathyroidectomy
* Requires intraoperative PTH monitoring (need an arterial line)
128
What are the different ways to image the parathyroid gland?
* Sestamibi scan
* Ultrasound
* CT (4D CT)
* MRI
## Footnote
Overall sensitivity around 70-80%.
All very poor at multi-gland disease
129
Preoperative Assessment for Hyperparathyroidism Surgery
* Assess volume status to avoid hypotension during induction
* Hydration w/ NS and diuresis with Lasix to decrease serum Ca levels
* Bone fragility
* Labs and Comorbidities
130
Anesthetic Considerations for Hyperparathyroidism Surgery
* Titration of muscle relaxants(pre-existing muscle weakness)
* Avoid hypoventilation, acidosis ↑ ionized calcium → cardiac dysrhythmias.
Tracheal manipulation during dissection
* Proper patient positioning
* Smooth emergence
* Evaluate for RLN damage
* Pain control
131
Post-operative complications for Hyperparathyroidism Surgery
* Neck hematoma
* Laryngeal swelling/ glottis edema
* RLN damage
* Hypocalcemia= tetany
* Acute arthritis
* Metabolic acidosis with deterioration of renal function (transient)
* **PARATHYROID CRISIS**
132
What Ca2+ level is considered a Parathyroid Crisis?
>15 mg/dl
133
Parathyroid Crisis Management
* Requires hydration (dilutes Ca++)
* Followed by diuresis with loop diuretic (promote Ca++ & H2O excretion)
* Glucocorticoids
* Calcitonin
* Dialysis
134
What is the purpose of intraoperative PTH Assay?
To confirm that all abnormal parathyroid tissue has been removed w/o the need to physically examine all glands
135
List the times you will draw a PTH during surgery.
* After anesthesia induction but before neck incision (0-min or baseline)
* During the manipulation of a suspected hyperfunctioning gland (pre-excision)
* 5-min after gland excision
* 10-min after gland excision
* 20-min after gland excision
136
A PTH decline of what percent indicates a successful parathyroid gland excision.
>50% decline in PTH
137
Outcomes after hyperparathyroidism surgery
* Approx. 99% success rate
* Increased bone density
* Resolution of hypercalciuria.
* Decreased risk of kidney stones
* Improvement in neurocognitive symptoms
* Improvement in functional ability in the elderly
138
What is the gold standard surgical technique for hyperparathyroidism?
* Full neck exploration
* 99% success rate
* Requires visualization of all four glands
