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Domain 2 Endocrine > Pheochromocytoma > Flashcards

Pheochromocytoma Flashcards

1
Q

What is the differential diagnosis of Arterial hypertension?

A 
Essential HPT
primary renal disease
Endocrine
Sympathetic stimulation
Miscellaneous
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2
Q

What is pheocromocytoma?

A

Tumors of the cheomaffin cells secreting noradrenaline, adrenaline or dopamine.
They Amy secrets >1 amine.

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3
Q

What other substances may theae tumors produce?

A

VIP

ACTH

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4
Q

Where are they usually situated?

A

Adrenal medulla 99%
Sympathetic paraganglua
May extend to from base of skull to anus

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5
Q

Prevalence of pheo

A

0.005%-0.01%
Both genelders
Incidence at peak 3rs - 5th decade of life

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6
Q

Which age group do they commonly occur?

A

Occurs in all ages but less common in children.

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7
Q

10 rule of pheo?

A

10% bilateral
10% familial
10% extrarenal
10% malignant

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8
Q

Which familial syndromes is Pheo associated with?

A

MEN2A: parathyroid adenama, medullary thyroid carcinoma, pheo

MEN2B: medullary carcinoma of thyroid, mucosa adenoma, marfanoid features, pheo

Hippel-Lindau Syndrome : haemangioma of retina, cerebellum, pheo

Neurofibromatosis : neurofibromas, cafe-au-lait spots, axillary or inguinal freckling, optic nerve glioma, pheo

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9
Q

What’s the presentation of pheo?

A

Hypertension
Palpitations, sweating headaches with HPT
Acute presentations includes: MI, pulmonary oedema, CVA

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10
Q

What biochemical tests can be done for diagnosis of pheo?

A

Vanillylmandelic acid
Urine Metanephrines - high tru e-positive results 98-99%
Plasma Metanephrines- more difficult to implement correctly

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11
Q

What radiological tests can be used to diagnose Pheo?

A

CT with or without iodine 131 labeled metqiodobenzylguanidine.
CAUTION : radio Contrast induces a pheo crisis as iodine taken up by cheomaffin tissue.
MRI in pregnancy and extrarenal

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12
Q

What additional investigation are needed for anaesthesia?

A

ECHO: hx if MI or signs of failure

Blood glucose

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13
Q

Preoperative : how is the pharmacological preparation done?

A

Alpha blockers: Phenoxybenzamine, doxazocine, prazocine, terazocine

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14
Q

Preoperative ;

phenoxybemzamine

A

Long duration
Easy to administer
Irreversibly and non selectively binds aplha 1
SE:

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15
Q

Phenoxybenzamine SE

A

Reflex tachycardia therefore a B Blocker is introduced when aplha blockade is achieved

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16
Q

Why is b Blocker not advised before adequate A blockade

A

Inhibition of b receptors mediated Vasodilation can result in unopposed A receptor mediated vasoconstriction due to catecholamines secreted by tumor which can precipitate Hypertensive crisis, heart failure and end organ damage.

17
Q

What other medications can be used preoperatively

A

Methyl-para-tyrosine - inhibits enzyme tyrosine hydroxylase thus reduces production of catecholamines
Calcium channel Blockers- nicardipine maybe equivalent to Phenoxybenzamine

18
Q

How is sympathetic blockade assessed

A

BP < 140/90 HR<100bpm

Erect and supine HR & BP should exhibit a marked postural drom of >20mmhgwith compansated tachycardia

19
Q

What are the main goals of preoperative pharmacological therapy?

A

Control hypertension

Facilitate intravascular volume : patient oral fluid and salt intake

20
Q

Perioperative: premedication

A

Required ie temazepam

21
Q

Preoperative monitoring

A 
Standard ASA: V5 lead, core temperature 
A-Line
CVP + large bore 
CO monitor
Urine catheter.
22
Q

Best induction agents to use

A

Propofol
Rami
Rapifen
Vec or roc

23
Q

Drugs to avoid

A 
Droperidol
Morphin
Atracurium
Pancuronium
Ketamin
Ephedrine
Halothane
Cocain
Metoclopromide
24
Q

Management of hypertension intraop: Mgso4

A

Can be started prior induction 2-4g bolus with 1-2g/hr infusion.
Blockers catecholamines release, block receptors, vasodilates and myocardial protectant

25
Q

Induction technique

A

Blunt intubation : lidocaine 1,5mg/kg ivi or mucosa atomizer,
Rapifen/ mgso4,
Relaxants : avoid Pancuronium and atra+cis
Maintainance: avoid des sympathetic stimulant, halothane causes dysarehytmias

26
Q

Management of hypertension intraop:nicardipine

A

Infusion 5-15mg/hr increase by 2,5mg/hr every 15minto effect

27
Q

Management of hypertension intraop: phentolamine

A

1mg iv boluses every 5-10min

Infusion 0.1-2mg/min titrate to effect

28
Q

Management of hypertension intraop: Nitroglycerin

A

20-4mcg every 5-10min

Infusion 5-20mcg/min max 400mcg/min

29
Q

Management of hypertension intraop: nitroprusside

A

0.5-1.5mcg/kg/hr max 8mcg/kg/min over 1-3hrs

30
Q

Management of hypertension intraop: b Blocker s

A

Not 1st line as they may cause unopposed A blockade

Propranolol 1mg boluses max 10mg
Esmolol load5-10mgthen 0.25-0.5mcg/kg/min
Labetalol 5-10mg boluses every 20-30min

31
Q

Post resection management BP mgmnt

A

CVP 10-15mmHg
Volume expansion: preload sevaleral liters of crystalloid
Vasopressors adrenaline or noreadrenaline
If resistant : Terlipressin1mg bolus followed by vasopressin 0.04U/min titrate to effect

32
Q

Postoperative management

A

ICU/HDU for 12hr
Monitor Glucose as catecholamine withdrawal may cause hypoglycemia
Steroid support if adrenals removed : fludrocortosone 0.1mg/day
If only one adrenal removed hyrocort 50mg
Narcotic requirements are decreased

33
Q

Pheocromocytoma in pregnancy considerations

A

Mortality rate 17%
Phenoxybenzamine and metaprolol safe
Can be respected <24weeks
Consider c/s as NVD has high mortality

34
Q

Management of unexpected pheo

A

Cancel surgery start pharmacological Rx

Do not remove whole in crisis higher mortality

35
Q

Laparoscopic concerns

A

Pneumoneperitoneum increase catecholamines levels
Use lowered pressures
Terminate insuflation if haemodynamicaly unstable sustained and refractory

Domain 2 Endocrine (8 decks)

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