Endocrine Flashcards

1
Q

what is the general structure of the thyroid?

A

paired bilobed gland - right and left glands

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2
Q

where does the thyroid gland typically lie?

A

caudal to the larynx, between 5th and 8th tracheal rings

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3
Q

where is the thyroid in relation to the trachea?

A

ventrolateral to the trachea

right gland slightly more cranial than left

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4
Q

why is the thyroid at risk of haemorrhage during surgery?

A

very well vascularised

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5
Q

why is it important to be aware of iatrogenic damage during surgery on the thyroid?

A

there are numerous neurological structures in the area which require careful identification during surgery

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6
Q

where can ectopic thyroid tissue be found?

A

lying in the midline from the tongue to the abdomen

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7
Q

why is is possible to have ectopic thyroid tissue?

A

as a result of the path the thyroid tissue undergoes during embryonic development

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8
Q

why do we place oesophagostomy tubes on the lhs of the neck?

A

the oesophagus sits more on the lhs of the neck, in contact with the left thyroid gland

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9
Q

what is a functional thyroid condition?

A

one which produces thyroid hormones

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10
Q

how can we categorise surgical conditions of the thyroid?

A

functional vs non-functional

benign vs malignant neoplasia

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11
Q

when benign conditions can affect the thyroid gland?

A

adenoma
adenomatous hyperplasia
cysts

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12
Q

what malignancies can affect the thyroid gland?

A

carcinoma

adenocarcinoma

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13
Q

what type of benign thyroid masses affect dogs?

A

typically small and non-functional - rarely diagnosed

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14
Q

what type of benign thyroid masses affect cats?

A

typically functional and cause hyperthyroidism

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15
Q

what is the most common type of thyroid mass in cats?

A

95% of all cases are benign adenoma/adenomatous hyperplasia

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16
Q

are malignant thyroid masses in dogs typically functional?

A

no - mostly non-functional, do not cause hyperthyroidism and are instead presented due to the mass itself

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17
Q

are thyroid masses often malignant in cats?

A

no - typically functional, benign masses

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18
Q

do thyroid cysts occur commonly?

A

no - rare

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19
Q

what are the main pre-operative considerations for thyroidectomy?

A

body condition score

likelihood of metastasis

cardiovascular effects

renal effects

ocular effects

co-morbidities - typically older animals

degree of medical stabilisation achieved

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20
Q

what are the pre-op cardiovascular considerations for thyroidectomy?

A

tachycardia
hypertension

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21
Q

what are the pre-op renal considerations for thyroidectomy?

A

pre-renal azotemia

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22
Q

what are the pre-op ocular considerations for thyroidectomy?

A

retinal detachment secondary to hypertension

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23
Q

what are the pre-op c-morbidity considerations for thyroidectomy?

A

CVS, renal, increased GA risk, cachexia, arthritis

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24
Q

what is the benefit of medical stabilisation before thyroidectomy?

A

improvement of asa status

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25
Q

what is involved in medical stabilisation of hyperthyroidism?

A

decrease HR with anti-thyroid meds

treat hypertension and stabilise rhythm with atenolol

support renal function - diet, supplements, fluids

try to increase body weight

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26
Q

what are the pre-operative considerations for thyroidectomy in dogs?

A

BCS - may be reduced due to effects of cancer

metastasis?

co-morbidities present as usually older animals

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27
Q

do dogs require medical stabilisation before thyroidectomy?

A

not usually needed, usually non-functional so far sew systemic effects

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28
Q

how wide should the clip be for thyroidectomy?

A

from level of jaw to thoracic inlet lengthways

wide clip - to jugular grooves widthways

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29
Q

what position should the patient be in for thyroidectomy?

A

dorsal recumbency with sandbag under neck to elevate, keep neck straight

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30
Q

why is it better to do unilateral thyroidectomy if possible?

A

risk of bilateral surgery much higher

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31
Q

how might the parathyroid gland(s) be salvaged during thyroidectomy?

A

sometimes reimplantation of the parathyroid tissue into the surgical site will allow for neovascularisation

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32
Q

what is the risk of reimplanting the parathyroid tissue?

A

risks seeding tumour

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33
Q

what are the surgical options for thyroidectomy?

A

several techniques for vet to choose from

need to consider whether unilateral/bilateral, esp in regards to removal of parathyroid glands

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34
Q

what are the complications of thyroidectomy which are unrelated to surgical technique?

A

GA risks - ASA status

unmask CRF if cat and/or a functional mass

hypothyroidism

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35
Q

what are the complications of thyroidectomy which are related to surgical technique and skill?

A

haemorrhage

seroma formation

laryngeal paralysis

horners syndrome

hypocalcaemia

recurrence of tumour

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36
Q

which thyroidectomy surgeries are at higher risk of haemorrhage?

A

possible with all, but particularly with canine invasive masses

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37
Q

how can haemorrhage be avoided during thyroidectomy?

A

careful surgical technique

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38
Q

what affects likelihood of seroma formation after thyroidectomy?

A

related to size of mass

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39
Q

how can we avoid seroma formation after thyroidectomy?

A

careful surgical technique

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40
Q

how can horners syndrome develop as a result of thyroidectomy?

A

damage to sympathetic trunk (rare)

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41
Q

what are the signs of horners syndrome after thyroidectomy?

A

anisocoria
third eyelid partially across

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42
Q

how can we avoid post-op hypocalcaemia from iatrogenic hypoparathyroidism?

A

protect the parathyroids by good choice of technique and careful surgical technique

staged procedure - remove one side only (whichever is larger)

consider pre-emptive peri-operative support e.g. pre-op vit D and post-op calcium (both oral)

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43
Q

when is recurrence of a thyroid mass more common?

A

presence of ectopic tissue
use of an intracapsular technique
with malignant neoplasia

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44
Q

what is important to consider when weighing up medical or surgical management for thyroid masses?

A

age of patient - will surgery be cheaper than life-long medication if patient is younger

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45
Q

how many parathyroid glands are there in total?

A

4

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46
Q

name all the parathyroid glands

A

left extracapsular (cranial)

right extracapsular

left intracapsular (caudal)

right intracapsular

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47
Q

what is the overall role of the parathyroid glands?

A

increase blood calcium

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48
Q

how are the parathyroid glands arranged?

A

in 2 sets of pairs

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49
Q

what are the options for medical treatment of primary hyperparathyroidism?

A

ethanol injection

heat ablation

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50
Q

what is the surgical treatment option for primary hyperparathyroidism?

A

parathyroidectomy

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51
Q

what is the most important post-op concern after parathyroidectomy?

A

monitoring for hypocalcaemia

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52
Q

which species more commonly develops primary hyperparathyroidism?

A

most commonly seen in dogs

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53
Q

what is the prognosis post-op for primary hyperparathyroidism?

A

usually benign, functional adenoma (95%)

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54
Q

what are the pre-op considerations for parathyroidectomy?

A

systemic effects of hyperparathyroidism

co-morbidities unrelated to hyperparathyroidism

medical stabilisation

complications

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55
Q

what systemic effects might we see in pre-op parathyroidectomy patients?

A

hypercalcaemia affects renal function

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56
Q

what might be involved in pre-op medical stabilisation of parathyroidectomy patients?

A

diuresis with high levels of IVFT to ‘dilute’ the calcium (?)

support renal function, care not to overhydrate

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57
Q

how wide should the clip be for parathyroidectomy?

A

level of jaw to thoracic inlet

jugular grooves widthways

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58
Q

what approach is used for parathyroidectomy?

A

ventral midline - px in dorsal recumbency

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59
Q

when might the associated thyroid be removed during parathyroidectomy?

A

if intracapsular/caudal parathyroid

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60
Q

are multiple glands removed during thyroidectomy?

A

almost always going to be removing one of four rather than multiples

61
Q

what complications might occur during thyroidectomy which are unrelated to surgical technique?

A

complications dur to ASA status

post-op hypothyroidism possible

62
Q

what complications might occur during thyroidectomy which are related to surgical technique?

A

haemorrhage

seroma formation

laryngeal paralysis

horners syndrome

hypoparathyroidism

63
Q

which types of parathyroid masses are more likely to haemorrhage?

A

possible with all, but particularly with canine invasive masses

64
Q

how can haemorrhage be avoided during parathyroidectomy?

A

careful surgical technique

65
Q

how can laryngeal paralysis be caused by parathyroidectomy?

A

if damage to recurrent laryngeal nerves

66
Q

how can laryngeal paralysis be avoided during parathyroidectomy?

A

careful surgical technique

67
Q

how might horners syndrome be triggered during parathyroidectomy?

A

damage to sympathetic trunk (rare)

68
Q

why can post-op hypocalcaemia occur after parathyroidectomy?

A

3 remaining parathyroid glands function is suppressed by the functional mass - delay for these to recover function

69
Q

what should be involved in post-op care after parathyroidectomy?

A

IVFT - according to clinical appearance and losses

analgesia - avoid NSAIDs

monitor for complications - renal function (BP), calcium

70
Q

why should NSAIDs be avoided after thyroidectomy?

A

protect renal function

71
Q

what is the prognosis for recovery after parathyroidectomy?

A

usually good

hypocalcaemia can be transiet (days) or take weeks/months to recover

72
Q

what is the endocrinological result/risk of unilateral thyroidectomy?

A

removes 1 of 2 thyroids

removes 1 of 2 caudal parathyroids (cranials left in place but may be damaged)

low risk hypocalcaemia and hypothyroidism

73
Q

what is the endocrinological result/risk of bilateral thyroidectomy?

A

removes 2 of 2 thyroids

removes 2 of 2 caudal parathyroids (cranials left in place but may be damaged)

higher risk hypocalcaemia

hypothyroidism

74
Q

what is the endocrinological result/risk of unilateral parathyroidectomy?

A

removes 1 of 2 thyroids

removes 1 of 2 caudal parathyroids (cranials left but may be damaged/already suppressed)

highest risk hypocalcaemia

low risk hypothyroidism

75
Q

when do initial signs of iatrogenic hypoparathyroidism usually occur?

A

within 2-3 days post-op

76
Q

what are the initial signs of iatrogenic hypoparathyroidism?

A

inappetence

weakness/lethargy

ptyalism

pawing at face

77
Q

what are the more advanced signs of iatrogenic hypoparathyroidism?

A

tremors

tetany

seizures, coma and death

78
Q

why can it sometimes be difficult to recognise iatrogenic hypoparathyroidism?

A

can be difficult to differentiate between true hypoparathyroidism and normal GA/post-op effects

79
Q

how can vitamin D supplementation help with post-parathyroidectomy hypocalcaemia?

A

increases calcium absorption from the GI tract and reduces loss through kidneys

80
Q

how should we monitor post-parathyroidectomy calcium?

A

various protocols recommended for when 1st test and how often should be checked

81
Q

what should we be testing when monitoring for hypocalcaemia post-parathyroidectomy?

A

ionised calcium rather than total calcium - bedside ideally

82
Q

what is the best outcome for post-parathyroidectomy hypocalcaemia?

A

try to allow the normal and homeostatic processes to sort themselves out without interference

83
Q

what is the backup plan for post-parathyroidectomy hypocalcaemia?

A

when blood calcium (ionised) drops and clinical signs appear, start treatment

84
Q

why is post-op hypocalcaemia tricky to manage?

A

the remaining parathyroids function is likely to have been suppressed - may require decreased calcium (just below normal) in order for glands to re-activate

85
Q

what are the hypocalcaemia treatment options?

A

vitamin D

oral calcium

IV calcium

86
Q

how should vitamin D be given for hypocalcaemia?

A

orally, 24 hours before surgery (takes 24-48hrs to have an effect)

87
Q

why is vitamin D beneficial for hypocalcaemia?

A

‘wakes up’ the systems ready for the drop in calcium

88
Q

what is given for oral calcium supplementation?

A

elemental calcium in divided doses for the owner to give at home

89
Q

what is given for IV calcium treatment?

A

10% calcium gluconate

90
Q

when/how should IV calcium be given for hypocalcaemia?

A

given slowly over 10-20 mins

give if clinical signs

give if levels very low with/without clinical signs

91
Q

why should IV calcium only be given if clinical signs present/levels very low?

A

over-treatment with IV calcium during hospitalisation will slow the recovery of the remaining parathyroid tissue

92
Q

why should patients receiving calcium treatment be monitored with ECG?

A

can severely affect heart function - monitor for arrhythmia and bradycardia

93
Q

what method should be followed for IV calcium administration?

A

initial bolus, followed by CRI

94
Q

what type of fluids should be avoided in patients receiving calcium supplementation IV?

A

fluids containing bicarbonate, lactate or phosphate

95
Q

why should fluids containing bicarbonate, lactate or phosphate be avoided in patients receiving IV calcium supplementation?

A

will precipitate calcium

96
Q

why should calcium not be given subcut?

A

can cause skin sloughs

97
Q

describe the orientation of the pancreas

A

right limb runs next to duodenum

left limb sits next to spleen

body is close to important structures (pancreatic ducts, common bile duct)

98
Q

how can the pancreas of a cat differ to the dog?

A

sometimes have a second ‘accessory’ duct

99
Q

what types of condition can affect the pancreas?

A

endocrine disease

exocrine disease

pancreatitis

pancreatic abscessation

pancreatic cysts

100
Q

which conditions of the pancreas can be treated surgically?

A

endocrine - insulinoma

exocrine - exocrine pancreatic neoplasia

pancreatic abscessation

pancreatic cysts

101
Q

how serious is exocrine pancreatic neoplasia?

A

highly aggressive

102
Q

why doe pancreatic abscesses often occur?

A

often secondary to pancreatitis

103
Q

what type of tumour is an insulinoma?

A

malignant carcinoma

104
Q

where to insulinomas often metastasise to?

A

lymph nodes and liver

105
Q

what are the clinical signs of insulinoma?

A

lethargy
tremors and seizures
collapse
peripheral neuropathy due to hypoglycaemia

very low hypoglycaemia (<2mmol/l) in an upright dog

106
Q

how is insulinoma diagnosed?

A

blood work (insulin/glucose ratio)
imaging

107
Q

what is involved in pre-op insulinoma management?

A

feeding regime - q4-6hrs, diabetic food, careful pre-op starving

exercise - gentle, regular

manage hypoglycaemia - good feeding and exercise, educate O on signs

108
Q

why should we have care with IV glucose administration in patients with insulinoma?

A

can push glucose even lower with exogenous glucose admin - encourages insulin production

109
Q

how can we manage a hypoglycaemic crisis?

A

oral - anything sugary

one-off IV - 0.5-1ml/kg 50% dextrose

glucose infusion - start with 2.5% solution, monitor blood glucose and titrate ASAP if needed

110
Q

what is involved in glucose management during partial pancreatectomy for insulinoma?

A

5% dextrose infusion during surgery with glucose monitoring every 30 mins

111
Q

what are the surgical considerations during partial pancreatectomy?

A

gentle technique - reduce risk of pancreatitis

small nodule - can be difficult to find

check liver - may have secondary mets

112
Q

what is the result of a partial pancreactectomy?

A

removes sources of insulin, provided remove all insulinoma tissue

113
Q

what different factors need to be considered post-op for insulinoma?

A

feeding and exercise regime

management of hypoglycaemia

drugs

complications

prognosis after surgery

114
Q

what might be involved in feeding and exercise management after partial pancreatectomy?

A

feeding as pre-op initially, may require feeding tube

exercise as pre-op initially

115
Q

why is it important to monitor glucose post-op for insulinoma?

A

micro-metastasis can result in persistent hypoglycaemia post-op - look for normalisation

116
Q

what drugs might be given post-op for insulinoma?

A

IVFT
analgesia
steroids - helps raise glucose level
octreotide
chemo (strepozocin) - for residual tumour and mets

117
Q

what complications should we monitor for post-op insulinoma?

A

persistence of hypoglycaemia

transient hyperglycaemia

pancreatitis

can develop diabetes mellitus

118
Q

what is the prognosis for insulinoma?

A

depends on staging -

stage 1 - can survive more than 2 years

stage 3 - can get 6 months with surgery

119
Q

what gives a better prognosis for insulinoma?

A

generally accepted that surgery gives a better prognosis than medical management alone

120
Q

where are the adrenal glands located?

A

close to kidneys and major blood vessels (CVC, renal vessels)

121
Q

what is the internal anatomy of the adrenal glands?

A

outer cortex
inner medulla

122
Q

what is produced by the adrenal cortex?

A

androgens
mineralocorticoids
glucocorticoids

123
Q

what is produced by the adrenal medulla?

A

catecholamines (e.g adrenaline)

124
Q

what type of masses typically affect the adrenal cortex?

A

adenoma/adenocarcinoma

125
Q

what type of masses typically affect the adrenal medulla?

A

pheochromocytoma

126
Q

what are the surgical conditions of the adrenal glands?

A

adrenal masses - benign/malignant, primary or secondary tumours (renal)

secondary - pituitary-dependent hyperadrenocorticism and secondary adrenal gland hyperplasia/hypertrophy

127
Q

what is the treatment option for pituitary-dependent hyperadrenocorticism?

A

hypophysectomy

128
Q

what are the main clinical signs of adrenal gland disease?

A

none (incidentaloma)

functional changes

haemoabdomen

129
Q

why is it important to know if an adrenal mass is functional?

A

patient with functional mass likely to have more complex medical needs for pre-op stabilisation and/or might not mean surgery is best treatment option

130
Q

what conditions can result from overproduction from the adrenal cortex?

A

conns syndrome (mineralocorticoids e.g. aldosterone) - seen in cats

cushings (glucocorticoids e.g. cortisol)

masculinising syndrome (androgens e.g. testosterone)

131
Q

what conditions results from overproduction from the adrenal medulla?

A

pheochromocytoma (catecholamines e.g. epinephrine/norepinephrine) –> intermittent hypertension

132
Q

why can adrenal gland disease result in haemoabdomen?

A

some adrenal masses will present with spontaneous bleeding, causing retroperitoneal swelling or haemoabdomen

133
Q

what can classify the severity of adrenal gland neoplasia?

A

aggression

134
Q

what type of tumour does a benign enlargement of the adrenal glands tend to be?

A

typically adenomas

135
Q

what type of tumour does a malignant enlargement of the adrenal glands tend to be?

A

typically adenocarcinoma

136
Q

how aggressive are pheochromocytomas of the adrenal glands?

A

can be benign or malignant

137
Q

why are malignant adrenal tumours at higher risk of haemorrhage?

A

can have a tumour thrombus where the tumour invades the vena cava

138
Q

what are the pre-op considerations for adrenalectomy?

A

ASA status - systemic effects of mass, co-morbidities

medical stabilisation to improve ASA status

unilateral vs bilateral surgery

139
Q

what systemic effects do we need to consider pre-op for adrenalectomy?

A

conns syndrome can cause hypokalaemia

cushings syndrome likely treated with endogenous steroid = poor surgical candidate

phaeochromocytoma –> excess adrenaline/noradrenaline = unstable patient

140
Q

what might be involved in pre-op stabilisation before adrenalectomy?

A

manage hypokalaemia with supplementation

stabilise cushings with medication e.g. trilostane

phaeo - stabilise with medication (e.g. phenoxybenzamine for 2-3 weeks pre-op)

141
Q

what is phenoxybenzamine?

A

alpha adrenergic blocker - can help manage phaeochromocytoma

142
Q

what is important to prepare before bilateral adrenalectomy?

A

have blood ready - haemorrhage a significant risk

143
Q

why does adrenalectomy surgery have a high mortality rate (15-20%)?

A

very challenging anaesthesia, surgery and aftercare

some will die from blood loss on table and some will develop post-op thromboembolism

short and long post-op periods very challenging

144
Q

how does functionality of the tumour affect peri-operative adrenalectomy management?

A

patients with functional tumours have more complex needs peri-operatively than non-functional to ensure fit for surgery

145
Q

what is important to monitor intra-op for adrenalectomy?

A

CVS function - ECG for arrhythmias, blood pressure

electrolytes

146
Q

what are the possible intra-op complications during adrenalectomy?

A

tumour rupture

haemorrhage

tachycardia/arrhythmias

hyper/hypotension

may need supplementation of gluco- and mineralocorticoids during surgery (dexamethasone, sodium, potassium)

147
Q

what are the possible post-op complications after adrenalectomy?

A

electrolyte abnormalities

hyper/hypotension

adrenal insufficiency requiring supplementation

delayed healing

pulmonary thromboembolism

SIRS/sepsis

148
Q

how can post-op adrenal insufficiency be managed after adrenalectomy?

A

requires supplementation (like an iatrogenic addisons) - mineralocorticoids and glucocorticoids

149
Q
A