Book 2, Case 4-Pheo, PONV

Question 1

How is diagnosis of pheochromocytoma made?

Answer 1

The measurement of free metanephrines in the plasma may be the
most reliable test for confmning the diagnosis. .urinary
metanephrines, and urinary vanillylmandelic acid.

Question 2

Side note-dont’ palpate what in pheo?

H

Answer 2

Do not palpate the abdomen

Question 3

Elevated Hct in pheo likely means:

Answer 3

suggestive of hypovolemia

Question 4

Duration of alpha blockade prior to surgery:

When can it be discontinued?

Answer 4

While the optimal duration of a-blockade is unknown, most experts
recommend initiating blockade at least 10-14 days prior to surgery. This allows time
to stabilize the blood pressure

As for when it can be stopped: Some clinicians recommend discontinuing
a-blockade 24-48 hours prior to surgery or administering a half dose on the morning
of surgery to reduce the risk of significant hypotension following vascular isolation of
the tumor (abruptly stopping secretion of catecholamines).

Question 5

How does a-Methylparatyrosine work? What are the side effects, and who is allowed to get it?

Answer 5

(a-Methyl tyrosine or metyrosine) inhibits the
rate-limiting enzyme, tyrosine hydroxylase, of the catecholamine synthetic pathway,
which results in a 40-80% reduction in catecholamine synthesis. Although this drug
is very effective, it is currently limited to patients with metastatic disease or those
requiring long term medical therapy (i.e. surgery is contraindicated) due to significant
side effects, including diarrhea, sedation, anxiety, depression, extrapyramidal
reactions, and crystalluria.

Question 6

Why do pts have sudden hypotension after pheo is taken out?

Answer 6

Interruption of the vascular supply to the tumor results in
an abrupt cessation of catecholamine secretion from the tumor into the blood stream.
This reduction in circulating catecholamines combined with hypovolemia,
vasodilation from residual a-blockade, and cardiovascular depression from
anesthesia, can lead to significant hypotension.

Question 7

Hypotension after pheo resection: how are you treating:

Answer 7

If hypotension did occur following
tumor resection, my initial treatment would be to ensure adequate volume
replacement with crystalloid or blood. If the hypotension were severe or persistent, I
would consider vasopressor therapy; if I suspected hypoadrenalism

Question 8

Is it important to provide alpha blockade prior to beta-

Answer 8

Yes, because blockade of vasodilatory receptors could
result in unopposed vasoconstriction, hypertensive crisis, and congestive heart failure
due to the effects of excessive circulating catecholamines on a-receptors.

Question 9

Pt with pheo has a decreased energy level-DDX

Answer 9

catecholamine induced cardiomyopathy/chf, or other cardiopulmonary issues

Question 10

IF they ask you if you’ll given a fluid bolus in any pt-make sure what:
Now in terms of pheo

Answer 10

Make sure to say that you will perform an exam, assess volume status.
Now in terms of pheo, some are hypovolemic secondary to chronically increased SVR, and others are normovolemic-especially those on alphablockers

Question 11

Remember!!!! If you’re in a situation where a PA could be helpful, but you don’t want to place one-you can always place a

Answer 11

TEE

Question 12

How does pneumoperitoneum complicate PAC and CVP?

Answer 12

It can complicate the interpretation of central venous and pulmonadry artery pressure measurements-making them less reliable

Question 13

What tube do you need to place for laparoscopy that you frequently forget to say:

Answer 13

OROGASTRIC OR NASOGASTRIC TUBE

Question 14

What to avoid in pheo pts on induction and just period:

Answer 14

• avoid drugs that directly exacerbate effects of catecholamine excess
• avoid hypoxia and hypercarbia which can stimulate the sympathetic nervous system

Question 15

Why no sux in pheo?

Answer 15

b/c sux can cause histamine release and/or abdominal fasciulations which can result in release of catecholamines from the tumor

Question 16

Can you do a pheo under regional anesthesia?

Answer 16

Possibly, but it would not be optimal. It does NOT block the sympathetic activity associated with tumor release of catecholamines, and the regional anesthesia may not be adequate to alleviate discomfort of abdominal distension.

Question 17

Avoid which drugs with pheo?

Answer 17

1-sux-abdominal fasiculation, and histamine releasing drugs (morphine and atracurium)
2-those that increase sympathetic activity (atropine, ketamine, ephedrine, pancuronium)
NO EPHEDRINE-assciated with significant HTN when given to pts with pheo

Question 18

Ten minutes after establishment of the pneumoperitoneum, the arterial blood
gas shows a PaC02 of 54 mmHg. What do you think may be going on?
and…what would you do? Are you going to give dantrolene?

Answer 18

-Assuming C02 was used to establish the pneumoperitoneum, this
hypercarbia most likely reflects the normal increase in arterial C02 that occurs during
the first 15-30 minutes following peritoneal insufflation (primarily due to absorption
of C02 from the peritoneal space
DDX: (1) inadequate ventilation, (2) C02 emphysema ( extraperitoneal
insufflation of C02), (3) capnothorax (movement of C02 into the thorax through
natural or iatrogenic communications between the peritoneal cavity and the pleural
and pericardia! sacs), (4) C02 embolism (usually occurs with the direct insufflation of
large amounts ofC02 into a blood vessel), (5) pneumothorax secondary to alveolar
rupture (risk increased due to smoking history, central line placement, and
hyperventilation to maintain normocarbia ), and….malignant hyperthermia

What am i doing? hypercapnia can stimulate an undesirable release of
catecholamines, I would ensure proper ETT placement and adequate ventilation;
auscultate the chest for equal and bilateral breath sounds;evaluate his blood pressure, cardiac rhythm, end-tidal
C02, temperature, and ABG.Next, I would examine the patient for signs of: (1)
subcutaneous emphysema (increased PETC02, increased PaC02, and subcutaneous
crepitating of the head, neck, and face); (2) capnothorax (decreased pulmonary
compliance, increased airway pressures, increased PBTco2, and increased PaC02); (3)
C02 embolism (initially the PETC02 is decreased due to decreased cardiac output,
increased PaC02, hypotension, hypoxia, aspiration of foamy blood from the central
venous catheter, increased pulmonary artery pressure, increased central venous
pressure, millwheel murmur, cyanosis, cardiac arrhythmia, and right heart strain on
ECG); ( 4) tension pneumothorax secondary to alveolar rupture

Am I giving dantrolene? In the absence of other signs of malignant hyperthermia, such as
generalized rigidity, increased temperature, peripheral mottling, rhabdomyolysis, and
a mixed metabolic and respiratory acidosis, I would not immediately treat with
dantrolene.

Question 19

UOP low during this laparoscopic pheo case-what would you do? ANd why does this happen in these cases?

Answer 19

transient oliguria often occurs during laparoscopic
surgery secondary to the hypercarbia and increased intra-abdominal pressures (urine
output may be reduced by 50% due to decreased cardiac output, sympathetic-induced
release of catecholamines, and/or increased secretion of antidiuretic hormone),

Cautiously provide volume replacement after considering fluid losses. Must be careful with patient’s pathology

Question 20

What to do about crepitus?

Answer 20

First confirm that pt doesn’t have capnothorax, check ETCO2. once your exam confirms that it is crepitus, ask surgeon to d/c insufflation, hyperventiate the pt, and then have surgeon recreate pneumoperitoneum using a lower insufflation pressure. IF pt COPD pt, you could delay extubation at end of case until hypercapnia was completely resolved.

Question 21

Pheo surgery proceeds and the patient’s blood pressure increases dramatically to
205/108 mmHg. What will you do?

Answer 21

After verifying the blood pressure, I would ask the surgeon to cease
any manipulation of the tumor; ensure adequate ventilation, normocapnia, sinus
rhythm, and a sufficient depth of anesthesia; and review hemodynamic data provided
by the CVP and PAC. If the hypertension persisted, I would consider administering
one of the following antihypertensive medications: (1) sodium nitroprusside (a potent
direct vasodilator that has a rapid onset and a short duration of action), (2)
phentolamine (a competitive a-blocker and direct vasodilator; onset and duration of
action or prolonged as compared to sodium nitroprusside; associated with
tachyphylaxis and tachycardia), (3) nitroglycerine (may cause tachycardia), (4)
esmolol, (5) labetalol (possibly useful for predominantly epinephrine-secreting
tumors secondary to its relatively greater B-blocking activity), or

Question 22

Pheo surgery:surgeon ligates the·vein supplying the
tumor. Shortly thereafter, the patient’s blood pressure drops to 74/46 mmHg .
What do you think is going on?

Answer 22

timing of this hypotension makes the isolation of the tumor, with
a subsequent decrease in plasma catecholamines the most likely etiology.

And don’t forget about these: Other factors that
often contribute to this hypotension include residual a-blockade, hypovolemia (i.e.
inadequate preoperative volume replacement, blood loss, and intraoperative fluid
loss), catecholamine-induced cardiomyopathy, and anesthetic-induced cardiovascular
depression. Of course other potential causes of hypotension, independent of tumor
isolation, should also be considered, such as congestive heart failure, vagal
stimulation (manipulation of viscera), arrhythmia, cardiac ischemia, massive blood
loss, and pneumothorax.

Question 23

Conjunctival edema-you delaying extubation? And what will you do?

Answer 23

First, his
conjunctival edema (possibly due to trendelenburg positioning and/or volume
overload) may be associated with laryngeal edema, placing him at increased risk for
loss of airway following extubation.
Therefore, if

further evaluation suggested volume overload, I would administer a diuretic, and
monitor the patient closely until he demonstrated adequate diuresis and decreased
signs of fluid overload (the return of normal renal function following
pneumoperitoneum release may make a diuretic unnecessary)

Question 24

BG low after pheo surgery-why do you think that this is? And what will you do?

Answer 24

Patients are at increased risk of developing significant hypoglycemia
following tumor removal because the drop in plasma catecholamines results in
increased release of insulin (the stimulation of alpha 2-adrenergic receptors in
pancreatic beta cells by epinephrine and norepinephrine inhibits the release of insulin)and reduced gluconeogenesis and glycogenolysis (epinephrine stimulates these
processes that serve to increase blood sugar). Therefore, fluid replacement following
tumor removal should include dextrose-containing solutions and the patient’s blood
sugar should be monitored closely for at least 24 hours post-operatively.

Question 25

Who is at risk for PONV? Regardless of their non risks (mention that), but still

Answer 25

Laparoscopic surgery: result of co2 diffusion into bowel, female, non smoker, motion sickness, volatile anesthetics, nitrous oxide

Question 26

What are anti nausea/vomiting things you can give that do not prolong QT?

Answer 26

Glucocorticoids, anticholinergic (scopolamine patch), Neurokinin receptor antagonists)

Question 27

Pt still has HTN after pheo surgery-what do you think?

Answer 27

Could be residual pheo. Alert surgeon, monitor pt, ensure pt is not hypercarbic, not in pain