June 8, 2025 • 32 mins
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This episode features a deep dive into The Anaesthetic Management of Phaeochromocytoma based on several materials.
Listen for a clear, concise overview powered by Google's NotebookLM AI, perfect for exam prep or clinical refreshers.
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Welcome back to the Deep Dive. Today we're jumping into
something pretty specialised. It's rare, definitely complex,
and honestly it sounds like it involves some really high stakes
in the operating room. It certainly can.
You send over a whole bunch of really fascinating sources on
this and what we're going to do,what we do best here, dive right
into them. Sounds good.
We're looking at pheochromocytoma today.
(00:22):
It's it's a type of tumour that presents some unique challenges,
especially, like you said, around the time of surgery.
Yeah, it sounds like even thoughit's not common, the material
you shared really hammers home how crucial it is for the
medical teams, you know, especially the anesthesiologist,
to really nail this. Absolutely.
Get it wrong and things can change very, very quickly.
(00:43):
Kind of like a hormonal time bomb is how I was picturing it.
If it's not managed just right around the surgery, things can
apparently go sideways really fast.
And unpredictably. That's a pretty good analogy,
actually. So our mission basically is to
sift through these sources you provided, pull out the the key
bits of knowledge and really understand why it's such a
(01:05):
challenge and you know how experts actually manage it.
Right. The core difficulty is that
potential for sudden, really dramatic swings and blood
pressure, heart rate, all drivenby these rogue hormones and
tumour releases. Careful planning, careful
execution, it's all absolutely vital, OK?
Let's start at the beginning then.
(01:25):
What exactly is a pheochromalocytoma?
OK, so. Fundamentally, it's a tumour and
it's made-up of these specialised cells called
chromathin cells. Chromathin cells, right?
And these cells are a part of your sympathetic nervous system.
That's the system that controls your fight or flight response.
Got it. So where do these tumours
usually show up? Well, the most common spot
there's sort of primary home is the adrenal medulla.
(01:48):
That's the inner part of the adrenal glands, which, you know,
sit right on top of your kidneys, OK.
Adrenals makes sense. But, and this is where it gets
really interesting, according toyour sources, these chromophane
cells or very similar tissue called paraganglia, they aren't
just in the adrenals, they can actually be found in other
places too. Like where?
Well, sometimes in quite surprising spots, like embedded
(02:10):
in the wall of the bladder or near the prostate, the rectum,
even inside the chest cavity near the heart sometimes.
Wow, the bladder. Seriously.
So it's not always just an adrenal tumour.
No, not always. The adrenal ones are definitely
the most common, but these extraadrenal ones that pair
gangliomas, they can be a bit sneaky, but the core problem
(02:30):
wherever the tumour happens to be is that it just pumps out
massive amounts of catecholamines.
Catecholamines. Those are the stress hormones
right? Like.
Adrenaline. Exactly.
Yeah. That's the group name for
hormones like norepinephrine, epinephrine, which is adrenaline
and sometimes dopamine as well. These are the chemicals that
normally kick your body into high gear.
So too much of these means your body's kind of stuck in
(02:52):
OverDrive, either all the time or like in bursts.
Precisely, these hormones interact with different
receptors, different sort of switches all over your body.
You got alpha receptors that mainly tighten blood vessels.
OK, hence the blood pressure. Issues, all right, And that's
where alpha blocker drugs come into play for treatment.
Then you have beta receptors which mostly speed up the heart
(03:13):
and make it pump harder. And that's where beta blockers
are used. Correct, and when you have way
too many of these hormones circulating, the system goes
haywire. The sources mentioned that most
of these tumours may be over 80%, mainly secrete
norepanephrine and that usually leads to sustained high blood
pressure, often really severe hypertension that doesn't
(03:35):
respond well to standard meds. But some secret Adrenaline,
Epinephrine. More.
Yes, and those tend to cause more sudden dramatic episodes,
paroxysmal symptoms, they call them, you know, sudden racing
heart, sweating headache. Ah, OK.
Which brings us to how people actually present.
I liked how one source called itthe Great Mimic.
It really is. Yeah.
(03:56):
Because these hormones hit so many different body systems, the
symptoms can be incredibly varied and easily.
And mistaken for what? Lots of other things.
High blood pressure is the most common sign, though nearly half
of patients have it, often quitesevere.
But there's that classic triad people mention.
Yes, the classic triad Headaches, palpitations, that
(04:16):
feeling of your heart pounding or racing, and episodes of heavy
sweating. But it's important to remember
not everyone gets all three or gets them severely right.
And you can see all sorts of other things too, like anxiety
or tremors, even heart problems.Oh absolutely.
The list your sources provided is pretty long.
Anxiety, nervousness, visual disturbances, shaking, your
(04:36):
tremors, heart rhythm problems, arrhythmias, even heart failure
or a specific type of heart muscle damage called
cardiomyopathy. Yeah, and that blood vessel
tightening the vasoconstriction can make the skin look pale.
You can get acute pulmonary edoema fluid in the lungs.
High blood sugar is common too because these hormones mess with
glucose metabolism. And weight loss sometimes.
(04:58):
Yes, particularly if there's a lot of epinephrine being
secreted. The body's just constantly
revved up burning energy. You know, one of the sources
shared this anecdote that reallydrove home that great mimic
idea. Yes, I remember that one, the
patient who presented with really severe difficult to
control diabetes. But no high blood pressure
(05:19):
history at. All exactly no hypertension, but
then an abdominal scan done for some other reason happened to
show a mass on the adrenal gland.
Initially the team wasn't, you know, super suspicious of
pheochromocytoma because that hallmark high blood pressure
just wasn't there. But wisely, because they saw the
mass, they decided to manage thesurgery as if it might be one,
(05:41):
just in case. And it was.
It was, and after they removed the tumour, the patient's
diabetes basically resolved, their blood sugar normalised.
It's just a fantastic example ofhow this thing can present a
typically and why you really have to consider it if you find
an adrenal mass, even if the classic signs aren't obvious.
Yeah, that's a great point. And it can pop up in other
tricky situations too, right? Like mimicking preeclampsia in
(06:03):
pregnancy? Yes, or causing hypertension in
kids, which is rare but something to think about,
especially if there's a family history of certain genetic
syndromes that predisposed to these tumours, like MNN
syndromes. Which all just highlights how
critical it is to actually diagnose this before someone
ends up having surgery for something completely.
Different. Oh absolutely critical.
(06:24):
Operating on someone with an undiagnosed, unprepared
fiochromocytoma is incredibly risky.
The mortality used to be sky high.
So how do they pin it down then?How do you confirm the diagnosis
these days? Well, according to the material
you sent the the preferred method now is measuring the
breakdown products, the metabolites of these
catecholamines, specifically something called fractionated
(06:46):
manifrecenes and normatenefrons.OK, not the hormones themselves.
Usually the breakdown products are more reliable because
hormone release can be episodic,but the metabolites hang around
longer. You can measure them either in
the blood plasma or in a 24 hoururine collection, and these
tests are much, much more sensitive than the older ones.
Like the VMA test, I remember seeing that mentioned.
Exactly. Urinary venolimandelic acid VMA.
(07:10):
That was used a lot historically, but the sources
say its sensitivity is actually pretty low, maybe only around
64% in adults. So you could miss cases, right?
And those old provocative tests where they actually tried to
trigger a hormone release with drugs like Glucagon, they're
almost never needed anymore because the biochemical tests
are so good. OK, so you've got the
biochemical proof of hormone excess.
(07:31):
Now you need to find the culprit, the tumour itself.
Precisely, localization is the next crucial step obviously for
surgical planning, and standard imaging techniques like CT scans
or MRI are usually very good at finding these tumours.
Even the ones outside the adrenals.
Yeah, CT and MRI are pretty effective for most of them,
including the extra adrenal ones.
(07:52):
But what if it's really hidden or they suspect it's spread?
Right. For those tricky situations,
maybe a tumour in a really unusual spot, or if they're
worried about recurrence after aprevious surgery or metastasis,
then they often turn to specialised nuclear medicine
scans. The main one mentioned is MIBG
centigraphy. Amici, how does that work?
MIBG is this radioactive tracer mitio dobenzolguanidine that
(08:16):
happens to be taken up quite specifically by chromophane
cells by the tumour tissue. So you inject it, wait a bit and
then scan the patient and the tumour should, you know, light
up. Cool, so it can pinpoint those
sneaky ones. Exactly.
It's very useful in those complex cases.
There's just a little note of caution that some medications
can interfere with the tumours ability to take up the MBG, so
(08:37):
that needs careful management before the scan.
Things like certain blood pressure meds or
antidepressants. OK, this brings us to what feels
like the absolute core of managing this safely.
Based on your sources, the preoperative optimization, this
seems to be where the huge leap in safety happened.
It's absolutely the game changer.
Your sources quote some dramaticfigures.
(08:57):
Mortality rates for field chromocytoma surgery dropping
from like 40 or even 60% historically way back down to
close to 0, maybe zero, 6% in experience centres today.
And that incredible improvement is almost entirely attributed to
getting the patient properly medically prepared before they
even get near the operating room.
So. What are the main goals of that
(09:18):
prep phase? What are they trying to achieve?
OK, several key things. First, you need to get the blood
pressure and heart rate under control.
Normalise them as much as possible.
Second, you want to optimise thefunction of organs that might
have been stressed by those highhormone levels for a long time,
like the heart. 3rd, and this isreally critical, you need to
restore the patient's circulating blood volume.
(09:40):
Restore volume. Why is that needed?
Is it low? Yes, often significantly
depleted. Think about it.
Yeah, those high levels of norepinephrine have been causing
chronic vasoconstriction. The blood vessels have been
squeezed tight for potentially months or years.
OK. So the body adapts to this
smaller vascular space by reducing the actual amount of
(10:02):
fluid circulating. If you then suddenly remove the
tumour, the vessels relax, the space gets bigger, but there
isn't enough fluid to fill it. And the pressure crashes.
Exactly. A profound drop in blood
pressure. So expanding that volume
beforehand is absolutely vital. And then the overall goal tying
it all together is to prevent that massive life threatening
(10:22):
surge of catecholamines, the catecholamine storm during the
surgery itself. Makes sense, and the standard
way to do this starts with alphablockers, right?
That seems key. Yes, absolutely.
That's the first and most crucial step Alpha Edgenergic
blockade. Typically this is done for about
10 to 14 days before the plannedsurgery.
OK. And beta blockers.
Beta blockers are only added after adequate alpha blockade
(10:44):
has been achieved, and even thenonly if they're needed, usually
to control a fast heart rate, tachycardia, or arrhythmias that
persist despite the alpha blocker.
And there's a huge warning aboutnot using beta blockers first or
alone. A massive warning.
Your sources repeat this multiple times and it's worth
stressing again. Giving a beta blocker without
first blocking the alpha receptors is extremely dangerous
(11:07):
in these patients. Why is that so bad?
Because if you block the beta receptors, which mediates some
vasodilation and increase heart rate contractility, you leave
the alpha receptor effects unopposed.
The catecholamines are still pouring out, hitting those alpha
receptors hard, causing severe vasoconstriction.
So the blood pressure skyrockets.
Skyrockets uncontrolled severe hypertension and it can even
(11:29):
lead to acute heart failure or pulmonary edoema.
Fluid backing up into the lungs.One source even mentioned a
report of pulmonary edoema afterjust a small dose of Propranolol
given before alpha blockade. It's a critical point.
Alpha blockade first. Always.
OK, crystal clear. So what kind of alpha blockers
are typically used? The sources discussed mainly two
(11:49):
types. The classic one is
phenoxybenzamine. It's a non selective, non
competitive alpha blocker, meaning it blocks both A1 and A2
receptors and it binds irreversibly or nearly so has a
very long duration of action, a half life over 24 hours.
OK, advantages, Disadvantages. Well, the advantages sustained
reliable blockade and that that long duration allows plenty of
(12:12):
time for that crucial volume expansion to happen gradually
over the 1014 days. The disadvantages are potential
side effects like postural hypotension, getting dizzy when
standing up, nasal stuffiness, and because it also blocks A2
receptors, it can cause reflex tachycardia, a faster heart
rate. Right.
What's the alternative? The alternative is using
(12:33):
selective A1 antagonists drugs like prazosin, terezosin or
doxazosin. These only block the A1
receptors, which are primarily responsible for
vasoconstriction. And they're competitive
blockers. Yes, meaning they can be
overcome by very high levels of catecholamines.
Unlike fenoxabenzamine, they generally have shorter durations
of action, especially prizosin. This means they might need to be
(12:54):
dosed more frequently, but it also allows for potentially
quicker adjustments. And because they don't block A2,
they tend to cause less reflex tachycardia.
Any preference mentioned? Doxazosin got a specific mention
in one source for its good bioavailability and once daily
dosing, and there was experiencesuggesting it provided
comparable blood pressure control to phenoxybenzamine, but
(13:16):
maybe with less troublesome hypotension or fluid retention
after the surgery. Interesting.
Does the difference matter on the day of surgery?
It can. With the competitive blockers
like doxazosin. You usually need to give a dose
on the morning of surgery to maintain the effect.
With phenoxabenzamine's long half life, that's less critical.
OK. What about other drugs used in
(13:38):
Prep? Calcium channel blockers.
Yes, calcium channel blockers like nicartopine or amlodipine
can also be used. Sometimes they're added to alpha
blockers if control isn't perfect, or occasionally,
according to some K series, theymight even be used as the
primary agent, especially if thepatient is Norma intensive to
begin with or really can't tolerate alpha blockers.
How do they help? They work by inhibiting the
(13:59):
influx of calcium into the chromovan cells and that calcium
entry is needed for the tumour to actually release its
catecholamines, so they sort of calm the tumour down a bit.
And Metarocene. Metarocene is another one less
commonly used, usually as an adjunct.
It actually works further upstream by inhibiting an enzyme
called tyrosine hydroxylase, which is essential for making
catecholamines in the 1st place,so it reduces the synthesis of
(14:23):
hormones. It might be considered for
patients with very high hormone levels, large tumours or
metastatic disease where you really want to decrease the
overall catecholamine load. And all this time you're
watching for that volume expansion.
Exactly. They often monitor the patient's
blood count, specifically the hematocrit, serially.
As the alpha blockade takes effect and the blood vessels
(14:44):
relax, the vascular space increases.
If the patient is drinking enough fluids, that space fills
up and the blood becomes relatively less concentrated, so
the hematocrit will drop. Seeing that drop is a good sign
that volume expansion is happening appropriately.
It sounds like a pretty intensive preparation period.
It is traditionally 1014 days, often starting in the hospital,
(15:05):
although the source is mentioneda trend towards safe outpatient
preparation if patients meet specific criteria.
Things like reaching target blood pressure levels, not
having severe postural hypotension, having a stable ECG
and minimal arrhythmias. These are sometimes called
Roizen's criteria. And it takes a whole team, you
said. Absolutely crucial close
(15:25):
collaboration between the endocrinologist managing the
blockade, maybe a cardiologist if there are heart issues, the
surgeon planning the removal, and of course the
anesthesiologist who will managethe patient during the
operation. Everyone needs to be
communicating. Right, so after all that intense
preparation, you finally get to the surgery itself.
And even with everything optimised, your sources are
clear, it's still a challenge. It absolutely remains a high
(15:48):
vigilance procedure, even in centres with lots of experience.
The main lingering challenge is the potential for unpredictable,
sudden releases of catecholamines from the tumour,
especially when the surgeon starts physically handling it
so. Communication in the operating
room is absolutely paramount. Non negotiable.
The surgeon must communicate clearly and frequently with the
(16:08):
anesthesiologist, especially warning them just before they
anticipate manipulating or touching the tumour, because
that's when you expect the hemodynamic fireworks to
potentially start. Is there like one single best
way to do the anaesthesia for these cases?
Interestingly, the material points out that there isn't
really high level evidence like big randomised control trials
(16:29):
comparing different techniques head to That's mostly because
the condition is so rare. Right.
Hard to do those big studies. Exactly.
So while the core principles of management are pretty universal,
the specific choices of anaesthetic drugs or techniques
might vary a bit between institutions or regions, often
based on the team's familiarity,experience and drug
availability. OK.
(16:51):
What about monitoring during thesurgery?
What's essential? Continuous beat to beat blood
pressure monitoring is absolutely mandatory.
This is done with an arterial line, a small catheter usually
placed in an artery in the wrist.
And they put that in before the patient's asleep.
Ideally yes, placed under local anaesthesia and maybe some light
sedation before inducing generalanaesthesia.
(17:13):
The key is to avoid causing painor stress during placement,
which could trigger catecholamine release while the
patient is still awake and unprotected by deep anaesthesia.
Makes sense. What else?
Central Line. Central venous access ACVL is
strongly considered almost routine in most centres.
Why is that so important here? Several key reasons 1, You need
(17:33):
reliable access for potentially rapid infusion of fluids or
blood if needed. Two, and very importantly, after
the tumours adrenal vein is clamped or the tumours removed,
you often get that sudden drop in blood pressure we talked
about. You frequently need to start
potent vasopressor medications to support the circulation and
those are much safer to give through a central line.
(17:53):
And 3rd, it allows for monitoring of central venous
pressure CVP which gives some indication of the patient's
fluid status, although interpreting CDP has its
nuances. Got it.
And standard monitors too, presumably.
Oh yes, routine stuff. ECG for heart rhythm, pulse
oximetry for oxygen levels, capnography for breathing,
temperature monitoring, urine output measurement via a bladder
(18:15):
catheter. All standard.
Anything more advanced sometimesused like those special cardiac
monitors? Occasionally, A pulmonary artery
catheter might be considered if the patient has severe
pre-existing heart problems likesevere cardiomyopathy.
Some centres might use advanced monitors that look at things
like pulse pressure variation tohelp guide fluid therapy in
(18:35):
ventilated patients and transesophageal
echocardiography. TEE, an ultrasound probe in the
oesophagus looking at the heart,is generally reserved for very
specific situations like known severe cardiac dysfunction or if
the tumour is suspected to be actually inside the heart's
chambers or pericardium. OK.
And the anaesthesia itself, whatdo they typically use?
(18:56):
General anaesthesia is the standard.
Sometimes a regional technique like an epidural catheter might
be placed as an adjunct primarily for post operative
pain control and maybe to help blunt some sympathetic
responses, but it's always used in combination with general
anaesthesia, not. What about the induction drugs
getting the patient off to sleep?
Common intravenous agents like propofol, etomidate or sometimes
(19:18):
thiopental are used. The main thing is to avoid drugs
known to stimulate the sympathetic nervous system.
Ketamine is the classic one to avoid here because of its
sympathomomatic properties. And the anaesthetic gases to
keep them asleep. Inhalational agents like
isoflurane and sevoflurane are commonly used and generally
considered safe. Dysplorine is often avoided
(19:38):
because it can cause sympatheticstimulation, especially during
rapid increases in concentration, and halothane,
though less used now anyway, is generally avoided because it can
sensitise the heart muscle to the effects of catecholamines,
increasing the risk of arrhythmias.
What about painkillers? Opioids.
The standard opioids like fentanyl or hydromorphone are
commonly used. There's a theoretical caution
(20:00):
about using very large doses of morphine due to potential
histamine release. Which could complete the
picture, but it's generally manageable.
Ultra fast acting opioids like REMA fentanyl are useful because
you can titrate them very finelyto blunt responses to
stimulation, but they provide nopain relief once stopped.
It sounds like keeping the patient deeply anaesthetized
(20:21):
during stimulating parts is key.Absolutely.
Maintaining an adequate depth ofanaesthesia, especially during
things like intubation, the surgical incision, putting in
retractors and especially tumourhandling is critical because
it's not just the tumour releasing hormones.
Stimulating the patient's own sympathetic nerves can also
cause norepinephrine release from nerve endings.
(20:42):
Right. And does the surgical approach
matter like open surgery versus keyhole?
Laparoscopic or keyhole removal is increasingly common and now
the standard for many adrenal pheochromocytomis.
It generally offers faster recovery.
However, the sources note that the hemodynamic instability,
those big swings and blood pressure can still happen with
either approach. Why is that?
(21:04):
Because the primary trigger is still the physical manipulation
of the tumour itself, which happens regardless of the
incision size. Also, with laparoscopy, the
insufflation of gas into the abdomen to createspace can
itself sometimes cause pressure increases by compressing things.
So you're prepared, monitoring closely, then the surgeon starts
handling the tumour. What happens then typically?
(21:25):
This is often the most challenging phase.
Intraoperatively, you frequentlysee quite brisk, sometimes
dramatic increases in blood pressure and heart rate as
catecholamines flood out from the manipulated tumour.
And how do you slam the brakes on that in real time?
You need potent fast acting intravenous drugs ready to go.
For the high blood pressure spikes, intravenous vasodilators
(21:46):
are the mainstay. Sodium nitroprucide or SNP is
often mentioned as a preferred agent.
Why SNT? Because it's a very potent
dilator of both arteries and veins, it works extremely
quickly, almost instantly. And crucially, its effect stops
almost immediately when you turnoff the infusion.
This allows for very fine 2nd to2nd control.
(22:06):
Nitroglycerin is another option,though it tends to affect veins
more than arteries. What about alpha blockers
intravenously? Yes, intravenous phentolamine is
another important tool. It's a competitive alpha
blocker, works rapidly, has a short duration of action, and
can be given as repeated bolusesor as an infusion to directly
counteract the alpha mediated vasoconstriction.
Any other interesting agents mentioned for controlling those
(22:28):
spikes? Magnesium sulphate comes up
again here. It could be used
intraoperatively, often as an infusion started after
induction. The idea is that helps blunt
catecholamine release and might alter the body's response at the
receptor level. It could be quite effective as
part of a multimodal approach, though the sources suggest you
often still need additional boluses of other agents during
(22:51):
peak stimulation. OK.
And calcium channel blockers too, like nicartopine.
Yes, intravenous calcium channelblockers like nicartopine can
also be used to control hypertension during surgery.
They offer another mechanism to help relax blood vessels.
What about the heart rate if that shoots up?
For tachycardia or tachyarrhythmias, you need fast
acting intravenous beta blockers.
(23:11):
Ezmolol is particularly useful here because it's very short
acting. Its effects wear off within
minutes of stopping the infusion, so you can precisely
control the heart rate without risking prolonged blockade if
the situation changes. Labetalol, which has both alpha
and beta blocking properties, can also be used in boluses.
OK, now what if the opposite happens before the tumour is
out? Sometimes the pressure dips
(23:33):
between the spikes. Yes, that can happen.
Brief hypotensive episodes can occur, especially if the patient
is very deeply anaesthetized or between bursts of catecholamine
release. If the patient has been properly
volume loaded beforehand, these dips are often transient.
If treatment is needed, small careful boluses of a pure alpha
agonist vasoconstrictor like phenylephrine are usually
(23:56):
recommended. Why phenylephrine specifically?
Because it directly constricts blood vessels via A1 receptors
without significantly affecting the heart rate or importantly,
causing release of the body's own catecholamine stores.
You want to avoid indirect acting agents like ephedrine or
mixed agents like epinephrine itself before the tumour is out
as they could worsen the situation.
(24:16):
Got it. Any drugs to be particularly
careful with around this time? Anti nausea meds.
Yes, the sources flag a couple. There's historical concern about
drop redol potentially triggering hypertensive crises
in these patients, possibly through complex interactions,
although some suggest small doses might be OK now.
But definitely midoclopramide regolin should generally be
(24:39):
avoided as it's been shown to directly stimulate catecholamine
release from pheochromocytoma cells.
OK, good to know. So the surgery proceeds, the
hypertensive spikes are managed,then comes the really critical
moment. The surgeon clamps the main
vein, draining the tumour or moves the tumour entirely.
What happens hemodynamically then?
(25:00):
This is often the second major point of potential instability,
but in the opposite direction. Suddenly, the primary source of
those massive amounts of circulating catecholamines is
cut off. Levels in the blood plummet very
quickly because these hormones have very short half lives.
And the immediate big risks shift from high pressure to.
To hypotension low blood pressure and also hypoglycemia
low blood sugar, the excessive catecholamines were likely
(25:22):
suppressing insulin release and promoting glucose production, so
when they disappear, blood sugarcan drop unexpectedly.
But hypotension is the main circulatory concern right after
ligation. Yes, that's often the most
immediate and pressing issue, though it's worth noting maybe
about half the patients can actually remain hypertensive for
a few days or even a week post op, perhaps due to lingering
(25:43):
effects or maybe receptor changes.
But profound hypotension right after clamping is very common
and needs anticipation. How do you manage that sudden
drop? First, you immediately stop any
infusions of vasodilators like nitropresside or beta blockers
like Ezmol that you were using to control the hypertension.
Second, you give fluid boluses. Remember that volume expansion
(26:06):
pre op? Now the vessels are relaxing.
The vascular tank is suddenly much bigger and you need to fill
it. And often, fluids aren't enough.
Often not, especially initially.Temporary support with
intravenous vasopressor infusions is frequently required
to maintain adequate blood pressure.
What kind of pressors? Pure alpha agonists like
phenylephrine can be used, or mixed alpha and beta agents like
(26:26):
norepinephrine, which is often afirst choice, or even
epinephrine might be needed depending on the degree of
hypotension and whether cardiac support is also required.
I saw vasopressin mentioned in the sources too for a resistant
hypotension. Yes, that's an interesting
point. Sometimes the hypotension can be
quite severe and resistant to the usual catecholamine
pressors. This might happen if the
(26:48):
patient's adrenergic receptors have become down regulated or
desensitised from the chronic exposure to high hormone levels
before surgery. So vasopressin works
differently. Exactly.
Vasopressin works on entirely different receptors V1 receptors
to cause vasoconstriction. There might also be a relative
deficiency of the body's own vasopressin release after the
(27:09):
stress of surgery, so adding a vasopressin infusion can be a
very effective strategy for refractory hypotension in this
setting. And this post op low pressure.
Can it sometimes linger for a while?
It can sometimes be persistent, yes.
One major reason, especially highlighted in one of your
sources comparing preparation methods, is the residual effect
of long acting alpha blockers used preoperatively.
(27:31):
Like phenoxybenzamine. Precisely.
Phenoxybenzamine's effect lasts much longer than the circulating
catecholamines, so after the tumour is out and the
catecholamins are gone, the phenoxabenzamine is still
blocking alpha receptors, contributing to vasodilation and
making hypotension harder to manage initially.
This might be less of an issue with shorter acting competitive
(27:52):
blockers like Doxazosin. That comparison study mentioned
something about fluid needs to. Yes, it observed that the group
prepared with phenoxabenzamine seemed to require significantly
more intravenous fluids postoperatively and had more
issues with peripheral edoema potentially related to that
prolonged non competitive alpha blockade compared to the
doxazosin group. Of course, you also always have
(28:13):
to rule out surgical bleeding asa cause for persistent
hypotension too. Right.
So it sounds like the whole journey from the first suspicion
through diagnosis, the intense prep, the roller coaster in the
OR and the careful post op phase, it really requires
constant vigilance and expertise.
It truly does. The perioperative management of
pheochromocytoma is without doubt challenging, but as your
(28:37):
sources consistently highlight, the understanding and strategies
developed over the decades have led to just remarkable
improvements in safety and patient outcomes.
It's a real success story in that sense.
And removing the tumour surgically is still the
definitive cure, right? Yes, for benign localised
tumours, surgery is curative. Getting the patient safely to
and through that surgery is the art and science we've been
(28:59):
discussing. And the absolute cornerstone of
that safety seems to be that meticulous preoperative prep.
Unquestionably adequate alpha blockade, careful volume
expansion, and then appropriate use of beta blockade only if
needed. That foundation is key to
mitigating the risks during surgery.
And having that experienced multidisciplinary team working
together. Absolutely essential.
(29:19):
Endocrinologist, surgeons, anesthesiologist, critical care
teams. Everyone needs deep familiarity
with the condition and needs to be communicating effectively, as
the sources say, while there might not be one single best
anaesthetic recipe proven by large trials.
Vigilance, communication and tailoring.
The pair works. Exactly.
(29:41):
Adapting to the individual patient, the specific situation,
the drugs available and anticipating the potential
problems. That's a core of successful
management. It's also really fascinating
that point you made earlier, howbecause this condition is so
rare, so much of our current understanding comes from
collective experience, from caseseries, from careful observation
over time, rather than those biggold standard randomised trials.
(30:04):
That's a really significant aspect the sources touch upon.
It really underscores the value of meticulous record keeping,
sharing experiences through casereports and series, and learning
incrementally when you're dealing with diseases that just
don't occur frequently enough for large traditional studies.
Well, this has been a truly deepdive through the material you
shared. We've gone from understanding
(30:25):
what this tricky tumour actuallyis, how it earns that great
mimic nickname through the absolutely vital steps of
preparing for surgery, navigating those really complex
moments in the operating room and then managing that critical
handover to the post operative phase.
It's it's really clear that while pheochromocytoma throws up
some serious physiological hurdles, it definitely does.
(30:47):
A knowledgeable, prepared and collaborative medical team,
guided by the principles laid out in these sources, has really
transformed what used to be an incredibly dangerous undertaking
into something much, much safer today.
The progress really is striking.It's a testament to careful
study, adaptation, and teamwork in medicine.
Which kind of leaves us with maybe one final thought to Mull
(31:08):
over. Building on that point about the
rarity and how we learn, given that so much of the expertise
relies on this accumulated experience from individual cases
and observations, how might future advances, maybe in how we
collect and analyse vast amountsof clinical data, you know,
perhaps through sophisticated electronic health records, maybe
(31:28):
even AI looking at patterns across many centres, how might
that continue to refine and evenpersonalise our approach to
managing unique and demanding conditions like this one?
Could it potentially teach us new things, new nuances that are
hard to capture even in small studies or case series alone?
That's a very compelling question.
How big data analytics might augment clinical experience for
(31:50):
rare diseases? Definitely something to watch in
the future of medicine. Indeed.
Well, thank you so much for sharing these sources and
allowing us to really dig into this fascinating topic with you
today My. Pleasure is a great discussion.
Welcome back to the Deep Dive. Today we're jumping into
something pretty specialised. It's rare, definitely complex,
and honestly it sounds like it involves some really high stakes
in the operating room. It certainly can.
You send over a whole bunch of really fascinating sources on
this and what we're going to do,what we do best here, dive right
into them. Sounds good.
We're looking at pheochromocytoma today.
(00:22):
It's it's a type of tumour that presents some unique challenges,
especially, like you said, around the time of surgery.
Yeah, it sounds like even thoughit's not common, the material
you shared really hammers home how crucial it is for the
medical teams, you know, especially the anesthesiologist,
to really nail this. Absolutely.
Get it wrong and things can change very, very quickly.
(00:43):
Kind of like a hormonal time bomb is how I was picturing it.
If it's not managed just right around the surgery, things can
apparently go sideways really fast.
And unpredictably. That's a pretty good analogy,
actually. So our mission basically is to
sift through these sources you provided, pull out the the key
bits of knowledge and really understand why it's such a
(01:05):
challenge and you know how experts actually manage it.
Right. The core difficulty is that
potential for sudden, really dramatic swings and blood
pressure, heart rate, all drivenby these rogue hormones and
tumour releases. Careful planning, careful
execution, it's all absolutely vital, OK?
Let's start at the beginning then.
(01:25):
What exactly is a pheochromalocytoma?
OK, so. Fundamentally, it's a tumour and
it's made-up of these specialised cells called
chromathin cells. Chromathin cells, right?
And these cells are a part of your sympathetic nervous system.
That's the system that controls your fight or flight response.
Got it. So where do these tumours
usually show up? Well, the most common spot
there's sort of primary home is the adrenal medulla.
(01:48):
That's the inner part of the adrenal glands, which, you know,
sit right on top of your kidneys, OK.
Adrenals makes sense. But, and this is where it gets
really interesting, according toyour sources, these chromophane
cells or very similar tissue called paraganglia, they aren't
just in the adrenals, they can actually be found in other
places too. Like where?
Well, sometimes in quite surprising spots, like embedded
(02:10):
in the wall of the bladder or near the prostate, the rectum,
even inside the chest cavity near the heart sometimes.
Wow, the bladder. Seriously.
So it's not always just an adrenal tumour.
No, not always. The adrenal ones are definitely
the most common, but these extraadrenal ones that pair
gangliomas, they can be a bit sneaky, but the core problem
(02:30):
wherever the tumour happens to be is that it just pumps out
massive amounts of catecholamines.
Catecholamines. Those are the stress hormones
right? Like.
Adrenaline. Exactly.
Yeah. That's the group name for
hormones like norepinephrine, epinephrine, which is adrenaline
and sometimes dopamine as well. These are the chemicals that
normally kick your body into high gear.
So too much of these means your body's kind of stuck in
(02:52):
OverDrive, either all the time or like in bursts.
Precisely, these hormones interact with different
receptors, different sort of switches all over your body.
You got alpha receptors that mainly tighten blood vessels.
OK, hence the blood pressure. Issues, all right, And that's
where alpha blocker drugs come into play for treatment.
Then you have beta receptors which mostly speed up the heart
(03:13):
and make it pump harder. And that's where beta blockers
are used. Correct, and when you have way
too many of these hormones circulating, the system goes
haywire. The sources mentioned that most
of these tumours may be over 80%, mainly secrete
norepanephrine and that usually leads to sustained high blood
pressure, often really severe hypertension that doesn't
(03:35):
respond well to standard meds. But some secret Adrenaline,
Epinephrine. More.
Yes, and those tend to cause more sudden dramatic episodes,
paroxysmal symptoms, they call them, you know, sudden racing
heart, sweating headache. Ah, OK.
Which brings us to how people actually present.
I liked how one source called itthe Great Mimic.
It really is. Yeah.
(03:56):
Because these hormones hit so many different body systems, the
symptoms can be incredibly varied and easily.
And mistaken for what? Lots of other things.
High blood pressure is the most common sign, though nearly half
of patients have it, often quitesevere.
But there's that classic triad people mention.
Yes, the classic triad Headaches, palpitations, that
(04:16):
feeling of your heart pounding or racing, and episodes of heavy
sweating. But it's important to remember
not everyone gets all three or gets them severely right.
And you can see all sorts of other things too, like anxiety
or tremors, even heart problems.Oh absolutely.
The list your sources provided is pretty long.
Anxiety, nervousness, visual disturbances, shaking, your
(04:36):
tremors, heart rhythm problems, arrhythmias, even heart failure
or a specific type of heart muscle damage called
cardiomyopathy. Yeah, and that blood vessel
tightening the vasoconstriction can make the skin look pale.
You can get acute pulmonary edoema fluid in the lungs.
High blood sugar is common too because these hormones mess with
glucose metabolism. And weight loss sometimes.
(04:58):
Yes, particularly if there's a lot of epinephrine being
secreted. The body's just constantly
revved up burning energy. You know, one of the sources
shared this anecdote that reallydrove home that great mimic
idea. Yes, I remember that one, the
patient who presented with really severe difficult to
control diabetes. But no high blood pressure
(05:19):
history at. All exactly no hypertension, but
then an abdominal scan done for some other reason happened to
show a mass on the adrenal gland.
Initially the team wasn't, you know, super suspicious of
pheochromocytoma because that hallmark high blood pressure
just wasn't there. But wisely, because they saw the
mass, they decided to manage thesurgery as if it might be one,
(05:41):
just in case. And it was.
It was, and after they removed the tumour, the patient's
diabetes basically resolved, their blood sugar normalised.
It's just a fantastic example ofhow this thing can present a
typically and why you really have to consider it if you find
an adrenal mass, even if the classic signs aren't obvious.
Yeah, that's a great point. And it can pop up in other
tricky situations too, right? Like mimicking preeclampsia in
(06:03):
pregnancy? Yes, or causing hypertension in
kids, which is rare but something to think about,
especially if there's a family history of certain genetic
syndromes that predisposed to these tumours, like MNN
syndromes. Which all just highlights how
critical it is to actually diagnose this before someone
ends up having surgery for something completely.
Different. Oh absolutely critical.
(06:24):
Operating on someone with an undiagnosed, unprepared
fiochromocytoma is incredibly risky.
The mortality used to be sky high.
So how do they pin it down then?How do you confirm the diagnosis
these days? Well, according to the material
you sent the the preferred method now is measuring the
breakdown products, the metabolites of these
catecholamines, specifically something called fractionated
(06:46):
manifrecenes and normatenefrons.OK, not the hormones themselves.
Usually the breakdown products are more reliable because
hormone release can be episodic,but the metabolites hang around
longer. You can measure them either in
the blood plasma or in a 24 hoururine collection, and these
tests are much, much more sensitive than the older ones.
Like the VMA test, I remember seeing that mentioned.
Exactly. Urinary venolimandelic acid VMA.
(07:10):
That was used a lot historically, but the sources
say its sensitivity is actually pretty low, maybe only around
64% in adults. So you could miss cases, right?
And those old provocative tests where they actually tried to
trigger a hormone release with drugs like Glucagon, they're
almost never needed anymore because the biochemical tests
are so good. OK, so you've got the
biochemical proof of hormone excess.
(07:31):
Now you need to find the culprit, the tumour itself.
Precisely, localization is the next crucial step obviously for
surgical planning, and standard imaging techniques like CT scans
or MRI are usually very good at finding these tumours.
Even the ones outside the adrenals.
Yeah, CT and MRI are pretty effective for most of them,
including the extra adrenal ones.
(07:52):
But what if it's really hidden or they suspect it's spread?
Right. For those tricky situations,
maybe a tumour in a really unusual spot, or if they're
worried about recurrence after aprevious surgery or metastasis,
then they often turn to specialised nuclear medicine
scans. The main one mentioned is MIBG
centigraphy. Amici, how does that work?
MIBG is this radioactive tracer mitio dobenzolguanidine that
(08:16):
happens to be taken up quite specifically by chromophane
cells by the tumour tissue. So you inject it, wait a bit and
then scan the patient and the tumour should, you know, light
up. Cool, so it can pinpoint those
sneaky ones. Exactly.
It's very useful in those complex cases.
There's just a little note of caution that some medications
can interfere with the tumours ability to take up the MBG, so
(08:37):
that needs careful management before the scan.
Things like certain blood pressure meds or
antidepressants. OK, this brings us to what feels
like the absolute core of managing this safely.
Based on your sources, the preoperative optimization, this
seems to be where the huge leap in safety happened.
It's absolutely the game changer.
Your sources quote some dramaticfigures.
(08:57):
Mortality rates for field chromocytoma surgery dropping
from like 40 or even 60% historically way back down to
close to 0, maybe zero, 6% in experience centres today.
And that incredible improvement is almost entirely attributed to
getting the patient properly medically prepared before they
even get near the operating room.
So. What are the main goals of that
(09:18):
prep phase? What are they trying to achieve?
OK, several key things. First, you need to get the blood
pressure and heart rate under control.
Normalise them as much as possible.
Second, you want to optimise thefunction of organs that might
have been stressed by those highhormone levels for a long time,
like the heart. 3rd, and this isreally critical, you need to
restore the patient's circulating blood volume.
(09:40):
Restore volume. Why is that needed?
Is it low? Yes, often significantly
depleted. Think about it.
Yeah, those high levels of norepinephrine have been causing
chronic vasoconstriction. The blood vessels have been
squeezed tight for potentially months or years.
OK. So the body adapts to this
smaller vascular space by reducing the actual amount of
(10:02):
fluid circulating. If you then suddenly remove the
tumour, the vessels relax, the space gets bigger, but there
isn't enough fluid to fill it. And the pressure crashes.
Exactly. A profound drop in blood
pressure. So expanding that volume
beforehand is absolutely vital. And then the overall goal tying
it all together is to prevent that massive life threatening
(10:22):
surge of catecholamines, the catecholamine storm during the
surgery itself. Makes sense, and the standard
way to do this starts with alphablockers, right?
That seems key. Yes, absolutely.
That's the first and most crucial step Alpha Edgenergic
blockade. Typically this is done for about
10 to 14 days before the plannedsurgery.
OK. And beta blockers.
Beta blockers are only added after adequate alpha blockade
(10:44):
has been achieved, and even thenonly if they're needed, usually
to control a fast heart rate, tachycardia, or arrhythmias that
persist despite the alpha blocker.
And there's a huge warning aboutnot using beta blockers first or
alone. A massive warning.
Your sources repeat this multiple times and it's worth
stressing again. Giving a beta blocker without
first blocking the alpha receptors is extremely dangerous
(11:07):
in these patients. Why is that so bad?
Because if you block the beta receptors, which mediates some
vasodilation and increase heart rate contractility, you leave
the alpha receptor effects unopposed.
The catecholamines are still pouring out, hitting those alpha
receptors hard, causing severe vasoconstriction.
So the blood pressure skyrockets.
Skyrockets uncontrolled severe hypertension and it can even
(11:29):
lead to acute heart failure or pulmonary edoema.
Fluid backing up into the lungs.One source even mentioned a
report of pulmonary edoema afterjust a small dose of Propranolol
given before alpha blockade. It's a critical point.
Alpha blockade first. Always.
OK, crystal clear. So what kind of alpha blockers
are typically used? The sources discussed mainly two
(11:49):
types. The classic one is
phenoxybenzamine. It's a non selective, non
competitive alpha blocker, meaning it blocks both A1 and A2
receptors and it binds irreversibly or nearly so has a
very long duration of action, a half life over 24 hours.
OK, advantages, Disadvantages. Well, the advantages sustained
reliable blockade and that that long duration allows plenty of
(12:12):
time for that crucial volume expansion to happen gradually
over the 1014 days. The disadvantages are potential
side effects like postural hypotension, getting dizzy when
standing up, nasal stuffiness, and because it also blocks A2
receptors, it can cause reflex tachycardia, a faster heart
rate. Right.
What's the alternative? The alternative is using
(12:33):
selective A1 antagonists drugs like prazosin, terezosin or
doxazosin. These only block the A1
receptors, which are primarily responsible for
vasoconstriction. And they're competitive
blockers. Yes, meaning they can be
overcome by very high levels of catecholamines.
Unlike fenoxabenzamine, they generally have shorter durations
of action, especially prizosin. This means they might need to be
(12:54):
dosed more frequently, but it also allows for potentially
quicker adjustments. And because they don't block A2,
they tend to cause less reflex tachycardia.
Any preference mentioned? Doxazosin got a specific mention
in one source for its good bioavailability and once daily
dosing, and there was experiencesuggesting it provided
comparable blood pressure control to phenoxybenzamine, but
(13:16):
maybe with less troublesome hypotension or fluid retention
after the surgery. Interesting.
Does the difference matter on the day of surgery?
It can. With the competitive blockers
like doxazosin. You usually need to give a dose
on the morning of surgery to maintain the effect.
With phenoxabenzamine's long half life, that's less critical.
OK. What about other drugs used in
(13:38):
Prep? Calcium channel blockers.
Yes, calcium channel blockers like nicartopine or amlodipine
can also be used. Sometimes they're added to alpha
blockers if control isn't perfect, or occasionally,
according to some K series, theymight even be used as the
primary agent, especially if thepatient is Norma intensive to
begin with or really can't tolerate alpha blockers.
How do they help? They work by inhibiting the
(13:59):
influx of calcium into the chromovan cells and that calcium
entry is needed for the tumour to actually release its
catecholamines, so they sort of calm the tumour down a bit.
And Metarocene. Metarocene is another one less
commonly used, usually as an adjunct.
It actually works further upstream by inhibiting an enzyme
called tyrosine hydroxylase, which is essential for making
catecholamines in the 1st place,so it reduces the synthesis of
(14:23):
hormones. It might be considered for
patients with very high hormone levels, large tumours or
metastatic disease where you really want to decrease the
overall catecholamine load. And all this time you're
watching for that volume expansion.
Exactly. They often monitor the patient's
blood count, specifically the hematocrit, serially.
As the alpha blockade takes effect and the blood vessels
(14:44):
relax, the vascular space increases.
If the patient is drinking enough fluids, that space fills
up and the blood becomes relatively less concentrated, so
the hematocrit will drop. Seeing that drop is a good sign
that volume expansion is happening appropriately.
It sounds like a pretty intensive preparation period.
It is traditionally 1014 days, often starting in the hospital,
(15:05):
although the source is mentioneda trend towards safe outpatient
preparation if patients meet specific criteria.
Things like reaching target blood pressure levels, not
having severe postural hypotension, having a stable ECG
and minimal arrhythmias. These are sometimes called
Roizen's criteria. And it takes a whole team, you
said. Absolutely crucial close
(15:25):
collaboration between the endocrinologist managing the
blockade, maybe a cardiologist if there are heart issues, the
surgeon planning the removal, and of course the
anesthesiologist who will managethe patient during the
operation. Everyone needs to be
communicating. Right, so after all that intense
preparation, you finally get to the surgery itself.
And even with everything optimised, your sources are
clear, it's still a challenge. It absolutely remains a high
(15:48):
vigilance procedure, even in centres with lots of experience.
The main lingering challenge is the potential for unpredictable,
sudden releases of catecholamines from the tumour,
especially when the surgeon starts physically handling it
so. Communication in the operating
room is absolutely paramount. Non negotiable.
The surgeon must communicate clearly and frequently with the
(16:08):
anesthesiologist, especially warning them just before they
anticipate manipulating or touching the tumour, because
that's when you expect the hemodynamic fireworks to
potentially start. Is there like one single best
way to do the anaesthesia for these cases?
Interestingly, the material points out that there isn't
really high level evidence like big randomised control trials
(16:29):
comparing different techniques head to That's mostly because
the condition is so rare. Right.
Hard to do those big studies. Exactly.
So while the core principles of management are pretty universal,
the specific choices of anaesthetic drugs or techniques
might vary a bit between institutions or regions, often
based on the team's familiarity,experience and drug
availability. OK.
(16:51):
What about monitoring during thesurgery?
What's essential? Continuous beat to beat blood
pressure monitoring is absolutely mandatory.
This is done with an arterial line, a small catheter usually
placed in an artery in the wrist.
And they put that in before the patient's asleep.
Ideally yes, placed under local anaesthesia and maybe some light
sedation before inducing generalanaesthesia.
(17:13):
The key is to avoid causing painor stress during placement,
which could trigger catecholamine release while the
patient is still awake and unprotected by deep anaesthesia.
Makes sense. What else?
Central Line. Central venous access ACVL is
strongly considered almost routine in most centres.
Why is that so important here? Several key reasons 1, You need
(17:33):
reliable access for potentially rapid infusion of fluids or
blood if needed. Two, and very importantly, after
the tumours adrenal vein is clamped or the tumours removed,
you often get that sudden drop in blood pressure we talked
about. You frequently need to start
potent vasopressor medications to support the circulation and
those are much safer to give through a central line.
(17:53):
And 3rd, it allows for monitoring of central venous
pressure CVP which gives some indication of the patient's
fluid status, although interpreting CDP has its
nuances. Got it.
And standard monitors too, presumably.
Oh yes, routine stuff. ECG for heart rhythm, pulse
oximetry for oxygen levels, capnography for breathing,
temperature monitoring, urine output measurement via a bladder
(18:15):
catheter. All standard.
Anything more advanced sometimesused like those special cardiac
monitors? Occasionally, A pulmonary artery
catheter might be considered if the patient has severe
pre-existing heart problems likesevere cardiomyopathy.
Some centres might use advanced monitors that look at things
like pulse pressure variation tohelp guide fluid therapy in
(18:35):
ventilated patients and transesophageal
echocardiography. TEE, an ultrasound probe in the
oesophagus looking at the heart,is generally reserved for very
specific situations like known severe cardiac dysfunction or if
the tumour is suspected to be actually inside the heart's
chambers or pericardium. OK.
And the anaesthesia itself, whatdo they typically use?
(18:56):
General anaesthesia is the standard.
Sometimes a regional technique like an epidural catheter might
be placed as an adjunct primarily for post operative
pain control and maybe to help blunt some sympathetic
responses, but it's always used in combination with general
anaesthesia, not. What about the induction drugs
getting the patient off to sleep?
Common intravenous agents like propofol, etomidate or sometimes
(19:18):
thiopental are used. The main thing is to avoid drugs
known to stimulate the sympathetic nervous system.
Ketamine is the classic one to avoid here because of its
sympathomomatic properties. And the anaesthetic gases to
keep them asleep. Inhalational agents like
isoflurane and sevoflurane are commonly used and generally
considered safe. Dysplorine is often avoided
(19:38):
because it can cause sympatheticstimulation, especially during
rapid increases in concentration, and halothane,
though less used now anyway, is generally avoided because it can
sensitise the heart muscle to the effects of catecholamines,
increasing the risk of arrhythmias.
What about painkillers? Opioids.
The standard opioids like fentanyl or hydromorphone are
commonly used. There's a theoretical caution
(20:00):
about using very large doses of morphine due to potential
histamine release. Which could complete the
picture, but it's generally manageable.
Ultra fast acting opioids like REMA fentanyl are useful because
you can titrate them very finelyto blunt responses to
stimulation, but they provide nopain relief once stopped.
It sounds like keeping the patient deeply anaesthetized
(20:21):
during stimulating parts is key.Absolutely.
Maintaining an adequate depth ofanaesthesia, especially during
things like intubation, the surgical incision, putting in
retractors and especially tumourhandling is critical because
it's not just the tumour releasing hormones.
Stimulating the patient's own sympathetic nerves can also
cause norepinephrine release from nerve endings.
(20:42):
Right. And does the surgical approach
matter like open surgery versus keyhole?
Laparoscopic or keyhole removal is increasingly common and now
the standard for many adrenal pheochromocytomis.
It generally offers faster recovery.
However, the sources note that the hemodynamic instability,
those big swings and blood pressure can still happen with
either approach. Why is that?
(21:04):
Because the primary trigger is still the physical manipulation
of the tumour itself, which happens regardless of the
incision size. Also, with laparoscopy, the
insufflation of gas into the abdomen to createspace can
itself sometimes cause pressure increases by compressing things.
So you're prepared, monitoring closely, then the surgeon starts
handling the tumour. What happens then typically?
(21:25):
This is often the most challenging phase.
Intraoperatively, you frequentlysee quite brisk, sometimes
dramatic increases in blood pressure and heart rate as
catecholamines flood out from the manipulated tumour.
And how do you slam the brakes on that in real time?
You need potent fast acting intravenous drugs ready to go.
For the high blood pressure spikes, intravenous vasodilators
(21:46):
are the mainstay. Sodium nitroprucide or SNP is
often mentioned as a preferred agent.
Why SNT? Because it's a very potent
dilator of both arteries and veins, it works extremely
quickly, almost instantly. And crucially, its effect stops
almost immediately when you turnoff the infusion.
This allows for very fine 2nd to2nd control.
(22:06):
Nitroglycerin is another option,though it tends to affect veins
more than arteries. What about alpha blockers
intravenously? Yes, intravenous phentolamine is
another important tool. It's a competitive alpha
blocker, works rapidly, has a short duration of action, and
can be given as repeated bolusesor as an infusion to directly
counteract the alpha mediated vasoconstriction.
Any other interesting agents mentioned for controlling those
(22:28):
spikes? Magnesium sulphate comes up
again here. It could be used
intraoperatively, often as an infusion started after
induction. The idea is that helps blunt
catecholamine release and might alter the body's response at the
receptor level. It could be quite effective as
part of a multimodal approach, though the sources suggest you
often still need additional boluses of other agents during
(22:51):
peak stimulation. OK.
And calcium channel blockers too, like nicartopine.
Yes, intravenous calcium channelblockers like nicartopine can
also be used to control hypertension during surgery.
They offer another mechanism to help relax blood vessels.
What about the heart rate if that shoots up?
For tachycardia or tachyarrhythmias, you need fast
acting intravenous beta blockers.
(23:11):
Ezmolol is particularly useful here because it's very short
acting. Its effects wear off within
minutes of stopping the infusion, so you can precisely
control the heart rate without risking prolonged blockade if
the situation changes. Labetalol, which has both alpha
and beta blocking properties, can also be used in boluses.
OK, now what if the opposite happens before the tumour is
out? Sometimes the pressure dips
(23:33):
between the spikes. Yes, that can happen.
Brief hypotensive episodes can occur, especially if the patient
is very deeply anaesthetized or between bursts of catecholamine
release. If the patient has been properly
volume loaded beforehand, these dips are often transient.
If treatment is needed, small careful boluses of a pure alpha
agonist vasoconstrictor like phenylephrine are usually
(23:56):
recommended. Why phenylephrine specifically?
Because it directly constricts blood vessels via A1 receptors
without significantly affecting the heart rate or importantly,
causing release of the body's own catecholamine stores.
You want to avoid indirect acting agents like ephedrine or
mixed agents like epinephrine itself before the tumour is out
as they could worsen the situation.
(24:16):
Got it. Any drugs to be particularly
careful with around this time? Anti nausea meds.
Yes, the sources flag a couple. There's historical concern about
drop redol potentially triggering hypertensive crises
in these patients, possibly through complex interactions,
although some suggest small doses might be OK now.
But definitely midoclopramide regolin should generally be
(24:39):
avoided as it's been shown to directly stimulate catecholamine
release from pheochromocytoma cells.
OK, good to know. So the surgery proceeds, the
hypertensive spikes are managed,then comes the really critical
moment. The surgeon clamps the main
vein, draining the tumour or moves the tumour entirely.
What happens hemodynamically then?
(25:00):
This is often the second major point of potential instability,
but in the opposite direction. Suddenly, the primary source of
those massive amounts of circulating catecholamines is
cut off. Levels in the blood plummet very
quickly because these hormones have very short half lives.
And the immediate big risks shift from high pressure to.
To hypotension low blood pressure and also hypoglycemia
low blood sugar, the excessive catecholamines were likely
(25:22):
suppressing insulin release and promoting glucose production, so
when they disappear, blood sugarcan drop unexpectedly.
But hypotension is the main circulatory concern right after
ligation. Yes, that's often the most
immediate and pressing issue, though it's worth noting maybe
about half the patients can actually remain hypertensive for
a few days or even a week post op, perhaps due to lingering
(25:43):
effects or maybe receptor changes.
But profound hypotension right after clamping is very common
and needs anticipation. How do you manage that sudden
drop? First, you immediately stop any
infusions of vasodilators like nitropresside or beta blockers
like Ezmol that you were using to control the hypertension.
Second, you give fluid boluses. Remember that volume expansion
(26:06):
pre op? Now the vessels are relaxing.
The vascular tank is suddenly much bigger and you need to fill
it. And often, fluids aren't enough.
Often not, especially initially.Temporary support with
intravenous vasopressor infusions is frequently required
to maintain adequate blood pressure.
What kind of pressors? Pure alpha agonists like
phenylephrine can be used, or mixed alpha and beta agents like
(26:26):
norepinephrine, which is often afirst choice, or even
epinephrine might be needed depending on the degree of
hypotension and whether cardiac support is also required.
I saw vasopressin mentioned in the sources too for a resistant
hypotension. Yes, that's an interesting
point. Sometimes the hypotension can be
quite severe and resistant to the usual catecholamine
pressors. This might happen if the
(26:48):
patient's adrenergic receptors have become down regulated or
desensitised from the chronic exposure to high hormone levels
before surgery. So vasopressin works
differently. Exactly.
Vasopressin works on entirely different receptors V1 receptors
to cause vasoconstriction. There might also be a relative
deficiency of the body's own vasopressin release after the
(27:09):
stress of surgery, so adding a vasopressin infusion can be a
very effective strategy for refractory hypotension in this
setting. And this post op low pressure.
Can it sometimes linger for a while?
It can sometimes be persistent, yes.
One major reason, especially highlighted in one of your
sources comparing preparation methods, is the residual effect
of long acting alpha blockers used preoperatively.
(27:31):
Like phenoxybenzamine. Precisely.
Phenoxybenzamine's effect lasts much longer than the circulating
catecholamines, so after the tumour is out and the
catecholamins are gone, the phenoxabenzamine is still
blocking alpha receptors, contributing to vasodilation and
making hypotension harder to manage initially.
This might be less of an issue with shorter acting competitive
(27:52):
blockers like Doxazosin. That comparison study mentioned
something about fluid needs to. Yes, it observed that the group
prepared with phenoxabenzamine seemed to require significantly
more intravenous fluids postoperatively and had more
issues with peripheral edoema potentially related to that
prolonged non competitive alpha blockade compared to the
doxazosin group. Of course, you also always have
(28:13):
to rule out surgical bleeding asa cause for persistent
hypotension too. Right.
So it sounds like the whole journey from the first suspicion
through diagnosis, the intense prep, the roller coaster in the
OR and the careful post op phase, it really requires
constant vigilance and expertise.
It truly does. The perioperative management of
pheochromocytoma is without doubt challenging, but as your
(28:37):
sources consistently highlight, the understanding and strategies
developed over the decades have led to just remarkable
improvements in safety and patient outcomes.
It's a real success story in that sense.
And removing the tumour surgically is still the
definitive cure, right? Yes, for benign localised
tumours, surgery is curative. Getting the patient safely to
and through that surgery is the art and science we've been
(28:59):
discussing. And the absolute cornerstone of
that safety seems to be that meticulous preoperative prep.
Unquestionably adequate alpha blockade, careful volume
expansion, and then appropriate use of beta blockade only if
needed. That foundation is key to
mitigating the risks during surgery.
And having that experienced multidisciplinary team working
together. Absolutely essential.
(29:19):
Endocrinologist, surgeons, anesthesiologist, critical care
teams. Everyone needs deep familiarity
with the condition and needs to be communicating effectively, as
the sources say, while there might not be one single best
anaesthetic recipe proven by large trials.
Vigilance, communication and tailoring.
The pair works. Exactly.
(29:41):
Adapting to the individual patient, the specific situation,
the drugs available and anticipating the potential
problems. That's a core of successful
management. It's also really fascinating
that point you made earlier, howbecause this condition is so
rare, so much of our current understanding comes from
collective experience, from caseseries, from careful observation
over time, rather than those biggold standard randomised trials.
(30:04):
That's a really significant aspect the sources touch upon.
It really underscores the value of meticulous record keeping,
sharing experiences through casereports and series, and learning
incrementally when you're dealing with diseases that just
don't occur frequently enough for large traditional studies.
Well, this has been a truly deepdive through the material you
shared. We've gone from understanding
(30:25):
what this tricky tumour actuallyis, how it earns that great
mimic nickname through the absolutely vital steps of
preparing for surgery, navigating those really complex
moments in the operating room and then managing that critical
handover to the post operative phase.
It's it's really clear that while pheochromocytoma throws up
some serious physiological hurdles, it definitely does.
(30:47):
A knowledgeable, prepared and collaborative medical team,
guided by the principles laid out in these sources, has really
transformed what used to be an incredibly dangerous undertaking
into something much, much safer today.
The progress really is striking.It's a testament to careful
study, adaptation, and teamwork in medicine.
Which kind of leaves us with maybe one final thought to Mull
(31:08):
over. Building on that point about the
rarity and how we learn, given that so much of the expertise
relies on this accumulated experience from individual cases
and observations, how might future advances, maybe in how we
collect and analyse vast amountsof clinical data, you know,
perhaps through sophisticated electronic health records, maybe
(31:28):
even AI looking at patterns across many centres, how might
that continue to refine and evenpersonalise our approach to
managing unique and demanding conditions like this one?
Could it potentially teach us new things, new nuances that are
hard to capture even in small studies or case series alone?
That's a very compelling question.
How big data analytics might augment clinical experience for
(31:50):
rare diseases? Definitely something to watch in
the future of medicine. Indeed.
Well, thank you so much for sharing these sources and
allowing us to really dig into this fascinating topic with you
today My. Pleasure is a great discussion.
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