104. Pulm PEEPs on Core IM – Pleural Effusions

Hi Pulm PEEPs! Today we have a special episode for you. Monty and Furf were invited on the Core IM Podcast to talk about the work up and management of pleural effusions. This is a great overview and we hope … Continue reading →

Episode Transcript

(00:17):
Hey, fellow poem peeps. Thanks for tuning in
today. Today, we have a special episode for
you. This is an episode of the Core
I'm podcast that both Monty and I joined
to discuss the workup and management of plural
fusions.
As you may know, we've done a prior
series on plural fusions, but we could never
get enough of discussing them. And we're both
avid listeners of the Core I Am podcast,

(00:37):
so this is a real treat. We hope
you enjoy the episode.
I've said this multiple times, and I can't
believe I've said this multiple times being a
proceduralist,
but, you know, you just can't shake the
internist at heart. Now this is where your
pretest probability for these things is is so
critical. That's Chris Capp, an interventional pulmonologist at
Northwestern. Welcome to the Core I m five
pearls podcast, bringing you high yield evidence based

(00:59):
pearls. I'm doctor Shreyas Sherbeti. And I'm doctor
Kalila Pice, an internal medicine resident of Beth
Israel Deaconess Medical Center. Today, we're talking about
the interpretation of pearl fluid studies. And we'll
also touch on some common plural diseases like
paradigmatic effusions as well as malignant pleural effusions.
Alright. So let's dive in with the pearls
we're gonna cover today. Remember, the more your
chest is held, the deeper your learning gains.

(01:20):
Pearl one, to thoracentesis
or to not? When should we think about
thoracentesis?
Pearl two, a deep dive into the Leitz
criteria and pseudoexudates.
What are some things to think about when
using Leitz criteria, and what are some other
diagnostic tests we can use to

(01:43):
augment? Pro three, analyzing plural fluid studies.
What are some common pitfalls with the plural
pH as well as the cell differential?
Pearl four, the spectrum of parademonic effusions. How
do we identify and treat parademonic effusions?

(02:04):
Pearl five, malignant pleural effusions. How do we
diagnose and manage milligopeural effusions?
Okay. Khalilah, let's do a quick refresher on
pleural effusions before we get into all the
nuances with plural studies. So first onto imaging
plurals and then when to pull the trigger
on thorsagesis.
So first things first, pleural effusions

(02:27):
are when there's a buildup of fluid in
the pleural space. That is the space between
the parietal and visceral pleura. And fun fact,
it's actually normal to have a little bit
of fluid in the pleural space, like pretty
minimal, 30 to 50 cc's. And the reason
why it's there is because that little bit
of fluid helps as a lubricant,
which allows the lungs to move freely. And
on an AP portable chest x-ray, we can

(02:48):
see a meniscus forming or some blunting of
the costophrenic angle at around 200 cc's of
the fluid. You can see that pleural effusion
at even lower volumes, around 50 cc's.
So x rays are great and appreciate those
nuances. I always feel like Pocus is is
better. It's more sensitive for the fluid. It's
easy to do repeatedly at the bedside. You
can fall at a fusion over time. And

(03:09):
doctor Christina Montemir, a plumbing critical care doctor
at John Hopkins and one of the cofounders
of the podcast, Palm Peeps, reminded us how
POCUS can be used to actually see features
of the infusion itself. As a resident, I
have called for a thoracentesis
because it looked like there was complete whiteout
of right lung. And then I went with
the IP fellow, and we actually ultrasounded it.
And it's like, oh, like, this is not

(03:29):
fluid. This is actually, you know, cancer, and
it's solid component, and there's no fluid around
it. But I wouldn't have known that if
I went and did an ultrasound or the
bedside.
Great story. And maybe the most important thing
with imaging with our patients is that we
can actually show our patients their images, and
those images can be really powerful. A lot
of people when you're talking about, like, you
have an effusion, they're like, what is that?

(03:51):
Is it in the lung itself? Is it
outside of the lung? So I actually like
to show them, like, their actual image, whether
it's chest x-ray or if they got the
CT or even just showing them on our
bedside ultrasound. Like, this fluid here, like, shouldn't
be here, and you may be having your
symptoms because of this. So, like, here is
a procedure that we can do. So I
try to, like, at least let them visualize,

(04:13):
you know, what is abnormal
and the amount of fluid that we potentially
could take off and how that could help
them from a therapeutic standpoint as also from
a diagnostic standpoint. Patients sometimes are like, wow.
Like, that much fluid was in me. Like,
I can't believe that. Or they're just surprised
to see, like, they're like, what color is
it? Yes. I think this is the biggest
thing I've changed in my practice,
is showing patients their actual

(04:35):
radiology findings day and night in terms of
their understanding, the kinds of questions I get
back, the misconceptions I can clarify.
So once we know that we have a
pleural effusion,
something that we need to think about is
if we should drain it or sample it
with a thoracentesis.
That way, we can ensure that we're ruling
out any of those scant misdiagnoses
like infection or malignancy.

(04:55):
So I think by and large, in a
new unilateral pleural effusion, everybody that can safely
get a thoracentesis
should probably get a thoracentesis.
We also sat down with doctor Dave Ferfarro,
one of the pulmonary and critical care doctors
at Beth Israel Deaconess Medical Center, and the
other cofounder of Palm Peeps. These are his
thoughts on thoracentesis.
And then in that same vein, if I

(05:17):
am having bilateral fusions and
I am trying to treat it and I'm
really not making any progress and it starts
to make me question my underlying diagnosis, then
I might try to get a little bit
more information. Or if there are some red
flag features,
like the patient seems to really clinically have
a bad pneumonia,
and so even though there are two effusions

(05:37):
there, one of them could be a parenemonic.
They might not be the same process.
Someone has a known underlying malignancy and they
could certainly have metastases to multiple parts of
their body, then I'm gonna go ahead and
tap the larger one, the bigger one, to
try to get some diagnostic information. So the
takeaway for when two orthocentesis,
we can ask ourselves, one, is it a

(05:57):
unilateral effusion? Two, is it a bilateral effusion
that's not getting better with your interventions?
Or three, are there any red flag signs
like significant dyspnea, fever, weight loss, hemoptysis,
where you would really want to work up
that pleural effusion more. And something that really
stuck with me after speaking with our discussant
is that it is super important to not
anchor. I always have to tell myself is

(06:19):
to not anchor. Up to thirty percent of
pleural effusions do have more than one etiology.
So if you get your fluid studies back
and it's transitive, that doesn't necessarily mean there's
not something else going on.
I love that. The good old two things
can be true lesson rears its head again.
And just to, like, say it explicitly with
some examples. Right? A patient can have a

(06:40):
malignant pleural effusion and also heart failure contributing.
Or for example, a patient could have a
parenemonic effusion,
but also has severe hypoalbuminemia,
say their album is less than one point
five milligrams per deciliter, and that could also
be contributing to the fluid buildup. Okay. So
let's recap. Pleural effusions are pathologic states in
which there's a buildup of excess fluid in

(07:00):
the pleural space. When to tap an effusion
is dependent on the individual patient, but you
should consider if this pleural effusion is new
and it hasn't been evaluated before, if it's
bilateral or unilateral, and if there are any
red flag signs like fevers, pleuritic pain, pneumonias,
or a lack of improvement after you've given
what you think is appropriate therapy. And, finally,

(07:21):
don't anchor. Studies show that up to thirty
percent of pleural effusions can have more than
one etiology. And actually, I bet that number
is just rising with our patients getting more
and more complicated.
Okay. So say you get that thorough on
a patient. Now it's time to interpret the
studies, keeping in mind that all of this

(07:43):
is done in the context of the patient
in front of us. Yeah. And typically, I'd
use the LIGHTS criteria, but recently, I have
actually been seeing people use a pleural fluid
only rule, which actually includes pleural cholesterol. So
I think it'd be helpful to go over
the pros and the limitations of each. Yeah.
Let's start with the Light's criteria. I just
wanna say that every time I hear this
story,
I am truly blown away. It turns out

(08:04):
that Richard Light was a resident when he
submitted his prelim findings,
and he submitted it to the American Thoracic
Society in 1971,
and they actually rejected him. And then he
believed in his work, so he submitted it
again, his manuscript, to the Annals of Internal
Medicine. And this time, it was accepted, and
now it's a landmark study. Man, imagine that.

(08:25):
If that is not a motivator to believe
in your work and your passion, I don't
know what is. So just to say it,
the light's criteria is if you beat any
of the following, it's an exudative fluid. So
one, if the pleural fluid to serum protein
ratio is greater than point five, if the
pleural fluid to serum LDH ratio is greater
than point six, or if the pleural fluid
LDH is greater than two thirds, the upper

(08:46):
limit of normal for the lab. I don't
know. I feel like I've tried so hard
trying to remember this and try to, like,
squint at the 0.5 and the 0.6 and
try to make some connections. But, Chloe, do
you have a better way you remember these
numbers?
Yeah. I think it's hard for me to,
but what I do is that if the
plural protein in the LDH is more than
half of the serum protein in LDH, then
I kind of assume that it's exudative. But

(09:08):
I do think a better way is probably
understanding the pathophysiology.
And in transitates, when that fluid is relatively
simple, we're really thinking about the hydrostatic and
oncotic pressure. And is there some reason that
more fluid is just going across? And so
those are things like heart failure, fluid overload
from renal failure, low albumin states where you

(09:28):
have low oncotic pressure, and just sort of
simple fluid builds up in that space. And
then we think the exudative side of more
complex fluid, this is really when something's happened
to that barrier and it's not functioning normally.
So some sort of injury or inflammatory
process, some pathologic state that's leading more cells,
more protein, more sort of complex material to

(09:49):
go into that pleural space. And in either
case, the buildup of fluid in that space
can impact the lungs that are right there
adjacent to the pleura, and that's why we
care about them so much. Oh, that's awesome.
That, like, really helps imagine why then the
protein plural to serum ratio greater than point
five or the protein plural to serum ratio
and why the LDH plural to serum ratio

(10:11):
greater than point six makes sense for eggs
data and not for transitive because you have
all these proteins and LDH leaking into the
plural space. Leitz criteria is wonderful. It works
really well. I think the thing that it's
best at is identifying that it's a transudate.
So if you don't meet any of those
criteria, I feel really, really comfortable that this
is a simple transudative effusion.

(10:31):
So when light's criteria called something transitive,
we can feel very confident in that. But
it does beg the question, are we sure
in the same way about the exudative effusions?
It does have some flaws of maybe I
hate to say over calling exit dates, but
that is the criticism of it, is that
sometimes it can over call exit dates. The

(10:51):
reason that it might have some propensity to
do this is that you're actually using LDH
twice. Right? And
so you are using this ratio and you're
using the higher limit of normal, and that
can skew things quite a bit. Yeah. That's
a good thing to consider. And then another
critique of the lights criteria is about pseudoexudates.
These are effusions that are classified as exudative

(11:14):
effusions based on the Leitz criteria, but actually
their underlying etiology is transudative.
And this is pretty common. I was surprised
to learn that twenty to thirty percent of
so called exudative effusions
are actually associated with things like heart failure
or liver failure, which is classically actually transudative.
The other thing is that we know that
people who are have a lot of infusions

(11:35):
are often overloaded. And if you're on chronic
diuretic therapy, you can, for lack of a
better word, concentrate your pleural space. Right?
So fluid is going in. It has certain
components. You're slamming them with diuretics to get
them to urinate more, and some of that
fluid will get drained by the lymphatics and
back in the circulation, and you sort of
concentrate the fluid that's left in the pleural

(11:55):
space. And so in those cases, we sometimes
call that like a pseudoexudative
effusion.
So I'd say the takeaway is that diuretics
can concentrate pleural fluid and increase pleural protein
and LDH levels. This is humbling because if
our patient who has heart failure or a
hepatic hydrothorax
is being diuresed and we get a thora,
we might go down this rabbit hole of

(12:17):
trying to work up an exudate of effusion
that is actually just a pseudoexudate.
And so the good thing, and the good
news is, is that there's actually three other
things we can look at to help be
a tie breaker and actually help us kind
of see, that's a pseudoexudate
and not an actual exudate. So the first
of the three is you're gonna peek over
at the difference between the albumin in the

(12:38):
serum and that of the pleural fluid. Yeah.
So similar to the sag calculation in cirrhosis,
this is more formally known as the serum
pleural albumin gradient or SPAC. And the second
thing we look at is the difference between
the protein in the serum and the plural,
AKA the serum, plural, protein gradient, or the
SPIG. But this does make sense because if

(12:59):
you look at the pathophysiology
and the transmitted effusion, it's the hydrostatic and
oncotic pressures that are driving the fluid into
the pleural space. So you would expect that
those larger molecules like albumin and protein are
too big, and so they would stay in
the serum and not move into the pleura.
So there would be a larger difference in
the serum, plural, protein, or albumin gradient.

(13:21):
Yes. And then put to put numbers on
it and help make sense why these numbers
make sense. Right? If the difference between the
protein levels in the serum and the pleural
fluid is greater than three three point one
grams per deciliter, that's gonna point to transidative.
And, again, if the difference between the serum
pleural albumin gradient is greater than 1.2
grams per deciliter, then that's gonna also point
to transidative. Again, those big molecules are staying

(13:42):
in the serum and not going to the
pleural, so you're gonna see a bigger difference.
And then the third and last thing that
can help us objectively differentiate a pseudoexudate
is the pleural pro BMP. If it's greater
than 1,500,
then it is most likely due to heart
failure. And the idea is that if there's
so much BMP in the blood, it'll likely
leak into the pleural space. Nice. Alright. I

(14:04):
think we covered a lot of good ground
with Leitz criteria and kind of some of
the nuances to unpack there. Let's move on
to the pleural fluid only rule. And effusion
is an exudate if the pleural protein is
greater than three grams per deciliter, if the
pleural cholesterol is greater than 45 milligrams per
deciliter, or the LDH is greater than point
four five times the upper limit of normal.

(14:24):
And this is great because it only uses
pleural studies, so you don't need that serum
level comparison. It also doesn't duplicate the LDH
like the LIGHTS criteria does. But let's think
about why we're using the pleural cholesterol. Why
would it be higher in exudated effusions? There
have been some pretty good data to suggest
that a cholesterol level above 40 is consistent
with exudate, and below 25 is very consistent

(14:46):
with transudate. I do send it a lot
of the time. You know, I think it
can be useful in those situations where your
borderline, you know, maybe one of light's criteria
is positive. So I think having that test
and it, you know, if it's really high,
then it can really point to you that,
yeah, there's some inflammation going on just because
the pathophysiology
utilizing the cholesterol is thought to be related
to degenerating cells and vascular leakage from increased

(15:09):
permeability,
and that is more consistent with kind of
an exudative effusion. So there are two schools
of thought. One is that inflammatory pleural cells
are releasing cholesterol when they degenerate. And the
second thought is that because that pleural cholesterol
is derived from the plasma and the pleural
capillaries are more permeable in these exudative states,
that plasma cholesterol is actually able to enter

(15:29):
into the pleural cavity. That's awesome. Right? So
I feel like if we get a pleural
cholesterol over 45, then we can be pretty
confident it's exudative. Should we just be using
the pleural fluid only criteria and then just
retire the Leitz criteria?
You know, and I think the reason that
Leitz criteria has stood the test of time
for so long is is it just works.
And so, you know, there's no reason to

(15:50):
kinda debunk something that isn't necessarily broken. You
know, if it's not broke, why would we
try to fix it? You know, I think
these other evaluations are great because we always
wanna improve upon ourselves. So I think the
cholesterol was additive. And I think the albumin
ingredient can be additive in the right patient.
But I think that the reason the LIGHTS
criteria is to divested time is just because
of that reason. You know, it just works.

(16:11):
I mean, ultimately, the pulmonologists
say that we should still use the LIGHTS
criteria. And this
is because the LIGHTS criteria gives us a
higher sensitivity, so it's able to catch a
lot of those really scary exudative effusions that
we don't want to miss. So why don't
we summarize this pearl so far? When we're
classifying an effusion as transitive or exudative, we
gotta think about the physiology here. With transitive

(16:32):
effusions, it's really increased hydrostatic and low oncotic
pressure that's at play. And then with exudative
effusions, there's injury and inflammation causing leaky capillaries.
And then we have these big molecules like
protein, albumin, LDH, cholesterol leaking into the pleural
space. And that really helped for me understand
why the Leitz criteria ratios are a certain
way to capture that. And Leitz criteria is

(16:53):
helpful. And we do have to keep in
mind that it uses LDH twice, so it
can over call exudates. And a pseudoexudate is
basically when you use Leitz criteria and it
calls it an exudate, but actually in reality,
it's a transitive effusion. And there's three tools
that can help us better clarify the effusion.
It's gonna be the difference between the serum
and the plural albumin,
the difference between the serum and pleural protein.

(17:16):
If it's high, if those differences are high,
then it's a transit date. And also, if
you're concerned about a cardiac etiology, get a
NT proBNPE. If it's higher than 1,500,
then that also points to a transitive state.
And lastly, pleural fluid cholesterol levels will be
elevated in oxidative effusions due to cell degeneration
and capillary permeability.

(17:41):
So we talked about pleural fluid LDH, protein,
cholesterol, pro and tBNP,
all helpful things, but there are also a
bunch of other tests we often get with
our plural studies, particularly the pleural pH and
the cell differential. Yeah. I'm really excited for
us to talk a little bit more about
all of these. So let's start with the
pleural pH. I'd just remind everyone, a normal
plural pH is about 7.6,

(18:03):
and most exudated perfusions
will get a pH less than 7.3.
And if the pH is less than 7.2,
this could mean a very poor prognosis for
our patients,
and it increases the likelihood of that pleural
space needing to be drained with a chest
tube. Yeah. And speaking of, like, super low
pHs, I definitely mean tricked by super low
pleural fluid pH in a patient that was

(18:25):
actually
well appearing, like, eating a sandwich.
And turns out it was actually the local
lidocaine that was used prior to the thora
that's acidic in nature. And then when it
came into contact with the pleural fluid, falsely
lowered that pleural pH. And then on repeat
diagnostic thora, which is unfortunate that we had
to get it, the repeat thora did show
that the pH was actually normal all along.

(18:47):
And the same thing can happen with if
there's some residual heparin in the syringe. Wow.
That's crazy and kind of scary. And I
think these stories bring up a really important
point that we're looking at everything, including the
patient in addition to those pleural studies. Beware
when your patient's eating a grilled cheese sandwich
and their pleural pH is 7.1.
That's true. Okay. The other thing that we

(19:08):
should know is that the pH does change
depending on the time outside of the body.
And so if there's a delay more than
even an hour, it can falsely elevate the
pH, and that can be falsely reassuring.
Now why don't we move on to the
cell count and the differential? In a normal
pleural fluid, we would expect there to be
very few white blood cells and only will
be neutrophils.

(19:29):
Okay. So if there's a neutrophil predominance, we
can imagine that that's probably an acute process
that's going on, especially at levels greater than
fifty percent of neutrophils. But we should keep
in mind that different populations matter. So in
our lung transplant patients, even at twenty one
percent of neutrophils, we are worried about an
infection.
Yeah. And the other takeaway here is that

(19:49):
neutrophils just mean acute inflammation.
Right? Doesn't necessarily mean infection.
Yeah. Exactly. So, like, more than half of
our patients with pulmonary embolisms will have a
neutrophil predominant pleural effusion, which makes sense because
PEs are a very acute process. Right. Nice.
Alright. Let's move on to lymphocytes. So usually,
we can expect there to be about 20%

(20:09):
lymphocytes in the pleural fluid. But say we
have more than 50% of lymphocytes, then we're
gonna think about more chronic processes going on.
And then lymphocyte predominant is sort of the
big large bucket. Lymphocyte predominant,
can be seen in malignancy, but it's also
the most likely
type of infusion for someone who has an
idiopathic effusion.
So somebody has recurrent effusions, we can't figure

(20:30):
out why. It's usually a lymphocyte predominant process.
Lymphocyte predominant can be seen in malignancy, certainly.
It can be seen in some sort of
more indolent infections. You know, tuberculosis is sort
of being the classic one. And then if
the pleural fluid lymphocyte is greater than 90%,
really, like, numbers that make your eyes pop
when you look at the EMR, that's gonna
be suggestive of, like, more rare things. Right?

(20:52):
Like lymphoma,
chylothorax,
tuberculosis.
And so you are worried about TB in
someone with a lymphocytic predominant effusion, your next
step would be adding on something like an
ADA or adenosine deaminase.
ADA is an interesting test in the sense
that, you know, I think in the right
patient population, it can be super, super helpful.
So if you have a patient from an

(21:12):
endemic area of TB, then they have a
pleural effusion, sending an ADA can be super
helpful. If it's elevated, it can help you
cinch the diagnosis because culture data from an
AFB from the pleural fluid is really low.
You're gonna get an answer about ten to
fifteen percent of the time. So an ADA
can be very supportive. And so in normal
conditions, an ADA in the pleural fluid is
low. So if you send off an ADA

(21:34):
and it comes back less than 40 international
units per liter, we can generally exclude tuberculosis
pruritus.
Let's move on to eosinophils.
There should be almost zero percent of eosinophils
in the plural space. So if you have
more than ten percent, there are quite a
few things it could possibly be. Eosinophils really
can be from grab bag of things, but
anything that irritates or violates the pleura will

(21:57):
need eosinophils to be there. So somebody has
a rib fracture, somebody has a pneumothorax,
somebody has actually had a prior tap. There
are certain types of malignancies
or inflammatory conditions can do that. Now one
of our reviewers even noted that some of
the most often misdiagnosis
he sees with his presence in fellows when
it comes to eosinophils in the pleura, in
his opinion, are more of the rare things
like asbestos related to pleural effusions or tuberculosis

(22:19):
pleuritis.
Yeah. And those are definitely things you don't
wanna miss. I was also really surprised to
hear that no diagnosis is even obtained in
about a third of patients with eosinophilic pleural
effusions.
Man. Idiopathic stuff is always so humbling in
how often it comes up. So so the
last part of our cell count in diff
is the number of RBCs.
A lot of your pleural effusions are gonna

(22:41):
have a fair amount of red blood cells
on them, but you really need a very
high percentage or a very high number of
red blood cells for that to be consistent
with the hemothorax.
The best test for that is actually to
send a pleural fluid hematocrit. And if it's
greater than 50% of the serum hematocrit,
then you're looking at a likely hemothorax.

(23:01):
So to reiterate, if we look at the
ratio of pleural fluid to blood hematocrit and
it's greater than 0.5,
this is diagnostic of a hemothorax.
And then another cool trick we learned is
that when you're sending off pleural fluid for
a culture, you've actually placed that sample straight
into the blood culture bottle and that's gonna
increase our yield. There's a recent paper. It's
a couple years old now, but inoculating your

(23:24):
blood culture bottles at the bedside before you
send them to the lab improves your yield
by about 10 to 12%. So it's actually
my practice now where I draw the fluid
and then either myself or someone else who's
in the room just directly inoculates 10 cc's
into the blood culture bottles just to improve
your yield. Okay. So we learned about a
lot of tests. So let's summarize some of
our takeaways. A normal plural pH is around

(23:46):
7.6,
but numbers below that, like 7.3,
suggest an exudative effusion. And then do try
to get the samples into the lab as
soon as possible, or else you might have
a falsely elevated pH.
And when we look at the cell count
of the pleural fluid, if there's greater than
50% of neutrophils, we can think that that's
an acute process. And if there are high
lymphocytes,
this could be a chronic

(24:08):
process like malignancy or even TB. If we
are worried about TB, we should send off
an ADA to help. Right. And then eosinophilic
infusions,
that can be just like anything that irritates
the pleura. And if the pleural to serum
hematocrit ratio is greater than point five, this
indicates a hemothorax.

(24:29):
Alright. Now let's take some of our interpretation
of plural studies and apply it to diagnosing
and treating parenemontic effusions.
Yeah. I think a great example is trying
to distinguish between uncomplicated
and complicated parapneumonic effusions. And in uncomplicated process,
you just have pneumonia there in the lung.
The portal space gets irritated.

(24:49):
Yes, more protein and cells and things are
pouring into there, but you don't sort of
have a frankly
infected
space. It's just sort of next to this
infected lung. And in those cases, we feel
a lot more comfortable
trying to just treat the pneumonia
and have the fluid maybe be drained once
as we're doing the diagnosis, but we're just
sort of monitoring it. And with these cases,

(25:12):
when we look at the pleural fluid biomarkers
in uncomplicated
effusions, this is basically when fluid
pleural fluid is gonna be greater than 60,
and the pH is gonna be greater than
7.2.
And this is different from a complicated parenemonic
effusion. This is when bacteria is actually inside

(25:33):
the pleura. And for this reason, we call
it complicated because it needs to be drained
to be resolved.
Man, I don't know if I'm, like, dating
myself here, but there was a time on
Facebook where people would actually update their relationship
status as complicated,
and I can't help but think about the
parallel that those complicated relationships just needed some
drainage
to help it out. I love that. I

(25:54):
think we can keep running with it. So
our complicated relationships are less sweet, kind of
like the complicated effusions where our glucose is
less than 60 because of all of the
bacteria.
And I would also say that our complicated
relationships can sour, kind of similar to the
complicated effusions, which are gonna be more acidic
with our pH less than 7.2.

(26:14):
Nice. That was so good. I love that.
Alright. Another pro tip on floral glucose being
low is that, yes, we have this cutoff
of the glucose being less than 60, but
it's not a hard and fast, especially if
you take the patient's serum glucose into account.
Now this is the situation where I think
having a serum level is helpful because you
wanna see if the glucose level is significantly

(26:35):
lower than the serum level. If you have
a patient who has a glucose level in
their serum of 400 and you have a
glucose level in your pleural fluid of 70,
then I think infection is gonna be going
higher on my list of potential diagnoses.
And annoyingly, the gram standing culture might be
negative or positive depending on the stage of
disease or where you tap. But if you

(26:57):
do see the LDH being greater than a
thousand, or if you see loculations or septation,
that loculation or septation on bedside ultrasound or
a CT can really help you clench the
diagnosis.
If I see septations,
if I see loculations in a really complex
space, that's gonna be a complicated effusion. I
don't actually even care what the fluid characteristics

(27:17):
look like because I can't be positive
that the fluid characteristics from one pocket are
the same as another pocket. And so if
it looks really complicated on my bedside,
ultrasound or on a CAT scan, I'm gonna
call that a complicated effusion. And just to
say explicitly, I really appreciated hearing how a
sample fluid in one pocket of a loculation
or septation

(27:37):
may be different than another, And that's why
we might see a higher number of bacteria
in one pocket versus another. Yeah. And last
but not least, if you tap an effusion
and you get frank pus, that is not
just a complicated effusion anymore. That is empyema.
So let's get a little bit more granular
in terms of treatment of these complicated parenematic
effusions in empyema. There's two main buckets, drainage

(27:59):
of the pleural space with a chest tube
and antibiotics.
I would make sure that those antibiotics have
anaerobic coverage in them because you're almost thinking
of this as like an abscess. But I,
at first, have much lower threshold to add
antibiotics that cover the broad spectrum bugs that
we most worry about, like Pseudomonas and MRSA.
And with the chest tubes for parenemonic effusions
and empyema, sometimes we need just a little

(28:21):
bit more help with the drainage, and that's
where fibrinolytic therapy comes in. And there was
an age old debate about which therapy we
should use. Is it tPA?
Is it Dornase?
Is it both? The MIST two trial gives
us our answer. TPA Dornase actually did improve
both radiographic outcomes and decrease the need for
surgery. There were no effect on on mortality
or hospital life of stay. The caveats to

(28:42):
using tPA Dornase,
I think are one, if you have a
really thickened plural rind, it's not gonna be
effective at decorticating or getting rid of that
plural rind. So the patient's gonna have some
long entrapment. These medicines are not gonna fix
that. Two, there was a very good retrospective
review of a very large data set that
looked at the safety

(29:04):
of Tv a doornase. Essentially, the bleeding rate
is pretty low. It was somewhere between two
and four percent. But if your odds ratio
for bleeding from tPA dornase out of the
pleural space goes up if you cannot stop
anticoagulation.
So in those situations, you know, you should
really consider dose reducing or maybe not using
it because, you know, obviously, you don't wanna
cause a pleural bleed in those patients. Yeah.

(29:25):
So to help recap the mystery trial and
management,
if we can, the combination of TPA and
Dornase is preferred
in our patients with complicated fusions and pyema
because it reduces the need for surgery, which
is always a good thing. But we do
have to keep in mind if our patients
on CT have a thickened pleural brine or
lung entrapment, aka the lung can't fully expand

(29:46):
because of some active disease, the tPA door
nase might not be as effective. And I
think a good way to end this pearl
is with the PSA that parenemonic infusions are
scary. And the reason we care so much
about them is because if we don't act
in time, of course, the patient could become
very sick and septic. Ultimately, they may require
a VATS decortication,
which is a very painful and invasive procedure

(30:08):
sometimes we can otherwise avoid. You know, I
think the old adage of the sun never
sets on a pleural effusion is probably only
really applicable anymore to patients who you're suspecting
an empyema. This is the consult that, you
know, you see a pneumonia and a pleural
effusion. This is the consult that probably should
happen even if it's 04:00, you know, on
a Thursday, you know, or on Friday or

(30:29):
even on the weekend. You know, this is
something that probably shouldn't sit and wait, you
know, especially with kinda some of the more
advanced treatments we have. But it should be
acted upon quickly, certainly within twenty four hours.
So to summarize, we have paranoid infusions, and
they really exist on a spectrum. On one
end, it's uncomplicated, meaning it's not infected fluid
and just kinda sitting near pneumonia, to complicated
effusions, which is actual bacteria in the plural

(30:51):
space, to, on the other end of spectrum,
empaema, which is franc pus. We can help
distinguish these
because complicated effusions in empyema will have a
glucose less than 60, a pH less than
7.2,
and an LDH greater than 1,000. And I,
again, really appreciate hearing that if you see
septations or loculations on ultrasound or CT, that
can be enough to call it complicated.

(31:13):
And so treatment of these complicated effusions and
empyemas require a chest tube, and sometimes they
also require a little bit more help with
breaking up the loculations
using tPA and Dornase therapy. And for antibiotics
and complicated effusions and empyemas, we want to
include anaerobic coverage, and then we should also
consider broader coverage, like for Pseudomonas and MRSA.

(31:38):
Okay. So say we are worried about malignancy
in a patient. Say someone's coming in with
a unilateral flow effusion, some weight loss, some
vague symptoms, and we need some plural studies.
There's been some data that has been published
about how much fluid to send. You wanna
send at least 50 cc's in this day
and age of eating next generation sequencing and

(31:58):
molecular testing and things like that. It's probably
a good idea to send more than that.
Your yield from your initial
plural fluid cytology is generally speaking around 50
to 60 to 65%.
If you're in that 30 to 40% where
you don't get an answer, your second one,
you will get an answer twenty five to
thirty percent of the time. So that second

(32:18):
thoracentesis
is usually the recommended
thing. One, it it can be diagnostic
in over a quarter of cases. And two,
you drain the patient dry and they feel
better. Right? And then if you still don't
have a diagnosis after that second one, then
pursuing kind of a more definitive biopsy is
recommended as long as it's within the patient's,
plan and goals and things like that. And

(32:39):
what's the definitive pleural biopsy? We can ask
our proceduralist whether it's medical fluoroscopy with IP
or VATS with our thoracic surgery colleagues. But
either way, once we've confirmed malignant pleural effusion,
I think the next big question is, what
do we do? And I think I asked
that because a lot of these effusions are
gonna come back. So I think the way
that I counsel patients is I tend to
be fairly conservative. You know, I think we

(33:00):
do a thoracentesis.
We get a diagnosis of malignant effusion. I
tell patients almost universally that we should wait,
see what happens, and then determine based on
the rapidity with which the fluid comes back.
If the fluid comes back quickly within a
week, then at that point, I'm talking to
them about the various management options. Yeah. One
of those management options is to repeat the
thoracentesis.

(33:21):
So we wanna give the patients a heads
up because they may be coming back every
week or every two weeks, and that can
be a lot for our patients. Definitely. And
so another option is an indwelling pleural catheter.
Right? They don't have to come in for
that. It's this basically soft silicone tube that's
inserted into their pleural space. It's not very
visible. It can be drained at home. And
so some people prefer that one. Sonal pleural

(33:43):
catheter placement
is ideal in the sense that it keeps
you out of the hospital. And then it's
as simple as putting in a chest tube,
essentially. But about a four to ten percent
infection risk for the lifetime of the catheter.
And most of the time, it's just colonization
and you can treat through it and keep
the catheter in. But sometimes it does lead
to full blown pleural sepsis or clogs the
catheter up so you have to remove it,

(34:03):
potentially put a new catheter in and expose
you to antibiotics. And then the other big
thing I always tell patients is, like, you
can't jump in a body of water or
take a bath, and you can't lay on
that side, generally speaking. So you really have
to you know, I try to be provide
as much informed consent as possible.
Oh, I actually did not know about the
bath thing, and I appreciate that because I

(34:24):
feel like nurses page us all the time
if, like, oh, can this person shower or
not? And I guess now I know I
can say, yes, they can shower, especially knowing
that, like, you know, it's not like hospitals
have baths of like, with a big body
of water or, like, those cold water morning
plunges that people are really into now. So
that's good to know. An alternative option to
the repeated thoracentesis and the indwelling catheter is
pleuridesis. And this is when we put a

(34:46):
sclerosing substance into the patient's pleural space. What
it does is cause irritation of the pleura,
and this ultimately results in the two pleura
sticking together, and this prevents fluid buildup with
the effusion.
So going back to Richard Light, he used
to call giving a sclerosing agent, and these
are some of the older sclerosing agents that
were probably more painful, but he used to

(35:06):
refer to it as tachy lordy syndrome where
the patient would get tachycardic and say lordy
lordy lordy which
is very corny. But it, you know, I
think it does serve a purpose that it
can cause a pretty significant inflammation in the
plural space. And so having an understanding of
maybe how we're gonna manage pain prior to
doing this and then counseling your patient, like,
yeah, this can cause a fairly significant pleuritic

(35:26):
type pain. So I am usually
injecting
bupivacaine
before I do any sort of pleurodesis
because it's a little longer lasting than lidocaine
with a half life. And then making sure
as long as they can tolerate taking it,
NSAIDs are generally speaking the best for this.
If not, then you're still gonna wanna hit
it from multimodal.
You know, I know we always wanna try
to limit narcotic use. In these cases, though,

(35:47):
sometimes, especially for a couple of days immediately
after the procedure, it's probably warranted. But also,
you know, lidoderm, lidocaine patches,
topical therapies can be super effective in this
patient population as well. And so to wrap
up this last pearl, if we're worried about
million and pleural effusion, we should tap that
effusion. And the cytology might come back negative
the first time, but on a repeated thoracentesis,

(36:08):
we can usually increase our cytological yield. And
when treating these recurrent pleural effusions, we do
have a couple of options to choose from.
These include repeated thoracentesis,
indwelling pleural catheters, and pleuridesis with a sclerosing
agent. And of course, each of these procedures
is not without side effects. And so really
important to kind of sit with that patient
and what their goals of care and wishes

(36:29):
are and what may be best for them.
And with that, that is a wrap for
today's episode. Thank you so much for listening.
If you got some value from this podcast,
our one ask is that you share this
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thanks to our reviewers for this podcast. Thank
you, doctor Steven Parkin, for the accompanying graphics.

(36:49):
And the episode was made as part of
the digital education track at the IBMC.
Opinions expressed are our own and do not
represent the opinions of any affiliated institutions. Thank
you.