Central Line
Episode Number: 105
Episode Title: New Findings
Recorded: July 2023
(SOUNDBITE OF MUSIC)
VOICE OVER:
Welcome to ASA Central
Line, the official podcast series of the American Society of Anesthesiologists,
edited by Dr. Adam Striker.
DR. ADAM STRIKER:
Welcome to Central Line. I'm your host and editor, Dr. Adam Striker. And
today I'm joined by Dr. Aaron Primm. Dr. Primm is an editor for Summaries of
Emerging Evidence, or SEE for short, and he joins me today to discuss some of
the findings in the current issue. We're going to learn a little bit about a
few recent studies, one that shed light on whether or not more aggressive
patient warming reduces adverse cardiac events and another that illuminates how
and if aggressive hydration has an impact on pancreatitis. Dr. Primm, welcome
to the show.
DR. AARON PRIMM:
Thank you for having me. Dr. Striker It's great to be here.
DR. STRIKER:
If you don't mind, I'd like to first hear a little bit about your work
with SEE. How did you get involved and what does your involvement look like?
DR. PRIMM:
Sure, yeah, I've been involved with SEE about four years now and just
came across it initially just from the ASA Monitor. You know, amazing that the
outreach works, really does. and so, you know, I contacted them, you know,
wanted to get more involved in and kind of try to find a good entry point to
some academic work and help with career development. And, you know, that was kind
of like my step in the door, you could say. I was really surprised when I when
I started that if you just kept doing the work and showing up and really
contributing, you can kind of lead up to the role on the editorial board like I
did. So it's a great program. I didn't need to know someone to get me connected
to them. It's really just the quality of writing and effort that you've put in
can really show through. So it's been a great experience.
DR. STRIKER:
Excellent. Well, there's one item about intraoperative hypothermia and a
recent trial that proposed that major cardiac adverse events would be greatly
reduced by aggressive, preoperative and intraoperative patient warming. Before
we talk about what they found, can you tell us a little bit about how that
study was conducted?
DR. PRIMM:
Yeah, I'd be happy to. You know, this was called the Protect Trial. It
was a multi-centered randomized controlled trial, and it was actually conducted
at 12 sites in China and also the Cleveland Clinic.
Just for some background. There had been a lot of smaller trials,
probably a couple decades ago, about hypothermia and kind of establishing the
risks of myocardial infections, bleeding complications. And then more
randomized trials in the 90s that kind of established these really increased
rates of morbidity from perioperative hypothermia.
And the goal in this study was to really assess if there was an
aggressive warming strategy that would be superior to just your typical warming
strategy in the operating room. So to be eligible for this study. It was
noncardiac surgery with general anesthesia, and it had to be for 2 to 6 hours,
and patients had to have at least one cardiac risk factor. And then they assign
them to the two groups. In the routine care group, they were not pre-warmed and
the intraoperative warming only occurred when body temperatures drop below
35.5°C. But in the aggressive warming group, they receive full body warming for
30 minutes before induction of anesthesia and the body temperature was actually
maintained above 37°C. And the two groups that they were trying to compare with
just a degree and a half difference in temperatures.
DR. STRIKER:
Okay. What did they find? What was the primary outcome?
DR. PRIMM:
So the primary outcome they were looking for was actually a composite of
myocardial injury, nonfatal cardiac arrest, and all-cause mortality within a 30
day time frame after surgery. So they were putting together these three things,
looking at both of these groups. And they total enrolled about 2500 patients
per group. And what they found was that they had at least one of the primary
outcome components in 9.9% of the aggressive group and 9.6 of the routine
warming group. And so, you know, they really did not find a difference between
the two groups. The relative risk was 1.04 value 0.69. So they really didn't
find a difference between these two groups in terms of warming. So they
concluded that we know that there's issues below 35 degrees, you know, these surgical
site infections and bleeding. But this tells us that we don't really need to
worry about aggressively warming patients to prevent major temperature related
complications.
DR. STRIKER:
Let's go back and just review what the risks are other than cardiac
issues with intraoperative hypothermia.
DR. PRIMM:
Yeah, of course. You're worried about that myocardial injury, of course,
because you're having increased blood pressure, sympathetic activation,
worsening that myocardial oxygen supply demand. And then that's the big thing
that, you know, they're worried about acutely in the perioperative period. But
there's also risk with surgical site infections. You know with hypothermia,
there's reduced delivery of the immune cells that injure tissue. And then
there's less, you know, tissue oxygenation and even mild hypothermia will
directly impair immune function and decrease antibody production. And the last
thing that they kind of hit on with all these past studies is there's a
decrease in platelet aggregation and issues with the coagulation cascade and
impairing enzymatic action. So the complication there is, as a coagulopathy,
ultimately requiring increased transfusions perioperative. So the big three
things: myocardial injury and surgical site infections and increased
transfusion requirements.
DR. STRIKER:
Okay, so now let's circle back and talk about were there any secondary
outcomes from this study?
DR. PRIMM:
Yeah. And you know, like we just discussed, they really looked at all
three of those issues and they also looked at hospital length of stay, 30 day
hospital readmission. And the bottom line is that they really didn't find
significant differences between them. Surgical site infections happened 7.2% in
the aggressive warming group, 6.3% in the routine. Group transfusions were 10%
in the aggressive group, 9.5% in the routine warming group. So, you know,
they're really showing that with this one and a half degree difference, none of
these outcomes were different.
DR. STRIKER:
Right. Overall, then what should anesthesiologists take away from this
new information when it comes to intraoperative hypothermia? Is it in general,
we should still make great strides to keep the patient warm or we just don't
have to go to great efforts to to overdo it?
DR. PRIMM:
Right, exactly. You know, I think what this is saying is that our
standard temperature management in the operating room is correct in the sense
that we are not causing harm by trying to be too aggressive. We know that
there's issues with patients becoming very hypothermic, like below 35 degrees.
But do we have to spend time, effort and resources to get them way above that,
way above 37 degrees? No, this study would argue against that. You know, in a
lot of other countries, it's not actually routine to use convection warming
devices during surgery, and only in certain cases will they actually do that.
And so it kind of follows our I would say our normal pattern of hypothermia
prevention is to turn it on at the beginning. We usually keep them around 36,
even though physiologically it's 37. But there's really no temperature related
adverse outcomes from that strategy.
DR. STRIKER:
Well talk a little bit about that with other countries not using
convective warming devices. I mean, what do they know that we don't or what do
we know that they don't?
DR. PRIMM:
Yeah, I think it's really just it's just a resource management issue for
the most part. When you have limited resources, there's probably a lot that
just relies on what they've seen work and what they've seen not work. I think
we have the luxury of being able to have better monitoring and these better
resources available to us, you know, to just to make sure that we never dip
below 35, 35.5 degrees.
DR. STRIKER:
Well, I do want to talk about the other study. So, if you don't mind,
stay with me through a just a short patient safety break.
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DR. JONATHAN COHEN:
Hi, this is Dr. Jonathan Cohen with the Patient Safety Editorial board.
Mitigated speech and incivility can both have negative consequences on team
performance in times of urgency. Health care professionals should voice a
concern at least twice to ensure it's been heard using an increasing level of
respectful assertiveness. One tool for using graded assertiveness is to use
cuss words. First, state your concern if the message is not received, explain
why you are uncomfortable with the situation. Finally announce that there is a
safety issue. Other acronyms for graded assertiveness exist, but whatever
method you choose should be universally used at your institution so that the
team gets accustomed to the signal words and understands their use indicates
that there is a serious safety concern that must be addressed. Being as direct
as possible while remaining respectful is the key to successfully communicating
a threat to patient safety.
VOICE OVER:
For more information on patient safety, visit asahq.org.patientsafety22.
DR. STRIKER:
All right. Dr. Primm, just as warming addresses some perioperative issues,
aggressive hydration is another recommended treatment for conditions such as
acute pancreatitis and an item in the 39 B issue of SEE looked at a study that
aimed to determine the difference in the development of moderately severe or
severe pancreatitis with aggressive versus moderate fluid resuscitation. Do you
mind telling our listeners a little bit about that study?
DR. PRIMM:
Yeah. So, you know, this is another study in that same vein. It's very
similar in that it was also a randomized controlled trial, multicenter parallel
group that was conducted in, I believe it was about 18 centers across four
different countries. And it was called the Waterfall study. And, you know, a
little background about this is that we know that early hydration was widely recommended
for managing acute pancreatitis. But really, the, you know, the evidence for
that practice is quite limited. And there really wasn't a sense of the volume
or the rate of fluid administration, only that lactated ringer's was
beneficial. And so this is kind of the starting point for this trial to try to
figure out if there was any advantage to a more aggressive fluid resuscitation
strategy. So in this study, they had adults that came in with the diagnosis of
acute pancreatitis no more than eight hours before enrollment and presented to
the emergency department, no more than 24 hours after pain onset. And these
patients were then randomized to either the aggressive or moderate
resuscitation protocols. And when they came in with Hypovolemia, the aggressive
group got about 20 mls per kilogram of lactated ringers over two hours, and
then an infusion of three mils per kilogram per hour. When patients were
assigned to the moderate group, they received 10mg/kg of lactated ringers and
then had an infusion of 1.5ml/kg per hour. So half the rate. And then
additional boluses were given in both groups if it turns out the urine output
was low or the systolic blood pressure was low. And then at different timed
intervals they use goal directed resuscitation and kind of assess the patients
and adjust it as needed as they went along. And, you know, if there was a
suspicion of fluid overload, they would stop or decrease the infusions. And
their primary outcome for this study was the development of moderately severe
or severe acute pancreatitis. You know, they wanted to see that if we're giving
the moderate amount or the severe amount of fluid, how many of these patients
would actually then go on to develop a moderately severe to severe acute
pancreatitis? And, you know, the study really has the strength that they use a
more realistic protocol in how patients would actually be assessed and treated
during the admission. But they're really just altering these two different
fluid strategies.
DR. STRIKER:
So what's the takeaway from that overall? What do you think?
DR. PRIMM:
Yeah. So the takeaway is that they didn't find a significant difference.
Again. Of the two groups, they found that severe pancreatitis occurred in 22%
of the aggressive group and in 17% of the moderate group. You know, no other
noticeable differences were found in any of the clinical outcomes.
And what's actually interesting is that they enrolled about a quarter of
the patients that they wanted to for an interim analysis, but it was actually
terminated early by the Safety Monitoring Board because of of a concern for
fluid overload. So the fluid overload was seen in the aggressive resuscitation
group in 20.5% of the patients, but only 6.3% of the patients in the moderate
group. And these patients were overwhelmingly treated with diuretics over the
other group as well. So they really found that having this aggressive strategy
was actually hurting patients and they weren't seeing any positive outcome from
doing that. There was also an accompanying editorial that came along with it.
And what they really were pushing for is that, okay, now we know, you know, a
better sense of how much fluid to give to these patients and what should be
done for them. So now let's shift to focus on pharmacologic interventions now
that we've gotten over this barrier.
DR. STRIKER:
Well between the two studies. What's to be gleaned from these when you
compare this one and the other one in general for the practitioner? Is there a
theme? What do these two studies overall encompass in telling the general
anesthesiologist?
DR. PRIMM:
There's a couple things. One of the big take home points is that sometimes
finding no difference itself is very helpful for clinical practice. We don't
have to be aggressive in warming patients or too aggressive and hydrating these
patients. You know, they both kind of go on this theme of moderation in
anesthetic care, right? Being overly aggressive just to see if it will help you
isn't always the best practice, and sometimes it's associated with outcomes
that are not safe for the patients. It's one of those everything in moderation
kind of scenarios where we really have to take a slow and step wise approach to
kind of approach these really important clinical questions that that we as anesthesiologists
come across every day. And they also have a study in 39B that we looked at that
also showed that patients with septic shock when they receive a liberal or
restrictive fluid strategy also had no differences in outcomes. So, you know,
these these studies are kind of building on each other to say that, you know,
we don't need to jump to the big guns, so to say right away. We can take a
careful stepwise approach to to solve these problems and also keep patient
safety in mind.
DR. STRIKER:
I do want to talk a little bit about how the information makes it to the
SEE issues, just the the mechanics of it, all of how the SEE selection and
vetting works.
DR. PRIMM:
Yeah, of course. We have, I think in every issue, you know, we're looking
over 200 articles from over 30 journals a month, you know, to put together this
continuing education program that is worth 60 CMEs over a year, by the way.
And, you know, we have a list of all these journals that we’ll actually read
through very carefully, try to select the articles that we think are pertinent
to anesthesiology clinical practice or just practice in general for all
physicians. Once those are selected, you know, the editor will send us out and
we'll actually kind of dissect down the articles and try to make questions for
this educational product that people can, you know, read a question, try to
answer it, and then really try to get hooked, you know, in with what we're
asking them. And it's not really trying to figure out if you know the answer or
not. It's more trying to get you to think about this new thing that we think is
interesting in this article that you might be able to take back to your
practice, your institution and change the way you practice. So like we said,
there's two issues a year and it's a great product and it's a great thing to be
involved with.
DR. STRIKER:
And how does this compare to ACE? Somebody out there wanting to do one of
those two programs that the ASA offers with regard to continuing education?
What are the differences between the two?
DR. PRIMM:
ACE I think, is more, you know, reviewing the knowledge that is out there
to keep up to date with your knowledge of the basics of anesthesia and to
review your your knowledge. And know a lot of resident physicians will use it
as part of Board prep. And it's a great way to remember things that you may
have forgotten over over years of clinical practice. You know, the big
difference with the summaries of emerging evidence is that we're really
presenting the cutting edge of science in our field and, you know, we're
getting you to think about the future of the specialty. And so they're kind of
geared toward different audiences and different groups of physicians might feel
they may get more out of one or the other. But I think it's great that the ASA
has two different products that people with varying interests can get into.
DR. STRIKER:
And so how would you say the SEE,I mean, you've been in it for a few
years. How would you say it's evolved over the years since you've been
involved?
DR. PRIMM:
Yeah, I mean, actually, I came into the program as a writer. Never really
had done the questions before. But, you know, it's been really a great personal
journey for me because you really just start at the beginning just trying to
glean the information, trying to understand what's happening, and you really
kind of evolve over time to really be able to understand the concepts, the
methods that they're using, the statistical analysis, you know, what makes for
a quality study or not, and really knowing the things well enough to write
questions that will really be interesting to the reader. And, you know, over
the years, you know, my personal experience, we've really been receptive to,
you know, the reader feedback. The people that are actually doing this online
or doing, you know, the paper version and trying to adjust it to the needs of,
you know, our base of anesthesiologists that love these products. Like I said
before, you know, it's just a great way to stay up to date with all the
information that's coming out because, you know, who has time to really read
all these journals, journal articles and really, you know, get what's pertinent
to your practice from it. Um, and, you know, one of the former editors on the
board had said that, you know, it's probably the best journal club that you
could ever be a part of. And, you know, I tend to I tend to agree with that.
Where else can you really have such an intense dive into all these different
articles from all these different journals about anesthesia? So I think it's
you know, it's been a wonderful experience for me. And I would encourage anyone
else that's interested to to take a look at it.
DR. STRIKER:
That brings up another question. If you're a subspecialist, does SEE cover
all the subspecialties fairly equally. How does that look?
DR. PRIMM:
Well, we you know, we certainly try. But there's there's there's always
people that are saying, oh, you know, there's there's too much pediatrics in
this edition. There's too too much regional anesthesia. There really is a
concerted effort to try to have, you know, a more even distribution of these
topics. We're doing some more ambulatory surgery questions, you know, in these
upcoming issues, things like that. So there really is a concerted effort. So we
really do hear what people are saying out there. And, you know, we hope that
everyone finds something for them.
DR. STRIKER:
And then if you want to be a participant in the program, not just
subscribing to it, but maybe writing questions, get involved like you have.
Where should our members go?
DR. PRIMM:
If you're an active ASA member, you can submit your CV to at see@asahq.org. Dr. Wade Weigel is the editor in chief, and contacting him or anyone at
through that route would be an excellent way to start. And, you know, if you
even just want to take a look at the product itself and see what it has to
offer, you can see it under the education and CME tab on the on the main ASA website
and you can find it there.
DR. STRIKER:
Excellent. Their program software out there to try to aid a physician in
distilling down some of the more pertinent articles or scientific findings out
there that are hard to to collate for one individual. It seems like the ASA is
doing the work for you with this program. It certainly is quite a valuable
resource for all the members.
DR. PRIMM:
Yeah, I'd agree. There's a lot of behind the scenes work and coordination
with the staff and a lot of meetings and a lot of writing, so there really is a
lot of work being put into the product. And you know, I think we, we hope that
people can see the quality that comes through in the writing and and what
people are able to to glean from from the product.
DR. STRIKER:
Wonderful. Well, Dr. Primm, thanks for joining us and not only sharing
some insights about the SEE program, but giving us a look at the current issue
and a kind of a sneak peek at what we can expect.
DR. PRIMM:
It was my pleasure. Thanks so much.
DR. STRIKER:
And for our listeners, if you want to learn more about SC, visit SC at
ww.org/sc. Thanks to all of you for tuning in to this episode of Central Line.
Please tune again next time. Take care.
(SOUNDBITE OF MUSIC)
VOICE OVER:
You can't read everything, so SEE does it for you. Learn what the
specialty is learning on your own time. SEE is available now with insights from
journals around the world. Try a sample question at asahq.org/see.
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