Central Line
Episode Number: 108
Episode Title: Low-Flow Anesthesia
Recorded: August 2023
(SOUNDBITE OF MUSIC)
VOICE OVER:
Welcome to ASA’s Central
Line, the official podcast series of the American Society of Anesthesiologists,
edited by Dr. Adam Striker.
DR. STRIKER:
Welcome to Central Line.
I'm your editor and host, Dr. Adam Striker. Today, I'm joined by two esteemed
anesthesiologists. Dr. Jeffrey Feldman is a professor of clinical
anesthesiology at Children's Hospital of Philadelphia and UPenn's Perelman
School of Medicine. And Dr. David Hovord is assistant
professor of clinical anesthesiology at the University of Michigan. They're
with me today to discuss the topic of low flow anesthesia. And so welcome to
the show, both of you.
Before we get started,
just a quick note for our listeners. This episode is sponsored by GE
Healthcare. I have not been compensated for this discussion, nor have my
guests. And we have independently developed this discussion. But we do
appreciate the sponsorship from GE HealthCare to help make our podcast happen.
With that, I'll start
off the discussion by asking both of you to introduce yourselves just a little
bit and tell our listeners a little about yourselves and describe your
relationship with the companies you work with and and
how that's relevant to our discussion with low flow anesthesia today.
DR. JEFFREY FELDMAN:
So thanks again for the opportunity to participate
this evening. So I've spent time with low flow
anesthesia probably since my training in the 80s, and it stems from having a
background in engineering and training at the University of Florida, where we
had an engineering group. But so over the years it's
been a topic of interest. I've had an opportunity to work with Drager in a role
as a consulting medical director in the past and currently doing some
consulting with GE, but, you know, have written about low flow anesthesia for a
while now. What's nice is that now with the focus on sustainability, there's a
renewed interest in the topic. And so it gives us a
great opportunity to to dig into the details and
really focus on how the technology that we have, the Circle system, which has
been around for many decades, is finally being used to effect, which is to to reduce fresh gas flows and conserve anesthetics.
DR. STRIKER:
Dr. Hovord?
DR. DAVID HOVORD:
I'm also glad to, to be
invited to, to join in with this discussion. And as you mentioned, I work at
the University of Michigan. I'm in charge of our equipment and supplies. And as
part of that, I run our green anesthesia initiative. So
we're super focused right now on figuring out how to reduce the carbon
footprint of the anesthesia agents that we give. And one of the ways that we're
focusing on doing that is with low flow anesthesia.
Now, you might be able
to tell already that I grew up in the UK and actually did
most of my training there, and a couple of years before I left, which was I
came to Michigan about ten years ago, we had this new device called an
End-title Control installed on our anesthesia machines. And when I came to
Michigan, we had the same anesthesia machines but couldn't find the setting
anywhere. And I spent a long time playing with the machines, trying to find it,
and come to find out that End-title Control has only recently been introduced
in the US market by GE because of delays in FDA approval. So
I've worked with GE, I'm doing some consulting work for GE, and we've also
installed End-title Control at the University of Michigan. But I think this
topic, as Jeff says, is really important now as we're
all starting to think about sustainability and the impact of our daily
activities on the planet.
DR. STRIKER:
Let's start with the
basics for our listeners. Dr. Hovord, can you share
what a working definition is of low flow just so everybody is on the same page
with their understanding -- what it is, what it isn't?
DR. HOVORD:
Yeah. So
you know, if you think about the currently available flows on an anesthesia
machine, you can range from 15l, which is most people would consider high flow,
all the way down to a closed system where you're just replacing oxygen
consumption, which could be as low as 150 CCS a minute. And that's a 100 fold difference between the two. So
most people, I think, would probably agree that the definition of low flow sits
somewhere between the two, probably towards the lower end and around one liter
a minute right now would probably be the universally agreed definition. At the
University of Michigan, we would consider low flow or the low flow we aim at
with our technological solutions to be 500 CCS a minute. Previous studies have
put that as ultra low flow. I'm not sure that the tag
really, really helps. I think the key is to learn how to go with lower flows
safely and figure out where that is for for you or
your institution, depending on the technology that you have available to you.
Probably the best kind of low flow is something that's lower than you're doing at the moment. But I think one liter a minute is a good
place to aim at if you're starting this journey.
DR. FELDMAN:
Another little footnote
to. David's discussion of the definition. You know, we were involved in
launching a course on low flow last year through the APSF that's available now
on the website as well. When we thought about the definition of the course, we recognized
that people tend to focus on individual numbers, but the reality is to safely and effectively deliver anesthetics and oxygen, that
number may change at different times in the anesthetic. For example, during
induction, one liter per minute may be too low to achieve a safe and effective
anesthetic. Nonetheless, there is a reduced flow below minute ventilation that
will be more environmentally responsible. And so as
you think about your practice throughout the continuum of induction emergence,
there are different settings for low flow that would be good choices but may
not be a particular number. And learning how to do that is part of the art.
DR. STRIKER:
Do you mind telling us a
little bit about the history of low flow? How far back does this go and how has
it evolved over time, the concept?
DR. FELDMAN:
It's interesting that it
goes back almost 100 years now to the work of Ralph Waters. He was the first to
really didn't introduce CO2 absorption per se, but he built on work that had
been done in the lab to make it a clinical tool for conserving anesthetics. And
so he really built the first rebreathing system, the
to and fro canister around CO2 absorbent, which
allowed him to reduce the amount of flow and anesthetic that he introduced to
achieve a safe anesthetic. And his accomplishments are really
pretty remarkable because he didn't have an oxygen monitor, he didn't
have an anesthetic monitor, yet he was able to accomplish this for thousands of
patients. In the 30s, he published a report of some thousands of patients that
he had done using this technique.
And it is interesting,
too, that the motivation was a little different back then. There were no
scavenging systems, so they wanted to reduce pollution, but it was pollution in
the operating room and exposure to the personnel and the operating room. Fast
forward today, we have scavenging systems, but pollution is still, still a
concern and now it's around the environment. So we've
known how to do this for over a hundred years now and it goes beyond the 17
year cycle you talk about from publication to practice, but fortunately we're
there now with some really nice technology to support the low flow practice.
DR. STRIKER:
Well, Dr. Horvord, Dr. Feldman just mentioned environment. You
mentioned that earlier as well. In addition, what are some other benefits both
to patients and the clinicians as it pertains to low flow anesthesia?
DR. HOVORD:
For patients, simply the
lower the flow you use, the less heat you lose the gas that comes out of the pipeline or the cylinder is cold and dry. So
you lose humidity and you lose heat. So I think they
are the two direct benefits to patients. Clearly moving from 600 or 500 CCS a
minute probably won't have a big difference in those for the patients. But certainly if you're in the maintenance phase, at least
moderately high flows reducing that will certainly have benefits.
One of the questions
that we get asked a lot as we're introducing our green anesthesia program in
Michigan is, you know, we're doing this for patients or the planet, and it's
very difficult to separate the two, really. We’re all products of our
environment. Patients live on the planet and are affected by the environment
that they live in. So there are indirect environmental
benefits to patients, whether that is today or whether it's in 20 years time. Guess who really knows.
In terms of benefits for
the clinician? Low flow anesthesia is—I think this is one of the reasons that
Jeff was kind of alluding to, se've known how to do
this for a long time and why don't we do it? I think it's the first thing to
go. Doing low flow anesthesia is slightly more complex. It requires you to be
more vigilant. It requires you to have a plan to think about what point you're
going to reduce the flows and how you're going to do that in a step wise
process. However, one of the benefits to reducing flows is that you can
probably use more modern, more expensive anesthesia agents as long as it's not
a desflurane. And so I think that's probably the major
benefit to the to the clinicians.
Health systems -- they
are all pushing for environmental targets to be met. And there's a financial
benefit, too, to the health system. If you reduce anesthesia, gas consumption,
it may not seem like a lot in the grand scheme of things, but that does exist.
DR. STRIKER:
Spending just a little
another minute or two on the environment. Dr. Feldman I think everybody
understands that polluting the environment is bad and the more we can minimize
that is good. But is there are there more specifics we need to be aware of as
it pertains to the environment? And also, as Dr. Hovord just mentioned health systems are a little more
engaged. How has that evolved over time? Maybe some specifics about the
advantages for the environment and then the desire for health systems to affect
that impact and how that's changed?
DR. FELDMAN:
So in terms of the impact on the environment, I
mean, we know that the inhaled anesthetics are many orders of magnitudes more
impactful in the atmosphere than carbon dioxide is. One of the arguments
sometimes is that, well, you know, compared to cars and buses and autos, it's a
small fraction. And and certainly there's some truth
to that argument. But when you look at the impact in a health system, that's a
different story. And some significant percentage of the total health system
impact seven, eight, 10%, something like that was just from anesthetics alone. So in the overall scheme of a health system's impact on the
environment, certainly the inhaled anesthetics play a role.
And then clearly the
health systems are are thinking about this. And it is
interesting in this country that it's not an economic driver as much as
recognizing that the health systems have a big impact on the environment and
trying to play a more responsible role.
The other comment I
would make in terms of the individual provider and their role in this is that I
think most people in this country recycle -- cans, paper, things like that on a
regular basis. And if any one of us stopped recycling tomorrow, well, maybe it
wouldn't matter so much in the scheme of the environment. But if all of us
stopped recycling tomorrow, now you're talking about an impact on the
environment. So, you know, I think as we think about our individual role in in
environmental responsibility, you know, it's the collective efforts of large
groups of people over time that really have an impact. And I think that's where
we have an opportunity in anesthesia, you know, that any individual anesthesia
provider, you know, in the course of their career,
they're going to do tens of thousands of anesthetics. And does it matter in any
one anesthetic? Probably not so much. But when you multiply it over their whole
career and then you multiply it by the number of anesthesia professionals, now
you're talking about a substantive impact, not different from the other things
we do to try to protect the environment in our lives as individuals.
DR. STRIKER:
Well, great. Well, have
more questions for both of you. So if you don't mind
staying with me just through a short patient safety break, that'd be great.
(SOUNDBITE OF MUSIC)
DR. SCOTT WATKINS:
Hi, this is Dr. Scott
Watkins with the ASA Patient Safety Editorial Board. Medication errors remain
one of the greatest threats to patient safety in the operating room. Anesthesia
providers often recognize drugs by the size, color or shape of the packaging
and use standard colored labels to designate classes of drugs. For this reason,
look alike, sound alike. Medications are one of the leading contributors to
medication errors in the operating room. Strategies to prevent errors from look alike sound alike drugs include arranging drug trays
so that look alike sound alike. Drugs are separated. Use of color
coded labels with tall man lettering. Use of pre-filled medication
Syringes. Using technology to scan barcodes and or vials. And using generic
rather than brand names. Finally, no discussion of safe medication practice
will be complete without a reminder to always observe the five rights, the
right patient, the right drug, the right dose, the right time
and the right route.
VOICE OVER:
For more information on
patient safety, visit asahq.org/patientsafety22.
DR. STRIKER:
Well, Dr. Feldman, let's
pick up where you left off. You're talking about how low flow anesthesia can
infect not only the environment as a whole, but how
the individual practitioners can contribute to that difference. Because I do
want to ask about patient safety. And I think that when we discuss a lot of
changes in practice as it pertains to anesthesiology, patient safety always
comes first. We would all agree with that. But I also feel that's kind of that
last hurdle that oftentimes people can't get over when it comes to their
individual practice, when it comes to practice change. And many times for good reason. Anesthesiologists are they're very
good at individual patient safety issues. And I think it's a it's an important topic as
we discuss these kinds of changes from what we're all used to and specifically
low flow anesthesia. So what are the safety concerns
and what strategies should our listeners be aware of?
DR. FELDMAN:
Yeah. So
it's a great question and it's certainly a paramount consideration. It's one of
the reasons that the low flow course came out of the Patient Safety Foundation
because we wanted to play a role in promoting that practice, but at the same
time ensuring that it's done in a safe fashion. And so, you know, what are
those safety barriers? So people are concerned about
inadequate oxygen supply to the patients, obviously a major safety concern.
People are concerned about inadequate anesthetic levels, which certainly a
major safety concern. You don't want to have a patient be aware or inadequately
anesthetized. And then another barrier relates to the Sevoflurane packaging.
And we can talk about that in a few moments if you like. But with regards to
oxygen and anesthetic concentrations, the wonderful thing now is that it's pretty standard on anesthesia delivery systems to have an
oxygen monitor. That's been true for decades. And an anesthetic concentration
monitor is also pretty much routine now. So you have
the ability to now practice in a more refined fashion, if you will, or
certainly more environmentally responsible fashion and use those monitors to
help guide your practice. So they're not just
threshold monitors to make sure you're not below a certain safe threshold, but
they're actually your friends or your partners in practicing low flow
anesthesia safely and effectively. And, you know, as we've emphasized
repeatedly in the course that we put together, you never want to put any
patient lower flows where you're all at all uncomfortable doing so from a
safety consideration. By the same token, once you learn the techniques and you
learn how to use the bedside monitors, it becomes really a pretty
comfortable practice and a very satisfying practice and also ultimately
a very safe practice.
DR. STRIKER:
Well, let's go ahead and
let's take the opportunity now to talk about the Sevoflurane issue. I'm not
sure all our listeners are familiar, but let's delve into it for a minute or
two.
DR. FELDMAN:
So Sevoflurane, if you look at the package insert,
the FDA required labeling, which was last updated in 2002 or 2003. It has a
minimum fresh gas flow recommendation for sevoflurane. And the specific
language is not less than one liter per minute for up to two mach hours and otherwise not less than two liters per
minute. And my impression in talking to even a lot of the residents that rotate
through where we are is that many practitioners really try to stick to that two
liter per minute lower threshold when they're using sevoflurane, which is, you
know, it's a reduced flow, but certainly not as low as you could get to be a
little bit more environmentally conscious or effective with your flows. So this package insert becomes a barrier, but in fact it's
really a medically obsolete recommendation. It goes back to compound A, which
is produced when sevoflurane interacts with carbon dioxide absorbents. And so the FDA requirement was to try to protect patients from
exposure to compound A. It turns out that Compound A is not indeed toxic in
humans, even though there was some renal toxicity in animals. And furthermore,
we've learned what carbon dioxide absorbent formulations produce Compound A and
many that are commonly and routinely used have limited the amount of strong
base and will not produce compound A. So not only don't you have to worry about
it as a toxic item in your patients, but if you're using many of the modern
absorbents which are commonly used, it's not even produced
and you can really use any flow that you want very safely with sevofluorane. And that's indeed the recommendation from the
APSF is that there isn't a lower limit of safe flow for sevoflurane use to any
more today.
DR. STRIKER:
Well, do you think the
adoption of the newer CO2 absorbents was one of the key factors in perhaps
adopting low flow anesthesia on a larger scale as we're seeing it more now?
DR. FELDMAN:
I don't know if it was
an important factor. Certainly if you look at the
marketing of a lot of those absorbents, they are marketed as low flow absorbents
or reduced flow absorbents. You know, that's often in the language, in the
marketing language. And so it recognizes that change
in formulation. And I do think it's, it is a way to help people become
comfortable using low flows once they understand that it's not going to produce
compound A, they're using that particular absorbent, It
removes another barrier and helps increase that comfort level. If you look at
the definition of low flow anesthesia that we put together for the course,
provider comfort is an element of that definition. So
we really never want people to operate at flows lower than than
they're comfortable with.
DR. STRIKER:
Well, Dr. Hovord, the hospitals and clinicians know they have a flow
rate issue. How do you monitor and quantify this problem within your own
organization or your health system?
DR. HOVORD:
That’s a really good question. I mean, no one comes into work
thinking, you know, I'm gonna, I'm gonna I'm going to use all the flows today, You know, I'm gonna see how high I
can push it. And think that probably most individual clinicians, you know,
don't think that they have a flow rate issue. But think when you look at the
data and think this comes to the second part of your question about how you
figure this this out really think you have to get the
data. And what we've done at the University of Michigan is create a whole
series of dashboards. And it's specific to to
anesthesia flow. And we've divided that into flows during induction and flows
during the maintenance phase. Just to reiterate, you know, the point that Jeff
made earlier about low flow, depending on the phase you're in. And we do focus
a lot on flow during the maintenance phase. That's the time that we spend the
longest time in. But actually, if you start your anesthesia off by pre
oxygenating at 15l a minute and then you leave it up there for ten, 20 minutes
afterwards with a sevofluorine at 2 to 3%, it will it will make going low flows in maintenance phase
largely pointless. So I think that's one of the things
that we've impressed on clinicians is that is to look at the manufacturer
guidelines for the correct flow for Preoxygenation and the machines that we
have at the University of Michigan, it's eight liters a minute. So we've done small things to try and help providers do the
right thing by making sure that the machines turn on to eight liters a minute,
which is exactly where they should be to achieve decent preoxygenation. And
then what we do is we collect data on flow rates during these various phases
and we email monthly feedback to clinicians along with a whole bunch of quality
indicators. And we do that via the mpog
collaborative, which is a data collection club which collects data from
hospitals and provides dashboards on on a whole range
of quality indicators and low flow anesthesia and environmentally friendly
anesthesia is one of them. For the maintenance phase. What we've done is we've
introduced End-tidal Control software, which is I think only available with GE
in the US at the moment. There are other manufacturers
in other countries which have similar technology and software. But what that
does is allow the clinician to set the desired end tidal agent and end tidal
oxygen concentration. And the machine then achieves that with the lowest
possible flow rate that it can. And you can set the default minimum flow rate
that you like. And at the end we set that at 500 cc's a minute. We're also
encouraging providers to use sevoflurane, just to echo Jeff's point about there
being no lower limit with Sevoflurane, and we consider that to be a safe
practice. And I think it is a shame that this compound A story has persisted
for so long because I think it really has limited the adoption of Sevoflurane
and Sevo is the most environmentally friendly
anesthesia agent in terms of its CO2 emissions, but also the fact that it
doesn't have any impact on the ozone layer, unlike Isoflurane, which because it
has a chlorine atom in it, interacts with ozone and contributes to the hole in
the ozone layer and the breakdown of ozone. So I think
there's two reasons really there to for us to think about sevoflurane and be
confident that we can use it at low flows.
One thing I think that
is important to note and again to echo Jeff, we don't encourage providers to go
to 500 cc's a minute if they don't have the End-tidal control software on their
anesthesia machine. Not all of the machines have it
yet. We're still in the process of rolling it out and provider comfort is is really important and especially
the educational level of the provider. So if you've
got a new resident, it's not an additional stressor that you really want to put
on a very junior resident at that point. So it's very
important that safety does come first and that providers do what they're
comfortable doing. And one of the ways in which you can become more comfortable
with low flow anesthesia is to learn more about it.
DR. STRIKER:
What do you think the
current behavior is stemming from when it comes to using higher flows
routinely? Is it just that current anesthesiologists learn that in their
training and haven't been able to break the habit? Or is it this this worry
because they don't maybe know all the details and they don't want to worry
about it, so they're just going to so they don't have
to think about it, use higher flows. I'm just curious to hear what you both
think about why as that behavior persists of using more flow than is necessary,
why that is.
DR. HOVORD:
Yeah, I mean, it's a
good question and I think it comes to the root of why what what
our motivations are to do anything really. I think they're probably the direct
issue is that the majority of patients, when you wake
them up, whether they've had a low flow anesthetic or a medium or a moderate or
a high flow anesthetic, they kind of look the same. And, you know, the patients
don't wake up any better if they've had a low flow anesthetic. I mean that's a
sweeping generalization. But I think there's a perceived lack of benefit to the
patient. And, you know, there are two concrete benefits that we can pin down
quite comfortably in terms of humidity and heating and then this massive
indirect benefit to the environment. But I think providers see it as adding
complexity to their anesthetic. I think it's probably the first thing that goes
when providers are worrying about one aspect of an anesthesia being complex or
having a particularly complex series of patients, and there's an education gap
as well. And like all of these things, I think one of
the other similar kind of fields would be with training for monitoring or
neuromuscular monitoring under anesthesia. Everyone kind of knows it's
important. We sort of know how to do it. But doing it every day requires habit
forming and it requires reinforcement and it requires
a lot of education to the providers that you're working with daily and with the
lack of perceived immediate benefit to the patient. I think that's one of the
barriers, the barriers that we're trying to overcome.
DR. STRIKER:
Dr. Feldman, what about
you?
DR. FELDMAN:
Yeah, I think, you know,
David makes a lot of great points. And just to add a couple of other
considerations. So there's a great quote in a book by
Ernst and Lowe on closed circuit anesthesia. It's kind of the Bible of closed circuit anesthesia. But in that book, they say
something to the effect that if every anesthesia provider had to pay for
anesthetic agents out of their own pocket, they would all use closed circuit
anesthesia. And and indeed, there are practices where
providers do pay for their own anesthetics. And in point of
fact, some of those places I've talked to use quite low flows as a as a
result. So, so they, they have a personal motivation, but that's not typical in
most practices. And I think, you know, part of it just comes down to people
become or we all become victims of our training in a sense. And when you're
using high flows, it is much easier to manage concentrations in the circuit. So if you think about it, there's really three
concentrations of, say, anesthetic or oxygen in the circuit. There's what's
delivered in the fresh gas flow, there's what the patient inspires, and there's
what the patient expires. When your fresh gas flow is at minimum minute
ventilation or above, that is there's no rebreathing, then you're delivered and you're inspired concentrations are the same. So what you dial on the vaporizer or what you dial in the
flow meters is going to be reflected in the inspiratory limb in the circuit. As
soon as you reduce your flows below minute ventilation, now there will be a
difference between your delivered and your inspired that you then have to manage. And it becomes pretty
intuitive after a while. But it it's not quite as straightforward as as using those high flows and I think that may be a factor
as well.
DR. STRIKER:
Yeah, certainly it makes
perfect sense. You know, the other question I wanted to ask you both before we
wrap up is you're both well versed in this topic. How do you both perceive the
future of volatile anesthetics in the field of anesthesiology?
DR. HOVORD:
Future volatile
anesthetics: we've at the University of Michigan have taken no position on the
environmental benefits of volatile anesthesia versus Tiva.
Total intravenous anesthesia certainly has environmental benefits in that it
doesn't produce any direct, you know, CO2 emitting gases. I mean, it's very
difficult to tease out, to be honest. What is the environmental cost of
manufacturing, transporting, disposing of Propofol. But I think it's pretty clear that it probably is an order of magnitude
better than doing the same for most of anesthesia gases. I don't think, though,
that we can just ask clinicians to wholesale move to Teva. I think that
volatile anesthesia is going to have a significant place in anesthesia practice
going forward. It has for a long time, but I do think it's incumbent on us to
use the least harmful version of it. And at Michigan, that is going to be
sevoflurane with End-title control, with education around the maintenance phase
and reducing the usage of that entirely. And I think that's probably going to
be the future across the board really. I think that continuing to use the most
polluting agents like Desflurane and nitrous oxide, I think that's going to be
very difficult going forward. I think Scotland just made Desflurane illegal,
which seems seems like a big step, but I suspect that
no one in the UK is really using desflurane much anymore anyway. Which is why
they took that step. I think tevos
going to play a bigger role going forward. But I think that we will still see
significant usage of anaesthesia going forward in the
future.
DR. STRIKER:
Dr. Feldman, you have
anything to add to that?
DR. FELDMAN:
Yeah, I guess just a
couple of quick thoughts. I mean, I certainly agree with David that both
inhaled and intravenous anesthetics are going to be around for a while. I
practiced pediatric anesthesia and, you know, inhalation anesthesia is
certainly very embedded in pediatric practice for the foreseeable future. And I
think the relative environmental impact of both of those techniques I think is
still arguable. You know, there's this notion out there that maybe Teva is
environmentally better, but when you look at the total life cycle of both, I
think it's unclear. You know, the pharmaceutical agents are in our drinking
water. What's the impact of that? You know, I just don't think we know. And
ultimately, I think we want to be comparing a very effective, environmentally
responsible practice using each of those agents to one another to see if if there really is a difference or not. And I'm not sure
there is if we're if we're really practicing as responsibly and effectively as
we can with each of them. And we're not doing that across the board yet.
DR. STRIKER:
You know, this brings me
to one other question. I don't use desflurane because, like you, Dr. Feldman, I
do pediatric anesthesia and I just don't end up using desflurane much ever. But
I am curious because I know it's because of the greenhouse gas potential, it
has really fallen out of favor. It's an expensive drug. One question I've
always had about the decrease in usage of Des is: we only have three currently
used volatile agents right now. What are your thoughts on taking that that one
tool away when we have such minimal amounts? And I'm not trying to defend Des
in any way, but I am just curious to hear your thoughts on eliminating one
volatile agent from our armamentarium. And I imagine there's probably
anesthesiologists out there that that feel this way. So
I think it's worthwhile to ask the question. Let's start with Dr. Hovord again.
DR. HOVORD:
Yeah. So, you know, I
was pretty much responsible along with our leadership team, for removing
Desflurane from the formerly at the University of Michigan. So just so you know
where I stand. I don't think you can really justify the use of it as a
curiosity. I don't think there's any place for it in widespread practice. I
don't think it adds any particular benefits that you
can't get from Sevoflurane. It's expensive. It's highly polluting. I think we
calculated that if you run one desflurane OR you can run 30 ORs on sevoflurane
at the same flow rate for the same CO2 emissions, You
just can't you just can't justify its use. Am I sad to see it go? Yeah. And you
know, this is the flip side of this. In 2012, I was made the liaison, or 2014,
I think the liaison to Bariatrics at U of M, and the guideline that I proudly
kind of wrote included the use of Desflurane because it was such a great drug
for those patients and that surgery. So yeah, I do have a, you know, a tinge of
sadness to see it go. But I think it's it's had its
day and I kind of feel the same way about nitrous oxide as well, in that
although they are there are definitely areas of use,
and pediatrics is one of them, where nitrous oxide is still going to be used
for a long time yet, that we need to certainly work towards eliminating the
infrastructure that leaks so badly. So the nitrous
oxide pipelines that leak about 90% of what you put into them. And I think if
we can do those few things, then we can make a massive impact on the CO2
emissions that we are responsible for in our daily lives. And, you know, people
ask, does that make any difference? Well, it's just what we have control of as
anesthesia providers and clinicians. You know, we do this every day. It's
something that's in our power to change. So why not change it?
DR. STRIKER:
Dr. Feldman?
DR. FELDMAN:
I agree 100% with David
on on Desflurane and nitrous oxide. Both. You know,
desflurane I haven't personally used in many years. We took the vaporizers off
our machines at my facility about 5 or 6 years ago, left a couple in the work
room and no one ever came to get them. So, so it's disappeared from our practice and we certainly don't miss it. Um, and then
nitrous oxide is another interesting one. We've, you know, it's a pediatric
hospital, large number of pediatric cases. We started a QI project to minimize,
if not eliminate, nitrous oxide use in our practice.
And over the last two years, we went from over 80% use of nitrous oxide during
inhaled inductions to closer to 10% now. And I personally don't haven't used it
during inhalation inductions for several years now. And I think given the properties
of Sevoflurane, nitrous oxide adds little to nothing. That's a little bit of a personal opinion. It needs to be documented by some some research. But certainly
that's been our experience at my institution that we can get by without it.
DR. STRIKER:
Well, before we go, Dr.
Feldman, do you want to just let our listeners know where, if they want to
learn more about this topic or change their practice, where is a good resource
that they can go to?
DR. FELDMAN:
Yeah. Thank you. I would I would really love to provide that direction. So,
you know, I chair the Committee on Technology for the Patient Safety
Foundation, and we launched a course it'll be a year ago in October. We
launched it at the last ASA on low flow. And there's a landing page on the APSF
website that contains a link to the course as well as supplemental information.
That's apsf.org/lfa. Low flow anesthesia. The course
is hosted on the ASA Learning Management System. It's available to any
anesthesia professional that wants to take it free of charge. It generates CME
and MoCA safety credits for physicians and similar credits for CRNAs. The
reality is it's a difficult topic to teach in a few words. The course uses
guided simulation, so it's a different approach than reading a textbook. It's interactive.
There's eight modules. Each one is designed to be
about a 15 minute interaction, so you can go into one,
come back to another one at some other time, go back and refresh yourself. You
know, we try to make it a pretty comfortable learning
environment. And, you know, thankfully we've had now over 400 people complete
the course since last October. So I think we're having
some impact with it. And I do think it's an effective way to learn and we
provided a lot of resources associated with that course. So
I would encourage everyone to take a look at it.
DR. STRIKER:
Great. Well, thank you
both, Dr. Hovorrd, Feldman, for joining us for this
fascinating conversation.
DR. HOVORD:
Thanks, Adam.
DR. FELDMAN:
Thanks, Adam. Really appreciate
it.
DR. STRIKER:
Oh, yeah. My pleasure.
And to our listeners, thanks for joining us on this episode of Central Line. If
you like the podcast, if you find it interesting, if you feel like you learned
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