my name is Max Feinstein and I'm an anesthesia resident at the Mount Sinai Hospital in New York
City. in this video we are diving into the wild world of glaucomflecken to understand whether or
not there actually exists an on/off switch for anesthesia, and why the description for this
video that's been viewed 22 million times is "nobody really knows what goes on back there"
if you find this video interesting or helpful I'd really appreciate it
if you liked it and subscribe to the channel. let's dive In
before we get started I do have to make the obligatory disclaimer that this video is not
medical advice. it's a YouTube video. so if you need medical advice, talk to your doctor.
if you're not one of the people who's contributed to the 22 million views
that this video has received, let's go ahead and watch it.
it's real quick and I'll get you up to speed on what we're talking about
hey Doc let me know when you got about 20 minutes left
okay yeah yeah no problem
and we are done. anesthesia you can wake the patient up now
is there a problem?
so you can't blame a surgeon for being focused on what they're doing,
but a little bit of a heads up would have been nice
what is it you think we do back here?
well you...
do you think we have a giant anesthesia
on/off switch that allows the patient to wake up instantly?
no..
so this actually speaks to why I made this YouTube channel to begin with,
because even among physicians there's not really
a great understanding of what exactly anesthesiologists do behind the curtain
no.
okay take your time
thank you
we're done?
yeah so I mean of course we do have a literal button that we use to turn off the anesthesia
(or a dial depending on what anesthetic we're delivering) and the effect that we're going
for is basically that a patient wakes up and is ready to go back to the recovery
room as soon as the last suture is thrown. but the reality is a lot more complicated
in terms of dosing the anesthetics and timing it for the end of surgery.
to address the question of what anesthesiologists actually do, the number one priority, no matter
what, is always keeping a patient safe while the procedure is going on. the second priority,
in my opinion, is keeping a patient comfortable. and then another priority that falls somewhere
after keeping a patient safe and comfortable is efficiently inducing anesthesia and emerging
a patient from anesthesia in a way that's not going to delay the operating schedule
efficiency is essentially the crux behind Glaucomflecken's video about the anesthesia
on/off switch. one of the big challenges for anesthesiologists is that safety and comfort don't
necessarily go hand-in-hand with efficiency. for example, general anesthesia is required for many
different types of surgeries and that involves a pretty significant depth of anesthesia and can
often involve administering paralytics that reduce the amount of movement that a patient will make
during surgery. the medications that are commonly used to provide general anesthesia have a tendency
to accumulate in the body, and the longer that that medication is given, well the more that tends
to accumulate. this concept is called a "context sensitive half time" where context is the amount
of time that an infusion or a medication has been administered, and half time is the amount of time
that it takes for the concentration of that medication to reduce in the blood by one half.
from a practical, clinical perspective, the sort of rule of thumb that I've heard is that
for every hour that a propofol infusion is run, for example, it takes 10 minutes for that to
wear off. in this example by Glaucomflecken, a two hour long surgery where propofol was
used as the maintenance anesthetic agent might take about 20 minutes to wear off,
so you can see why a 20 minute heads up is actually extremely accurate. so job
well done Glaucomflecken. the various volatile anesthetic gases like isoflurane, sevoflurane,
and desflurane all accumulate to different extents in a patient's body during surgery, and therefore
take a varying amount of time in order for a patient to be rendered conscious again after
the anesthesia has been turned off. for example desflurane leaves a patient's body quite quickly
and can lead to a pretty quick emergence, but there are also downsides that come along to the
specific anesthetic agent, for example harm to the environment, much more so than say sevoflurane.
generally speaking there's nothing that we do in medicine that doesn't come without some downside,
so picking out one anesthetic agent over another for the sake of efficiency may
mean a trade-off in terms of something else like cost, or safety, or damage to the environment.
in addition to giving a patient an appropriate anesthetic depth, the anesthesiologist is also
responsible for making sure that a patient's pain is well controlled, and that's very
commonly done using an opioid like fentanyl or hydromorphone. but it's important to keep in
mind that the administration of medications like opioids can serve to reduce a patient's level of
consciousness, and that's especially true when combined with other agents like propofol or one
of the anesthetic gases. that's something that can lead to an increased amount of time for a
patient to emerge from anesthesia. so on the one hand, an anesthesiologist could go very light on
the opioids and lead to a very quick emergence, but then it's pretty likely that a patient would
wake up pretty uncomfortable. on the other hand, an anesthesiologist could give a lot of opioids
and the patient would wake up comfortably, but it would just be a really extended wake-up period.
on top of all of this, another complicating factor is the use of paralytics like rocuronium
or vecuronium, which have a tendency to last for a while and are necessary for many different types
of surgeries so that the surgical field can be still for the surgeon to operate. while there
is a very rapid acting reversal agent called sugammadex that can be used for some of the
neuromuscular blocking drugs, that also doesn't come without its risks including a very small
percentage of people who develop anaphylaxis to it, as well as the possibility for sugammadex
to render hormonal birth control unreliable for up to a week. and at least at the present time,
it's a pretty expensive drug, clocking in somewhere around $100-200 per dose to be able
to reverse a patient's neuromuscular blockade. the alternative reversal regimen that has been
used for many years is neostigmine combined with glycopyrrolate, which can counteract
some of the side effects of neostigmine. this is less expensive but does take a while, like
10 or 15 minutes, in order to achieve its maximal effect. just another reason why having a bit of a
heads up before the end of surgery is going to be an important way to make sure that neuromuscular
blocking drugs have been reversed and a patient is breathing appropriately before they're emerged
from anesthesia. taken all together you can see that an anesthesiologist has to keep a patient
safe comfortable, and then make sure that they can efficiently go from a state where
a patient is under general anesthesia, not aware of anything, not feeling any pain, and not moving,
to a state where they are awake, breathing on their own, alert, and ready to leave the operating
room right after the last suture has been thrown and the surgeon says that the surgery is all over.
this is made all the more complicated by the fact that every patient is unique,
and differences like age, medical comorbidities, type of surgery,
duration of surgery, and genetics, just to name a few characteristics, are all going to change
the amount of time that it takes for a patient to emerge from anesthesia. so just because an
anesthetic plan worked with perfect timing for one patient doesn't mean that it's necessarily
going to work for the next patient, even if they're very similar in a lot of ways.
with all that in mind, we can circle back to the question of how exactly do we turn off
the anesthesia and make it seem like it's just a switch going off? it's really an illusion that can
be accomplished a number of different ways, and I'll share several examples. one is simply having
an awareness of how long it's going to be until the end of surgery, and using your own experience
to take an educated guess for how long it's going to take for a patient to emerge from anesthesia. I
think it's reasonable in a lot of cases to, say, turn off a propofol infusion maybe 20 minutes
before a surgery ends if the surgery has been two hours long, and assuming that a patient has
an appropriate amount of analgesics like opioids on-board. this requires an excruciatingly high
amount of vigilance to make sure that the patient shows no signs of being too light with anesthesia,
and if they do appear to be coming light with their anesthesia as the last sutures are thrown,
then the anesthesiologist needs to administer more medication, for example a small bolus of propofol.
another technique that I commonly use for very long surgeries is to turn off
the primary maintenance agent, which is the anesthetic that I've used to keep the patient
under general anesthesia, for the duration of surgery, and turn that off about an hour or so
prior to the expected end of the surgical procedure. and then importantly replace
that with a different maintenance agent. recall the concept of context sensitive
half-life where a medication is going to take longer to have half of its plasma
concentration depending on how much time it's been administered for. so if I have a medication,
for example isoflurane that I've been administering to a patient for 10 hours,
and I expect it might take an hour for that medication to wear off, then I'll turn the
medication off an hour before the anticipated end of surgery, and then start, for example,
a propofol infusion. if the propofol infusion is only running for an hour, that may take 10
minutes or less to wear off so than I can expect to be able to really finely dial in how much
time it takes to emerge a patient, even if the surgery was very long like a total of 11 hours.
as a senior resident reflecting back on the earlier portion of my anesthesia training,
I recall having thought that the sign of a high quality anesthesiologist
was someone who could induce anesthesia very quickly and get through procedures
like intubation and IV placement very quickly. and while that may be true,
I've developed an even greater appreciation for anesthesiologists who can very quickly emerge a
patient from anesthesia, particularly if it's been a very long surgery,
and also making sure that a patient emerges very comfortably and in a very safe manner.
if you enjoyed this video, check out this video I made where I go
through some of the commonly used medications to deliver a general
anesthetic. thanks very much for watching. I'll see you next time
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