what's up everybody my name is max feinstein and i'm an anesthesia resident at mount sinai
hospital in new york city in this video i'm going to be talking about the basic monitoring
equipment that's used in anesthesiology. if you find this video interesting or helpful
i'd really appreciate it if you liked it and subscribed to the channel. let's dive in!
it's pretty much impossible for me to overstate the importance of monitors, and even the most
basic monitors are going to provide vital information about a patient where any sort
of abnormality - for example high blood pressure, low blood pressure, any sort of changes on EKG,
changes on pulse oximetry reading - any sorts of abnormalities here could be indicative of,
in some situations, life-threatening issues that are going on with a patient during surgery
that need urgent or emergent attention. so even though this video is about basic monitors don't
let that fool you because everything that i'm about to show you here is extremely important
to the anesthesiologist. and bear in mind that when a surgery is going on the only person
who is watching all of these vital signs at all times - you guessed it - anesthesia.
one of the main reasons that i wanted to make this video is to give some insight into what's actually
going through an anesthesiologist's mind during surgery. and from the surgeon's perspective it can
often seem like maybe the anesthesiologist is just over there staring blankly at the computer screen,
they might be planning their next exotic vacation to some foreign, strange place like
florida or something. but in reality what's going through the anesthesiologist's mind
is they are trying to assimilate all of the data that is continuously coming at them
while also trying to take care of the patient, draw up medications, administer medications,
understand what's going on in the surgical field, be able to respond to any sort of changes.
for example if there's a major bleed that happens unexpectedly and they need to be able to respond
to that while also paying attention to what's going on with the patient's vital signs. so let
me show you all the basic monitoring equipment that i use on a daily basis for pretty much
every one of my cases, and i'll show you how that equipment displays information that is
read continuously by me during any procedure and is displayed on this screen right behind me.
starting at the very top of the screen is an ECG which stands for electrocardiogram. an
electrocardiogram is a device that allows me to see the electrical activity of the heart. this
is extremely important to me as an anesthesia resident because that allows me to understand
whether there are any sorts of pathologies that are going on with the heart during surgery. now
surgery can be an extremely stressful process on the body which can increase the demand on
the heart and increase oxygen consumption in the heart. if there's not enough oxygen supply, and
consumption outweighs the supply to the heart - which is of course a muscle - then that can
lead to electrical conduction abnormalities, that can lead to parts of the heart not getting
as much oxygen as it needs to, and then it stops working as well as it needs to which in the worst
case scenario can lead to an intraoperative myocardial infarction which is of course an
emergency. so if i can detect any differences on the electrocardiogram and anticipate any sort of
problems that are happening during surgery i can hopefully be able to prevent some sort of major
intraoperative event like myocardial infarction. so this is what a five lead EKG looks like,
and as you can see each one of these leads is labeled, here for example LL stands for left leg,
LA stands for left arm and so forth. so i'm gonna go ahead and connect these EKG leads to myself.
also just a quick tip: one of my favorite mnemonics is to help set up EKG leads, and to
remember which colors go in what orientation, so the mnemonic is "smoke over fire" which refers to
the black EKG lead over the red EKG lead on the left side and also "snow over grass"
which is the white EKG lead on the right side going over the green EKG on the right side
so what you can see on the screen here, in addition to my resting heart rate being
concerningly high and/or me just being nervous filming this right now, is that i only have
two leads that are pulled up. and the reason for that is the two leads, which are leads II and V5,
these are the most sensitive leads for detecting any sort of ischemic changes that are going on
in the heart. now if i want to pull up all five leads i can go ahead and do that, but
under ordinary circumstances during surgery these are the only two leads that i've got pulled up.
the next monitor i want to show you is pulse oximetry which essentially refers to how much
oxygen is being carried in a patient's blood. there are a lot of different
types of pulse oximeters, which are devices that measure oxygen saturation,
and the one that i've got here today is a sticker that looks just like this
and the sticker will get put on a patient's finger typically, but there are devices that are made to
go on a patient's ear or nostril or toe or any area where there is blood that's going through,
and my machine is going to be able to capture oxygen saturation. in order to get this device
connected, all i do is peel off the back end. and i like to place this device on my patient's ring
finger typically. that helps me avoid putting in an area that could be dangerous for the patient,
namely putting it on their index finger because for whatever reason, oftentimes when patients
wake up from surgery they have this desire to start rubbing their eyes and they'll typically
do it with their index finger or maybe their middle finger, and if they're not fully aware of
what's going on and they start rubbing their eyes they can have a corneal abrasion. so in order to
avoid that typically stick with the ring finger if i can. let's go ahead and get this connected
so as you'll notice this device actually makes sound, and there are two components of the sound
that i'm listening for. both of them are extremely important for me as i'm taking care of a patient.
one is how frequently that tone is going which gives me a patient's heart rate,
and the other is the pitch of that tone so if a patient's oxygen saturation starts to go down then
the pitch of this tone also starts to go down. and the reason why this is so vital for me is because
it allows me to look away from the monitor, start taking care of other aspects of patient care,
and still have an understanding of what's going on with the patient without having to
look at the monitors. i just want to point out several important aspects of pulse oximetry:
one being that this monitor actually gives me an indication of how good of a signal quality i have,
which can be decreased by any sorts of illness like peripheral vascular
disease or even if a patient's just really cold, it can be difficult for the monitor
to pick up a good quality signal. and so that signal is indicated here on the monitor
with either zero, one, two, or three stars that are next to the pulse oximeter
and the other thing worth pointing out is that the pulse oximeter and the electrocardiogram
actually pick up separate readings of a patient's heart rate. now they should be very concordant,
but in some situations you get interference with one monitor or another, for example
surgeons use devices like electrocautery that interfere with the electrical signals of the ECG
which can cause that to not read. so if i'm unable to get a heart rate picked up on my
electrocardiogram, then at least hopefully i'll be able to get that on pulse oximetry.
next up is capnography which refers to carbon dioxide, and specifically how much
carbon dioxide is being exhaled by a patient. this is also referred to as ventilation. so
the amount of carbon dioxide that's being exhaled is an excellent marker for how much carbon dioxide
is in a patient's blood, which in and of itself is an extremely important factor that plays into
things like a patient's acid-base status which can affect cardiac function. it can affect brain
function, kidneys and so forth. so for me to be able to monitor capnography is extremely
important. and it's also important because a lot of the interventions that i can do,
including making adjustments to my ventilator or administering different types of medications,
can have important effects on capnography, so it's something that i want to keep track of throughout
the duration of surgery. measuring capnography is extremely straightforward. essentially you just
need any sort of device that is going to get from wherever a patient's breathing into the machine
here, which has a monitor that can detect co2. now when a patient's under general anesthesia,
i have a device that i can connect directly to the endotracheal tube that will pick up the amount of
carbon dioxide being exhaled, but because for this video i didn't particularly feel like intubating
myself, i'm going to use a non-invasive capnography device which is essentially
this special nasal cannula which has, in addition to an oxygen port here,
a connection that specifically measures capnography and hooks up to the machine just like
this
and as you can see on our monitor here, this measures the waveform of how much carbon dioxide
i'm exhaling. it's a little bit difficult to get a clear picture of as i'm talking because
this is only measuring what's coming out of my nose, so if i just stop talking for a second
you'll be able to see exactly what my capnography looks like
in addition to reflecting pulmonary function and showing
evidence of diseases like COPD or asthma, capnography can also be really important for
understanding how much cardiac output there is because there tends to be a direct relationship
between cardiac output and capnography. so if i have a decrease in cardiac output
i would expect to see a decrease in capnography, so that's something that i need to be attuned to
as i'm taking care of the patient and looking at their capnography during surgery.
next is blood pressure monitoring, and categorically speaking there are two different
ways that we can go about it- one is non-invasive blood pressure monitoring which is probably what
you're used to, which involves a blood pressure cuff being put around an extremity and then being
able to pick up on pulsations of an artery as that artery is being squeezed and then let go,
and then the machine is able to determine what the blood pressure is based on how those pulsations
occur. the other category of blood pressure monitoring is invasive blood pressure monitoring
which essentially entails taking a device and literally putting it inside of a patient's artery
and then transducing pulsations from that artery to be interpreted by the machine to tell me what
their blood pressure is. my decision to use either non-invasive or invasive blood pressure monitoring
is really going to be dependent on a number of factors including how sick is the patient, because
if the patient is very sick, for example they have a lot of cardiac pathology and i'm concerned that
there might be major changes in blood pressure as i'm inducing anesthesia or as the surgery is going
on, then i'll want to know on a second-by-second basis what their blood pressure looks like,
but if i'm working with a pretty healthy patient and they're coming in for an elective surgery
then non-invasive blood pressure monitoring is fine and i can get a blood pressure reading
once every three minutes typically, or i can space that out to as much as once every five
minutes if it's really a minor procedure and the person is pretty healthy to begin with
for the sake of me not having to cannulate my own radial artery and also you know being
able to keep my job i'm going to show you what non-invasive blood pressure monitoring looks
like which is essentially what you're used to seeing at a doctor's office
this is an example of a blood pressure cuff. they come in all different sizes so i can take
care of patients of all different sizes and this can go either on the arms or it can go on the
legs so as long as there's an artery underneath this should be able to pick up pulsations from
that artery and then come up with a blood pressure reading so it looks just like this
now that i've got this connected i'll go ahead and take a blood pressure reading and as you can
see here i'm able to set this machine so that it actually cycles at whatever frequency i'd
like it to, and then one of the other important points that i want to indicate here is that i
can actually set the volume for when this has completed cycling. and so again this is one of
those things that you have to think about when you're in the operating room-- you get busy,
you're taking care of a patient, administering drugs - and the blood pressure cuff has finished
cycling. i want to make sure that i'm notified about it so i need to make sure that this alarm is
loud enough to cause me to turn my head and look at my monitor once a blood pressure has finished
cycling. when you're placing a blood pressure cuff it's important to bear in mind that if you're
putting the cuff on the same side as the pulse oximeter, as i've done in this case, then every
time the cuff inflates it's going to decrease blood flow to the pulse oximeter which can either
make it appear as if the patient is desaturating, or the pulse oximeter might just stop picking up a
reading altogether. this is one of those classic setups for the joke on the med student where the
resident knows that the pulse oximeter and the blood pressure cuff are on the same side and
as soon as the blood pressure cuff starts going off and the patient appears to be desaturating,
the resident will go "oh my god is everything okay?!" and the med stone will be like "oh my
god the patient's desaturating!" and the resident will be like "gotcha! same side pulse ox and blood
pressure cuff" i wouldn't actually do that to a medical student but it is worth pointing out.
last but certainly not least is connecting a thermometer to a
patient. and the thermometer not only tells us that we've made the operating room very cold,
but also gives us a sense of what a patient's core body temperature is which can influence a number
of really important physiologic factors like metabolic processes that occur in the blood. and
it's also important to have an eye on the temperature in case the patient's having an
adverse reaction to medication. there could be an anaphylactic reaction that may be manifest as
fever, and there can also be transfusion related reactions when talking about blood products,
and it's also possible to have a condition called malignant hyperthermia which as the
name implies involves a very high temperature although that tends to be a later manifestation
of that particular disease. but all these reasons go to show that temperature is an extremely
important factor to monitor. A patients core body temperature can accurately be measured in the
pulmonary artery, in the esophagus, in the naso-pharynx, and also the tympanic membrane,
but we can use less invasive places as well. for example just putting on
a temperature probe that's on a sticker anywhere on the skin - usually underneath the axilla - is
acceptable for most surgeries. here i'll show you what a skin temperature probe looks like - you
just take off the back side of the sticker - this is what the probe itself looks like, and
you can put this pretty much any place you want like i said i typically go underneath the axilla
now that i've got it hooked up it'll take a minute to actually get the temperature
underneath my axilla but i can keep track of that right here on my monitor.
well that wraps up this video. i hope you found it helpful and if you have any feedback i'd love
to read it in the comments below. thanks very much for watching and i'll see you next time