Airway Transcripts PDF

9/15/24, 12:37 PM Transcript Transcript Put a video of that in the instructional videos for their reps going forward. I know they don't like it. I love it. Everybody hear me okay? Yep. Yes. Cool. And you can se...

9/15/24, 12:37 PM Transcript Transcript Put a video of that in the instructional videos for their reps going forward. I know they don't like it. I love it. Everybody hear me okay? Yep. Yes. Cool. And you can see my screen? Yes. And it looks like we're recording. Awesome. So hi, everybody. Nice to be here virtually. So start the lecture. It's 11, I think. 1101, a little late. This lecture is pretty dense, so I'm just gonna move fast through it. There's a lot of slides. So the reading, primarily, I based this on Nagel Hout's chapter 24. I did throw up a fair amount of supplementary articles for you guys. Lot of them were just, like, either the difficult airway algorithm, like, the document that that comes from. Just for, like, your reference for that, we'll kinda cover some of that the abbreviated way during the lecture, but just so you guys have that article. Recently, I came across an interesting article about the apneic sort of oxygenation strategy that was published in JAMA not too long ago. Again, like, the summary is pretty easy to read, and then you guys have the article as a reference if you want. I know there's some workbooks I got assigned this week that are due, I think, on the date of the exam. So that's there. And then once the new version of Miller comes out, then we'll start looking at that a little bit more too. Learning objectives. So just describing their way anatomy and innovation. That's the first batch of slides. So So I moved this from last week to this week just because it tracked a little bit more you know, tracked a little better with the other information in this lecture. So, the key components of standard airway assessment will hit those probably in fairly good detail. I think that's a super important part of this lecture. We'll talk about basically, like, how those assessments, align with just every patient that you might see, which ones if they have a specific anatomical characteristics then to be careful about. I'll run through the sort of standard induction. I think that's the main thing I'm gonna focus on with this one. And then I just wanted to take the stuff in the chapter and have it in here for your reference. We'll cover some of the stuff, but it's not stuff you're gonna see for a while. So, but just some of the advanced induction techniques and some of the advanced technologies for intubating people. We'll talk I'll present different Airway tools for you guys, and then sounds like Airway SIM will be tomorrow. So then we'll get to get our hands on some of that stuff. And then we'll talk, a little bit about the process of safely getting some of the sleep and then sort of core competence of activation criteria. And, again, just to backtrack a second, for the most part, the supplementary articles that I post, they're mostly for your reference. I think they're good to, like, check https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 1/52 9/15/24, 12:37 PM Transcript out, but I probably won't be basing any test questions on those things. I'm hoping to have some kind of study guide for you guys. I'm not promising, but I'm hoping to have a study guide for you guys maybe a week before the next exam and or the first exam. And if there's anything I wanna test from there, I'll put that in the study guide. But for the most part, like, anesthesia learning happens kind of across a couple of different sort of parallel processes. So one is talking you through the stuff I think is gonna be really valuable as new providers. And then another part of my own process of learning when I was a student is, you'll just have people, like, tell you interesting things or share interesting resources that might not make a lot of sense in the moment. But, at some point in the future, someone will talk about it. You're like, oh, I've got an article about that. I'll check it out or something like that. I try to keep a little bank of interesting articles to share, like, when I'm clinically precepting that track along with whatever topic might be pertinent for that day. So, again, these are more just like something to just kinda keep in your back pocket. And then if they come up later, it'll be interesting. I have a lot of supplementary materials for next week, and most of that this guidance I'm giving now will probably track for that. So how do we breathe? This is maybe a question you guys haven't thought much about. I think it's an important question. As anesthetists and also just humans who breathe, like, I think it's important to discuss this. So, I prefer to post this question kind of in person, but usually what I say because most people, like, don't know how to answer that right off the bat. And I usually say just, like, from kind of a physics perspective, how do we breathe? So we have neural pathways and sensors that sort of trigger our process of breathing. But when you're spontaneously breathing, then basically you're working on negative pressure ventilation. So we have chemoreceptors in our brainstem and in our carotids that aren't really initially triggered by hypoxia, but hypercarbia is sort of the primary driver there. So your arterial carbon dioxide goes up a little bit to some area up to level where it sort of triggers the chemoreceptors. Those that then send signals down your phrenic nerve to basically, you know, engage the diaphragm as well as the intercostal muscles. That basically opens up your chest cavity. So if everyone take a big breath right now, just a deep breath, like a big yoga breath, and breathe out. So we all felt our chest expand. And so basically, what happens internally is you have negative intrathoracic pressure at that point. The pressure in your chest becomes sub atmospheric or below the pressure of the atmosphere, and air gets strong inside. So it's just a pressure gradient. And when we exhale, it's usually sort of those the diaphragm relaxing and the chest wall kind of collapsing on itself just https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 2/52 9/15/24, 12:37 PM Transcript with the tissue elasticity. It all wants to kind of draw back together, and that's like passive exhalation. So we can forcefully exhale if we need to or want to. But that's sort of like a thing we don't normally do when we're breathing. We're just doing this kind of gentle breathing, negative pressure inspiration, and then passive expiration. So that's how we breathe at a very basic level. And I usually like to frame it like this because then when we start bag masking people or putting them on positive pressure ventilation on a ventilator, that seems like a subtle shift, but it's like a non normal style of, breathing. It's unnatural. Right? So for the most part in our life, our lungs are used to seeing atmospheric pressure or sub atmospheric pressure. And when you're using positive pressure ventilation, that's just like an a non normal physiology. So I just like to frame it like that before we get into some of more or more advanced topics. And then why do we breathe? So, kinda like what I was saying before, the two main components are really to, get oxygen in, which we all kind of understand. So right our aerobic metabolism utilizes oxygen in the Krebs cycle of just for maintenance of our metabolism, sort of metabolic function, like cellular respiration, all that stuff. But then the secondary why is to get carbon dioxide out. So then that's like the waste product that aerobic respiration creates. And so either not enough oxygen or too much CO2 is bad. Why CO2? CO2 is an acid, and it can throw off our pH if we have too much in our body. So, in it's actually the more dangerous thing in the short term because our pH, there's very little flexibility in a normal pH. And so that's the initial trigger to get you breathing, and then there's enough oxygen just kind of in the air to keep you oxygenating well. Right. So the first block here is airway anatomy and innervation. Like I said, everything's pretty dense, so just bear with me. The anatomical structures, so the nose is a primary passageway for air to enter the lungs. There's a large surface area within the turbinates and sinuses that allows for humidification and some mild filtration of the air through cilia and that kind of stuff. There's 3 arteries that supply that part of the, airway. It's seamless there, and then it's innervated basically by the maxillary and ophthalmic branches of the trigeminal nerve, so cranial nerves. There's some sympathetic innervation, by the superior cervical ganglion, which would cause vasoconstriction, and then there's parasympathetic innervation by the the facial cranial nerve in a ganglion, and that'll give you vasodilation. So if our nose if if we start sneezing and and our noses then get stuffy, some of that is, you know, blood congestion within the sinuses and then also making, you know, mucus and that kind of stuff. So that's, more of, like, the parasympathetic part of it. And here's just a picture. I grabbed most of these from the chapter, so they should all look familiar if you've https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 3/52 9/15/24, 12:37 PM Transcript looked at the book. So we have, 4 turbinates in there. You can kinda see just there's a lot of surface area because of all the turbinates and their little folds. So, basically, most of the time, you should be breathing through your nose, and then the air gets warmed and humidified on the way down to the lungs. So so the nasopharynx, now we're talking about the oropharynx. This is kind of a busy slide, but it's sort of stuff, you know, you'll need to identify when you're doing, airway assessments. So all the teeth, we'll talk a little bit more about the teeth a little bit later. The hard palate, the soft palate, the uvula, the, fauces. That's not a word I knew before, but I it's in the chapter, so I just brought it up as, like, a vocabulary word for everybody, bosses. The uvula, the tongue, that's kind of the main stuff for the airway assessment. So the hard palate, interior, one half to 2 thirds, the top of the mouth, it's fixed. It doesn't flex or anything. The soft palate is the last half or third of the top of the mouth, and it can stretch with eating, can contribute to airway obstruction, and then the tonsils, the tonsil pillars, and the uvula. Yeah. So the the palatine tonsil is in there, kind of in the back on the right and left. And so tonsils are part of your assessment as well. So the fossus, it's basically the opening into the oropharynx. It's just behind the oral cavity. It's sort of, ordered at the top by the soft palate laterally by the different arches, tonsil pillars, and then inferiorly by the tongue. And just to show that there, then it's kind of in the back and those 2, the right and left arrow off the uvula sort of captures, like, the edge of it. An important aspect of mallepotic classification. We don't use this term a lot, but it's, like, kind of what you're looking for. Then the pharynx is subdivided into the nasopharynx, oropharynx, and hypopharynx. We talked about the nasopharynx. We talked about the oropharynx, and now we'll get into the hypopharynx. So the whole thing the three levels. So the nasopharynx, is from the level of c 1. The skull base is superior to it. The soft palate is inferior, and then all this just kinda tracks down. So then the oropharynx is usually at the level of C2 or 3. The soft palate is the upper border, and the epiglottis is the lower border. Hypopharynx, So it's the lowest part. It's usually at the level of c 56. The epiglottis is superior. The cricoid cartilage is inferior. And then we'll kind of hit on this, the innervation stuff is important, and it's definitely tested on boards and will probably be a test question. So the hypoference is innervated by the superior superior laryngeal nerve and recurrent laryngeal nerve. The interior branch of the, superior laryngeal nerve, has sensory output to the hypoferrance above the vocal cords, including, like, these structures here listed, and then the external branch, provides motor function to the cricothyroid muscle, and then the recurrent laryngeal nerve is sensory innervation, below the glottis and to the trachea. https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 4/52 9/15/24, 12:37 PM Transcript Just gonna I don't see anybody in the chat here, but just making sure I'm looking at the chat. So recurrent laryngeal nerve, again, like, big important thing that's definitely on boards. It's called, recurrent because they branch off the vagus nerve, and then they loop around a couple of other structures, and I'll identify that. And second here, the right sided recurrent ligeral loops around the subclavian artery and then the left recurrent loops around the aortic arch. Unilateral injury and the and these are definitely, like, important things to know about. You know, we can injure these nerves intubating, carelessly, but others places where we are really interested and worried about this are, like, knee kinda neck surgery. So, thyroidectomies, parathyroids, that kind of stuff. And so they use nerve monitoring tubes when they do these. And so these injuries are things to consider, when you're doing those kinds of cases. So unilateral nerve injury will cause vocal cord paralysis on the one side, and that's usually not problematic. The patient will be kind of forced afterwards. In my ICU career, I did I worked in a thoracic surgery ICU for 6 years. And, sometimes in those cases, there could be, like, a vocal cord injury, and so people would have unilateral, vocal cord injury, and the cord doesn't work on that side. And so it's things ENT I do are vocal cord injections, or they can even, like, put in a little prop that kind of keeps the vocal cord out a little bit. But and so unilateral injury is, like, not great, but it's not, like, a a thing that causes great concern. Bilateral injury, can cause unopposed adduction of the vocal cords, which can result in stridor and severe respiratory distress. So, basically, like, the cords fold in and, won't fold out. So that can be a little bit scary. And so those are the recurrent laryngeal nerves, things to be concerned about. So injury to the, superior laryngeal nerve is not usually associated with any respiratory distress. So here's a little bit of the innervation here. So the, the ganglion sort of at the top left there. The superior laryngeal, you can see them coming off of the vagus. There's an internal and external branch. The vagus then can, continues down. The recurrent, you can kinda see it looping over the inanimate artery. And then you can see some of the cartilages there, but they're on I have so many graphics in this lecture. So we'll see that again soon. The larynx, that's kinda where we do most of our, like, important business. I see some of the chat. The injuries are I don't think they're like, once a nerve gets damaged, then they're not usually the the nerve itself doesn't come back. But like I said, ENT will do they have a couple of procedures they could do to kinda make people mostly normal. They can inject the vocal cord with some kind of filler that, like, within the tissue that kind of just, like, plumps it up and pushes it into more of a midline position. Or I've also seen it's just like a little piece of plastic that they put in. And so it's https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 5/52 9/15/24, 12:37 PM Transcript another thing if people have this as a history. I think I've had it 1, maybe 2 times where people have these little bits of plastic in to push whatever side is injured, into, like, make it more midline. And so, maybe in the last year or so, I had someone with one of those, and he had a note in his chart from the ENT guy that had placed it. And just that ENT guy just recommended, using the video scope and just using a small tube. So I think we used a 5 0 MLT tube. And with those smaller tubes, you can pass them through the buttock opening without really disrupting the cords too much. And so that's how we managed them. So the nerve won't likely regenerate, but, they have some kind of mitigating procedures that they can do to give people relatively, normal phonation. So, anyway, the larynx back to that, that's, is mostly where we do our kind of intubating business. Begins with epiglottis, extends down to the critical cartilage. Purpose of that anatomical structure is phonation. It can you know, one of its main things is to protect the lower airway from aspiration. So the gag, cough reflex, are all part of that. And then basically, the normal function is just providing a patent passage between the hypoferrance and the trachea, not letting food or water or anything else get down there. The blood splice from the external carotid, which branches into the superior thyroid, and then superior laryngeal artery, which provides blood flows above the glottis, and then the inferior laryngeal artery, which is infraglottic. The larynx is comprised of 3 single cartilages. So the thyroid cartilage, the cricoid cartilage, the epiglottis, and then 3 paired cartilages, the arytenoids, the corniculate, and the cuneiform. Then there's some intrinsic and and extrinsic muscles. And then these are all bound together by ligaments, membranes, synovial joints, and also suspended by the high bone, via a couple of ligaments and membranes. So, again, like, I think this is just right from the chapter. So on the left is sort of the front and back view, I believe. So you can see, like, the thyroid there in the upper left. That's the front view. So you can see the epiglottis kinda hides behind, the hyoid bone. You can see the thyroid thyroid AOID membrane, the kind of lateral horns of the thyroid cartilage, the body, the cricothyroid membrane, the cricoid bone, and then the, cricotracheal membrane. And then on the reverse view, you can see more of the epiglottis, couple of the the membranes, the corniculate cartilages, the arytenoid cartilages, some of the other ligaments and stuff. Then on the right, so there's a hyoid bone, thyroid hyoid ligament, membrane, the thyroid cartilage, the laryngeal prominence, which is like the Adam's apple, we call it, the cricothyroid ligament, and then the other cartilages. And, like, why do we need to know all this stuff? Right? So, like, vocal cord injury, like, we talked about, some of the advanced airway things that we will kind https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 6/52 9/15/24, 12:37 PM Transcript of go through real quick towards the end of the lecture. You know, I think for some of those, like, like, I don't know what it's called. Like, the kind of reverse intubation where you put up a wire through the mouth and then intubate over that. You're usually putting the the needle somewhere, like, you know, the carotid artery ligaments. So just knowing the anatomy is super important for these advanced things, but also just like our normal everyday intubating, job that we do, just knowing the anatomical structures and how they're innovated are really important. Here's one kind of including more of the muscles and some of the nerves. So you can see, like, the internal laryngeal nerve. I could probably read off everything here, but, you can see the the recurrent laryngeal nerve on the left there and then the front view, the tracheal rings. So the larynx, this is the, you know, your optimal view if you're trying to intubate somebody. So just, again, like, I'm sure you've seen some of the stuff before, but just to review it a little bit, the epiglottis usually sits at the top there. The corniculate cartilages, the cuneiform cartilages, The trachea is kind of like the place you're looking for. You got the vocal folds, the vocal cords. But, anyway, these are important. I think I showed this before, but so then just a list of the intrinsic muscles of the larynx, kind of how they're innervated, what their main function is, more of the muscles. So then the trachea, the cricoid cartilage is at the level of the 6, cervical vertebrae. It's connected anteriorly to the thyroid cartilage by the cricothyroid membrane. The cricoid cartilage is the only complete cardinal cartonalogous cartonologous ring in the airway. Sorry. A lot of, complex words here. So it's like something to know. That's a fun fact. The trachea begins at the cricoid cartilage and then extends to the crina. The crina is usually at the level of the 5th to thoracic vertebra vertebrae. It's usually about 10 to 20 centimeters long in the adult, and they're 16 to 20 c shaped cardinal cartinologist rings that open posteriorly with a trachealis muscle at the posterior side. So, why is that important in case no one's ever thought of it before? So the front is where, like, you want some bone there to protect your throat from injury. But on the back end, you know, the esophagus runs parallel to it posteriorly. So you want some flexibility in that system, for it to expand and contract. So that's why they're just c shapes. And so there there's a muscle that runs along the posterior side that can allow it to stretch. So it helps to accommodate the esophagus during the swallowing, like I just said. And then it can also the muscle can constrict and narrow the trachea. And, basically, like, if we are under Poiseuille's law, you can create more force through the lungs. So if you're coughing or something like that, you can generate more force that way when the diameter of the bronchus is narrowed. So that helps with that. Then at the china, https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 7/52 9/15/24, 12:37 PM Transcript the trachea bifurcates into the right left mainstem bronchi. And then, just to refresh these facts, so in the adult, the right mainstem bronchus branches off at a more vertical angle than the left. And then so if you put your tube in too deep, you're more likely to the biases to the right, arraignance mainstem intubation. So that's why we listen after we intubate. And then here's just a picture of that. So you can see the trachea with the, cartilage and the swings in the front there. And I don't think I have a picture on the back, but, you'll see, like, the muscle striation and the c shaped rings on the on the posterior side. And And then down to the crina, you can see the right mainstem bronchus comes off at, like, a less acute angle. And so the tube is more likely to attract down the right hand side than versus the left hand side. And then the diaphragm is kind of at the bottom of the system. So dove shaped muscles situated between the pleural and abdominal cavities. It's in a beta by the phrenic nerve. And then when the phrenic nerve is activated, then the diaphragm will flatten out and it expands, increasing atrial frol acid volume causing a relative negative pressure in the thorax, which draws air in. And then, like I said, normally a passive recoil of the rib cage and relaxation of the diaphragm causes exhalation, but it can also be forced. Thing I find interesting about this system, which maybe you've thought about, if you haven't thought about, most of our breathing, right, it's one I think it's the only system in the body that basically normally operates on anomic signaling, but it can be controlled by somatic signaling. So if you wanna take a deep breath, if you're doing a forced exhalation, if you're singing, if you're turning on and on during a lecture, like I am right now, most of that signaling is actually intentional speaking. But if you're just, like, doing some other activity quietly, it's just operating on its own. So it's one of the only systems in the body that could either be controlled intentionally or falls back to this automatic process. So, anyway, that's interesting. So the exam, this is, like, all really important stuff. So and just to kinda bring it back to the last lecture I did for you guys. Once you've looked up the history and physical and you know your patient on paper, then it's time to, like, meet them either later that day or the next morning and then check some of this stuff. So we're already, like, verifying some of their past medical history stuff, and then the big important systems are running through them, like I described last week. But then this is sort of, like, part of your physical exam. So, when we're looking our patient up, looking through the chart, then we're, looking at their prior airway notes. That's super important. It's really easy to find them in epic nowadays, and I think that's, like, one of your big things to do when you're learning how to intubate. It's just always checking if there's an airway note to kinda give you a https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 8/52 9/15/24, 12:37 PM Transcript sense of, like, is this gonna be a chip shot? Were they able to get in and easily, but they needed some other, piece of equipment like a bougie? Did they have a partial view? You know, when you guys are brand new to this, it's gonna take probably a month or 2 to start feeling more comfortable with intubating. And so, if you have a prior airway note, I always felt, like, a little bit more reassured as a student that, like, somebody could innovate this person, and maybe it gives you a little heads up of if you need anything special. You know, if they I can intubate somebody with a really bad view now, but early on in my career, I just didn't have that skill, that comes later. And so if the peep if the prior provider was able to intubate, but they had a grade 3 view or whatever, then that might be, like, a reason for you to be like, oh, maybe I'll call for a d blade or something in the morning, versus if it was, like, a totally easy grade 1 view, then, you know, maybe you'll try to DHL that time. And then once we see them, then we're kind of just, like, looking at them when we walk in. We're gonna ask them for their mallepati scores. So, like, open your mouth real wide. I usually frame that as, like, I'm gonna ask you to do some weird things here in a second, and it's just part of our anesthesia assessment. So, like, open your mouth wide, stick out your tongue. We're gonna people more people have beards nowadays. I think I made this complaint last time. So sometimes it can be hard in men just to really recognize someone's federal mental distance just by looking. So, we'll check that. Usually, just kind of like fingers under the chin. There's a certain amount of, like, conditions, syndromes that people can have that are associated with extremely small thrombital distance or microdaphtha, we call it. It's a technical term for it. So, like, Pierre Robin, Treacher Collins, and there's, like, a bunch of other syndromes. But those are the probably the 2 I first learned about, though they're all rare and you don't see them that frequently. Kind of when you're asking them to open their mouth, you're checking out the size of their tongue. Macroglossia is a large tongue, and so that's something you're worried about in these assessments. So people with Down syndrome or trisomy 21, tend to have big tongues that sort of, like, protrude out of their mouth, because it's so big. It's like, does it fit easily, in the mouth? So that's just like another thing you're eyeballing when you're starting your assessment. The upper lip bite test, I feel like, is a good one. So we also call this, it's actually not the intern size or distance. Sorry. That's a mistake. But it shows you some jaw mobility. You're asking them to kind of, like, extend and flex their neck to check their neck range of motion, and then just doing, like, a rudimentary dental exam to make sure, that there aren't, like, loose teeth right at the front where you'll be intubating. The famous Malinpati score, I never worked with a guy, but he worked at my old https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 9/52 9/15/24, 12:37 PM Transcript hospital, doctor Malinpati. So he devised this thing. So you can see class 1, you have a complete visualization of the soft palate and the uvula. Class 2, complete visualization of the uvula. Actually, it's not complete, but it's, like, a little less than complete. So you can see most of it, but maybe not the tip of it would be like a class 2, class 3, visualization of only the base of the uvula and the soft palate. And then for a class 4, you aren't unable to see the soft palate at all, and you're just looking at the hard palate and tongue. These are probably my 3 favorite assessments. So this one's called the interincisor gap, and it's basically like mouth opening. It's the distance between the upper and lower incisors, so the front teeth. So definitely during DL, you want someone with a good intern size or gap. So it's usually, over 6 centimeters is great. Less than 3 can be considered a predictor of difficult intubation. So when you notice someone with, like, kind of a small mouth opening, then it can be challenging to get whatever you're gonna use into the mouth. So the the ringoscope blade, we'll talk in a little bit about this. But, when you're DLing someone, you're trying to line up a few angles, to if you line up the angles and you can usually line up the patient's, like, anatomical structures that you wanna see through with your eye so you can do a direct visualization. So, the size of the mouth opening definitely influences this. We talked about the inner incisor gap of less than 3 centimeters is can predict a challenging airway. And so this thing, this narrow gap that I'm talking about, so it creates a sharper angle between the oral and glottic openings. And so it can be challenging to line up those anatomical structures with your eye or your visual, angle to get a good view. Like, kind of prominent incisors, or like buck teeth can, a, get in your way, a, make making those angles work a little bit more challenging, and then there's always a risk of, like, dental damage. If they're really protruding into where you wanna be looking. Then we're looking for looser or upper teeth. This so I learned all these things as a student. And then part of your job in the next year is just, like, applying them really rigorously, like, on every patient for a long time. And then with that experience, you tend to, decide which ones have, like, a higher yields than others. But I think, you know, the entrance size or distance has an extremely high yield for intubating, predicting intubating conditions. Thromental distance is also another favorite of mine. So it's really just like kind of the jaw length. So a measure of potential submandibular space into which we will displace the tongue during laryngoscopy, and it's measured from the thyroid notch to the lower border of the mentum at the tip of the chin. 6 centimeters is normal. Smaller is associated with difficult intubation like we talked about before. So mandibular hypoplasia are kind of like a short jaw gives us less. So, you https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 10/52 9/15/24, 12:37 PM Transcript know, what we're doing big picture when we're dealing someone, and we'll get more into the details, but just give it a first pass here. We're scissoring the mouth open as wise as we can. We're dropping the blade in. Usually, people teach, like, kind of, pointing the tip of the blade towards, like, the right molars, sneaking around the tongue and lifting it, coming back towards midline and then looking down. And so what you're doing with that lift is you're really the glottis doesn't really move a lot. You're more like displacing the tongue anteriorly to then move it out of the way so that you can line up the glottis with the oropharynx with your eye. This is the angle I keep talking about. So glottis, oropharynx, eye, you want one line of sight on all that when you're doing a direct, visualization. And so if they have a short chin or, like, not much room here, you just don't have as much room to displace the tongue out of the way. And so, that you can have a partial view in those cases. So there's less room to displace the tongue. But ultimately, what you're looking for is a good match between the armamental distance and tongue size. So if someone has a pretty small tongue, but everything is sort of proportional in size, I've definitely had a number of people that look like they might be they have a short term mental distance that look like they might be challenging your way. But I have a decent view. And I think in those cases, I was like a little confused. Like, oh, they look like they would have been hard intubation, but they had a great view. And it's this match that we're talking about. So some people have a small fundamental distance, but a good match with their tongue size. And then you still have an easy intubation even though they have a short And then the thing that you'll hear a lot going forward, but just to say it here, anyone who's had neck radiation, that's a thing that's a red flag. If you see that in the chart, if they've had cancer up here and gotten a lot of radiation to the neck area particularly, that tissue gets really constricted and kinda scarred down from the radiation, and so it doesn't move like normal. And so these tests aren't that reliable in those cases. So, just as like a thing to put on your radar. So if you see head and neck radiation in some of this chart, that's usually a red flag. So when I say short environmental distance, this is kinda what I mean. I don't know that these kids are syndromic or have Pierre Robin, but Pierre Robin kinda looks like this, particularly the guy on the left where there's you can see, like, his chin sticks out, but there's, like, one finger breadth there. So this is the kind of case where you might consider getting a delayed. You definitely should consider getting a delayed and might be considering, like, a weight fiber object or something like that. Like, these views are extremely, interior, and it can be really hard to get a view with a DL in these cases. And then the third one, I don't use this one so much, but they https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 11/52 9/15/24, 12:37 PM Transcript cover it in the book, so I thought I'd hit it. So it's basically just the mandibular hyoid distance. So it tells us a little bit about if it's 2 finger breaths, then the glottis might look far away. In prepping this slide deck, I actually found it kind of interesting. Sometimes there are things like I didn't necessarily have the words for. And so this reading these chapters kind of give me some lingo around this stuff. But I definitely had some, views where I've, like, got a decent view and I can see the cords. It just looks the glottis looks really far away. And sometimes the light from the DL blade doesn't reach all the way down there well. So, sort of a distant glottis. I've definitely seen that before. And so if they have a wide, mandibulo hyoid distance, then it could tell us that the glass will be distant. Or if it's short, it could tell us it'll be tucked under the tongue when we're looking and we won't have a great view of it. So you're measuring it from the junction of the mandible and the neck, that area to the tip of the thyroid notch. And like I said, it kinda just helps you assess the relative position of the larynx. We talked about the over or under 2 figure breaths. So other tests we can do. So neck range of motion, I mentioned, the mandibular protrusion test. That's actually a useful test. I do that. Maybe not every time, but, sometimes if someone looks like they don't have great jaw mobility or mouth opening, that's the thing I'll do. And so you're basically asking someone to bite their upper lip with their lower teeth and people that can, bite at or above the, vermilion line on the upper lip, they've got, like, a good protrusion test. And then if they can't really move their jaw that much, then that tells you, a little bit more about just, like, how well you can displace the jaw when you're trying to DL them. And then an important caveat for all this stuff, and, like, when I have med students or really new learners, I always talk about this. So, like, what's the sensitivity and specificity of these tests? How reliable are they, with telling us someone will be a difficult intubation? They're not all that reliable, honestly. And but that's some of your job to figure out in the next year is just, like, applying them to everybody and then kinda seeing where they track. So, like, I was saying as a new intubator, like, oh, they had these anatomical structures where I thought they would be challenging, but they were easier than I thought. Or, oh, this one looked like it was gonna be a chip shot, and I just had a lot of trouble with it. So kind of after intubating, like, reviewing kind of what happened and how it tracked with your preop airway assessment, Those things are important to do. And I think you'll end up seeing what my assessment is now, which is that these assessments are useful information, like, useful data points, but won't guarantee you an easy or difficult airway. But they track maybe, like, 5050, I'd say. I think the thermal distance probably tracks at a higher rate. Maybe it's, like, 78% https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 12/52 9/15/24, 12:37 PM Transcript consistent. But my best advice is to combine them for the best predictive ability and then go from there. But as we'll talk about a little bit later with the difficult airway algorithm, You wanna kind of get as once you start down induction and start down that pathway, then your sort of choices are limited. And so part of what I'm not climbing so much these days, but I was doing, like, rock climbing for a while. I got I had a buddy that was Intuit, during my, CRNA program. So a classmate of mine. And we ended up doing, like, a fair amount of indoor and outdoor rock climbing outside of Boston. And in the climbing field, they basically frame it as they call it beta. So alpha is like, I've been on the wall, and I know, like, where it's tough or where it's easier. Beta is like, I haven't been on the wall, but I'm, like, looking at it and kinda trying to predict, like, where the the climb might be most challenging or I'm talking to someone that's already been there. So if you can get beta on an airway before you start down the induction pathway, that's all useful information and is definitely worth your time to do. But like I said, sometimes the beta is not a 100% tracking with easy or difficult airway, but it's like the best view we have, before we head down the induction pathway. Dental exam. So we'll just kinda briefly cover this. So the teeth are all numbered. This is more like from dental science or whatever. But in I think my next slide is that epic screen that I showed you before in the dental exam, but, I present it this way because that's what the dental exam looks like in epic, and you guys will get good at that. So you can see there's 32 teeth. They kinda start with number 1, on the back left, I think. And then goes down to 16 and then 17 to 32 on the lower part. So we have, like, anterior and posterior teeth. The incisors, upper and lower, kind of the main ones you're concerned about, and then just asking about any loose teeth. So, dental exam and then also just like BMI, just to post that for you guys so you have it. But BMI is associated with a couple of things, mainly around difficult team asking, but just to pop it on the slide here. So here's the physical exam screen I showed you guys from my last lecture, but the dental exam is in the bottom left there. And, like I said, I don't have a full shot here, but there's a place where you can mark missing, loose chipped teeth on there. And then basically, like, the dental model looks like the the screen I just showed. Right. So now that we've done our exam, what are the risk factors we've identified? And then these are all just kind of the red flags. I think this might be for Miller. But, yeah, length of upper incisors. So if they're relatively long, that's that's always a little bit of a concern for either dental damage or just them being in the way. What's the condition of the teeth? Are we likely to hurt any of the teeth in there? What's the relationship of the incisors to the mandibular incisors? So are they a good match, or is there a https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 13/52 9/15/24, 12:37 PM Transcript prominent overbite? That usually means the overbite's gonna hang in your view and kind of be in your way. Ability to advance mandibular incisors in front of the maxillary incisors. So that's upper lip bite test, visibility of the uvula for the malapati score, the shape of the uvula. I don't know that I've ever appreciated that, but it's just something that was on the list here. Heavy facial hair, that's always a little bit of a concern, particularly for masking. The compliance of the mandibular space, so kind of the the area under the chin. And like I said, if it's if there's a gothic mass or some other mass there, if it's non resilient or stiff, that usually kinda comes with, radiation, like I said. Thermostat distance. So if it's short, the length of the neck, the thickness or the circumference of the neck, that shows up in a lot of places including, like, the stopping questionnaire, and then the range of motion of the head and neck. So if people can't extend their necks very well, it's hard to deal them. And here's just another graph on that. So just again, like, things to watch out for, just as your reference. So the things that we have seen, then what are they associated with? So in the case, like, I think, I like that when we teach this stuff, we sort of delineate what predicts a difficult bag mask ventilation with what predicts a difficult laryngoscopy because those things are like kind of 2 separate problems. And so I like that we conceptualize them as 2 separate problems. So it can be hard to get a mask here with someone with a big beard, altered anatomy and some of the ways I've talked about. Or if they have an NG tube, it can be hard to get a seal where the NG tube, slides up from underneath your mask. If they have any obstruction of the upper or lower airway, either be a tumor or if they have OSA, obese patients with a lot of redundant upper airway soft tissue, or like a large abdomen that could press down against where you're trying to apply pressure with the bag mask ventilation. Those things can be problems. They said, like, age over 55 is related to loss of upper airway tissue elasticity. I don't know that I mean, that's probably like a general fact. I don't know that I think of people being over 55 is like more difficult to bag mass ventilate. But interestingly, and I don't know that this like, on first glance, I was kinda like, oh, that doesn't quite make sense to me. But people without teeth, they tend to be harder to bag mask ventilate. So the teeth kind of prop open the mouth in this way that helps reduce obstruction. And so people don't have teeth, and you often need an earlier way to establish bag mask ventilation. Stiff lungs, you know, people with decreases in pulmonary compliance or something else. And then sleep apnea or snoring, those are all indications of challenging mask ventilation. Usually it's enough with 2 hand masks in an earlier way to get through with most people. Sometimes you need some neuromuscular blockade https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 14/52 9/15/24, 12:37 PM Transcript onboard, and we'll talk a little bit more about that sequence during the difficult airway part of the lecture. But those are kind of the indications for challenging mask and then indications for challenging DL. So just looking again, like, you guys are really new to this and haven't really examined many people yet. But as you get more reps with this skill, you'll be able to just kinda glance at somebody and be like, I've definitely done this where you're, like, kinda walk by before you even talk to them. And you, like, call your anesthesia tech. You're like, hey, can you get me the GlideScope? Because I think I'm gonna need it for this next one without even talking to the patient. So, once you get enough reps with this skill, you'll be able to eyeball people. The 3 three two rule, that's just what I talked about prior. What's their amount of body score? So, scores 12 don't necessarily correlate with much from what I could see in these chapters, but a class 3 or 4 can't is statistically associated with increased DL. Obstruction of the upper airway. So again, like masses or tumors, obesity with increased neck circumference, redundant soft tissue, that can always be a little bit of a challenge. And then like I said, radiation, masses on the neck, those are definitely like red flags. And I'm already kinda taking deal off the table if I see someone that's had radiation in the past. Neck mobility. So if someone's a trauma and is wearing a c collar, if they just if they've had prior, like, c spine surgery, if they just have, like, degenerative joint syndrome and they just can't move their neck very much, then those are all kind of indications that you might have a more challenging intubation experience. The we sort of look at the whole neck range of motion when we're doing our assessment. I'd say, like, the chin to the chest move is a little less useful. So if someone has some reduced mobility there, that's not necessarily a red flag in my mind. But if they can't stretch their neck back very far, that's more of a red flag for me. And then also operator experience. So that that's what you guys are gonna experience in the next year. So there'll be airways where you, like, just can't figure it out. And then your CRNA you're with is just gonna, like, pop it right in, and you're gonna be like, oh, man. Again, it just kinda comes with time, experience, repetitions, doing it. So that's that's what your next year is gonna look like. Other indications, I mean, so I I'm not gonna really talk about the cracker thyroid airway replacement, but for like an LMA, you know, if they have restricted mouth opening, if they have obstructions of the upper airway, they've distorted anatomy or stiff lungs, like those are reasons that you might think about not using an LMA in that case. Sometimes there's a gray area where you're like, we could do an LMA or we could intubate, and then you kinda run down some of these checks to decide which direction you're gonna go in. And then a cricothyrotomy, I've never done https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 15/52 9/15/24, 12:37 PM Transcript before. And I don't think it's gonna be useful to spend that much time on these things because they're pretty rare. Alright. So standard induction, I feel like this is a good frame just to kinda start the conversation. So we've looked our patient up the night before. We know about their past medical history, the medsiology is also if we talk about the first lecture. We've met them in pre op. We've, done our airway assessment like I just covered. We've run through all the systems and double checked everything we found in the chart, see if there's anything that seems like a red flag in the chart that actually might not be a big deal, talking face to face with the patient or things that weren't on your radar, when you look them up, And then just checking to see if there's something that you didn't see that might be a problem. So once you've done all that stuff, you've got your plan, you've talked to all your people, then the nurse from the OR calls you and says the room's ready, then you bring the patient back. Right? So we're back in the room. We've moved the patient over from the stretcher to the bed. We've put on all the vital sign monitors. Right? So at UVA, everybody comes, like, in pre op, they get a finger probe put on. If they're not getting a block or something that requires monitoring ahead of time, they don't usually have EKG leads on, and their cuff sometimes is on. The cuff sometimes is stuffed under the pillow. Sometimes it's wrapped around, the side rail, the stretcher. But getting all that stuff, plugged in and running and associated with Epic when you get back in the room before you think about giving any meds or preoxygenating, all that stuff's done. So now we got whoever we need in the room. We're ready to go. So then we start the standard induction process. I usually frame this as associated with a difficult airway algorithm. So the difficult airway algorithm is an extremely busy slide. And so you guys probably have looked at the article, the slides coming up. It's so busy that sometimes it can be unless you've done it a lot, it can be hard to identify, like, the kind of key points in the difficult airway algorithm. So I'm just gonna talk about them now. So the way I like to frame this, is that with the difficult airway algorithm, before you move on to the next step, you have a fallback position. I like to call it. So if any of you are military, you know what that means. So before you advance, you have a place to retreat to. So that's why the standard induction starts with preoxygenation. Right? So the patient spontaneously breathing, they're still awake. We've got the mask on their face that's connected to the circuit. And we're, we've made sure we've got a good seal, and we can see our end tidal waveform that's clear and shows us where we have a good seal on our monitor before we do anything else. So we have our flows, like, somewhere between, like, 510, just oxygen, no air, and we're just having the patient breathe. https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 16/52 9/15/24, 12:37 PM Transcript Sometimes you tell them to take deep breaths. Maybe that's fine for part of it, and then they don't need to really deep breathe after maybe a minute or so that this portion can be more extensive or less extensive time wise depending on what your kind of clinical suspicion is of your patient. So if you have a really big patient, they tend to desat more quickly. And we can talk about why that is later. But, if I have a real big patient and maybe it looks like they won't be a chip shot airway, maybe I spend more time preoxygenating them upfront. On at UVA, and I think this is pretty standard nowadays. Most places use like this GE monitor system. And so on the lower left hand part of the screen, there's two green numbers. 1 is the fraction of inspired oxygen, which is sort of what's coming from the machine. And then it also captures what's the expired or like end tidal oxygen. So the inspired, you're just gonna get what you get from the machine. But the expired is really shows us how far along you are on this process. So when we're preoxygenating, we are right. Nitrogen's about, I don't know, 79% of the atmosphere. Oxygen's about 21%. And then there's a bunch of like other gases that are less than 1% of atmosphere. So I mostly talk about this as nitrogen and oxygen. And so we're trying to, get a mix of nitrogen and oxygen. That's basically the opposite of what the atmosphere is providing to us in our patient before we make them apneic. Right. So, like, we've got our propofol plugged in, like, in the standard induction sequence, we are going our plan is to make them apneic. And so we're gonna try to build in some extra time or like a margin of safety for getting them to sleep and then getting our breathing device in. So preoxygenation is like the core to this and it's super important and you all should be doing it. Even when you're like a new even if the patient looks like a chip shot, if you're like a brand, it's like your 1st day or 1st week and you haven't intubated any any real life people before, that's also a good reason to do it because you guys are just gonna take longer and we might have to change providers. And so just, like, giving yourself a good safety margin with adequate preoxygenation is super important. So we're preoxygenating. Sometimes you talk about I'll call this, like, nitrogen washout. So we're replacing the nitrogen in the lungs with as much oxygen as we can get in there. And like I said, atmospheric oxygen is about 21%, and atmospheric nitrogen is about 80%. When we're preoxygenating patient, we want to kind of flip that on its head. So we want our expired oxygen to be somewhere above 70 to 80 if you can get it. It can take a little extra time to get someone above 80, particularly again if they're like big or have pulmonary issues. But once we get them adequately preoxygenated, then we usually give some Lido first because the propofol burns, and then we inject an instigating dose of propofol. So once https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 17/52 9/15/24, 12:37 PM Transcript you get the propofol, the patient will stop reading. And before you bag mask, you just usually do, like, the eyelid checks. So you just kinda gently kinda rub your fingers across their eyelashes. And if they don't flutter their eyes, then they're asleep enough to then try to bag mask ventilate. People and you'll see this when you start in clinical. People tend with propofol, their brain goes to sleep, but they still have a lot of muscle tone in their body and glottic tone. And so, it can be hard for the first breath or 2 to, like, drive enough air past the vocal cords if they have a lot of muscle tone. And so that that's like a thing you'll see a lot. So anyway, push the football. They go to sleep. We start trying to bag mask ventilate and we're having trouble at first. And you guys this is actually like a really tricky move. And we'll talk a little bit more about it in a second. But, you know, you're struggling with it a little bit. We end up putting in an oral airway. Still, maybe they have a big beard and we just like don't have a great sense of if we're able to bag mass ventilator or not. And so the kind of difficult airway algorithm branches off in 2 different directions now. But, sort of like historically or kind of like classically the way they teach this is that if you can't bag mass ventilate and you've adequately preoxygenated your patient, one valid choice is just to let them wake up. Right? And so this is our fallback position. After our first move forward, we've gotten the patient asleep and then out breathing effectively. One of the things you absolutely can do is just let the patient wake up. Right? So if you've adequately preaxinated someone, you can get somewhere between, like, 7 to 10 minutes of apnech time. And how long does propofol last? Probably about 5 minutes. And so you've got, like, a nice match there where if we can't keep going down our airway algorithm, we're gonna back out of it. And our fallback position initially is just to, like, let the patient, wake up on their own, and they're unlikely to desat, in a young healthy patient if we've preoxygenated them adequately. So, that's just, like, the first example of, like, we're proceeding down the airway pathway, but really any airway pathway is, like, the difficult airway algorithm because we're always on the lookout for that. And so having a fallback position is important. So we're gonna one valid action at that point is just to back out and just wake the patient up, and they're unlikely to be harmed in that case because we've preoxygenated them very well. So why do we do this? I talked about it. So the first step, nitrogen washout, fills the lungs with mostly oxygen and allows for safety optic time up to 8 minutes, and I'll be patients with the normal functional residual capacity. You do need to have a good mass seal, higher flow of O2 in the machine with no air blood in, and then having the patient just take large tidal volumes for 3 to 5 minutes. Usually 5 minutes is a long preoxygenation time, https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 18/52 9/15/24, 12:37 PM Transcript but I'd say like 2 to 3 is sort of the typical one. And then our goal is the fraction of expired oxygen above 70%. And then so there they go to sleep. They don't have lash reflex. So then we're gonna try to diagnose and isolate them. And so just to refresh this, like, in my opinion, it's a very challenging skill, but it's maybe the most important skill. I think for my class, and I remember my student, like my cohort, everyone's like in a rush to intubate. And that's definitely an important skill too. But bag mask ventilation kind of seems like, oh, this is stupid. Why don't I need to learn how to do this? But it's your initial rescue maneuver in almost any situation. And so you want to get good at it. Your preceptors will kinda work you through some of this and you'll do some of it in sim as things go along, as you guys progress over this year. But getting practice with it, it's super important. If you have big hands, it's usually a little bit easier though. One of the docs I worked with at my old hospital had she's a small lady and had tiny little hands and she could like, watching her, like, bag mask somebody was actually kind of it. She just, like, got it. She owned that airway. And so even if you have small hands, it's not, you know, gonna preclude you from being successful at this, but it can be a little bit more challenging at first. I've got some pictures that will, kind of flesh what I'm talking about out, but, the CE shape. So like we make a C with kind of our thumb and our first finger and then the E is the other three fingers on our hands. When you have the mask on the patient, you're usually doing with this with your left hand initially because your bags usually on your right side. So you're gonna get good at this with your left hand. So the c e shape, you're putting the mask on the patient, but you're sort of pulling the jaw up to the mask and not pressing the mask down. You'll be corrected on this a bunch your 1st month or 2 because you it's gonna take time for to make sense, like, kinesthetically while you're, like, in the environment. But you're not pressing the mask down. You're kinda pulling the jaw up to the mask. When you have the APL valve engaged and you're bagging the patient and you're looking for chest rise initially, maybe some fog in the circuit, and then you're always looking for end tidal. And so that's, like, the gold standard of, like, oh, I'm able to adequately bag mask this patient if I have end tidal. Again, just to reiterate, people with real thick necks, people with high BMI, particularly with a BMI over 30 with a lot of redundant neck tissue. They can be challenging. Beards for sure. Patients who are dentists have a OSA or an NG tube like I talked before. They can be challenging. And so we consider, like, an oral airway in a 2 hand mask if the patient has any of those characteristics. So here's the single provider mask. So this is 1 or 2 handed, but you can see on the picture on the right, the c e movement. So the c is the thumb and the first finger kind of along the outer https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 19/52 9/15/24, 12:37 PM Transcript rim of the mask. And then the next three fingers in the e shape are on the jaw. And you're basically, again, like pulling the jaw up to the mask. And you can kinda see the guys the patient's neck is extended a little bit there. And that's often how that looks. You're just kinda like tracking up with the jaw and then sort of pushing down with your c shaped fingers. So you're kinda doing 2 moves at once. For a single provider doing a 2 hand bag, so you can see on the left is the 2 hands. So it's basically a double c e, and then you need a third person to, like, actually pump the bag. But, those are pretty classically, you know, things you're gonna see very frequently in day to day practice. And so just kinda getting familiar with them and working on them in SIM is important. This is sort of 2 providers. Sometimes on the left there, your doc will kinda reach over. And one place where when you're a new provider, you lose seal is kind of along in this diagram, like this provider's left hand. Like you can apply a lot of pressure on the left side of the patient's face with the one handed maneuver, but you have to kind of roll the pressure over across to where your your second hand might be in the future. So, sometimes your attending or CRNA will just kind of, like, push the cheek up on the right hand side of the patient's face to kind of, like, help with the leak. And so that's kinda what you're seeing here. And then as the number one provider, then you're handling the bag. But, for 2 hand providers, like I was talking about before, you do the double CE if you're doing all the masking yourself, and then whoever's with you in the room will bag mask ventilate. Oral pharyngeal airway or nasal pharyngeal airway, those are both important tools and things for you to learn about and get used to. An oral airway is a super important tool to have out. It took me a while to come to this, but basically, I have an oral airway out for every patient now. And I also have a tongue blade out because we stock them and so and they're wood. So I usually open them up. But those are things you're gonna use very frequently. And sometimes, you know, you'll be surprised at when you need them. And so just always having an oral airway out, and a tongue blade is super important. I do that for every patient when I'm intubating. And then a nasal pharyngeal airway, they're not that commonly used with induction. But if you're doing a mask and running somebody deep, these are kind of your, MAC case. If you're running a MAC case and running somebody deep, then these are sort of your 2 choices that they're obstructing. If you've tried just like repositioning and then stuff, some some of people just need this. A thing someone was telling me about recently, which is interesting and I wanna pass along to you guys. An OPA is easier to get in, but it stimulates the gag reflex a little bit more. And so patients are a little more likely to, like, over time wanna spit it out, but it's easier to https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 20/52 9/15/24, 12:37 PM Transcript get in. So that's, like, one way to think of the OPA. The NPA is a little bit more stimulating to get in with a patient, but they tend to tolerate it better over time. And so, this has kinda changed my practice a little bit. We do a lot of total joint replacements at UVA under spinal and mac. And, depending on, again, usually the BMI of the patient. If you're trying to run them deep so they're not moving, they will often obstruct. Like, maybe half the time they'll obstruct and you either need to, like, shove a pillow down below their shoulders to kind of extend their airway some, turn their head left and right a little bit, and you fuss around with that stuff for a little bit. And then, you're still they're still becoming apneic. NPA might be a good choice in that case. Again, it's like a softer airway, so there's less likely to be tissue damage. And, well, like, one trick there because it's more stimulating to put in is maybe you give a little extra bolus or propofol, like maybe 2 or 3 cc's, Slide it in while they're a little bit deeper, and then just kinda let them come back up to whatever level you had them at. And then that that's a trick, and then they tolerate that a little bit better than the, oral French all your way. The book has a chapter or, like, a section in this chapter on apneic oxygenation. So this is just an interesting article that came one of our anesthesiologists emailed it out to the group a couple of months ago. So this group, did the study. It's sort of what you know, it doesn't exactly track for us, but it's, it was done on ICU patients that needed to be intubated. And so they randomized, 1300 people. That's a lot. They randomized 1300 people to either, having, like, a standard, mask oxygenation or this non invasive ventilation, preoxygenation. And, again, look at the article. There's also, like, the plain language summary that's there that's easier to kinda blast through. But, basically, what they found is that, the incidence of hypoxemia, which is like an o two sat of less than 85% between induction of anesthesia and 2 minutes after intubation, they found an 18% incidence of hypoxia in the bag mask group, but only 9% incidence of hypoxia in the in this, like, apneic noninvasive ventilation preoxygenation system. And so, basically, what they did was they put high flow nasal cannula on the patients, had them run it at a high flow rate. So, like, over 15 liters a minute. And then basically once they induced the patient, that kept running, while the patient was apneic, while they were trying to do the airway. And they found that, the physics of the driving force of the air kind of still mixed oxygen with the air in the lungs and provided them better apnea time than bag mass ventilation. Because bag mass ventilation, basically, like, you're oxygenating them, and then you take the bag off. And then it's just like atmospheric air blowing around and mixing. And so they found this, like, high flow setup was a little bit better. I'm gonna take a break later, probably, maybe around 12:30. https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 21/52 9/15/24, 12:37 PM Transcript And so I'll take a formal break of 30 minutes, Myra. So just let you know that. Check away. There we go. So it was a cool article to see. And again, like, it'll be something that'll come up in a year and you'd be like, oh, yeah. Yeah. I saw that article. Blah blah blah. But then the thing you guys are all here to talk about, laryngoscopy with intubation. So I found the chapter also did like an interesting framing of basically like conceptually differentiating direct laryngoscopy from video laryngoscopy and also that being a separate procedure than tracheal intubation. So I like that they frame them as 3 distinct procedures. So DL is directly viewing the glottic opening. Video laryngoscopy is indirectly viewing the glottic opening on screen. And then tracheal intubation is actually intubating somebody, putting the cord, the EC tube through the cords, but above the crown. Right? And so we don't DL or BL people without the intention of, tracheal intubation, but I like how they made them through distinct procedures. So we'll talk about each one of those things. So the direct laryngoscopy technique. So the techniques are a little bit, different between if you're using a MAC or a Miller blade. I'm more of a MAC guy. So I've got some pointers on Miller, but, Mac is the blade I use every day. So the Mac blade, the curved blade, the anesthetist placed the tip in the vallecula and then gently list to elevate the epiglottis indirectly. Whereas for the straight blade, the tips placed sort of behind the epiglottis and general forces applied to lift it directly. The thing you guys are gonna hear about a lot is it's important to avoid levering the blade. So you never wanna you wanna keep your wrist still and not, like, lever back. The trick is sort of lifting your arm. So it's ways I've heard it described in my career are like it doesn't come from your wrist. It comes more from your deltoid. You're like lifting up and trying to point the tip of the blade towards the upper right corner of the ceiling. And that sort of like the idea comes more from the shoulder and you're kinda looking up and pointing towards the right of the, to the ceiling. Right corner of the ceiling. There's another tip here called burp technique. So it's like glottic manipulation. And so it's usually not you at first, but, often when I'm helping or with an anesthesiologist, they'll kind of grab the larynx and manipulate it. And so cricoid pressure is kind of part of this. So they're basically pushing the glottis in, like, posteriorly or pushing down. So that's carotid pressure. And then this burp technique is sort of like, again, backwards. So, like, posteriorly. And as you're pushing down, you're gonna, like, track the glottis up towards the head and towards the patient's right hand side. And so, just to introduce this concept to you guys. What, I think I like to talk about is when you're learning to DL, your part of your job in the next year is building out, like, your algorithm for, like, okay. At first, I know https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 22/52 9/15/24, 12:37 PM Transcript how to scissor them out and I know how to drop the blade in. And if I don't have a perfect view just with those two moves, I'm not sure what to do next. And so what you you'll see people model the next couple steps to you. And then as you gain more experience, you'll start to know what, like, the third next thing to do is and the 4th the next thing to do. And so probably my 1st month or 2 intubating, I'd kinda like I dropped the blade in and sort of lift like they tell me to and not see much. And then kind of, you know, you're starting to come along when you start to do the next thing. Like, you take your right hand out of the mouth and some people, like, will put it on the the back of the patient's head and extend their neck a little bit. That's, like, the next move you might do. Or take your right hand around and grab the glottis and push it down. So, usually, if you don't have a good view, the glottic opening is almost always interior. So it's like if the patient's laying down, then it's kind of like the glottis is too high towards the ceiling. And so one of the first moves you'll learn is like, oh, maybe it's out of the way up. I'm going to push the glottis down so I can see if I can get a view. Usually, if you can kind of get a view real quickly, then you sort of know where the glottis is. And then you can kind of intubate intubate a little bit more blindly. But you always kinda wanna get a sense. And so if you get a view of the chords or even if you get a view of the 2 arytenoids by doing that, then at least you have a sense of like, oh, yeah. We're just gonna kinda go up on that track there. So burp, cricoid pressure is the thing that people do kind of instantaneously, at least the UVA. But the burp technique is, like, actually, there's a couple more moves than just pushing the glottis down. So you track it upwards towards the head and then to the patient's right, and that usually gets some kind of view on the screen for you or to your eye. So we talked about Miller and MAC blades. So the MAC is the the MAC is the curved blade, the Miller is the straight blade. I'll talk more about the MAC procedure, in a second or 2. But then, in my opinion, the MAC blade is easier to get into the mouth because the blade is curved, and so you can kinda slide it around the arch of the tongue. The Miller blade or so the MAC blade is easier to get in the mouth because it sort of is designed to fit with the anatomical structures a little bit better. But when you lift and are getting a view, it gives you less reliable of a view. So that's my take. It's easier to get in, but you have a less reliable view. A Miller blade is a little more challenging to get into the mouth. So with a straight blade, if you just go straight back, you run into the back of the throat. And so some of it's kinda angling the blade around the teeth. One trick that I know about is, like, kinda coming in more around the molars because, you have a more forgiving angle there. So it's kinda sinking it down by the molars and then kinda https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 23/52 9/15/24, 12:37 PM Transcript getting it, center line. The trick with the Miller is just you just kinda hub it and go all the way in. And when you lift, you're usually in the esophagus. And so you just see kind of a field of pink. And then as you bring it back slowly, you'll often see the apple the glottis just like fall into place and then you've got your view. So the technique is a little, it's it's harder to get in the mouth, but usually have a reliable view. And that if you just kinda have it and then sink back slowly, the glottis will just kinda fall down in your view. So those are kinda my tricks for that. I see someone in the chat. So why so this question in the chat, why is nature view difficult? So I think that's actually a good question. Let me close the chat here. That's actually a really good question. So and you'll see a little bit later in the lecture, like the d blade. So we have GlideScope, McGrath, CMAQ. There's all these manufacturers that make, like, a more hyperangulated blade. So the Miller blade, I think, is like a 30 degree curve and the d blade is a 60 degree curve. And so the way I like to talk about this when I'm talking with new innovators is when you're DL ing, so you scissor, you drop the blade in, you take a look. Every blodic opening, if you don't see it right away, it's gonna be anterior. So like up out of your view, up. And why is that challenging airway? I mean, it's not necessarily like a difficult airway because it's a pretty common anatomical event. But again, people with short environmental distance, you don't have really enough room to displace the tongue enough out of the way to get a good view of the cords. And so what happens is it's out of your view anteriorly. And so that's important to talk about because the first structures you see will be the arytenoids because that's like the first thing to form to view if you're if you're doing like cardiacoid pressure pushing the glottis down. And so basically, if it's out of your view up, what are the 2 moves? The 2 moves are to push it down. And sometimes you can displace enough of the tongue that it kind of shifts and you can get a view of it. The key with the d blade so so if it's out of view anteriorly and I've got this, like, 30 degree curved blade and I can't see, well, what's the trick if the glottis is up here? It's to increase the angle on the blade and then put a camera in in in the end. Right. Your eye can't see around that 60 degree angle but if you put a camera at the tip of the blade then you're looking right at that at the glottic opening. And so that's anterior airway is, like, an extremely common term that people use, and that's sort of, like, what the contact context is for the anterior airway and why it can be challenging. Because you if you don't have a good view, then it's out of you interiorly. And so then there's a couple moves. You either push it down, sometimes you get a view from that, or I'm using a d blade. But that's why d blade's so useful because this is, like, very common. The standard endotracheal tube. Again, I'm just https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 24/52 9/15/24, 12:37 PM Transcript trying to like focus on the standard stuff because that's the kind of cases you'll be getting at first. So you can see kind of, some of the details here. So, there's a cuff at the end. Almost every endotracheal tube you'll use for adults at least is cuffed. They're almost always beveled, and you can kinda see the bevel on both of these pictures. The bevel so some of the I mean, they're, like, clever engineering things that you don't I don't think about every day, but they're clever engineering things that, engineers and other anesthesia providers have come up with over time. So if you have just, like, a no bevel tube, then you can get hung up on tissue as you're trying to push the tube through the glottis. And so the bevel kinda gives it less surface area on the front to get hung up on anything. So the bevel, the tip of the bevel might get caught up, but if you're you know, depending on, like, what you can do, we call it corkscrewing. Like, when you put it in in a in a tracheal tube, the force is kind of going in this sort of, like, forward backward direction. But if you, like, have a decent view and the tube seems like it's caught up on something, often the bevel tip is, caught on some tissue. And so then the next move in addition to this forward and backward move is like corkscrewing that we call it. And so the bevel tip keeps it allows that if you corkscrew it then you can kinda come off that tissue and go into the glottis. So that's why the tip is beveled. If there's a big, like, mucus plug or something down there that you just, like, drive the tube right into, then you've got the Murphy eye on the side. In case the main, orifice is clogged, you've got a Murphy Murphy's eye as a side port to ventilate through. So it's like an additional safety measure there. There are no opaque lines. So, like, in a OR, we're not really, like, doing chest or X rays to confirm placement because we're listening. You you know, we've got entitled c o two that tells us right away that we're in the right spot. So we're not necessarily doing chest x rays, but most tubes have a radio opaque line on them. And then you're using this high volume, low pressure cuff to seal off the upper airway from the lower area. Right? If we're using positive pressure ventilation to ventilate the lungs and you forget to put the cuff up, then all the air is going to preferentially blow out of the mouth where there's less resistance than going into the lungs where there's more resistance. So you need to inflate that cuff to then separate the upper and lower airway so that when you apply pressure and positive pressure ventilation or bag mass ventilation, the pressure doesn't leak at the mouth, but dries down into the lungs. So Murphy eye on the left here, I'm just, like, looking at the, the graphic. So the Murphy's eye just insurance that even if the primary opening is occluded, some ventilation will still occur and then the leftward facing tip. So it proves the view of the vocal cords during the https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 25/52 9/15/24, 12:37 PM Transcript endoscopy, a narrow point with which to part the vocal cords. So if you had a big wide flat tube, you could catch the vocal cords. So the angle on the tube in addition to that core screw maneuver I was talking about, it just lets you kinda slide in that narrow space with the tip and then force it open with the rest of it. It increases the diameter of the primary opening, make it less likely that it will be occluded by secretions. Right? Like a a hole that's flat, is one diameter, but if you cut it to the side, then it's a wider diameter. So it's just like another safety mechanism. So standard disposable single use cuff plastic tube. The goal is to place it at trachea, patent airway for ventilation, common features. So, basically, this 15 millimeter universal adapters on the end of it. You plug in your circuit onto that and it and it, matches up perfectly. The high volume low pressure cuff. So, basically, it sits against the tracheal wall to burn aspiration or backflow of pressurized air, but you don't wanna cause barotrauma, and so it's a low pressure cuff but high volume. So you usually need somewhere on the order of, like, 8 to 12, cc's of air, to put it up. I don't routinely check the cuff pressure, but at least at UVA, we have manometers in all of the, anesthesia machines. So it might be, like, a good thing just when you guys are brand new to start doing that. I think it'd be useful. The bevel tip, like I said, just a little place passage of the vocal cords and murphy eye. It's an additional opening and kind of in case there's an obstruction of the main, orifice of the the cuff. Most tubes that we use are gonna be cuffed. We do use cuffless and, like, neonates and infants. You see them mostly in pedes. And then the cuff inflation, there's a pilot balloon at the tip of it that the syringes on when you're intubating, and then a one way valve in there. So and the goal is to inflate to the minimum volume that prevents air leaks. So then checking cuff pressure should be less than 25 centimeters of water to avoid any barotrauma rather like mucosal injury. I har have hardly ever used nitrous in my career, but there's some chance that nitrous, can move across the balloon membrane into the cuff and expand it and create higher pressure. So if you're using nitrous, it would be a good idea to check the pressure once it's been on for a little bit. So ET tubes are sized measuring the internal diameter of the tube. Size affects airway resistance, so a wider tube allows for less resistance. And if the patient spontaneously breathing, then less work of breathing. I tend to pick smaller sizes, and that's kinda how I framed it in this lecture. Most people you meet will say, like, oh, women get sevens and then get 7a half. I tend to go smaller, so I tend to think 6a half for women and 7 for men. And then some of that is also based on how tall they are. So at the tubes get a wider internal diameter, they also make them longer. And so if I have a really tall guy, I might pick a 7a half or an 802 for someone https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 26/52 9/15/24, 12:37 PM Transcript who's like 65, 67. And kind of the reverse, if I have a a lady who's like 5 feet tall, I might pick a 602 or 6 5. So smaller endotracheal tubes increase resistance to airflow, but larger ET tubes risk trauma, sore throat. I've even heard stories of, like, vocal cord injury from bigger tube. So I unless you have a good reason to pick a bigger tube, like, this patient's gonna I know this patient's gonna go to the the ICU at the end of the case, and I might pick a bigger tube that they can bronc through up there because I know he's gonna be sedated up in the ICU for a long time. Unless you have, like, an actual reason to pick a bigger tube, I tend to pick smaller tubes. Here's some specialized tubes just for your information. They have preformed tubes, so they have one called, like, a ray tube, And it's got, like, a really, sharp angle coming off of it, and they're not that long. But, basically, sometimes in an ENT case or some other thing, they don't want the tube to just, like, come way out or be kind of flopping around in where they're working. So a right angle tube or ray tube tends to come out of the corner of mouth of the mouth and then make a sharp angle kind of wherever you want it to. And then you just hook your circuit up there, but it kinda keeps the tube from being in the way if they're working on, like, the eyes or something like that. Armored tubes have, like, a wire that is wound throughout the body of the tube. And so, ostensibly, they're supposed to prevent kinking. I definitely had one ENT case where the surgeon must have been leaning on it. And the problem with, armored tubes is if they get kinked, they don't really go back into their own shape. So we ended up having to swap the tube out in that case because it got kinked. Versus the softer tube will kind of go back to its original form, and then maybe you can kinda position it better out of their way or something like that. But armored tubes are not a panacea as far as preventing kinking. I think they're harder to get to kink, but then once you kink them, the, like, the metal just kinda forms in that shape, and it it's hard to get them on kinks. Microlaryngeal tube. So I kinda talked about that with the guy who had the vocal cord stent. So, they're usually 5 O tubes. They're pretty long, and they're usually for, like, laryngeal surgery. So they can go through the tubes, but the, ENT people can still manipulate the cords that they need to. I've never seen this in the site. It was just in the chapter, but I guess there's an integrated video camera on the tube itself, which sounds really interesting, but it's probably pretty expensive. Laser resistant tube. So if, you know, most commonly, this is done for if people have vocal cord polyps or something, then the ENT surgeons will laser those. And so you need a laser safe tube in those cases and then, double them in tube. So if you're doing a thoracic surgery case, they allow for 1 lung ventilation. Alright. It's 12:30. So I'm going to leave this running, but pause for https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 27/52 9/15/24, 12:37 PM Transcript about 30 minutes. So I'll be back in whatever 30 minutes is at, like, 101, and we'll get started again. Okay? Thanks, everybody. Alright. You guys can hear me? Yeah. Cool. And you can see the screen? Yes. Perfect. Right. So this is kinda what I was mentioning earlier. So, again, like our first pass on it, but I think as you intubate more, you'll get a sense of what I'm talking about here. So when you're dealing someone, a lot of what we're doing when we're thinking about positioning is trying to align these angles like I was talking about before. So, basically, you wanna line up the glottis with the oropharynx with your eye and to have, all of them be on the same trajectory. So that looks like it's kind of c or kind of you can look into the spot that you want. So one is just sort of like someone laying in bed in a natural position maybe without a pillow. Then b is this neutral position with a little bit of head extension and a pillow. So, no, this is kind of, like, just a graphical sort of visualization of what I'm talking about. So some of what you're trying to do is in c there where you're, like, in a specific position, you've got their head tilted back, you're sort of looking into their mouth and trying to align the glottic opening with that view. So we talk a lot about sniffing position. I'm sure that's the thing you guys have heard of before. When I was a student because, like, all this stuff, you'll hear me talk about it, and then you'll kinda forget about it. And then at some point, someone will, like, make a point in clinical about it. And then I'm hoping you'll have a couple of neurons that remember this stuff, and then you can add more to the those little banks of neurons. But ramping and sifting position, I don't know that I was that aware of it. Maybe my 1st year as a student. And then, in my old house quote culturally, we ended up kinda building ramps. 1, somebody gave me, like, a great, like, lecture on how to build the ramp and, that's one of those things I was talking about last week where I kinda would shop questions around. So if we had a ramp, I'd have a few people just show me how they build their ramps and you'll kinda see different things. Part of your job as a student over the next year 2 years is, like, to see how lots and lots of people do different things and then kinda decide for yourself what your preferences are, you know, what you've seen consistently work, and then kind of taking those things and bringing them into your kinda daily practice. And so that's part of why I would shop these questions around because everyone does things slightly differently. And so I had a few people show me how to make ramps and, basically, you use the blankets and the warmer. You pull them out and you just kinda stack them up. But what we're looking for in a ramp and so this is kind of a heavier set person and that's typically who you're thinking about ramping. Though, nowadays, kind of with efficiency in mind, I tend to just manipulate, you know, the https://www.turbolearn.ai/transcript/e17bcc45-0c8e-434f-aa95-d458a4d04473 28/52 9/15/24, 12:37 PM Transcript stretcher for intubating on the stretcher or the OR table. And you can get most of this just from angling the table. But we're in sniffing position, we're looking for the tragus and the sternum to be aligned, which can be a little tricky to get that perfect, but you're trying to kind of get close to that, while also sort of opening up the patient'