Hello, thank you for joining me. My name is Dr. Aura Bollinger, and today I will be presenting basic airway management. I have no disclosures. A little background about me, I have been a CRNA for coming up on 21 years now. I graduated from Santa Maria University back in 2003, where I'm currently a full-time faculty member as well. In my 20 years, I've worked in a variety of clinical settings, from independent practice in rural America to large medical institutions in the urban setting in an anesthesia care team model. Right now, I currently maintain my clinical practice at Kaiser Roseville Medical Center, specializing in OB anesthesia, obstetric anesthesia, which is one of my true passions. There, I am the clinical coordinator for our students at Santa Maria University, but also the US Air Force, so that's a lot of fun. My other true love is teaching students. I love it when people like you come to talks like this and are just starting their journey and follow their dream, and then later I get to teach you in anesthesia school and then watch you walk at graduation and achieve your dream of becoming a CRNA, so welcome. By the end of this presentation, you're going to be able to be familiar with the upper and lower airway anatomy, describe how to perform a thorough airway assessment and be able to identify difficult airway predictors. You'll be able to describe and differentiate between various airway management devices, including indications and contraindications. You'll know the clinical indications for supraglottic airways and tracheal intubation, and you'll be familiar with the basic intubation technique and rationale for the choice of laryngoscope blades. Finally, you'll be able to describe and basic clinical airway management of the airway. Effective airway management is a cornerstone of a safe anesthetic practice. If we don't properly secure or manage a patient airway, it can result in hypoxic brain injury or death within minutes. In fact, up to almost 17% of anesthetic deaths are the inability to maintain a patent airway. So as you can see, it's a critical skill for anesthesia providers that we effectively establish an airway and ensure that the patient has adequate ventilation. Now to gain competence airway management skills, it requires the knowledge of the anatomy physiology of the airway, the ability to assess the patient's airway for anatomic features that will correlate with a difficult airway management, the skill with many devices that are available for airway management, and the appropriate use of the ASA difficult airway algorithm. Let's get familiar with airway anatomy. The airway is actually divided into an upper and a lower section. The upper section or the upper airway is at the level of the cricoid cartilage, which is at the larynx and above. So any structures like the nasopharynx, the oropharynx, the pharynx, the hypopharynx, and the larynx itself is considered the upper airway. The lower airway is any anatomic structures that are below the level of the cricoid cartilage. So this includes our trachea, our bronchi, our bronchioles, terminal bronchioles, respiratory bronchioles, and then finally our alveoli. For the purposes of this talk, we're going to be just focusing on the upper airway, which again is anything at the cricoid level and above. The pharynx makes up the majority of the upper airway, and it's divided into three sections. We have the nasopharynx here, the oropharynx, and then the hypopharynx down lower. In humans, the airway is primarily a conducting pathway. Air will pass through the nasal cavity here, where it's warm and humidified, and if you can look at the anatomy here, it is such that there's much resistance to airflow through the nasal passages as compared to the mouth, and actually will account for two-thirds of the total airway resistance in the upper airway. Now moving a little further down, you can see that the oropharynx here is separated from the nasopharynx from the hard palate and then the soft palate. The hard palate is stationary and hard, but the soft palate will rise and fall here while we eat and drink to prevent food and liquids from passing from the mouth into the nose, and then we don't aspirate. I mentioned this anatomical feature here of the soft palate because it's relevant to anesthesia. When we have an individual or patient asleep or under general anesthesia, this is the structure here, or this is a structure here, that can fall back against the nasal passages, and it actually blocks airway movement and causes symptoms of sleep apnea or snoring. However, it is the tongue here in the oral cavity which is not only the predominant source of airway resistance in the oropharynx, but also the source of airway obstruction when that tongue muscle, the genioglossus muscle, relaxes during anesthesia. The tongue falling back into the airway is the number one cause of airway obstruction. So moving down here into the hypopharynx, the epiglottis here is the feature that demarcates the oropharynx from the hypopharynx. The hypopharynx is the most caudal portion here in the pharynx, and it's a crucial connection where food, liquid, and air pass. It's sort of the fork in the road, if you will. Here the airway will divide anteriorly into the trachea, into the airway, or posteriorly into the esophagus. Now just below the hypopharynx and just above the tracheus, it's the larynx. The larynx here functions in respiration, phonation, and airway protection. The barrier is the epiglottis, and that's the mechanical barrier between the pharynx and laryngeal opening. The larynx is supported by nine cartilages. We've got three that are paired and three that are unpaired. This slide will show the three unpaired. We'll look at the other ones in another slide. We've got the epiglottis, the thyroid cartilage, and the cricoid ring. This is what we call the set of unpaired cartilage. Again, the epiglottis is that mechanical barrier. The thyroid cartilage is the largest cartilage in the larynx. It provides structure and protection. Most people know this as the Adam's apple. You can actually touch your neck and feel it, especially as you swallow. Next is the cricoid cartilage, which is the only complete cartilaginous ring in the whole airway. It will go all the way around. It serves as an attachment for muscles and other cartilage and ligaments that are involved in the opening and closing of the airway and those that produce speech. When anesthesia providers assess a patient's airway, there are a few things that we're looking at that can clue us in into whether we think a patient might be a difficult airway, difficult to manage, difficult to ventilate, difficult to intubate. Some of the things that we're looking at are their malampoti score, their inter-incisor gap indentation, their thyromental distance, mandibular protrusion, and the atlanto-occipital joint mobility. We'll go through each one of these. The one airway assessment that I think anesthesia providers universally do on each of our patients is we ask them to open their mouth, we look in the back of their mouth, and we assign a malampoti score. What this is is a classification system that correlates the oral pharyngeal space with the ease of viewing the airway and ease of intubation. So with you looking at the patient at eye level, you ask them to hold their head in a neutral position and then ask them to open their mouth as wide as they possibly can and stick their tongue out. Well, without phonating, so don't tell them to stick their tongue out and say ah. But just like you see in this picture here. What we do then is we assess the visible structures in their mouth using the acronym PUSH. So the pillars, the uvula, soft palate, and hard palate. As you see here in what would be a class 1 airway, we see the tonsillar pillars, we can see the anterior and posterior pillars there, and we see both of the hard palate and the soft palate are visible and a full view of the uvula. Moving over here in the class 2 airway, you begin to lose some of the visibility in the tonsillar pillars, most notably the posterior pillars. And the opening gets a little bit smaller, the tip of the uvula is a little bit blocked off, and you can still see the hard palate and the soft palate. Moving over to a class 3 airway, you lose a little bit more, you lose the tonsillar pillars completely, almost the uvula completely, and you're starting to see only a little bit of the opening there. Moving into the class 4, which is our highest risk airway, you can see here that you can only visualize the hard palate. And so this is a clue to us that this patient may be difficult to intubate or ventilate. Okay, so what would these malampotis look like on a real patient? Here we've got someone that is clearly a malampoti 1 score, where you can see the uvula, the tonsillar pillars, the hard palate, and the soft palate, all the way to a class 4 airway here, where in this gentleman, you can just see the hard palate. I like this slide because I wanted to also mention to you that the size of the tongue, while we don't have a scoring system for that, you do want to note the size of a patient's tongue, because remember that is the number one cause of airway obstruction in a patient, especially when they fall asleep, and especially after you do anesthesia. I also wanted to mention the difference in the size of the mouth, which will be our next subject here when we assess mouth opening. Do you see how small this patient's mouth is compared to, say, the gentleman over here at the class 3 airway? So this is also a class 4 airway with a small mouth, would be a very, very high risk patient as far as intubating and ventilating. One of the other airway assessments we look for is the inter-incisor gap, which is just a fancy way of saying your mouth opening. So we look at the size of your mouth opening, assess whether or not the space available is enough space to place and manipulate airway devices. Usually, a normal mouth opening is about two to three finger breasts. You can kind of test on yourself if you've got an adequate mouth opening. I would, but I don't want to mess up my lipstick. With regard to dentition, the long incisors, like this picture that you see here, patients that have prominent teeth or prominent incisors, it reduces that size of the inter-incisor gap, and that can actually impede viewing of laryngeal airway structures when we go to intubate a patient. Also, it risks dental damage during intubation as well. Now, the thyromental distance helps us estimate the size of the subvandibular space here. We call it TMD, thyromental distance. It's measured from the thyroid collage to the tip of the chin or the mentum here, and it usually is shortened in people that have receding chins, just like the lady in the picture here. What we do is we just take our fingers when we assess the patient's airway. We take our fingers and just see how many finger breasts we have from the tip of that mentum to the thyroid collage there. Anything less than three can correlate with a poor airway view. The other one is a sternal mental distance, and that's measured from the upper board of the manubrium to the tip of the mantle as well, and we have the patient extend their neck there. And do we go to our patients with the measuring tape and check how many centimeters their sternal mental distance is? No, but it is something that we do sort of eyeball when we talk to a patient, but we definitely do check the TM distance with our finger breasts. The ease of intubation and viewing of the airway structure relies on the ability of the patient to extend their neck so that we can get a good line of sight and align the airway accesses, which I will talk about in future slides. Limited range of motion of your neck correlates with a more difficult time in securing the airway, and there are many conditions that can impair a patient's cervical range of motion. Osteoarthritis, rheumatoid arthritis, neck masses, obesity, short neck, thick neck, short TM distance, just to name a few. The other thing that we look at is the mandibular protrusion, or we call the upper lip bite test. And this is when you ask a patient to sublux their jaw, which is basically moving your lower teeth forward in front of your upper teeth. It's kind of like a bulldog, looks like, so go ahead and try that yourself. What this does is it assesses the function of the temporal mandibular joint. If you're unable to do this, it might give us a clue that you might be a difficult intubation because we do need that mobility of the TMJ to instrument the airway. So that is what we call the upper lip bite test or mandibular protrusion, just the moving of your lower teeth in front of the other teeth, in addition to looking at your cervical range of motion. So those are the other two things that we assess when we look at a patient's airway. When we induce anesthesia, the patient goes from this awake state with the ability to protect their airway to an unconscious state with an inability to protect their airway and potentially obstruct their airway. So unless we ventilate the patient with a face mask, this apnea can rapidly lead to death as CO2 levels rapidly rise and oxygen levels drop. The anesthesia face mask, which I know you've all seen here, is the device that we most commonly use to ventilate an apnea patient or to deliver anesthesia gases during surgery. It's highly effective. It's minimally invasive and requires really the least sophisticated equipment to get the job done. And it's a vital aspect of airway management and the delivery of anesthesia. You really need to be good at mass ventilation skills. They're fundamental to our practice of anesthesia. In fact, one could argue that it's the most important skill of an anesthesia provider because people don't die because you couldn't intubate them. The actual cause of adverse outcomes related to difficult airway management is the ability to oxygenate, ventilate, prevent aspiration, or a combination of these factors. So even if you can't intubate a patient, as long as you can get a face mask on there and ventilate a patient, you can save a life. So becoming proficient at ventilation with a face mask is, as you can see, critical to the practice of anesthesia and one of the first things that we learn in anesthesia training. There are a few ways we can mask ventilate a patient. Most often, the face mask is held on the patient's face in the operator's left hand, like this top picture here, leaving the right hand free for other tasks. Usually, it's reaching back and squeezing the anesthetic bag to deliver a positive pressure breath. Sometimes, a two-handed mask ventilation is needed. One provider will give a nice little effective jaw thrust and maybe a little bit of a neck extension to open up the airway, while the other provider squeezes the bag and delivers a breath. Down at the bottom picture, we do have these elastic mask straps that are really helpful, especially for providers that have petite hands or short fingers, or if you want to put the straps on and then you're free to use your both hands to perform other tasks while the patient's receiving oxygen. If you are delivering anesthetic gases this way, we can put the mask on, place the elastic straps, and these are cases where the patient can just breathe anesthetic gases and maintain spontaneous respirations. It's just really important that we make sure that there are no gas leaks around the mask so no one else in the room gets sleepy as well. These mask straps are really, really helpful for patients that are obese, edentulous, or have beards when it's really hard to get a mask seal. So, two hands or a mask strap is really, really helpful in ensuring an adequate mask seal when you're mask ventilating these patients. Remember when I mentioned the number one cause of airway obstruction was that tongue falling in the back of your throat? Well, that wasn't actually recognized until the late 1800s. When they realized that, the only way they could displace that tongue and move it forward was to open the mouth with a wooden screw and then pull the tongue out forward with either some forceps or a steel-gloved finger just to displace that tongue and open the airway. That was literally the height of non-surgical airway management at that time to get a patent airway. Now, fortunately for us, oral airways and nasal airways were designed to create this air passage by displacing the tongue from the posterior pharyngeal wall. And they're placed when it's difficult to generate enough sufficient positive pressure to deliver adequate ventilation. We turn to a nasal airway or an oral airway or another airway adjunct to help relieve these obstructions. You can estimate the size of an airway by aligning it, as you see here, with the patient's profile and then sort of approximating the anatomic path that it would take. The distal tip of the airway should be at the angle of the mandible here, and the proximal end should just be anterior to the mouth or the nose, whichever you are using. If the patient is not anesthetized deep enough, the insertion of an oral airway or nasal airway can elicit a gag reflex or make the patient cough, and so we don't want to do that. You want to make sure the patient, if they're anesthetized, are deep enough that they're not going to respond to that. typically nasal airways are a little bit less stimulating than an oral airway, so they're less likely to cough and gasp. But what we don't want to do is to have it be so stimulating in a light plane of anesthesia that they have a laryngospasm, which is when the vocal cords close. So you have to be very careful when you're doing this in a sedated patient. The end of the last century saw a swing towards supraglottic ventilation using supraglottic airways. And these are devices that isolate the airway above the vocal cords, also known as laryngeal mask airways or LMAs. So you'll hear me say LMAs, but what I'm talking about is a supraglottic airway. The LMA has become an invaluable supraglottic airway device for both routine use and also use with difficult airway management. It can be the primary means of managing an airway or it can be used for rescue ventilation in the event that either you can't successfully face mask ventilate a patient or if you fail to intubate a patient. As you can see, there are many varieties, many iterations of the supraglottic airway. They all have a flexible shaft connected to a silicone rubber mask that seals with the airway in the hypopharynx, which I will show you actually in the next slide. You'll get a closer look. The most common LMAs that we see in our anesthesia community here are B, which is the unique, C, which is the classic LMA, G over here, which actually is a little bit more rigid of a shaft and preformed, and then the ProSeal. Now, one of the downsides of the LMA is that it does not protect against gastric contents. Remember, this is above the vocal cords. So what they did to try to address that shortcoming was they created an LMA or a supraglottic airway called the ProSeal. What that does is it allows for an area, a tube here, so if gastric contents were to come up, they would go out of this tube and not into the lungs, and you can actually place this in suction as well. So that LMA tries to adjust the shortcoming of all supraglottic airways in that it does not decrease the risk of aspiration. However, the ProSeal at least is a move towards that direction. Now, I know it's hard to picture how an LMA or a supraglottic airway actually sits in the back of the throat to help ventilate, so this is why this slide is going to be so helpful. As you can see, the LMA sits in the hypopharynx here with the anterior opening here facing the laryngeal inlet and with the esophagus right here. The distal tip of the cuff here should be against the upper esophageal sphincter right here, with the proximal end here being at the base of the tongue. So at the base of the tongue. The LMA has an inflatable cuff here and here that when you fill it with air, it creates a seal in the hypopharyngeal space in the hypopharynx, and then this allows positive pressure ventilation. So you're giving it breath out here, and then it's delivered to the trachea and to the lungs here, delivered to the trachea and lungs. Although that distal tip of the LMA mass sits in the esophageal inlet here, it's important to know that it does not reliably seal it even though you inflate the cuff with air. And the LMA was not designed to protect against the aspiration of gastric contests, nor does it reliably do so. So that's why that LMA ProSeal that I mentioned in the last slide has been a great invention, because any gastric contents that comes up, if you were a ProSeal, it would bypass the laryngeal opening there and come out of a special tube here that you can place the suction. So that's a nice little feature. So one of the take-home messages here is the LMA or supraglottic airways do a great job at maintaining an adequate patent airway. You can ventilate the patient through this opening here. It does create a seal in the hypopharynx, but not a reliable seal that prevents aspiration of gastric contents to come up, which is why you would never use an LMA in a patient that just had a full meal or doesn't have an NPO status of at least eight hours. There are several reasons that we would choose to use a supraglottic airway, say, over mask ventilation or tracheal intubation. It is a less stimulating airway device than, say, an endotracheal tube. It's more definitive and less labor-intensive than just actually mask ventilating a patient during a surgery. You can either breathe spontaneously with a supraglottic airway, or you could actually take over the breathing a little bit. As long as you don't exceed a certain pressure limit, you can give them positive pressure ventilation as well. It is part of the difficult airway algorithm, which I'll mention later. So it is a rescue airway device when intubation should fail. And we can actually use this supraglottic airway to intubate through the LMA if we did need a definitive airway, such as an endotracheal tube. Again, it's fast and easy. Because it's less stimulating sympathetically, the patients typically have a better hemodynamic stability with it. You don't get the hypertension and tachycardia you would if you had an endotracheal tube in. And because it's less sympathetically stimulating, you don't need as much anesthesia on board to place it. Because it doesn't require any paralysis, say like as a tracheal intubation does, you don't have to give a muscle relaxant to place an LMA or supraglottic airway. And then again, you avoid just placing an endotracheal tube altogether, which is more invasive with higher risks. Now, the downside of it is because it doesn't protect you from vocal cord spasm, which is a laryngospasm. Remember, this is a supraglottic airway, so it's above the glottis. So the vocal cords are still there and vulnerable to stimulation where they could spasm or even close, and that's a serious event. They can, especially if they're hyperinflated, they can cause mucosal damage in the hypopharynx, so we have to be careful about that. And then as I mentioned in the last slide, it doesn't protect the airway from gastric reflux coming up in aspiration. I bet you thought I'd never get to this point. Now, let's talk about intubating the trachea. Tracheal intubation remains a cornerstone of traditional airway management. In fact, it's the gold standard for airway management. It gives us our definitive airway that us anesthesia providers just love. It gives us maximal protection against aspiration of gastric contents, and it gives us full control to positively pressure, ventilate our patients with higher airway pressures than we can get from a supraglottic airway. There are many reasons why we would choose to do a tracheal intubation on a patient. This is just sort of a short list here. Some of the more common ones are, again, to prevent the risk of aspiration of gastric contents in those patients at risk, and then surgical needs. If there's a surgery that requires muscle relaxation, we would, in fact, need an endotracheal tube for that. Any position in surgery that's other than supine, side-lying, prone position, or any long surgeries, anything typically over two to three hours, we would want an endotracheal tube in place. And then it also depends on the type of surgery. Any surgeries involving the head or neck, like with ENT surgery, we want a definitive airway in place. We don't want a supraglottic airway to get dislodged, and there tends to be some more swelling in the airway as well. Any surgery that requires lung isolation, in thoracic surgery, when we do lung surgery, we actually have to deflate one of the lungs, which you could not do with a supraglottic airway. So that requires a very specialized endotracheal tube. When the patients are critically ill, if we anticipate they're going to need to be on a vent post-operatively and going to the ICU, sometimes we just simply can't place supraglottic airway for whatever reason. It just doesn't seat well, we can't ventilate through it, then we just move to an endotracheal tube. In a patient that we think is going to be a difficult airway, we actually would choose to go ahead and intubate them rather than a supraglottic airway, because we know that we can get definitive airway. And then anyone with a neuroset of a Glasgow Coma Scale of less than eight, when at this point they're unable to protect their own airway, which then relates back to the risk for aspiration. The basics of our anesthesia intubating tools consist of endotracheal tubes here, laryngoscope handles, laryngoscope blades, and then our face mask here that we talked about already. There are endotracheal tubes that come in an array of sizes, from pediatric sizes to adult sizes. Some of the pediatric tubes actually don't have one of these cuffs here, they're cuffless. Some of these endotracheal tubes are wire-reinforced to resist kinking, some have a metallic wrapping for surgeries that involve the laser, and some even have a more of a preformed shape for surgeries such as ENT surgeries. Endotracheal tubes are made of PVC and are of course single-use only. When you ventilate through the end here, the air comes out the distal tip here or a little side port here that we call the Murphy's eye. The Murphy's eye there is kind of an alternative passage for air, just in case the tip of the endotracheal tube is up against a tracheal wall or is occluded for some reason. Here you see a blue radiopaque line, and this is so that the tip of the tube can show up on a chest x-ray, so you could check placement as you guys are familiar with in the ICU. We do have a couple different size, what we call laryngoscope blades, and this is what actually enters the patient's mouth. I will come back and talk about those in a second, but those two different kinds of blades, there are different sizes and kinds, these are just two of the more common ones that we use. They attach to a laryngoscope handle here, so you can take the blade off and use whatever blade size or type of choice. Now this handle here is actually a little bit heavier than you would imagine because it holds a battery that is used to illuminate the very distal tip of the end, so that when you place this in the back of the patient's mouth in the hypopharynx, you get a nice bright view of the glottis when you go to intubate. Now coming back to the laryngoscope blades, these are something that is the anesthesia provider's choice. We all use the handle, but we get to decide which kind of blade that we want to use, and sometimes this comes down to preference. Some people just have a little bit more luck with a curved blade, some people just have a little bit more of a preference for what we call straight blade. This is called a Macintosh, or we call it a Mac blade, and this is a Miller blade. Some of the benefits of a Macintosh are thought to be that it does cause less trauma to the teeth, there's more room for passage of the airway, the endotracheal tube, once you place it in the mouth. It's said to have a larger flange size, which makes it easier to sweep the tongue to the left and out of the way so that you can view the glottis. And because it doesn't actually touch the epiglottis, there's no trauma to the epiglottis. And so you just sort of displace it out of the way to get the view of the glottis. And I'll show you another picture on another slide so this makes more sense. The other most common laryngoscope blade is called the Miller blade or the straight blade. It's thought to have better exposure of the glottic opening. Once you're in there, Miller people have said that you actually have a better view of the glottic opening than you do with the Mac blade. It does have a smaller profile so it's really great for those people with those small mouth openings or have a small maneuverable space or very large incisors. There's less of a risk for dental trauma. And it's useful for people where we have identified through our airway assessments whose larynx looks like it just be a little bit more anterior than we would expect. And usually a larynx that sits a little more anterior typically correlates with just a little bit more challenging visualization of the vocal cords. But ultimately, the optimal blade tends to be the one that the provider really has the most experience and the most success with. With real estate, it's location, location, location. But with intubating, it's position, position, position. Positioning is everything when it comes to intubating a patient, especially if you're going to use the traditional method of direct laryngoscopy. Because with direct laryngoscopy, the goal is that you've got to produce a direct line of sight from the operator's eye to the larynx. And this is done by creating a visual access that's achieved by aligning these accesses here. So we've got the OA, which is the oral axis, the PA is the pharyngeal axis, and the LA is laryngeal axis. If we can properly position a patient, usually what we call the sniffing position, just slightly flexing the head, a little bit of elevation, we can help align the pharyngeal and the laryngeal axis. So if you can imagine standing at the head of the bed and you place the laryngoscope blade in the mouth, you could have potentially a straight shot and a nice view of the glottis when you look in there. Easier said than done, of course. A very large tongue can get in the way and an inability to align these accesses typically can be predicted when you do your physical examination. So do you remember a few slides back when we covered all the multiple airway assessments? We looked at the Malampati score, the neck mobility, the mouth opening. All of these kind of help predict how well or how unable we would be able to align these accesses here and get a direct line of sight here. While there is no one measure that may be adequate to determine the ability to get those axes aligned, there are those several predictors that we can anticipate that kind of clue us into whether a patient is going to be difficult to intubate or not. And then we make just consider some alternative methods of intubating the patient rather than do direct laryngoscopy because we have already determined that would probably be a little difficult to align these accesses. I like this picture because it gives us a nice glimpse of just how these accesses align to achieve that clear view of the glottis and the vocal cords. And the vocal cords truly are where your target is because that's where the endotracheal tube is going to go. So when one aligns these accesses here, you can see how you get a direct line of vision here to the glottic opening and then the vocal cords would be sitting right here. This is why we call this direct laryngoscopy. And in the next picture, I'll show you an even better reason why we call it direct vision laryngoscopy. Okay, so just building on the last slide, these pictures do a really great job at showing you the direct line of sight that you can achieve when that patient is placed in sniffing position and those oral pharyngeal and laryngeal accesses are aligned. So here you can see why it's called direct vision laryngoscopy because you're directly visualizing the vocal cords of the glottic area, which is this anterior portion here. I also like this slide because we could revisit those blades. Here on the left, we have the curved Macintosh or Mac blade. And here on the right, we have the straight blade, which is known as the Miller blade. And as you can see here, this white structure here is the epiglottis. With the Mac blade, you don't actually manipulate the epiglottis. It sits in this little area here. You can't really see, but it's called the vallecula. But with an upward motion, it will cause a lifting of the epiglottis and then the vocal cords would be right here and you can visually see the vocal cords. With the Miller, you just simply simply pass the epiglottis and lift up the epiglottis in order to achieve a viewing of the vocal cords. So that's a nice picture just to show you the difference. And this is why one of the advantages of the Mac blade is there's no trauma to the epiglottis because it simply doesn't touch it at all. Whereas the Miller, you might get a little trauma, although that's very rare as well. So let's just briefly walk through the steps of how we intubate a patient. If the mouth doesn't fall open naturally, then we can actually open the patient's mouth manually by using a technique that we call a scissoring technique. And so that's what this picture is here. But most of the time, the mouth falls open once they've been induced with anesthesia and they're unconscious. The laryngoscope handle and blade is typically held in the left hand and the endotracheal tube is held in the right. So you left handers out there like me, you will just learn how to do things with your right hand with precision, believe me. The blade is inserted into the right side of the mouth with care taken not to avoid any contact with the lips or the teeth. You don't want to damage the lips or have any dental damage. Both blades do have a flange along the left side of their length that's then you use to sweep the tongue to the left side of the mouth, which is why you want to enter in the right side of the mouth then sweep the tongue to the left once you're in there. And this is a really, really important step because without getting that tongue out of the way, you're not going to get a great view of the glottis and the vocal cords. So as you advance the blade into the hypopharynx and toward the epiglottis, the tongue is being compressed to the left side of the mandibular space, giving you that room that you need in the mouth. And then you have that room to pass the endotracheal tube in the right side of the mouth here. Once the blade reaches the base of the tongue, with your left arm and shoulder, you sort of lift in this anterior caudate direction, or rather a forward and upward movement. I'll show you in the next slide to demonstrate this a little bit better. But this will expose the glottic opening. And if all goes well, you should get a nice view of the vocal cords just beyond there, which in this picture, if you look really hard, you can actually see the vocal cords thanks to that bright light provided by the laryngoscope blade. So again, scissoring the mouth open, kind of sweeping the tongue to the left, the endotracheal tube would enter here, a little upward movement here, not so much rocking back on the teeth, but just an upward movement. It should open and expose the glottis and the vocal cords right there. Once you do that, you pass the tube about one to two centimeters past the vocal cords, and then you inflate the pilot balloon with about five, 10 cc's of air, and then you give some positive pressure, ventilation, and confirm placement. Now, there are a few ways to confirm placement. There is obviously a chest rise and fall, bilateral chest rise and fall, ideally. Condensation in the tube, so you hear the breath sounds, oxygenation, pulse oximetry increases, but the gold standard for placement and verification of an endotracheal tube is sustained endotracheal tube. And when I say sustained, it's usually three or more breaths. So sustained endotracheal tube is the gold standard for placement of an endotracheal tube. This slide will help describe that movement of the left arm that I was trying to describe in the last slide. Once your blade gets into, and you're in the base of the tongue there, what you're going to want to do with that left arm, it's almost like a forward upward movement, but more of an upward movement. What that will do is it will lift the epiglottis if you're using the MAC blade, and then expose the glottic opening and the vocal cords should be right there. Same goes for the Millerton blade. You're just going to be lifting the epiglottis there. It's a forward upward movement. What is important here is that we don't want to rock this back and forth. This movement this way, but not so much rocking back and forth. What that will do is just put unnecessary pressure on the lip and the teeth. And that's where most of the time the dental damage occurs. And then if you get the patient in a nice sniffing position, you align that pharyngeal and laryngeal axis, enter the mouth on the right side, sweep that tongue to the left, have that forward upward movement of the left arm, you will see the beautiful vocal cords, which is your target. Here is a closer look at your target. This is the whole glottis here. These two white structures are actually the two vocal cords and those are the paired cords there. We've got the other paired cartilages here. I won't go through that, it's just beyond the scope of this, but this is where those three paired cartilages would live. Here's the epiglottis. It is one of the unpaired cartilages and a little more floppy and less rigid than the others. Now think about if you were doing direct laryngoscopy and you got this view, what laryngoscope blade would you be using, that curved Macintosh or that straight Miller blade? If you're thinking the Macintosh blade, you're correct because you're not actually lifting the epiglottis. You're in this upper part here, that forward upper movement just sort of displaces it and lifts it out of the way. And that's one of the beauties of the Mac blade. Although a Miller blade would also give you a beautiful view too by just lifting the epiglottis out of the way completely. Now under here would be the esophagus. Remember this is the hypopharynx areas, just cephalad to the glottic opening here. And so the esophagus is right below here. So you could see why people would sometimes, especially beginners, accidentally intubate the esophagus. And if that were to happen, sometimes if you don't have a great view and you can't really visualize the endotracheal tube going through the vocal cords, you think you might have intubated, but it actually went in the esophagus in which case you would not get bilateral breath sounds or chest rise and fall. And you wouldn't get that sustained endotracheal tube that you need to confirm placement. Now, once we get down there into the glottis and we get a view of the vocal cords, we actually have a scoring system for that view as well, much like we had the Malampati score. A grade one view is the ideal view. That's when you get to see the entire glottic opening. Grade two, you just see some of the, only the posterior aspects of the glottic aperture. And so it would look a little bit like that. Grade three is a little bit worse where you're just seeing the tip of the epiglottis and grade four is the absolute worst when you just don't see really anything except soft palate. And so what we do is when we go to intubate a patient in our electronic records or any of our anesthetic charting, we write down the view that we got once we went in there intubating. This is really helpful if a patient comes back for another surgery. It's helpful to have that information that they were a grade one view or they were a grade four view. And then that would change things. If you had suspicions in your airway assessment that that might be difficult, but then you went back into their anesthetic record and saw that with the last intubation, with their last surgery, they actually were a grade three or grade four and they were difficult to intubate. That would certainly change your airway management plans. And here's what it would look like in a real person. Here is a nice grade one view. Here, you can just see a little bit of the glottic opening. You can't see all of the vocal cords. These two are the paired carvages called the arytenoids. You could only really see the bottom of the glottic opening and the arytenoids. Here, you could only see the tip of the epiglottis. That would be a grade three. And here, all you're seeing is that soft palate. So that's really important information to document to help the next person. When you get a great view of the glottis and you enter that tube with your right hand and you actually visually watch the tube go through the vocal cords, that is a lot of reassurance that you have been successful in intubating. Of course, you're gonna confirm, but it's when you don't actually visualize that tube going through, you wanna really, really make sure that you do have correct placement. So this is a beautiful view here. Yes, it does get juicy down there sometimes, but this is a nice view. You would go one to two centimeters past the vocal cords and then inflate this cuff here so it doesn't become dislodged and withdraw. Now let's move on to some frequently asked questions. One of the most common questions that we get is what do you do if you have trouble intubating a patient? Although direct laryngoscopy remains the most common method for tracheal intubation, it's not always successful on the first attempt, even with a skilled provider. When direct laryngoscopy is difficult, anesthesia providers have an array of backup equipment as you can see on this slide, these are just a few, for advanced airway management. While advanced airway management is beyond the scope of this presentation, I did want to highlight video laryngoscopy, which you can see here in many of these pictures. Video laryngoscopy has offered us a quantum leap in airway management that addresses many of the shortcomings of the direct vision laryngoscopy. Image-guided laryngoscopy now dominates modern airway management in patients who prove to be difficult intubations or who are predicted to be difficult intubations. Sometimes we will just go straight to the video laryngoscope instead of the usual blade and handle. With the video laryngoscopes, you don't need that direct line of sight that we talked about from the provider's eye to the glottis. Video laryngoscopy mimics the operator's actions of direct laryngoscopy, but places an image towards the distal end of the laryngoscope blade. This moves the provider's point of view past the tongue, avoiding the need for a direct line of sight to the glottis by aligning these axes. So this works really well for those patients that don't have that full cervical range of motion. The video laryngoscope can make up for that. So you can see why it might be perfect for those obese patients, patients with short TM distance, receding chins, or that limited cervical range of motion. In the event that direct laryngoscopy is unsuccessful, what the provider will do next to manage that patient airway really depends on a few things. One, their experience, any available airway adjuncts that they have at their facility, as well as personnel that they have to help them, and then the context and the urgency of the situation. Having said that, all anesthesia providers know and should be referring to our difficult airway algorithm. It was developed to help guide clinicians in the heat of the moment with patients who either have a predicted difficult airway or is proving to be a difficult airway in the moment when one or more of those recognized techniques is not successful. So as you can see here, here's a schematic of the decision tree. It does look like a lot. It's kind of overwhelming to look at, but once you learn it, it does make perfect sense. And again, helps us to achieve adequate ventilation, which is in the end is what we need and we want. This is a good question. How do you decide what type of airway device or what technique you're gonna use with tracheal intubation? There are quite a few things that we consider when we create an anesthetic or an airway management plan so that we have a favorable outcome and successfully can intubate this patient without trauma. We first do a very thorough airway history and physical examination. We do our physical examination and we do all of our airway assessments that we discussed. We go back into the anesthetic records and see what their anesthetic history was and their previous experiences. We take into consideration whether we think we're gonna be able to easily intubate this patient with direct or indirect laryngoscopy with the direct laryngoscopy that it's with that blade and handle, or do we think we might want to, based on our findings, maybe go for one of the alternative methods, one of the advanced airway techniques, which is, say, video laryngoscopy with what we call a glide scope or a CMAQ, something that has a video where you don't necessarily need to align those axes to get a great glottic view. The video laryngoscope does it for you. Again, we wanna assess their risk for aspiration because if they're not a risk for aspiration and it's an appropriate surgery, we might decide not to even intubate them, but we could get away with a supraglottic airway, and that might be the better, less invasive choice for the patient. And again, we review the patient's anesthetic history. I think I mentioned that. We just wanna make sure that we look back on previous experiences. Sometimes patients are great historians, but sometimes they're not. So anesthesia providers usually do a really, really good job at documenting their experiences once they're in the airway, how easy it was, how difficult it was, the grade view that they got, and if it was a grade one view versus a grade four view. We take all into that consideration when we decide what kind of airway technique or device we're going to use for the patient. Another question that people often have is how do you decide when you're gonna place a supraglottic airway, an LMA, or an endotracheal tube? Well, with a supraglottic airway or LMA, we choose to do this when mask ventilation is difficult. It helps us maintain a patented airway. If we have shorter surgeries, typically less than two or three hours, it's an option. When the surgical position is supine or maybe a slight tilt to the side, we use it in our difficult airway algorithm. It's a rescue airway management when we can't get the endotracheal tube in, but we can ventilate with the LMA or supraglottic airway. However, I want to point out that supraglottic airways, because they aren't perfect for everyone, and there are some contraindications. One, you don't want to give it to anyone that has had a full stomach. So anyone that just went to In-N-Out Burger and came in for surgery, you would not put a supraglottic airway because it does not prevent the risk of aspiration. Anyone that's obese, any trauma patient, most likely they do have a full stomach. Pregnant patients, because they have gastroparesis is one reason, and also they have that truncal obesity type, that gravid uterus that's pushing up on the stomach that increases their aspiration risk. Diabetic gastroparesis, slowing of the emptying of the stomach, and then uncontrolled GERD. We don't want them to have the acid reflex that comes in, that comes up. When we would decide to intubate a patient would be when we need to give positive pressure ventilation to the lungs when they do have that full stomach, and we wanna prevent gastric contents, or they have uncontrolled GERD, and we need to prevent the aspiration of their gastric contents. When the surgical procedure actually requires muscle relaxation or paralysis, or position is anything other than supine, a sideline, a prone, any long surgery, so anything that's greater than two to three hours. Anyone that we predict that's gonna have a difficult airway, we do wanna make sure that we have what we call a definitive airway with an endotracheal tube in, so that we can give positive pressure ventilation. When we do surgeries where the surgery is around the face and the neck, we're like ENT surgery, we like to have a definitive airway in, and not have a supraglottic airway, because that can get dislodged very easily. When we need to frequently suction patients, we'd rather do that with a tube. It's obviously more effective with a tube. And when we're doing intra-abdominal surgery, which often requires paralysis, and intrathoracic surgery, we need a definitive airway and endotracheal intubation. And then when simply we just can't do a mass ventilation, and a supraglottic airway is just either difficult to place, or it's just not seating well, and we can't adequately ventilate through it, we will choose to just opt for an endotracheal tube. Are there any complications to tracheal intubation? This is another common question that we get. Yes, there are. Nothing is without its risks, but they are pretty rare and mild. The complications to tracheal intubation can essentially be divided into three groups, or three periods. There's the complications that occur during actually direct laryngoscopy and tracheal intubation when we're placing the tube, and then there's while the tube's in place, and then there's any complications that can occur immediately, or a little bit more delayed after we extubate the patient. Some of the more common things that we see as anesthesia providers are dental trauma, especially when they have the prominent incisors like we mentioned earlier in the presentation. Lip lacerations, sometimes the airway device can just kind of nick a lip. Hypertension and tachycardia, if you don't give enough medication before you do laryngoscopy, it is a very, very stimulating procedure, and blood pressure and heart rate will skyrocket if you are proactive about pre-treating that. Laryngospasm occurs when you remove the endotracheal tube, and the vocal cords can actually have a little spasm, and that can impair ventilation. And then one of the most common things that we see is a sore throat, and that's just the mere act of that tube being in place. Having said all that, certainly the benefits of a properly placed endotracheal tube far exceeds any of the risks of actual tracheal intubation. Well, thanks for hanging in there till the end. Let's review everything you just learned. You became familiar with the airway anatomy. You learned about the various airway assessments that we use and their importance in identifying potentially difficult airways. You learned about the various airway management devices such as bagged mass ventilation, oral and nasal airways, the supraglottic airways, and all the tools that we use for direct laryngoscopy for tracheal intubation. You learned the fundamental skills required for direct vision laryngoscopy for tracheal intubation and how to confirm placement. And you learned the indications and complications for tracheal intubation. Airway management is a critical part of anesthesia practice, and as you can see, it's both an art and a science. You really need to know the airway anatomy and physiology and sometimes pathophysiology that will help you formulate an appropriate airway management plan, as well as being familiar with the airway equipment and then being also competent at the variety of the airway management skills and techniques that we have to offer. It's important to remember that no two airways are the same, just like no two patients are the same, and each patient will require a customized approach based on their needs, their risk factors that you've identified, and the situation at hand. If you stick to the established standards and protocols, including the difficult airway algorithms, you can minimize complications during both your anticipated or unanticipated difficult airways. Well, I hope you enjoyed this presentation on basic airway management. I wish you all the best in your journey, and I hope to see you someday again.

CRNA

airway management

Dr. Aura Bollinger

upper airway anatomy

difficult airway predictors

supraglottic airways

tracheal intubation

ASA difficult airway algorithm

direct laryngoscopy