Hello. This talk is on airway emergencies. My name is Todd Dorman. I'm at the Johns Hopkins University School of Medicine in Baltimore, and we're going to talk about airway emergencies. The objectives for today's talk include we're going to go through what are the signs and symptoms of an airway emergency. We're going to talk about how to recognize a patient that is at risk for an airway emergency, and then we're going to review how to manage that airway emergency, including the use of accepted algorithms. The outline for today's talk will be to cover some of the issues and anatomy of a normal airway, talk about respiratory insufficiency and the airway, discuss emergent airway control, including medications in emergencies, discuss the difficult airway, and then discuss the special circumstances of a can't intubate, can't ventilate, and the need for surgical airway potentially in that population. Before we discuss the airway, let's just talk about a couple of things related to airways outside the operating room. So intubation outside the operating room is often urgent, and so there's less time to organize all the appropriate resources. So being well prepared well in advance is required. Often intubating for respiratory failure, so the patients have limited reserve and will have desaturation much faster than is seen in the operating room, especially for normal patients. The airway is more likely to be difficult in the non-operative setting. There could be airway edema from prior intubations, or patients may be likely at the extremes of age, they may have obesity, they may have neck range of motion abnormalities, etc. Often, we can't do what we do in the operating room, which is we rely on the fact that we try to use strategies that allow us to wake the patient back up so they can just begin spontaneous ventilating again if we're having difficulty. That's usually not an option in the emergency circumstance of airway management outside the operating room. Still not a bad strategy when appropriate, but often not possible. And we may lack access to additional help. In the operating room, there's usually groups of operating rooms, meaning there's groups of airway providers, and so it's easy to get knowledgeable, skilled help quickly, which may not be true outside the operating room. What are some of the indications for managing an airway for intubation in particular? So there's the airway issues, there's respiratory issues, and then there's circulatory issues. If we started at the bottom, circulatory failure, such as shock or pericardial pulmonary arrest, would be classic issues. For respiratory failure, it's hypoxemia or hypercarbia, and or it may just be excessive work of breathing. And then finally, for airway protection, this can be seen in some patients with depressed levels of consciousness, or in the need for deep sedation, or if they have some sort of compromised airway anatomy. Let's use a question to help guide the presentation. And what should a clinician do if, at their first attempt to intubate, and an unstable critically ill patient fails? Should they try three times before getting help? Should they get help? Should they change the type of olymposcope blade being used? Should they wake the patient? Should they try video laryngoscopy? Let me pause a second so you can reflect and choose in your mind an option. The best answer here is get help. Although you may be allowed up to three attempts, you don't want to start trying to get help when you're at the third attempt. You want to get help the moment you discover that you're having any difficulty. So the key cornerstones of philosophy around airway management are that an awake airway is always best because the patient is spontaneously breathing, and so the airway is patent. If the first attempt fails, get help. We just covered that. If you can't intubate or bag mask ventilate, then use an alternative airway. And if you can't do that, then you're going to have to utilize the can't intubate, can't ventilate algorithm. Then you're not only going to call for help, but you're going to begin the process of doing a cricothyroidomy. So given this is outside the operating room and there's not a scheduled case and the events tend to be urgent to emergent, you need to have a complete plan in place. So you need to have a general medical assessment of the patient in terms of their hemodynamics, their comorbidities, potassium level as some of the agents can cause hyper release of potassium. You're going to have to think about how will you position the airway in order to maximize your ability to be successful. So in a sniffing position, are you going to use a ramp? Do they have an airway issue or a c-spine issue that requires manual inline stabilization? Are you going to use cricoid pressure? What agent are you going to choose? Should you give a paralytic? What blade are you going to choose and is that going to be a direct laryngoscopy or a video laryngoscopy? And then do you know the can't intubate, can't ventilate strategy and what is your institution's mechanism for getting you help and getting you assistance with a surgical airway if required? So whenever you're thinking about the neck, you want to make sure that you've at least thought through, I'm sorry, if you're ever thinking about the airway, you want to make sure you've at least thought through issues related to the neck. In a person who you're concerned about their neck having instability, then you do manual inline stabilization. You remove only the anterior portion of a c-collar if they have a collar on. You put your thumbs on the mastoid as in the picture and you cradle the head with your palms. You do not apply traction. You're holding inline a stable neck. Although everybody in the ICU should take time to learn how to manage an airway, you're going to actually save more patients by the ability to bag mask ventilate patients while you're waiting to get help, especially in some of the difficult airways. So what are the risk factors for difficult airway? Well, you can see that there are a variety of here. Most of these are anatomic, malampite score, decreased thyromental distance, which is here, the unstable spine that creates limitations, thick neck, large BMIs. These are all fairly similar. They're sort of anatomic limitations to the ability to bag mask ventilate. But you also have things like decreased pulmonary compliance that is important. And patients who are edentulous can be very difficult at times as well. You're going to want to think about whether you need a nasal trumpet or an oral airway to help facilitate bag mask ventilation in some of these scenarios. Although under A, you can see the grades of you when you do laryngoscopy, if you're just trying to think about bag mask ventilation and the potential for a difficult airway, then we use this classification system, the malampite classification. And you can see here one, you can see the uvula and beyond. Here you can see you don't see the tip of the uvula. Now you can't even see the uvula. Now you don't see anything. So this tends to be a very narrow opening, a very anterior location to the trachea and a large tongue creating a bad scenario at a very difficult airway potentially. So while you're thinking about the patient and their difficulty of being a bag mask ventilating patient or while you're bag mask ventilating them in some scenarios because of the urgent nature, you're going to want to start thinking through what are the risk factors for a difficult intubation. And again, you have several anatomic issues in terms of the jaw and malampite score, thick neck, decreased range of motion, et cetera. But again, you have tracheal stenosis, a history of difficult intubation. Pregnancy is its own issue relative to anatomy, reflux possibilities, potential airway edema that exists as part of pregnancy. So you're going to be thinking through so that you can have in your mind as you're building your plan, what are the risks of difficult intubation? If you believe the risks are high, then you may want to call for a difficult airway team if your institution has that or for assistance and help before you even begin proceeding. So a lot of people don't know about capnography or capnometry. So let's just start with a question. Failure to use it in ventilating patients contributes to what percentage of deaths from airway complications? So is it a small percentage or a high percentage or in between? I'm not asking about pulse oximetry since that's now ubiquitous and everybody should understand how to use it and what its limitations are. But capnometry or capnography is relatively new in the clinical environment outside the operating room and so how important is it to know what the CO2 exhalation is? The answer is on the subsequent slide, but it's 70%. Here you can see in the executive summary from the fourth annual national audit project, which is from the Royal College of Anesthetists, you can see that the monitors that are possible are your EKG, pulse oximetry, some sort of blood pressure monitor, and then this capnography, capnometry issue, and you can see that it contributed to more than 70% of ICU-related deaths. So you've gone through what the general medical issues are, the risk factors for bag mask difficulty, for intubation difficulty, and you're going to begin making sure you have all the right equipment and you're going to begin thinking about the patient and getting them in the correct position, and that best position is known as a sniffing position. You can see these pillows are here. It's causing the nose and the chin to thrust slightly forward so you get that, am I sniffing something in the air? One person has described it as sniffing the morning air. In PrEP, you're going to then begin thinking about, well, what's my induction plan here? Obviously, the goal is to facilitate a safe intubation, but you're going to have to think again about what are the medical assessments, those comorbidities, the mental status, the cardiopulmonary status, drug elimination, et cetera, and you may be thinking about are you going to give sedatives or hypnotics, paralytics, local anesthetics, or do you just need to proceed and do an awake intubation in the patient? Frequently in emergency circumstances, we don't know the status of the patient in terms of the last time they ate or drank. They may have diabetes with some degree of gastroparesis. They may be in the hospital and have significant pain, which has caused delayed gastric emptying, could be pregnant, et cetera. So we find ourselves in a position where we have to consider a rapid sequence induction. So the goal here is to minimize the time the airway is unprotected from induction until tracheal intubation. So you want to make sure that you're thinking about which patients you're going to do an RSI in. The secondary benefits are to minimize the amount of time in apnea so you get less risk of desaturation. And most commonly in the ICU, because all of these variables may be at play, it's more commonly to think about that this should be your rule rather than the exception. Now historically, we've taught people to do cricoid pressure as part of a rapid sequence induction. The pro is that the movement of the esophagus is irrelevant for you to be efficient and or effective with this maneuver with cricoid pressure. And it reduces the diameter of the hypopharynx. And I'll show you an anatomic picture in a second. The reasons against it is that the esophagus can be displaced lateral to the cricoid ring. And if people don't know how to do it, they can actually cause the airway to appear more difficult or maybe it may just be more difficult to actually intubate the patient. So this is the image I promised you of the cricoid pressure compressing the post-cricoid hypotharynx. You should be aware that recently a study showed that the, like some similar earlier studies, that this was not a very effective approach, cricoid pressure, and that maybe shouldn't be done. I can tell you that most anesthesia practices that are used to doing cricoid pressure have continued to do it. But we need to watch this over time because there may be an ongoing movement to move away from cricoid pressure. But again, in most circumstances now, even though it's far from perfect, most people think that it's the best way to try to minimize the amount of aspiration that may occur. Clearly, you need to have people who are skilled at knowing where the cricoid is and how to apply cricoid pressure. And as I mentioned, you need to be able to have ongoing communication with the person who's doing the airway management and the person holding cricoid because they can displace the trachea to the side, making it more difficult to intubate. We said one of the philosophical principles was an awake airway was better when the patient can tolerate having an awake airway. So you want to think about awake intubations. You want to give something that might be a drying agent like glycopyrrolate beforehand. You're going to think about how are you going to topicalize the airway and do you have an atomizer and do you know how to do that. This is not with a bupivacaine or similar agents that can produce other problems, but with lidocaine, do you do nerve blocks and are you careful around coagulopathic patients? Do you have a bite block? Do you have equipment for a fiber optic intubation as part of that awake or do you need that? And then how are you going to secure your endotracheal tube once you're in? So this is part of the process of being prepared for an awake intubation. So the answer to this question is embedded in these medications and it's asking which of those medications has a side effect of myoclonus. And the answer to that is etomidate. And I cover that in the sedation and analgesia talk. Since you need to choose an agent for induction, the most common ones are here, propofol, etomidate, ketamine. You can do a benzodiazepine induction, but if you don't have significant experience with that, then you really shouldn't be. Here's the dosages, the impact on heart rate or blood pressure. You can see they're all respiratory depressants and then they have side effects. Etomidate most notably for the adrenocorticoid suppression. Ketamine, which causes an indirect release of catecholamines, usually is supportive of the blood pressure unless basically the patient is completely almost out of catecholamines from being under stress for such a prolonged period of time. So let's briefly walk through the agents. So ketamine has less respiratory depression, has actually some bronchodilatations that can be useful in patients who have reactive airway disease. It's thought to be less hemodynamic label, as I just mentioned in the previous slide. But if the patient is already out of catecholamines, it is a direct myocardial depressant, so you can see worsening hypotension. And then it increases salivation. So again, giving that drying agent, an anti-sialagogue early is extra important if you're using ketamine for induction. Etomidate tends to be more cardiovascular stable, and so it can be used in those who have cardiovascular instability. But it does cause adrenal corticose suppression, whether that's in continuous infusion or even single dose. And the myoclonus can be a problem, as I mentioned earlier. Because of the perceived hemodynamic stability of both etomidate and ketamine, they've been compared. Sorry, next slide here. And here's an article from The Lancet. And you can see that the etomidate group had slightly lower probability of survival than the ketamine group. So some people will use this as a reason for picking one versus the other. But please note that although the hazard ratio is 1.2, that the confidence intervals cross 1. So technically, statistically, there's no difference between the two groups. The next step you're going to have to think about from a medication standpoint is, are you going to use a neuromuscular blocker? So these were introduced into the practice in the 1940s. They interrupt nerve impulse transmission at the neuromuscular junction. They are principally used by anesthesiologists, although intensivists clearly use them in the ICU. And if you went back 20, 30 years, they started to hit sort of a heyday of frequent use in the ICU. But given the lack of data around their benefit, the potential harm that they can cause, and the more difficulty they create in terms of awakening trials and spontaneous breathing trials, their use has decreased over time. This is just a reminder of what the nicotinic acetylcholine receptor is that we're trying to target with these agents. So this question's asking you if you're going to use a neuromuscular blocker, then you need to know about this issue of are they depolarizing or nondepolarizing? And so they're saying that four of these five are nondepolarizing, and one is not a nondepolarizing. So which one is the depolarizing agent? And the answer is succinylcholine, and we'll cover that in the subsequent material. So succinylcholine is an important agent for airway-controlled neuromuscular blockade. It's depolarizing, so it fires the muscle. So you see patients have fasciculations about 45 seconds or so after the administration of succinylcholine. Its rapid onset and short duration of action are some of its advantages, and it's hydrolyzed in the plasma by a plasma esterase. It can be dangerous to use, however. In renal failure, it burns. In other cases of hyperkalemia. And then there's some other side effects of succinylcholine that have led many people into the use of some of the fast-acting nondepolarizing agents. And so the use of succinylcholine has fallen significantly over the last decade or so. Nondepolarizers fall into a couple of different classes. The first is the benzyl isoquinolones, and this is like atricurium or cis-atricurium. And here is given to you a guide of what the intubation does. You can see the onset is fairly quick. You can give it as an infusion, and it uses Hoffman elimination and ester hydrolysis. So there's really no accumulation, making it and cis-atricurium quite useful in the ICU. And here is the additional information on cis-atricurium to facilitate you with the important final bullet that its clinical duration is unchanged in both renal and hepatic disease. So becoming a very common, especially by constant infusion agent in this very small population of patients in the ICU who require this after induction. The remainder of the nondepolarizers are aminosteroidal, and so vecuronium is one of the prototypical ones. Again, we've tried to provide you with some of the dosing information. Its elimination is somewhat unchanged in liver and kidney disease because of the dual pathway. If its liver metabolism and elimination is decreased, the kidney picks up to counterbalance that to some extent and vice versa as well, and it does have an active metabolite. Faster onset agents that would be useful in this category are the drug rocuronium, and you can see its onset is at about two minutes, and so it's become the alternative to succinylcholine, as I mentioned earlier. It really doesn't have any significant metabolism, and it's eliminated primarily through the liver. So as a general issue, neuromuscular blockers have side effects that we don't like. They can cause the patient to appear to be asleep, but the patient could have awareness. That would be horrible, and then the side effect of, if they're given continuously or for prolonged periods of time, they can relieve the prolonged muscle weakness. That can be muscular, neuromuscular, axonal, et cetera. To monitor them, you have to know how to use a monitor like a peripheral nerve simulator looking for a train of four, and when you do use them outside of intubation, if you're gonna use them more continuously, then your goal is almost never to have no twitches. It's usually to have a small number of twitches so that the patient is reversible at any given time and to avoid accumulation and the monitoring for that accumulation through the loss of twitches. So because one of the philosophies is that an awake, spontaneously breathing patient is better than one that is not, the common question is, do I paralyze the patient to control the airway or not? And so you will get good or excellent intubating conditions about 35% of the time without a neuromuscular blocker and about 95% of the time with a neuromuscular blocker. Sounds like you should lean towards using one when you can. There's a lower prevalence of hypoxemia, so it can be easier to bag mask, ventilate, and or to intubate the patient, and a lower complication rate in the non-OR setting. So you're gonna lean towards giving these unless there's an absolute contraindication like, I'm sorry, an absolute contraindication. So I mentioned that learning how to do mask ventilation is important and critical. You actually save more patients being able to mask ventilate than intubate. It doesn't protect the airway, so it's only a temporizing measure, and it requires very minimal equipment and it can be readily performed but needs to be learned and practiced potentially in a simulation setting. We've worked our way through understanding the medical issues and risk for mask and risk for intubation, and then some of the airway issues and then induction decisions around induction agents and the neuromuscular decisions. The next is, what's the tools are we gonna use to do the intubation? This is gonna be through a direct laryngoscopy, a video, blind nasal, intubating LMA, fiber optic, or otherwise. And some of this is what you're familiar with and you've been able to practice with, can be very important in helping make some of this decision. Let's just talk about a couple of these, but not all of these. So direct laryngoscopy using either a Mac blade, a Macintosh, or a Miller blade still remain a stalwart of airway management and airway control. The Miller blade is smaller. It's a straight blade. It yields a much narrower view. It's good for a big floppy epiglottis because you slide it under the epiglottis and then you lift the epiglottis and the periglottic material, I'm sorry, tissue out of the way so that you can intubate below it. And it can be useful in patients who have a decreased thyromental distance because the airway tends to be quite anterior. The Mac blade is a very common use blade. It's the curved blade. You're gonna put this into the molecular and then you lift the periglottic tissue up and out of the way. It can be very useful if you have to place a bulky endotracheal tube like a double lumen and you can facilitate suctioning, et cetera. Growing in use of the video laryngoscopy or video laryngoscope, the advantages are it doesn't require a straight line of sight. For novices, they tend to have a slightly higher success rate with this. And everyone, if you have a device that has an external monitor, can share the same view. Many of these now are portable with the monitor actually on the device itself so that you can't share the view in that circumstances. The disadvantages can be additional time to set up and to intubate. There can be blood and debris which then obstruct the view and you can't just suction as easily. It can fail inpatient with altered head and neck anatomy. And it doesn't replace the ability to be able to do fiber optic intubation. Finally, it shows you the larynx but not the pharynx. And so if the pharynx is making it difficult to pass the endotracheal tube, then a direct laryngoscope approach might be important over the video approach. So at times you may need to consider a blind nasal intubation. Really the thing that's most important here to not do it in coagulopathic patients. Don't do it repetitively and get excessive bleeding. That can then cause the airway to be more difficult. But specifically, it should be avoided in patients that have a basal or skull fracture. So the hallmarks of that are called raccoon eyes or this battle sign of the hematoma behind the ear. You can do fiber optic intubations. It's obviously a gold standard for a difficult airway. It offers the least amount of neck movement if they have some sort of C-spine issue. The disadvantages, again, are you're relying on the little camera so the blood and debris can obstruct that lens. It can be expensive. And in many circumstances, it's just not readily available. Again, if you're going to see these sorts of patients, you may want to think through and plan to have these more available. All our ICUs at Hopkins, every single ICU has a airway cart that is part of it for routine presence so that we never get into trouble not having the correct equipment and managing an airway. One of the devices mentioned to help you intubate or as a saving device in people that you're having difficulty intubating or ventilating is the LMA, the laryngeal mass airway. Again, there are a variety of these in the marketplace, some that help facilitate intubation, some that are more standard just uses an LMA. It doesn't protect the airway from aspiration, but it does make it easier to ventilate many patients that you might not be able to ventilate or intubate otherwise. And so you want to be skilled and practice, again, potentially in a simulation-like environments how to deal with the use of an LMA. Importantly is to have thought through what to do about the difficult airway. And this is the difficult airway algorithm from the ASA. You can see here, here's you started awake intubation or intubation after induction of the general anesthesia on the diagram, but you don't want to think about it just induction of the patient in, again, the ICU setting, for instance. And then you can see face mask ventilation is adequate. So you can be a little bit more patient and non-urgent. And then the more inadequate the bag mask ventilation is, the more rapidly you need to move into multiple attempts getting help, trying an LMA, trying not to get more blood and make the airway even more difficult and getting prepped potentially for doing some form of a surgical airway if required. Now, if you're having trouble bag mask ventilating and you've tried to intubate and you can't, while help is coming, et cetera, and while you're potentially placing an LMA to try to buy time for help to get there and additional resources, then you most want to think about what groups of patients. So you commonly see this in facial trauma, bloody airways, people who've had multiple attempts, head and neck radiation because of limitation in movement, burn patients, et cetera. Again, as I've mentioned several times now, you may want to consider placing an LMA as a bridge to a more definitive airway. Remember, there's no absolute contraindication to a cricothyroidomy in an adult who is dying and you can't ventilate or intubate, okay? So I'll say that a couple of different times here in a subsequent slide as well. Get a surgical airway, even if that's a needle cricothyroidomy, much better than the patient dying. And cricothyroidomy is relatively contraindicated in the pediatric, but notice it's only relative. Again, he'd be better off with a cricothyroidomy and a live patient. Live cricothyroidomy and a cricothyroid approach instead of some other approach. So it's a very superficial location. There's absence of critical structures in most patients, so there tends not to be thyroid or any of the vessels related to the thyroid right there. There's less risk of esophageal perforation because of the circumferential cricoid cartilage. It's faster and easier to do than a tracheostomy. And it may have a higher incidence of airway stenosis, particularly in kids, but again, that's quite controversial still. So as hopefully a reminder for those who have been trained, if you need to do a needle cricothyroidomy, you're gonna think about mild airway extension. Again, if there's no C-spine injury, you're gonna locate that cricothyroid membrane. You're gonna have a syringe that's partly filled with saline so that you can see the gas bubble through. You're gonna advance that needle with a slightly caudal direction, and you're gonna be aspirating until you see the bubbles appear, telling you that you're in an air-filled structure, which should be the trachea. And then you're going to take the syringe off and advance the catheter that's on the needle into the airway. If you need to, you can even put a wire in and potentially then advance an airway over that wire if necessary. If you can't do a needle cricothyroidomy or you have the tools and the ability and or you have the extra hands from let's say a surgeon or somebody who is skilled at this particular procedure, you can proceed with a surgical cricothyroidomy in these can't intubate, can't ventilate patients. Again, some mount neck extension if tolerable given any neck injury. You wanna locate the cricothyroid membrane. You make a vertical skin incision is preferable. Horizontal cricothyroid membrane incision below that vertical skin incision. Use Mayo scissors or a scalpel handle to try to dilate that incision and get it a slightly wider. And then you insert something like a 6-0 into the tracheal tube or tracheostomy tube into that hole. Remember, even though you go into the hole, the tip may not track into the trachea. You could conceivably track into the mediastinum. So you need to be careful that you actually have an adequate airway despite you placing a device. For these surgical type airways, the complications for the needle or catheter kinking, inadequate ventilation because of the bore of the needle, barotrauma if you haven't allowed exhalation and air trapping to be minimized, and you can get subcutaneous emphysema. From the surgical standpoint, you're making a bigger incision, so there's bleeding, there's passage of that tube into the false track as I mentioned. You can ultimately get infection or subglottic gustinosis as well. And their fourth national audit project out of the Royal College reminds us that you wanna limit your number of intubation attempts. If you're in a can't intubate, can't ventilate circumstance and waking the patient is not an option, then give paralytics to try to facilitate the ability for subsequent airway management to be easier. You're gonna wanna think about subglottic airway devices such as an LMA to buy you time so that you can get additional people and resources. And you need to be able to do surgical or needle and you need to be taught them and you need to practice them. You can't just sort of walk in the room and think that you're gonna be able to get away with doing them. Remember these sage words when you get to this can't intubate, can't ventilate scenario. It's not the procedure that kills patients but delaying or not doing it that can cause harm. After intubation, the most common problem is hypotension in patients. Again, assuming that you've been adequate in getting the airway controlled and you've heard breast sounds that are bilateral and you've measured in title CO2, but the hypotension can be caused from loss of sympathetic drive. Just taking away the work of breathing or the medications that were used. You could have a heart attack around the time of airway management. Remember that you've been bag mass ventilating the patient, potentially needle ventilating the patient, et cetera. So a tension pneumothorax can occur. And so remember that if they arrested the first time with some problem and you've now managed their airway, the management of their airway could lead to an additional arrest of a second etiology. And as I mentioned, a tension pneumothorax and potentially auto-PEEP depending upon the device and your ability to allow for exhalation. So the key points of this are to have a complete plan, to think this through well in advance, to be prepared to potentially have equipment and medications that are available locally so that you can more quickly obtain airway control and try to stay out of the can't intubate, can't ventilate. Don't be macho. If you're having any difficulty, get help earlier and consider an LMA to buy time for some subsequent airway management approach.

airway emergencies

recognize

manage

difficult airways

airway control

preparing in advance

surgical airway