Hi, my name is Alex Niven. I am a professor of medicine in the Division of Pulmonary and Critical Care Medicine at Mayo Clinic in Rochester, Minnesota. And it is a privilege and pleasure to join you today to talk about the topic of airway management and bronchoscopy for the Chest Critical Care Medicine Board Review. I have no conflicts of interest to disclose related to this topic. And we're going to start with airway management. I like to start each section just talking a little bit about how the topic that I've been assigned to discuss relates to the ABIM critical care exam blueprint. And as you can see here, airway management actually cuts across several topics that are included in that summary. So the topics of endotracheal intubation and tracheostomy fall under mechanical ventilation, for which there's a significant section of the test. There's also topics covered in terms of analgesia, sedation, and neuromuscular blockade, in addition to a variety of different upper airway diseases. So we're going to systematically cover these over the course of the next 45 or so minutes. Now I'd like to start when it comes to airway management, talking about the published rates of complications that have been illustrated in the literature over the course of the last 20 plus years now. We know the critically ill patients in whom emergent intubations are necessary are more difficult to intubate, and operators often encounter a difficult airway, defined as difficulty visualizing the glottis or placing the endotracheal tube in about 10% of emergent intubations. And although arguably there is a steady decrease in the number of or the rates of complications shown in these studies from 1995 to 2021, I'm going to suggest that the rates of hypoxemia shown here in blue, hypotension in orange, and cardiac arrest or death shown in red are still pretty unacceptable for a routine procedure that we do essentially on a daily basis in our intensive care units. And of course, that data was done in controlled randomized trials. And that stands in stark contrast to the InTube study that was now published several years ago in JAMA that looked at a cross-sectional airway management experience across the globe in a variety of different ICU settings and almost 3000 patients. And this patient population, almost half the patients experienced at least one major event during intubation. And you can see the definitions here for cardiovascular instability, the need for phasopressor or fluid bolus, severe hypoxemia and cardiac arrest, and the resulting morbidity and mortality in this population was significant. So we still have a significant challenge as a community and an opportunity to improve the safety and effectiveness of this procedure. Why is it so hard to intubate somebody in the ICU? Well, I think we all are acutely aware of the challenges that we confront in this procedure on a daily basis. Often we face a patient who needs to be emergently intubated, and we therefore have limited time to do a systematic airway assessment. And as opposed to our colleagues in the operating room, many of our patients have full stomachs, so the risk of aspiration is greater. When we think about airway challenges in the ICU, most authors divide these challenges up into physiologic difficulties and anatomic difficulties. From a physiologic standpoint, our patients often have significant acute on chronic cardiac or pulmonary disease that leads to greater degrees of hemodynamic instability during induction and more rapid onset of hypoxemia after induction and apnea that leads to shorter time for successful intubation and greater risk for severe complications, including cardiac arrest. From an anatomic standpoint, many of our patients present to us with altered levels of consciousness, perhaps airway edema, and certainly frequently upper airway secretions that must be removed before we can adequately visualize the glottis. Now one of the things that I really want to highlight is the tremendous increase in risk that we see in obese patients who require emergent airway management. This is really due to a variety of different reasons. Obese patients are much more difficult to mask ventilate, partially because it is more difficult to get a tight mask fit due to anatomic considerations and extra accumulation of fat in the face and around the jaw. Because again of upper airway narrowing and deposition of fat, we run into increased upper airway resistance that makes it more difficult to control the upper airway and perform adequate bag valve mask ventilation to provide pre-oxygenation. There's ample evidence that obese patients have decreased glottic visualization. We know that the modified Malin-Potti score, where we ask people to open their mouth and stick out their tongue without saying ah, the higher the score, the greater the likelihood that we will encounter more difficult Cormac-Lehane grades of glottic visualization. So a modified Malin-Potti score of three to four, where we're seeing only the soft palate or only the hard palate, is often correlated with grade three or above airways, where we're seeing very little glottic visualization at all. And because of the increased adipose tissue in the back and the neck, it's very difficult to position obese patients in a sniffing position, which leads to airway axes misalignment. And it's important to recognize as well that those patients who have a lot of excess weight in their chest when they lay flat, that weight can shift up towards the head, and that also can create mechanical difficulties when placing a hyper-angulated blade. From a physiologic standpoint, the extra adipose tissue makes the chest wall heavier, resulting in lung compression and a reduction in the functional residual capacity. And what that means from a physiologic standpoint is it's much more difficult to pre-oxygenate obese patients prior to induction, and after ablation of respiratory effort, we see much more precipitous declines in oxygenation, shown here on the right in this classic graph published in Anesthesiology in 1997, where you can see obese individuals' time to desaturation after paralysis is much, much shorter than moderately ill or normal adults. Perhaps the greatest or most significant landmark study looking at the contributing factors to airway management complications was the Knapp 4 study published in the United Kingdom in 2011, and this was a cross-sectional analysis of every airway episode performed in that country over the course of a 12-month period. And what they found was that a good quarter of adverse airway events occurred during emergent airway management in either the ICU or the emergency department, and the primary failure modes that led to those adverse airway events were the failure to identify high-risk patients, the failure for airway teams to systematically formulate and then execute an airway plan, and the last challenge was difficulty managing problems in a logical and organized manner. And although certainly patient-related factors were a significant causal or contributing factor, poor education or training of members of the airway team, bad judgment, lack of familiarity with equipment or resources, and poor communication were also very important factors. So what I'd like to spend the rest of this block doing is talking a little bit about a systematic evidence-based airway management approach, highlighting the importance of planning, preparation, and teamwork to maximize the safety and first-pass success of this procedure, thinking about preparation and pre-auctionation, the approach to intubation itself, rescue oxygenation is the primary priority when the first intubation attempt is unsuccessful, and really any airway manager needs to be prepared to perform a front-of-neck airway if that rescue oxygenation is unsuccessful. Now, what sort of things are potentially board-worthy as we move through this outline? Well, in terms of identifying at-risk patients, the MACOCHA score is still the best validated risk scale for identifying difficult airway or the potential difficult airway patient in the intensive care unit. Now, although I personally find this score a little cumbersome to implement in clinical practice, I do like the fact that it highlights some of the major risk factors of increased airway difficulty, including a high modified malampotty score, as we've talked about before, the presence of obstructive sleep apnea, again, reflecting back to those risk factors of obesity, reduced cervical spine mobility, which reduces the ability for us to align the airway's axes if we're doing direct laryngoscopy, and limited mouth opening, which makes it difficult for us to fit a blade and a tube into the mouth and be able to visualize what's going on. Certainly, when people have decreased muscle tone or increased intracranial pressure, that presents a significant physiologic challenge when it comes to intubation. And the more severe the hypoxemia baseline, the less time you're going to have in terms of that intubation attempt. And obviously, training and skill matters. There are a variety of different anatomic features that have been published as indicative of identifying a difficult airway. Detsky did a very nice meta-analysis of all of these papers back in JAMA in 2019, and highlighted the fact that really none of these anatomic features are particularly predictive in terms of sensitivity and specificity of a difficult airway. But of them, the upper lip bite test, where you ask a patient if they are conscious to bite their upper lip, is very helpful in terms of identifying somebody who has decreased jaw mobility or potentially large incisors. So you can see the images here moving from left to right, and so the higher the class that you see when you ask somebody to bite their upper lip, the greater the degree of difficulty you are going to encounter in terms of mouth opening and jaw mobility in terms of opening the airway to visualize the glottis. Now, what other things are really important in terms of preparation and pre-oxygenation? Well, the first thing that I do whenever I come into an ICU room and I'm preparing to intubate is to place 100% oxygen on the patient to maximize the amount of time that I'm going to have after induction to intubate. And that 100% oxygen washes out all the air in the central airway dead space, creating essentially a functional oxygen reservoir in that setting. Now, it's important to highlight that if we have time and we recognize that the patient is high risk to begin with, considering an awake intubation is always an option and perhaps something that we use a little bit less frequently than we should in the ICU setting. Patient positioning is incredibly important to maximize glottic visualization and first pass success. And I just wanted to mention the fact that there are a number of studies looking especially at pregnant and obese patients, suggesting that head of bed elevation or a ramped position may actually help to delay desaturation and provide better glottic visualization. Now, it's important to highlight that the one prospective randomized trial that has been published in the ICU looking at the ramped position actually demonstrated greater difficulty with direct laryngoscopy using this approach. Those authors, however, kept the head in a neutral position with that ramped position. Subsequently, multiple different authors have discussed how the positioning of the patient might matter in that sort of situation to maximize the view. And we'll talk about that in a minute. There are older quality improvement studies that advocated routine fluid bolus and vasopressor management in the setting of patients who are likely to develop hypotension during induction. There are now two prospective studies looking at fluid bolus that have failed to demonstrate a significant benefit. And quite honestly, the data in terms of vasopressors is still unclear. Although over time, I will confess that personally, I use preemptive vasopressors more and more in my clinical practice. This is a really nice image of an obese patient and the corresponding MRI changes that you can see that sort of highlights some of the considerations should you choose to use a ramped position. So you can see in the top row here, because this patient has additional adipose tissue in the back, the head and neck is buried in the pillow. And as a result, the airway ends up being fairly anterior. By building up the back of the occiput to align the external auditory meatus with the sternal notch and position the neck so that you see cervical flexion with atlanto-axial extension, that creates a situation where there is better alignment between the oropharynx or the larynx and the glottis and provides better glottic visualization with direct laryngoscopy or video for that matter. Now, let's talk a little bit about pharmacology. I think in general, we tend to omit premedication in this setting because of the emergent situation that we face. When it comes to the selection of induction agents, the evidence is clear that propofol provides the best intubating conditions. But when we use full induction doses, which in the operating room typically is one to two milligrams per kilogram, hypotension is common. And so if you choose to use propofol in an ICU patient, we typically recommend dose reducing by 25 to 50%, especially if the patient is elderly or has lower blood pressure to start with. And again, preemptive vasopressors in the setting can often be very effective. Etomidate and ketamine are often selected in the intensive care unit because of their better hemodynamic profile. These agents have been studied head to head combined with neuromuscular blockade using a rapid sequence induction technique in a large multicenter prospective trial in France. And we're shown to be equivalent in terms of both their hemodynamic effects and their ability to achieve first pass success along with glottic visualization. Certainly, there's been lots of conversation over the years in terms of the risk of reduced adrenal steroidogenesis with etomidate, which is certainly the case, but does not appear to translate into any sort of meaningful change in clinical outcomes. And ketamine can often cause a pressor response where the heart rate and blood pressure goes up unless your patient is catecholamine deficient, in which case you don't see that. And there is one trial looking at a combination of ketamine and propofol in a prospective randomized manner compared to etomidate and basically didn't show any difference or benefit of using that combination. And I've got a chart here that again shows the typical dose, onset of action, and duration of the effects of these agents. And again, just to underline, in older adults or patients with hemodynamic instability, we typically dose reduce these a good 25 to 50%. Now, the available evidence would argue that using a rapid sequence induction approach that includes administration of an induction agent, followed immediately by neuromuscular blockade, offers the best initial glottic visualization and chances of first pass success. Traditionally, succinylcholine has been the agent of choice because of its rapid onset of action and short duration. And you can see here the typical dose of 1 to 1.5 mg per kg. Rocuronium has been growing in popularity largely because of the ready access to Sugamidex, which is a reversal agent and is very effective at shortening the duration of Rocuronium symptoms. I simply highlight the fact that Rocuronium's onset of action is a little bit longer. It takes a little bit more time for Rocuronium to kick in. There's a little bit of a dose adjustment here. And just want to underline the fact that there is no such thing as dose reduction in the setting of neuromuscular blockade. If you choose to use lower than these doses, you will basically create all the risk without any benefit in terms of improved glottic visualization. An eminently testable board question is to talk about the contraindications for succinylcholine. Certainly, if patients have a history of side effects to anesthesia or a history of malignant hyperthermia, that is something that would prompt you to stay away from this drug. Although the increase in potassium is somewhat variable based on the available studies with the administration of therapeutic doses of succinylcholine, you can see really quite dramatic hyperkalemic responses in patients with significant neurologic disease, chronic neurologic disease, myopathy, crush injury, or severe burns, or following prolonged immobility. And for those reasons, we tend to stay away from succinylcholine in those patients. Now, after we have systematically planned and prepared, pre-oxygenated our patients, positioned them appropriately, and articulated a plan and a backup plan with clear oxygen cutoffs that would make us stop and bag the patient up again, it is important to review the best practices when it comes to the actual procedure of intubation. We know, based on a large prospective study done by the Pragmatic Critical Care Trials Group that was published in the New England Journal in 2019, the bag valve mask ventilation after induction is safe and effective to potentially attenuate the risk of hypoxemia following apnea. And we also have very little evidence to support the routine use of apneic oxygenation. So this is where we provide typically higher flows of oxygen either through nasal cannula or high flow nasal cannula after induction to delay the time to desaturation. We know that our chances of first pass success are greatest when we combine an induction agent with a therapeutic dose of neuromuscular blockade using rapid sequence induction. And there continues to be mixed data in terms of the use of video laryngoscopy versus direct laryngoscopy systematically in unselected ICU patients. Although it is very clear that video laryngoscopy provides a better glottic view and probably reduces the time to first pass success in patients who have difficult features. However, because you are placing the tube indirectly using the video scope rather than directly visualizing the glottis when you're using a direct laryngoscope blade, it may take just a little bit longer to intubate using a video laryngoscopy approach. What to do if you can't get the tube in the first time? Well, really the message here is to remember that oxygenation, not intubation, is the priority in this setting. So, if you are unable to intubate the patient on first or subsequent attempts, the first step after that is to return to bag valve mask ventilation, highlighting the five points that maximize this technique. So, two-person approach, one person holding the mask with a jaw thrust on both sides, the other person bagging, ensuring that there is a good seal and the patient's head is positioned well. Applying a PEEP valve to help increase oxygenation, sometimes raising the head of bed 15 to 30 degrees again will help with FRC and pre-oxygenation attempts. And then, if you haven't used it already, an oral or nasopharyngeal airway and using therapeutic paralysis can maximize the chance of you turning your blue patient into a pink patient. If your patient returns to an adequate oxygen saturation, well, you got to do something differently. And so, there you can use different devices, you can use video laryngoscopes, you can use a salvage direct laryngoscopy with a Bougie, which quite honestly is the most common rescue attempt that's been done in the emergent intubation trials with great success, or place an extraglottic airway until help can arrive. All of these things are very reasonable in this situation. If you can't restore adequate oxygenation, well, then really you move down an emergency pathway that leads to two rapid options. The first step, if bag valve mask ventilation is unsuccessful, is to place an intubating extraglottic airway to reestablish oxygenation and ventilation. And if that is unsuccessful, then every airway operator should be prepared to perform a front of neck airway using a cricothyroidotomy. Now, there are a variety of different ways that you can do a cricothyroidotomy. The four-step technique is most rapid, where you identify the thyroid cartilage, go immediately below that, make a linear incision, identify the cricoid cartilage, punch through with a knife, and then insert a cricoid tube. For individuals who feel less comfortable identifying anatomic structures, using a bougie to basically railroad an endotracheal tube through the hole in the cricoid cartilage has been shown to be safe and a little bit more effective for inexperienced operators. But since we're doing this procedure rapidly under duress and blindly, there is the small but real risk of esophageal perforation, airway displacement with subsequent subcutaneous emphysema and threatened airway, and certainly there are vessels on either side of the airway that can result in bleeding. But it's an important thing to consider early, especially if you encounter somebody who has significant upper airway abnormalities or significant soilage that presents great difficulties for glottic visualization. So to summarize this section of the airway management and bronchoscopy module, ICU airway management complications remain unfortunately unacceptably common, and that's because of the anatomic and physiologic challenges that we face on a regular basis in our patients. And unfortunately, we also face a significant prevalence of obesity in our ICU population, which is probably the biggest risk factor because of challenges in pre-oxygenation, more rapid desaturation, and anatomic difficulties with glottic visualization. Using our standard airway approaches, planning, preparation, and teamwork are the keys to success to maximize safety and first pass success. Remember, the two best ways of risk stratifying patients are using the upper lip bite test and then the Cocha scale. And when you are unable to intubate a patient on the first attempt or encounter a patient who is difficult, oxygenation takes priority over intubation and be prepared to leverage bag valve mask ventilation to ensure safe levels of oxygen throughout the procedure with early use of an extra glottic airway and preparation for cricothyroidotomy. So with that, I'm going to move to my next section, which is tracheostomy management. So tracheostomy is a common surgical procedure performed in ICU patients with acute respiratory failure. It's very helpful for the management of patients with difficult airways or patients likely to undergo prolonged mechanical ventilation because it removes the endotracheal tube from the mouth, which promotes better oral hygiene and clearance of respiratory secretions. And because it's a more stable airway in the neck, it can also facilitate early mobilization and conditioning, especially for trauma patients. And there's lots of qualitative work that's described the improvements in comfort, oral nutrition, and the ability to engage in speech therapy after the performance of a tracheostomy. Sometimes you will hear people talk about the use of tracheostomy to facilitate liberation from the ventilator. And that's really because placing the tube in the neck basically bypasses the dead space of the upper airway. So it reduces a little bit the work of breathing. And because these tubes are often a little bit larger, it also decreases the artificial airway resistance. Well, the diameter is the same, but the tube is a little bit shorter. And obviously, when you're weaning patients, it's easier to take them on and off the tracheostomy with a ventilator to give them spontaneous breathing trials. Now, the timing of tracheostomy has been a challenge ever since I started in my training back really at the end, at the turn of the century. And suffice it to say, in terms of a brief summary, that the data in terms of appropriate tracheostomy timing and the benefits of early tracheostomy remains a topic of some debate. The most definitive work in this area was a meta-analysis of 15 randomized controlled trials, a little bit over 3,000 patients looking at early versus late tracheostomy. And what you see in patients who receive a tracheostomy procedure early is no difference in terms of short-term mortality, risk of ventilator-associated pneumonia, or hospital length of stay. Not surprisingly, because these individuals can be taken on and off the ventilator very easily with a stable airway, you see a shorter length of stay in the ICU and a little bit of a shorter duration of mechanical ventilation, along with less use of sedation. And those are really the big signals that are out there. As a result, most experts recommend the consideration of tracheostomy as somewhere around 10 to 14 days into mechanical ventilation, and that remains, I think, the common standard for most institutions. Now, there are lots of growing interventional pulmonary programs across the country, which has led to a significant increase in the use of percutaneous tracheostomy. And there's a lot of advantages to this technique. It's a bedside procedure, so it reduces the administrative complexities of scheduling an operating room. As a result, it can be done more rapidly and at less cost. And because the procedure is a medical procedure, where we make a skin incision, insert a needle through the second or third tracheal inner space, and then thread a wire and dilate, as we would with a central line, there's typically a lower overall blood loss and risk of infection with the procedure, although the long-term complications compared to a surgical tracheostomy are very similar. Disadvantages, early studies in terms of percutaneous tracheostomy described a fair degree of tracheal laceration and perforation. And positioning is incredibly important to be able to expose the appropriate area of the anatomy. And so obviously, we're not going to be able to hyperextend an unstable cervical spine. And if we can't identify the anatomic landmarks, it becomes a little bit more difficult to do this at the bedside. This just highlights the standard that we now use in terms of percutaneous tracheostomy. So this is showing a view through a bronchoscope, which is right now in position right at the end of the endotracheal tube, which has been pulled back almost to the level of the glottis, that provides the operator performing the tracheostomy the ability to see their needle go through the anterior tracheal wall, marked here in blue, and reduces the risk then of posterior tracheal laceration or esophageal injury, and allows you to directly visualize then the steps of the procedure and the ultimate placement of the tracheostomy tube, as you can see here on the right. There are two common tracheostomy tubes, the Shiley on the right, which has a rounded or ovoid base to it and an inner cannula. We often use a Shiley early on. So during initial tracheostomy placement, because blood and secretions is the rule rather than the exception, and in a fresh tracheostomy, it then allows us to remove the inner cannula, clean it, and replace it without a great deal of difficulty. On the right, you see the bivona. So as one of my good colleagues used to describe, bowtie bivona is the way that you recognize the plastic shape of the ties or the tie anchor here. Bivonas are really advantageous in patients who require chronic tracheostomies because the profile of the balloon is a little bit less prominent, allowing one to deflate that balloon and breathe around the tracheostomy with less difficulty and secretions. But it doesn't have an inner cannula, and so typically we use bivonas after the tracheostomy tract has matured, so after at least seven days. Common complications associated with tracheostomy includes dislodgement. Because the tracheostomy tract has not epithelialized for the first week or so after the procedure, replacement of a tracheostomy that is displaced in this period of time should be done fiberoptically, preferably in the hands of an expert and the operator who performed the procedure. If you were asked what to do in this sort of situation on a board exam, the immediate correct answer is to perform orotracheal intubation to stabilize the situation, passing the endotracheal tube past the tracheostomy hole and blowing the tube up so that you can restore ventilation and oxygenation. Now once that tract is mature, then it's no big deal. You can basically take the tube and pass it back into the trachea, ensuring that the tube passes smoothly and without resistance fairly safely. We encounter a situation at least once a year where people fail to recognize the best way to manage obstruction. If you have a Shiley catheter, a Shiley tracheostomy, no big deal. If your tracheostomy is obstructed, the patient is struggling to breathe and you can't pass the suction catheter, just remove the inner cannula and pull it out to restore the opportunity to ventilate or oxygenate. With a bivona, you can simply remove the tracheostomy. It's an entirety, clean it out, and most tracheostomy patients have an obturator or replacement tracheostomy immediately available at the bedside. Tracheitis or stomal infection is most common in the immediate post-procedure period in more debilitated patients with poor degrees of nutrition and are typically treated with topical therapy with or without systemic antibiotics. And then tracheomalacia is something that is a late complication and is often associated with inappropriate levels of balloon inflation. Bleeding is another thing that we worry about significantly in tracheostomy patients. Early bleeding is almost always due to localized bleeding in or around the surgical site that can often be controlled with direct cauterization. Late bleeding is often related again to inflammation, granulation tissue, or local infection with friable tissue. But over time, especially in adults with poor degrees of tissue and nutrition, that tracheostomy can migrate with its stoma closer to the large vessels that you can see on this image to the right. And the biggest thing that we worry about is a tracheoinominant fistula, which can sometimes be a catastrophic and life-threatening event. And again, you can see just how close the inominant artery here is to a typical tracheostomy site in this 3D reconstructed image. Tracheostenosis we see less and less commonly in clinical practice. Tracheostenosis is caused by ischemic mucosal damage, typically when the balloon of the tracheostomy is inflated to a degree that it is greater than the mucosal capillary perfusion pressure. So typically greater than 20 or 30 millimeters of mercury for greater than 24 to 48 hours. This is much less common nowadays with high-volume, low-pressure cuffs. And I think it just underlines the fact that it's really important to make sure that your respiratory therapists are monitoring cuff pressures and keeping it below 15 millimeters. Tracheoesophageal fistula is a rare and typically late complication following tracheostomy or in the setting of other central airway cancers. Typically, we see this related to mucosal ischemia and posterior tracheal wall erosion. And diagnosis is typically identified using either CT imaging or esophagram. If the patient is a surgical candidate, definitive management using esophageal closure and tracheal reconstruction is likely the optimal approach to maximize outcomes. Frequently, these patients, however, have multiple comorbidities that are prohibitive to consider surgery, in which case, palliative tracheal and esophageal stenting has become quite common. So in conclusion for this section of this talk, I want to highlight the fact that tracheostomy decreases the duration of mechanical ventilation, ICU length of stay, and use of sedation, but little else. And so starting to talk about tracheostomy within that 10 to 14-day window is still a reasonable timeline to consider the timing of this procedure. Certainly, the standard of care now is to perform bronchoscopic guidance whenever you are doing a percutaneous tracheostomy. And just remember, if you're asked to choose what type of procedure is most appropriate in this setting, if there's an unstable cervical spine, we need to go to the operating room. And in terms of common complications, early we worry about obstruction. Remember how to troubleshoot that Shiley versus Babona catheter, local bleeding and stomatitis. We want to make sure that we watch the cuff pressures to reduce the risk of tracheal stenosis and tracheomalacia. And fistulas and complex bleeding are rare but often life-threatening complications of tracheostomy, of long-term tracheostomy management. Finally, I'd like to spend a few minutes on bronchoscopy. Really, when it comes to the ABIM blueprint, there's not really a lot that covers bronchoscopy in the ICU. So there's a little bit of a comment in terms of airway control with airway disease, and hemoptysis is the other topic that I think directly relates to this procedure. Now, bronchoscopy in the ICU is really used for a variety of different indications. As pulmonologists, we are very comfortable using the bronchoscope to help guide the endotracheal tube for awake intubation. And other common indications include airway assessments, looking for foreign bodies like this aspirated tooth that you can see in this picture, and for diagnostic evaluation to look for ventilator-associated pneumonia, hemoptysis, potential removal of central mucus plugging resulting in significant hypoxemia and symptoms, and to identify and potentially remove aspirated foreign bodies. In terms of preparation and monitoring, we typically use lidocaine along with either deep sedation and endotracheal intubation or moderate sedation with midazolam and fentanyl for this procedure. In general, we tend to avoid benzocaine and tetracaine due to the concerns for the potential risk of methemoglobinemia, a common problem with large volumes of these medications, and typically the oxygen saturation sits around 85% with the onset of significant levels of methemoglobin. We always want to make sure that we do this with an adequate monitoring safety net in place, and I think it's important to recognize the fact that the risk of hypoxemia, arrhythmia, and bleeding is increased in critically ill patients, especially those patients who are coagulopathic, thrombocytopenic, or on agents such as clopidogrel. And typically, we don't do a lot of transbronchial biopsies in this setting because, again, of that risk of bleeding and the significant increased risk of pulmonary hypertension and uremia in this population. So let's spend a word or two on hemoptysis. Massive hemoptysis is defined variably in the literature, but typically is described as expectorated blood anywhere between 200 and 1,000 milliliters over the course of a 24-hour period, and certainly massive hemoptysis of any volume that results in respiratory insufficiency meets this definition. This is a high-risk event with significant associated mortality, and the most common conditions that are associated with this condition worldwide includes cavitary lung disease, either from tuberculosis or mysotoma, bronchiectasis, cancer, or following significant procedures in the lung, either bronchoscopic or through an interventional radiology. The classic approach to massive hemoptysis includes first placing the patient in the lateral decubitus position with the bleeding side down, followed by definitive airway management. And although there are a lot of different approaches that have been described in the literature, including main stem placement of an endotracheal tube, placing a dual lumen endotracheal tube, as you can see here in figure B, placing an endotracheal tube and then a bronchial blocker through it in figure C, or a rigid bronchoscope in figure D, I don't have ready access to a rigid bronchoscope in my ICU. And in general, in clinical practice, we should think about placing the largest possible endotracheal tube that we can to minimize the risk of obstruction from blood clots and to facilitate subsequent intervention. And after that, then we work on isolating the non-bleeding lung, typically with the use of a bronchial blocker. Now, it's important to recognize that imaging using a standard chest x-ray is not very reliable to identify the bleeding side for a patient who comes in bleeding spontaneously that's not been associated with a procedure. CT is a little bit more helpful in terms of identifying both the location and the etiology, but bronchoscopy remains the standard in terms of early identification of the bleeding source when this is unclear and for management considerations, including placement of a bronchial blocker and the use of cold saline, epinephrine, or now tranexamic acid, which is shown to be as effective, if not more, than epinephrine. And then this is where I call my interventional pulmonary friends, who have all sorts of different tools to reach for in terms of hemostatic agents, APC, and potentially stenting to stop massive hemoptysis in this setting. Unfortunately, when we see lots of blood in the airway, it's very difficult to control that situation bronchoscopically, and in those sorts of situations, bronchial artery embolization is highly effective in the right hands, although recurrent bleeding symptoms without a definitive sort of definitive control of anatomic abnormalities is also very common. Remember, the biggest thing that we worry about in terms of complications from bronchial artery embolization is the inadvertent embolization of the anterior spinal artery during that procedure, which is a rare but potentially devastating complication. And although in difficult cases, we will often involve our surgeons to assess the patients, it's important to recognize that mortality rates with surgery for massive hemoptysis is high and even higher if the procedure is done emergently. Finally, a word or two on upper and central airway disease. The last image really showed what challenging situations we can find in the setting of malignant airway obstruction. Most commonly, malignant airway obstruction comes either from head and neck cancer or post-operative complications of its management. Not surprisingly, the common tumors in the chest and neck are the things that most often compromise the airway, in addition to primary airway tumors such as squamous cell, adenoid cystic carcinoma, and mucoepidermoid tumors. Don't forget that metastatic disease can also cause threatened airways with endobronchial metastases, which most often come from the kidney, breast, colon, sarcoma, melanoma, and lymphoma. And that differential is worth remembering. When we think about the management of tracheal obstruction, certainly surgery can be considered. Either definitive tracheostomy to bypass upper airway lesions or even definitive tracheal resections can be considered for local disease. But unfortunately, many of these patients are not great surgical candidates or have too extensive airway involvement to think about a definitive tracheal resection. If you are faced with a threatened airway, in general, we recommend staying away from fibrooptic bronchoscopy because the friable tissue involved with the tumor often increases the risk of bleeding and worsening airway compromise. So really, in these situations, emergent rigid bronchoscopy is the most effective way to re-establish the airway, frequently through mechanical coring of the central airway followed by balloon dilatation and stenting. Now, a few last pearls that are favorites for board questions. Negative pressure pulmonary edema is most often encountered in children or young men who have airflow obstruction, who are emerging from general anesthesia. If the larynx is stimulated during emergence, you can sometimes develop reflex laryngeal spasm, and that leads to basically respiratory distress. So you can imagine a young, healthy person breathing against a closed glottis can develop significant intrathoracic pressure swings, resulting in postoperative pulmonary edema, hypoxemia, bradycardia, and potential aspiration. And typically, the management of this situation is to resedate and even re-intubate the patient until they stabilize, followed by, again, followed by, again, controlled extubation. In addition to removing the triggering stimulus, sometimes we can get away with administering CPAP and 100% oxygen, but often these patients need re-intubation using rapid sequence induction. There is a second postoperative pulmonary edema category, a POKE2, which is seen following the relief of a chronic airway obstruction, such as resection of an upper airway tumor. There are now guidelines that have been published in terms of the risk of post-intubation stridor, and those have been published now for a number of years, and I think are fair game for a board question. We know that risk factors for upper airway stridor and swelling following intubation include traumatic intubation, more prolonged intubation, a larger endotracheal tube placed in women who typically have smaller glottic apertures, and individuals who require multiple re-instrumentation of their upper airway. A few important things to highlight. The guidelines currently state that the cuff leak test should be reserved only for high-risk patients because it is a relatively insensitive but specific predictor of upper airway obstruction. In other words, a negative cuff leak test is not as predictive as we would like it to be in terms of identifying upper airway edema. There are now three randomized trials looking at the use of steroids in patients who have a clear failed cuff leak test that suggests a decreased risk of re-intubation and post-extubation stridor. The guidelines recommend use of the cuff leak test in high-risk patients using the features that we described on the previous slide to re-stratify individuals, and if there is a negative cuff leak test or an abnormal cuff leak test, a trial of corticosteroids prior to extubation. So, the pearls for this section includes underlining the importance of a systematic approach to maximize bronchoscopy safety, stay away from benzocaine and tetracaine sprays as it's associated with methemoglobinemia, and be aware that there is increased bleeding risk in the setting of combined coagulopathy and thrombocytopenia, clopidogrel, or pulmonary hypertension. If you're faced with a patient with massive hemoptysis, protect the airway first after placing them in a lateral decubitus position with the largest tube you can find, and if you face a threatened airway, think about early surgical tracheostomy to bypass upper airway abnormalities or rigid bronchoscopy to maintain airway control while re-establishing a patent airway. Supportive care is typically the best first approach for negative pressure pulmonary edema with CPAP and oxygen with re-intubation for more clinically severe cases, and reserve the cuff leak test for high-risk patients only when you evaluate them for extubation. Thank you very much, and I wish you the best luck on your upcoming board exam. you

airway management

bronchoscopy

tracheostomy

ICU intubation

difficult airways

complications

obese patients

systematic planning

pharmacological agents