Thank you very much for the honor of being here today. We're going to talk about some pitfalls and common errors in airway management. And really, we're going to talk about how to prevent those with some really basic things that we can do in the ICU. Heard about me already, work in a lot of different ICUs, also work in the military. And most of my work is in the ICU, but I am an anesthesiologist as well. No disclosures that are really pertinent to this talk. So in the brief time we've got this afternoon, we're going to talk about some anatomical and physiological considerations for obese patients while we're managing their airways in our intensive care units. We'll talk about some techniques to prevent physiologic derangements, mainly hypoxemia and hypoxia. And then we'll talk about, as we go through this, some pitfalls to avoid during the active airway management of obese patients. I'm sure you'll hear a lot more about this from my co-speakers, but I think we all recognize that the prevalence of obesity is increasing not only in the world, but in the United States. And what's pertinent to this particular aspect of ICU management is that obesity is a risk factor for some problems we can have with airway management, particularly with non-airway extubation failure. It's a risk factor for the physiologically difficult airway, meaning that these patients do have metabolic derangements that we need to appreciate and take into consideration. And we'll talk a little bit about predictive factors for difficult airways in terms of bag valve ventilation as well as intubation. It's worth reviewing the pathophysiology very quickly here because it's very pertinent, and this really becomes rapidly self-critiquing when we don't pay attention to this and prepare. The problem with obese patients is they actually have a normal PAO2. Their airways, in fact, when we intubate, there's some statistical association with difficult airways in terms of intubation. But what we really have a problem with is their reserve. They just don't have a great reserve. They have decreased lung compliance, compression of the small airways at the lung bases, which results in atelectasis and shunting. Shunting is really the major pathophysiologic problem many times when we're preparing, especially a critically ill, obese patient, for airway management, definitive airway management. And at a risk for aspiration, which we have to pay attention to. The pathophysiology is really related, though, to the decreased functional residual capacity, which is something we talk about all the time in the anesthesia world and in the critical care world. But these patients have a decreased FRC, which means they don't have a great reserve. So when we talk about pitfalls, what we're really talking about, the number one pitfall is just trying to prevent hypoxemia because that can rapidly decline quickly and get you into trouble. And so anything we can do to prevent that, especially in a critically ill, obese patient, is going to be of paramount importance for us. And this is now a classic graph that shows the time to desaturation. You can see the left curve in the red is obese patients desaturate quickly, quicker than any other population. Obstetric patients, notably, are not listed here, but they also desaturate quickly. But obese patients are really at the forefront for that time to desaturation. So something we really need to be aware of. So there's a lot of different ways we could tackle this in 18 minutes. We could talk about a lot of cool stuff like crikes and wake fiber optics. And I'm happy to talk to anyone who wants to hear about that after the talk. I'm going to focus on just really basic measures that all of us can do. And I mean all of us because this isn't just about doctors. Anybody who's involved with the patient, these are things we can do to optimize airway management. And it's not just about intubation. That is our end goal is having a definitive airway. We're talking about the ability to mask ventilate and prevent hypoxemia and prevent other derangements. So these five Ps are what I'm going to focus on. Each of them, if not paid attention to, can be a pitfall in terms of the patient declining very quickly. So we'll start really briefly with prediction. And you can talk for an hour on this. But patients that are difficult mask ventilation, that's a difficult airway. It's a difficult airway as we define it formally. If you can't mask a patient, or you're not going to have that ability to do that, and you can see obesity is an independent risk factor for difficult mask ventilation, this is going to be something that can get you into trouble. So that is and has been shown to be a pretty powerful independent risk factor. A little bit less so for intubation. There's studies with mixed results. There's some studies that say we can really, just by looking and using obesity as an independent risk factor, there's a little bit of an association with a difficult intubation, but it's not as profound as the ability to mask. But nevertheless, anatomical problems, and we can do this very simply from working outside in, starting with the teeth, working your way down into the larynx, looking for external landmarks, thyromental distance. I'll show you this slide here, which is out of the Wall's Manual of Emergency Airway Management. And they have three different mnemonics that each can be used for prediction of bag valve ventilation, endotracheal intubation, or a surgical airway, cricothyroidotomy. And each of these scoring systems, based on the literature, obesity does factor prominently. And in fact, for crics even, it's not listed there in the same way, but anatomy of having a large neck can obviously be a huge problem in terms of trying to secure surgical airway. So these are just some mnemonics that we've used, but I do think the first pitfall to avoid is to be ready to just really, I think it's pretty obvious when you have a patient who's really super morbidly obese that you wanna consider each of these patients to be a potentially difficult airway. I think that's the first place to start. The second place to start, and this is where you can really make a difference. I personally cannot tell you how many times we've had records in the chart of patients being difficult airways. We take all the precautions, mainly repositioning the patient, and then we wind up with what would have been a grade four view to a grade one view. So simple positioning can make a huge difference, but what does the literature really say about this? The sniffing position is taught widely. This is really talking about aligning those three axes, the oral, pharyngeal, and laryngeal axes to get you on final approach to the vocal cords when you're performing laryngoscopy. It's really simple. You flex the neck, and then you extend the head on the neck. And this is something we like to do with every patient, regardless if they're obese or not, but we don't have the luxury if they have a cervical spinal injury, of course. But when we have an obese patient, this is really, if you can do this, I would strongly encourage thinking about this. The ramp position, we'll get into the evidence base in a second, but this is really your best bet to get yourself in good shape. Not only will it help you with a better view when you perform laryngoscopy, it will also help you stay away and allow you to get your handle of your laryngoscope in. What we're looking for here, you can have a proprietary device like you see in the left, and we do have a few of those in our hospital, but most of the time, we just use blankets. You don't need any special resources for this. But by creating that ramp and plateau and looking to get that ear to sternal notch level, that's your optimal position, and this can often have a dramatic improvement in your view and your ability to manage that airway quickly and efficiently on the first pass. There's other variations, such as this device. I've never used it, but it's reported in the literature. This was a small study of 60 patients, but they found a faster time to laryngoscopic view and securing the airway with an endotracheal tube. It's really just a variant of the ramp position. And so, okay, we're in the ICU. It's great if we have time to ramp the patient up and we can grab blankets, but we can't always do that. Sometimes you're called in rapidly and you don't have enough time to even do that because you're trying to pull out your endotracheal tube, get your drugs ready. It's a lot. It can be a lot. So if you can't do that, if you can't, maybe the next best thing to think about is the reverse T position, reverse Trendelberg position. I won't go through all the data here, but you can see a longer time to apnea, meaning that when we go apneic, you have a longer time before desaturation occurs. And then when it does occur, you get a faster recovery time. So this is a really simple intervention we can do in the majority of our ICUs. It's better than just putting the head up. You really do need to tilt the entire bed. That's what this study showed. This was a small study that was later confirmed by another larger study where they looked at these different positions and did find some beneficial effects. So what's really best? I think there's no overall benefit for non-obese patients. So we don't ramp every non-obese patient. We just use sniffing position, although you certainly could, there's other things we can do for that population. But for obese patients, I would strongly recommend you really consider that ramp position. It is statistically associated with improved laryngeal views. It's also improved with better first pass success rates. And the more the BMI, there's a linear relationship with the view staying consistently good so that when you go in with your laryngoscope, you're able to get it. Intubation time has also been shown to be decreased when you execute this position. All right, pre-oxygenation. This is a hot topic in a lot of different areas as well. And just a couple quick physiologic things to review. When we actually do this in the operating room, we have the luxury of doing this in the operating room. What we're doing is the fractional alveolar oxygen concentration. We're trying to increase that so that we can wash out the nitrogen. And by doing that, we can measure this in the operating room. It's not prevalent in most ICUs, but you can check the end tidal oxygen concentration. And when that's really high, above 80, well, 90 is even better, but when you're at 80%, you've got about two liters of oxygen in those lungs. And that's about eight to 10 times your normal oxygen consumption. Now, this is in healthy elective patients. Half that for critical care patients, or maybe even more. It might be even 25% of this. But it will provide you a little bit of a reserve if you can pre-oxygenate and you have the luxury of doing so. And this is the physiology of it. You're basically washing out the nitrogen. You're trying to fill what remaining FRC is available with oxygen. And if you can do that, your time to desaturation will decrease, will increase, actually. So in other words, a patient won't desaturate as quickly. But even so, even so, you're not going to have a huge window even with this technique. But it's something we should try to pay attention to because it does provide us a little bit of a cushion. And better yet, if we can put on non-invasive ventilation, this has been looked at in several studies. This is just a systematic review that also, a meta-analysis that has a force plot here that's very much in favor of prolonging the safe apnea time by doing adequate pre-oxygenation and also increasing the PaO2. And so that was demonstrated here with these studies. Now there's a couple other tricks we can do when we get to pre-oxygenation. I've done this a couple times, mostly just with teaching with residents and fellows, just kind of probably, I'm not sure if it really works all that great. It's not really widely supported in the literature. I have a couple of references here, but you can take a ray tube, which is just a bent, you can see that bend on the tube, a very pediatric ray tube, and kind of stick it right next under the cheek there and kind of insufflate some oxygen. That's one technique that's been described. Probably not as effective as some other techniques though. And I think these are the ones that I do try to implement whenever possible. So nasal CPAP can be really effective. A couple advantages here. One, you've got that continuous positive airway pressure. Two, if you do have a patient, and patients that are obese do, may have a tendency to be more at risk for aspiration. In fact, a lot of our ICU patients who are gonna be managing their airways is oftentimes for an aspiration event. And so you're not able to really suction well if you're doing a full face non-invasive mask, but if you have this, you do have the ability to suction. So it's another advantage. And this has been shown in several studies to also give you a better apnea time and prevent hypoxemia. And this is just another device. I've not used this, but it is reported in the, it's reported in the literature in some small studies, just a proprietary device that basically does the same thing, nasal CPAP. So what if you don't have that? A lot of places won't have that. You may be in an austere setting, maybe you're in a smaller hospital. What basic things can we do to try to really pre-oxygenate our patients better? This is one thing you can do. You can put a nasal pharyngeal airway in, put a nasal cannula over that, and crank it up to 15 liters a minute. And that actually has been shown to work. It's been shown to give you a little bit more apnea time, maybe a minute and a half. I'll take a minute and a half. I'll take that a lot of times. That can be the difference between maybe a mishap with your syringe falling on the floor or dropping a vial of drug on something or trying to find something, you're bougie, whatever. So I'll take that. But you know, it's just, this is really not probably the best way to pre-oxygenate, but it is one more way to pre-oxygenate. And then of course we have the high flow nasal cannula, which we've all used extensively, I think worldwide at this point. And what does the literature on that show? It's not quite as strong as you may think. And here's the problem with this. A lot of these studies I'm showing you are done in elective bariatric populations, not truly critically ill patients. Okay, so that's important. We're extrapolating a lot of these data to a population that's much sicker and has even worse of a reserve than what we were describing earlier. But you know, versus a face mask, there was an absolute risk reduction here, which is pretty significant and a low number needed to treat. So if this is an option and you have it, the problem with high flow nasal oxygen or high flow nasal cannulas, it doesn't provide the denitrogenation as well. It just doesn't because your mouth's open and you're not really closing that off and washing out the nitrogen to really try to maximize your reserve. And that was also shown here. This is where they use a regular nasal cannula and they actually didn't find, they found the duration of safe apnea was actually kind of the same in both groups. And even with the high flow nasal cannula, and check out that pressure. That's 120 liters a minute. Most of our high flows that I've used, 60 to 80, not 120. I don't think I've ever gone that high. Maybe you have. But they didn't find much of a median airway pressure and they did measure it in this study. So it's another option. Unfortunately, with obese patients, we're not seeing a ton of data that it's incredibly, incredibly effective, but it's another option to have in your armamentarium. There's a lot of studies in the ED literature. This is just one nice systematic review and meta-analysis. Again, shows a forest plot very much in favor of apneic oxygenation. But the problem is when you look at these studies, and this one in particular, not an obese population. So this is a whole separate topic. I know we've had lots of good talks on this in the past years in SCCM. I just think you have to be careful with extrapolating some of this to the obese population. I would say non-invasive ventilation's the way to go, preferably nasal CPAP if you can do it. So we'll talk about performance quickly here. So should you use a video laryngoscope? I'm gonna give you my bias. I think the answer is yes. I think the answer is yes. In this day and age, I've got one in the back of my car. I do. Kind of nerdy like that with the EMS stuff. So I can't say that they're that prohibitively expensive. If your hospitals are pushing back, I think this is a really helpful device. There is a systematic review that you're probably aware of this. Pretty good relative risk in terms favoring video laryngoscopes. I'm very agnostic to the type of, at our institution, we use a lot of GlideScopes and CMAX, but I've used them all at this point. And they're all very effective. They provide good QA. And they have been shown to be a little bit less traumatic. And I think the biggest thing for us is critical care professionals. For everybody in the room, it provides situational awareness. Everybody can kind of see what you're seeing and anticipate the next move, especially our respiratory therapists and our nurses. So that's why I am very much in favor of video laryngoscopy. And in terms of using this in obese patients, they did look at this in one study of 100 patients, the CMAX versus the McGrath. Both were effective. There were no failed intubations. And both groups had a very high success rate of first pass success of placing the endotracheal tube. Briefly, post-intubation management. There's some great talks, which I'll reference at the end, here at Congress. But going back over this physiology here, a lot of what we see is related to the transthoracic pressure and also that decreased FRC. The cranial displacement of the diaphragm, it's really the caudate displacement of the diaphragm. When that diaphragm, I'm sorry, cranial, when the diaphragm comes up, you're losing that residual capacity and you're losing your ability to have any reserve. And that's why you really have to be cognizant of that once you place the patient on the ventilator. And it's really a whole separate talk, but I will just quickly tell you that, think about, you can think about early recruitment maneuvers and literature on this in obese patients is a little mixed. One study I quote here used a recruitment maneuver up to 50. PEEP is generally in the range of 10 to 26, usually around 15 on average. So more PEEP than not. We have to watch the hemodynamics. Again, a separate topic and talk. And really being careful about predicted body weight, just as a reminder. I think we all know this very well. And also if you extubate a patient, I will tell you in my practice, I have a very low threshold to put somebody on non-invasive ventilation, an obese patient. You'll get pushback sometimes because it is labor intensive. It does require your respiratory therapist to do one more thing. You know, it's a lot in this day and age with short staffing. But it has been shown to decrease respiratory failure, especially if you have a patient with obstructive sleep apnea. Have a low threshold if you're dealing with a surgical population post-op to use that modality. And then finally, I really admire Dr. Barra and his team at the MGH. This is one of their first reports, 70 obese patients. They basically have a cart. It's more than a cart. It's a whole bunch of gadgets that really optimize the ability to ventilate patients who are obese. In this study, they had BMIs around 50. And they found a dramatic decrease in mortality with this small study. But I really admire what they're doing up there with manometry and multimodal techniques to make sure that they're really maximizing the ability to ventilate obese patients. They find, what they oftentimes find, is very high PEEP levels that we normally would not target. But they are able to do that with objective measurements. So in conclusion here, I just want to remind you that there is a really good book on this. It's out at the education section. Airway Mechanical Ventilation, which is done by SCCM. Has some, the first four or five chapters are all airway management. Branson's gonna talk tomorrow about trauma patients and how to ventilate. And he'll get more into the ventilation. I'm gonna personally be in the front row on that one. Never miss a talk by Rick Branson. And then patient-ventilator interactions as well, which I didn't go over, but that's another big part of this. And then finally, there is a nice systematic review in this month's Critical Care Med that talks about the utility of ultrasound for prediction of difficult airways. So just in conclusion, think about your five Ps. And that'll help you avoid the pitfalls of catastrophic hypoxemia and hemodynamic demise. Thank you very much.

airway management

obese patients

ICU

prevalence

video laryngoscopes

predicted body weight