airway, what is the incidence, the outcome, and prediction, give you a little overview on the topic. This is something that's very close to my heart and also an area of my research. Before I start, I want to tell you that I have no, my disclosures, I have no actual or potential conflict of interest related to the content of this presentation. Now when you look at complications of tracheal intubation in the critical area, and these are the large series that are available, most of them are national audits or, you know, clinical center studies, and you can see that the complications associated with airway management in critically ill patients are significantly higher than what you see in the operating room. Now why are complications so high? I come from a background of anesthesiology, and I also do about 20% of anesthesia still, so I have the opportunity to, you know, look at airway management in the operating room and in the intensive care unit in the same period of time. And in my mind, there are three fundamental differences between airway management in the two locations. Now one is the ICU environment, that is really very, very complex, I'm sure you all agree. The second is the experience of the operator, and the third most important are the patient related factors, which I'm going to be talking to you about. Now this is me trying to intubate a patient in the intensive care unit. You know, unlike in the operating room, just getting to the head end of the patient is such a struggle. There's so much clutter around me, there's so many monitors. This may be any time in the day or the night, and this is not just a patient who I have to intubate. This patient is in septic shock, so I also have to look after the hemodynamics. I just have this male nurse who's going to help me push some drugs. So this is, the environment itself makes airway management very complex and increases risk of complications. In addition to this, the experience of the operator matters. These aren't the experienced anesthesiologists whose core competency is airway management. You might have people from various specialties and, you know, at various levels of training. So the experience of the operator also makes a difference to the incidence of complications. And most importantly is the patient itself. Critically ill patients, because of their critical illness, they, you know, these alterations increase the risk of complications. And very often they have an imbalance between the oxygen delivery and the supply. The consumption may be high because of severs, sepsis, tachypnea, et cetera. And you may also have low delivery because of low cardiac output, anemia, lung disease, low FRC that is seen. And this itself, you're already starting with a patient who has quite a bit of an imbalance. You may be familiar with Benioff's curve. And this talks about the desaturation after you give a muscle relaxant to this patient. So these critically ill patients, they already start with a low FRC if they have pneumonias or other conditions. In addition to this, because of the critical illness, they have high oxygen consumption. And they rapidly desaturate after, you know, after the muscle relaxant is given on the x-axis. You can see the time in minutes. And you can see the saturation on the y-axis. And even the response to pre-oxygenation may not be as good, even if you give adequate pre-oxygenation. And you have to keep this in mind. For example, if you're pre-oxygenating someone with a normal lung versus someone who has, say, ARDS or a pneumonia, and you're trying to achieve the same end tidal O2, you know, these patients already start, sorry, with a low FRC. And you may not be able to achieve the same. So low content of oxygen in the lung, low FRC, and they rapidly desaturate. Now, all along, when we're taught airway management, we're always obsessed with anatomically difficult airway. That's what we're trying to technically get the tube in. And we are also looking at anatomical difficulty. And how do I technically get this tube in? Now, the physiologically difficult airway is a relatively new concept. It's an emerging concept. And we wrote this review in Clinical Opinion of Anesthesia some time back with my colleagues. And what is the physiologically difficult airway, really? So it is the critical illness itself increases the risk of airway management, tracheal intubation, and transition into positive pressure ventilation. So when you talk about a physiologically difficult airway, we are talking about one in which the patient's physiological alterations increase the risk of complications during tracheal intubation and transition to positive pressure ventilation. And these may be pathophysiological alterations, as you see in critical illness. Maybe hypoxia, cardiovascular instability, right ventricular dysfunction, and increased intracranial pressure, as well as even physiological alterations that you may see in a morbidly obese patient or even a pregnant patient. These are the alterations that increase the risk of complications. And these are high-risk intubations. Now, this is still an emerging definition. And many members on this panel are part of a Delphi process where we've involved experts to identify various, not only the definitions, but also to look at various aspects of management in this high-risk group, which we call the physiologically difficult airway. So if you look at the routine steps of airway management, especially a rapid sequence intubation that is commonly done in critically ill patients, these patients, as I've already mentioned, have what we call a physiologically difficult airway. Now, in addition to this, this physiologically difficult airway, as I mentioned, increases the incidence of morbidity and mortality. Now, in addition to this, if they also have an anatomically difficult airway, this further increases the risk of complications that you see in this group. So every intubation in these patients with physiologically difficult airway should be considered as a high-risk intubation, and a lot of care should be taken for this. I'm sure you've all heard about the INTUBE study. And this was published in JAMA. And I was very fortunate to be the second author on this paper, and also the co-PI of this study with Vincenzo Russotto and the Italian group. Now, the studies that I showed you previously were all single-center studies that were done on national audits. Now, this was the first real-world observational prospective study that looked at data from the 29 countries, large number of patients, 197 centers across five continents. And what they tried to look at was, how are people intubating these critically ill patients, and what is the incidence of complications? I'll just give you a snapshot of this study. The primary outcome that was looking at is, what are the complications that occur within 30 minutes of intubation? And it was a composite endpoint of hypoxia, cardiac arrest, and cardiovascular instability leading to hypotension. Now, it's very interesting, because if you look at the demographics of the patient, the most common indication for intubation was respiratory failure, which was seen in about 50% of the patients. And the second most common was neurological impairment, which was seen in the 30%. And if you look at the complications as a primary endpoint, 45% of the patients had one of these complications. OK, that's one in two intubations you do in a critically ill patient with a physiologically difficult airway has a complication. And what was a surprise finding in this study, that it wasn't hypoxia that we usually imagine. It was hypotension, which my colleague is going to speak about in some time. 42% of the patients had hypotension. We don't imagine patients to have hypotension. We're always worried about hypoxia when you're not able to get the tube in. And about 9% patients had hypoxia. So perhaps over time, we have become better at peri-intubation oxygenation. And we're not seeing as much hypoxia. But hypotension is a real complication that we don't realize occurs very frequently in patients with a physiologically difficult airway. And cardiac arrest was seen in about 3% patients. Now, if you look at the intubation procedure, and this is just, I'm just giving you some highlights of the data because I can't present the whole study. What's very interesting is that 40% of the patients were intubated with the induction agent propofol. And look at the incidence of hypotension. So propofol was the drug. And most of the people using propofol were the anesthesiologists. They were the bigger culprits than the ED or the internal medicine guy who were using ketamine or etomidate. So propofol, maybe the use of this drug, may be one of the reasons. And the other very interesting finding is video laryngoscopy was used only in 17% of the patient. And this is not from the developing world. This was also in the developed world. The penetration of video laryngoscopy in the intensive care is very low. So it's not an issue of availability. It's just about utilization was really very low. Stilette was used more commonly than the Bougie. And this was another very shocking finding. And that was that most people use auscultation to confirm tracheal intubation, whereas capnography, which is considered as the gold standard to use consistent waveform capnography, was only used in 25% of the patients. That means only one in four patients. And we know that if you have even a single episode of an esophageal intubation, the risk of hypoxemia is almost 50%. And if you have a second episode, it's even higher, unlike in the operating room. And I'm sure you may have heard of the National Audit Project, which was done about 10 years back in the UK, where they looked at peri-intubation complications. And they looked at the subgroup of the complications that occurred in the critically ill patients. And they had 164 complications. The interesting finding of the subgroup data analysis from the critically ill patients was that more than 60% of the deaths in the ICU complications led to death or brain damage, led to only 14% in anesthesia. And these events were likely to occur more out of hours when they were managed by doctors with less anesthetic experience and led to permanent harm. And the really important finding was that failure to use capnography contributed to 74% of the cases of death and permanent neurological injury. Now, this created a lot of sensation 10 years back. But even today, capnography is used only by one in four people in the intensive care unit. So we really have a long way to go to promote capnography for safe airway management practices. Another important finding was that repeated intubation attempts. So even between the first and second and the second and third attempt, there was associated with severe hypoxia and cardiac arrest. And this emphasizes the importance of having first pass intubation success. You have to do whatever is required, whatever tools you need, the experience of the operator. Everything is required. You must get it in the first time. Because every subsequent attempt is associated with increased complication. And one of the most important findings of this study was that a patient who has a complication or cardiovascular disability or cardiac arrest, this was associated with an increased 28-day mortality. Now, we've had many studies that look at complications. But we've not looked at mortality. So a complication that occurs during tracheal intubation, maybe some hypotension that you take care of, or hypoxia, or whatever it is, actually has an impact on 28-day mortality. So this intubed study was the first study that showed that those transient complications that occurred during tracheal intubation actually have an impact on long-term mortality. And we should be very careful about taking all measures to mitigate complications that occur in the physiologically difficult airway. The other, what we did was, because the incidence of hypotension was 42%, that was quite a surprise finding in the intubed study. So what we did is we did a sub-study of this. And we took all those patients who had cardiovascular collapse or hypotension. And then we did a multivariate analysis to identify what were the factors that were associated with this hypotension. And what was very interesting, that one of the independent risk factors was the use of propofol. We published this in the Blue Journal. So our conclusion in this study, I don't have time to present the details, was peri-intubation cardiovascular instability was associated with an increased risk of complications and 28-day mortality. But the use of propofol as induction agent was identified as a modifiable intervention, significantly associated with complications. So the important message is that irrespective of the blood pressure, starting blood pressure, propofol is not a drug that should be used in critically ill patients. Because a lot of times, these patients who present with acute hypoxemic respiratory failure, they're tachycardic, they're hypotensive because of the sympathetic drive. And that gives you a false sense of security. Because you say, OK, the blood pressure is fine. I can use propofol in this patient. And the moment you anesthetize them and you lose that sympathetic drive, you have precipitous fall in blood pressure. So the message from this paper is, irrespective of the starting blood pressure, propofol is not a drug that should be used in critically ill patients. So I'd like to conclude with my take-home message here is that, what is a physiologically difficult airway, really? So this is one in which the patient's physiological alterations increase the risk of complications during tracheal intubation and transition to positive pressure ventilation. So we should start thinking about physiological alterations and not just anatomical difficulty. And we should focus on the physiologically difficult airway, which has significant increases in complications. And critically ill patients have this physiologically difficult airway. And this is due to the pathophysiological alterations, such as hypoxia. You see cardiovascular instability, right ventricular failure, increased intracranial pressure. And all these increase the risk of complications. If you have a brain-injured patient and you're trying to do an intubation in this patient, any rise in ICP will further increase the risk of complications. And the intubation study that was done recently, this is a real-world study, has shown us that the incidence of complications are very high, almost 1 in 2, with 42% having hypotension, which is more frequent than hypoxia, as we imagined, and about 9% having hypoxia. And patients who experience these kind of complications during tracheal intubation have a higher risk of a 28-day mortality. So we shouldn't take these complications lightly, because they have a bearing on long-term outcomes like 28-day mortality. And with that, I thank you very much for your attention. Thank you very much.

airway management

physiologically difficult airway

intubation complications

critically ill patients

INTUBE study