SCCMPod-545 CCM: Improving Intubation in Critical Illness

Dr. Enfield: Hello, and welcome to the Society of Critical Care Medicine's podcast. I'm your host, Kyle Enfield. Today, I'll be speaking with Dr. Garrett McDougal and Dr. Ben Forestell about their article, "Direct Laryngoscopy versus Video Laryngoscopy for Intubation in Critically Ill Patients, a systematic review, meta-analysis, and trial-sequential analysis of randomized trials," published in the 2024 issue of Critical Care Medicine. To access the full article, visit ccmjournal.org. Dr. McDougal is currently in his third year of emergency medicine training, in the Department of Medicine, and Dr. Forestell is in his fifth year of emergency medicine and critical care medicine as well, both at McMaster University in Hamilton, Ontario. Dr. McDougal and Dr. Forestell, thank you for being with us today. Before we start, do you have anything you'd like to disclose?

Dr. Forestell: I have no disclosures.

Dr. McDougall: No disclosures. Thanks for having us.

Dr. Enfield: I would love to know a little bit about your practice environment. We have listeners who are from many different areas, and so if you guys could just start out telling us a little bit about where you work, what the system is like, and where you are in training, and maybe we'll start with you, Garrett.

Dr. McDougall: Yeah, certainly. I'm a third-year trainee in emergency medicine, FRCPC that is, here in Hamilton, Ontario at McMaster University. My practice environment is very similar to Ben's.

We practice in a surgery care emergency department in Hamilton, which is the trauma referral center for the province, or sorry, for the region, rather. Additionally, there are several ICUs in the vicinity which we work in. This includes a neurotrauma ICU, a medical-surgical ICU, a cardiovascular ICU, and then two separate ICUs with emphasis on transplant patients, nephrology patients, thoracics patients, and then another with emphasis on cancer patients.

Dr. Enfield: Awesome. What about you, Ben?

Dr. Forestell: Yeah, so Garrett and I are fortunate to be colleagues and work together clinically quite a lot. My practice, as mentioned, is within the tertiary referral centers here at McMaster University in Hamilton, splitting time between the emergency department and the ICU.

Dr. Enfield: So your publication, which from a title standpoint is just a mouthful to get out, but is also really interesting. I wanted to know, Ben, why did you guys decide to do this meta-analysis? What was the question that you hoped to be answering with this work?

Dr. Forestell: Yeah, so our meta-analysis is driven by our desire to consolidate what we do clinically with the best available evidence, and given how frequently we intubate critically ill patients in both the emergency department and ICU, and the potential, as we know, when intubating these critically unwell patients, that adverse events occur, that peri-intubation, cardiac arrest occurs. It was important for us to understand what is the best technique that we can use to deal with these critically unwell patients. Interestingly for both Garrett and myself, we both started our residency in emergency medicine.

For myself, during the COVID pandemic, and Garrett starting at the end of the COVID pandemic, where locally with the idea of reducing aerosols, the practice moved towards almost exclusively using hyper-angulated video laryngoscopy for the intubation of our critically unwell patients in both the emergency department and ICU settings. So that was our clinical interest. We're now using video laryngoscopy more frequently.

Is it helping our patients? And of course, along came the device trial in the New England Journal of Medicine published a few years ago. And based off of this well-performed pragmatic trial, there appeared to be a strong signal supporting the superiority of video laryngoscopy as compared with direct laryngoscopy in that research setting.

But as we all know, even a well-performed trial is nice, but by being able to perform a systematic review and meta-analysis, we're able to consolidate all of the previous studies and get a better understanding of the evidence base across different populations, different operators, which technique would be best for intubating our critically unwell patients. So that was the impetus for the development of systematic review and meta-analysis.

Dr. Enfield: It's interesting that you mention the shift to almost 100% video laryngoscopy during the COVID pandemic, because that is definitely was the practice pattern at my hospital as well, where we were not only to reduce the aerosolizing, but we just realized that the patients decompensated quickly sometimes. And so we were trying to increase our first pass success rate. And now I don't think I've seen an intubation without a video laryngoscope since COVID, because at least in the ICU is really the preferred and standard of care.

I wonder if you got any pushback from mentors or coauthors when you were starting this to say, this is the standard of practice, and we do have this large randomized control trial. Did people feel as you were going into that this was a question that really needed to be answered, or did people push back and say, hey, this is already been done?

Dr. Forestell: I think the challenge when performing a meta-analysis is oftentimes we have a few foundational papers, which are able to give us relatively good estimate as to what the outcome of the systematic review will be. So a priori, we had the device trial, which showed improved first pass success rates with video laryngoscopy. However, Garrett and I are lucky to have mentors here locally, both clinically and from a research perspective in Dr. Sameer Sharif and Dr. Bram Roshwerd, who perform high-level evidence synthesis in the form of meta-analyses using the best methodology and have consistently spoken to us about the importance of consolidating all the available evidence and literature to increase the certainty in how we assess the results of trials, and in particular, systematic review and meta-analysis, the amalgamation of all those trials.

So although it could be reasonable for someone to change their practice based off of the device trial alone, I think by performing a systematic review and meta-analysis, it gave us increased precision and increased certainty in the outcomes that we will discuss. So I think that was the benefit of performing this trial. I think that was the benefit in performing the systematic review and meta-analysis, and we were lucky to have that support locally to proceed with it.

Dr. Enfield: Garrett, as you were going through this, were there any particular challenges that you encountered when doing the study, or do you feel like the methodology and the literature search was fairly straightforward?

Dr. McDougall: You know, I think as Ben mentioned, we had some great support in the form of wonderful mentorship, and they have a very well-defined pathway in their approach to meta-analysis. And so I think from a study design and methodology perspective, things flowed very nicely and were quite straightforward. There were a few challenges in specific with this study.

The first relating to the patient population. So obviously, you know, critically ill patients being intubated are a highly heterogeneous patient population, different case mix, things of this variety, and that has quite significant impact. And the second being the operator profiles, and we were looking at operators from the most junior to the most experienced of anesthetists.

And so with this, we ended up with a high degree of heterogeneity. And I think this probably best shown in our trial sequential analysis, which if you look at it, you can see that we didn't reach our information size. And although this is the case, I think there's some editorialization here to say that despite not achieving our information size, I think the effect direction is quite certain.

And while further studies might, you know, further clarify the magnitude of that effect, it's unlikely to change the direction of the effect. And so that is to say it's unlikely to nullify the benefit that we see with use of video laryngoscopy. I think there's some other challenges here too, particularly a video laryngoscope is not a video laryngoscope.

There's standard geometry devices, there's hyper-angulated geometry devices, there's channeled versus non-channeled devices. There's devices of designs that I would never have even fathomed that are currently in use in practice. And so I think there's, again, a lot of heterogeneity introduced by the varying devices.

And then I think another challenge that we really encountered here related to our subgroups, there were many studies that didn't comment on different considerations like difficult airways, soiled airways, emergent versus elective cases, so on and so forth. And I think these are all really important questions that we didn't quite have, you know, sufficient data to be able to address fully. And then I think a final issue with any research in the resuscitation space, particularly in the airway management space, is there's generally non- standardization of co-interventions, pretreatment, and then heterogeneity within these, you know, where people paralyzed, what induction agents were used, was this person pre-oxygenated?

And I think we have really great and emerging evidence for many of these co-interventions to suggest that these things are quite important. So predominantly our issues with the study arose from heterogeneity in the patient population, in the devices used, and then also in the kind of co-interventions that these patients received.

Dr. Enfield: Let's dig into those results. I think, you know, the primary outcome is probably not as interesting considering we had a priori ideas of what it was going to be, but Ben, you could start talking about what you found in this study.

Dr. Forestell: Yeah, I'll go through our results. One thing that's important as I'm describing the results is I do use terminology from the GRADE methodology. So this is the Grading of Recommendations, Assessment, Development, and Evaluation methodology, which we use for systematic reviews.

And I just want to say that because when I'm describing outcomes with moderate certainty, I'll use the word probably. When I describe our outcomes with low certainty, I'll use the descriptor may. And when I describe the outcomes with very low certainty, I'll just say the result is uncertain.

I think this is just important terminology so listeners are not confused when I'm using these words, which prior to GRADE methodology were discouraged from being used in the description of results. So going through the results of our study, we found 20 RCTs, which met our inclusion criteria. And this was a little over 4,500 patients.

Now the primary outcome of interest was first pass success rate of intubation. And we found that video laryngoscopy probably increased first pass success rate. This is an outcome with a moderate certainty of evidence with a absolute increase in first pass success of about 10%.

This outcome held true across the spectrum of operator experience from very novice intubators, medical students, early residents or interns up to very experienced intubators. So mid and late career intensivists or anesthesiologists. However, the benefit appeared to be in our subgroup analysis most pronounced in the novice intubators.

Other outcomes included video laryngoscopy probably decreasing esophageal intubation. Again, this is with a moderate certainty of evidence. And we did find that video laryngoscopy may also decrease dental injury in aspiration.

These are with a low certainty of evidence. Now when we think of some of the patient important outcomes, understanding that patients probably don't care if they're intubated the first time or the 10th time so long as they survive their hospital stay, we found that there may be no effect on mortality at longest time point from using video laryngoscopy as compared with direct laryngoscopy. But this is with a low certainty of evidence.

Similarly, for peri-intubation complications such as hypoxia and hypotension, we found that there may be no effect with the use of video laryngoscopy as compared with direct laryngoscopy. But these outcomes, again, are with a low certainty of evidence and wide confidence intervals. Hence, using the descriptor of may end up being a low certainty of evidence.

One other subgroup of interest is considering the devices used. As we know, you have standard geometry, video laryngoscopy, hyper-angulated, and even other styletic devices. We found, regardless of the device used, that first pass success rate was increased with video laryngoscopy as compared with direct laryngoscopy.

Dr. Enfield: Gary, was there anything that was really surprising to you when you guys looked at these results? Anything stand out or just something that you were not expecting to find?

Dr. McDougall: You know, I think, as you mentioned, the findings around first pass success are not particularly surprising. I think we went into this with, as you mentioned, again, a priori assumption that there would be benefit there for the use of video laryngoscopy. I think what was surprising to us and probably more surprising to senior anesthesiologists is that that effect held, even for that most expert group of intubators.

And interestingly, in discussion with several such individuals since this publication, I think there's almost a sense that this doesn't, the evidence doesn't necessarily apply on the individual level and is more so representative on a population level. So I think that was a little surprising for us. And I think also a little surprising for those individuals as well.

Certainly not surprising that it's particularly beneficial for really junior intubators. I think my initial thought was that most of that benefit probably related to the hyper-angulated geometry of the video laryngoscope. Interestingly, that's not what we saw in our subgroup analysis.

And so I was a bit surprised that we didn't see a benefit for hyper-angulated as compared to standard geometry video laryngoscopy. And so this suggests that maybe we just didn't have sufficient data to fully interrogate this, or potentially it has more so to do with improved views just through use of video technology rather than the geometry itself. I think similarly, it was unsurprising that there was decreased incidence of dental injury, which probably relates to less necessity to twerk the laryngoscope to achieve a view, lesser incidence of esophageal intubation because of probably increased glottic visualization.

And then I think the other thing finally that was a little bit surprising was that we didn't see any clear benefit for people that were intubated emergently with video laryngoscopy as compared to those that were intubated on an elective basis. And I think for Ben and I working in the emergency department, we see a lot of crash intubations where the situation is very emotionally charged and quite stressful. And I think video laryngoscopy really is useful in that situation because it helps to mitigate the amount of fine motor capacity required.

And so again, a little bit surprising for us that we didn't see a clear benefit there for video laryngoscopy in that subgroup of emergently intubated patients.

Dr. Enfield: I wonder if you might opine just a little bit, just taking it off topic a little bit. I found the success rate improvement for experienced providers to be a little interesting as well. And I'm thinking back, you know, our experience with using ultrasound to put in central line, but that first became sort of the common practice, which sort of predates the beginning of your emergency medicine training.

There was a lot of people who were like, well, I've been doing this for years. I don't need to do that. But we know that really the success rate is improved with that visualization.

Do you think that these findings really support that anytime we can improve our view of things, we make everyone better and that the resistance to change really is something that we need to focus on as well as we move forward with? We improve technology. How do we help providers who are new to that technology move along with it?

Because we can make everyone do better regardless of their skill level.

Dr. Forestell: Yeah, I think this is the real challenge with the knowledge translation and encouraging providers to use what certainly a population level appears to be best for most of the patients in front of them. I would say locally, and again, I believe the COVID pandemic probably accelerated this transition to a video laryngoscopy first approach. Almost every single emergency physician attending or critical care medicine attending I've worked with will reach for the video laryngoscope first.

I would say the few people who have held off are those who are perhaps later career who have often experience in the operating room being both anesthetists and intensivists who have probably tens of thousands of intubations underneath their belts, most of these being with direct laryngoscopy. And I think in a meta-analysis, despite our definitions of experienced intubators, novice intubators, and those in between, it's going to be very challenging to capture those very experienced individuals who have a greater armamentarium of tricks that they've used to increase the success long term. So, I think this paper, even if there are a few people who may be resistant to going to a video laryngoscopy first approach, I hope it at least encourages those people to make sure they're familiar with both techniques, even if they feel like direct laryngoscopy is their best, and slowly but surely, as I think video laryngoscopy will bail them out of the more challenging anatomic airways, time and time again, feel comfortable to have both their anecdotal experience and then the experience that is reflected in almost 5,000 patients in our study that we are going to improve outcomes by using video laryngoscopy in terms of first pass success rates.

Dr. Enfield: So, for either one of you guys that wants to jump in first, is this paper launching a next line of inquiry, or do you feel like you're sort of at a stopping point here and are going to move on to a different question, knowing that there are so many great questions out there to be answered in critical care still?

Dr. McDougall: You know, I think this is something that Ben and I have spoken about at length. We both have interest in staying in the resuscitation space for research, staying in the airway space for research, and are currently doing some other work related to induction agents. I think definitely there's some subordinate questions that arise from this work, particularly things that we've spoken about, like difficult airways, soiled airways, emergent versus elective intubations.

Unfortunately, I don't think we quite have the data to really fully interrogate those questions quite yet, and so I think that's something that we'll pursue eventually as further data becomes available, but it's not quite there just yet. And then, of course, there's questions about the device characteristics as well, and I think we're both interested in this question of hyper-angulated versus standard geometry and channeled versus non-channeled video laryngoscopy. I think that as video laryngoscopy becomes more prominent, we're going to see more and more data in this space, and hopefully that'll enable us to reassess things better, analyze and better inform providers in their airway management approaches.

Dr. Enfield: Ben, anything for you?

Dr. Forestell: Yeah, I think the challenge now is to look at the patient populations who were excluded from most of the trials in our review. So, as Garrett mentioned, the soiled airway, so the patient with massive hemoptysis, hematemesis, or bowel obstruction. Anecdotally, sometimes the camera on the video laryngoscope will become obstructed and you have to reach for the direct laryngoscope.

Is there a role for performing a trial in that patient population? I think it'll be challenging to recruit, but would be informative to know on a population level is there a benefit of one technique versus another. For patients with already difficult airway characteristics, some of these patients were excluded from the trials in our review.

Is there a benefit there? You know, first the question of video laryngoscopy versus direct, which I imagine there would be a benefit of video laryngoscopy based off of what we've seen in our review, and the fact that even though patients may not be labeled a difficult airway based off of the anatomic appearance prior to recruitment and randomization, inevitably, as we know in the emergency department and ICU settings, patients have challenging airways surprising us. So, explicitly looking at population, but then again, as Garrett mentioned, what is the role of geometry of the video laryngoscope blade? So, locally we have hyper-angulated video laryngoscope blades and find involves minimal manipulation for both awake video laryngoscopy for patients with anticipated difficult airway and patients with in particular c-spine injuries and c-spine collar were intubating in the trauma bay.

So, we're providing less manipulation. Should we? Is there a role for performing an RCT in that patient population, or can we say it probably is better to be using video laryngoscopy?

That's where it gets the challenging part in terms of trial design. I'd say locally, we don't have any either observational or prospect of randomized trials in this space, but I know it's something that the pragmatic airway research group, as they continue to perform their studies as device, as the Bougie trials have shown, maybe that's an area of ongoing need for research.

Dr. Enfield: Thank you guys for both of that. Is there anything that we failed to cover that you wish we had covered?

Dr. McDougall: One thing that comes to mind is that while this paper shows superiority of VL as compared to DL, as we've been alluding to in that last bit of discussion, there's clearly patients who this may not be the case for. And I think this is particularly the soiled airway and other similar challenging airways. And I think in this case, in those airways where maybe DL is more appropriate, we're going to find ourself in a real bind, particularly with my generation, where we only have video laryngoscopy skills.

And so then you find yourself in a situation where now you're pushed to use direct laryngoscopy in an already challenging airway. And this is a skillset with which you're unfamiliar. And so I think ideally, having both VL and DL skillsets and knowing when to transition between them should be part of our toolkit.

And at the end of the day, I think this probably makes an argument for breaking out your direct laryngoscope once in a while to develop and maintain the skillset so that you have it in your back pocket for that particularly challenging airway where DL is most appropriate.

Dr. Enfield: Great points all around. And thank you guys so much for taking time out of your day to join me on this podcast. This concludes another episode of the Society of Critical Care Medicine's podcast.

If you're listening on your favorite podcast app, and you like what you heard, consider rating and leaving a review for the Society of Critical Care Medicine podcast. I'm Kyle Enfield.

Announcer: Kyle B. Enfield, MD, is an Associate Professor of Medicine in the Division of Pulmonary and Critical Care at the University of Virginia. He received his undergraduate degree from the University of Oklahoma.

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