Amanda Wilde (Host): Welcome to MDCast by Tampa General Hospital, a go-to listening location for specialized physician-to-physician content and a valuable learning tool for world-class healthcare. In this episode, we'll focus on posterior glottic stenosis, an upper airway blockage or narrowing that is oftentimes a result of intubation. We'll cover early recognition, management, and prevention with laryngologist Dr. Manish Shaha. I'm Amanda Wilde, your host. And Dr. Shaha, welcome. Thank you for being here and sharing your expertise.

Dr. Manish Shaha: Oh, thank you for having me.

Host: Why are we now seeing an apparent increase in posterior glottic stenosis? And to what extent is this truly iatrogenic, the result of medical intervention, or is it simply being better recognized now than it was in the past?

Dr. Manish Shaha: I think it kind of plays into both worlds. We definitely have better recognition. Why? Because after it was first described back in 1980, we found that there's more cases that we can see because we have better technology. We have flexible laryngoscopes in our clinics with distal chips and HD screens. And we can get really close to the area where the damage happens, and we can actually identify these problems a lot more commonly than in the past.

And then, I think the other issue is that we actually have a real increase in iatrogenic injury to the posterior glottis, which just to remind everyone, is the back part of the vocal folds, where you can get scarring and cause major problems after prolonged intubation. And I think all of us have survived through the crazy years of COVID when people also survived but had long intubations. And that has definitely caused an increase in the referrals we see for laryngotracheal stenosis in general, as well as the pediatric ICU cohort as well.

Host: Which aspects of airway management most directly contribute to posterior glottic injury? You mentioned duration of intubation might be a factor. Also, tube size, cuff pressure, repeated instrumentation, or all or none of the above?

Dr. Manish Shaha: I mean, I think you pretty much summed most of it. But just to kind of give a general idea, what I would say about this is that the interarytenoid area, which is mucosa at the back part of the vocal folds, it sits directly in the area that I think the airway is most vulnerable. And that's the mucosa overlying the cricoid cartilage, and that's where basically the tracheal airway is the thinnest.

So, if we put a tube down there, it goes to reason that that tube is going to start causing erosion. And there's been a lot of evidence showing that after one week, seven days of being intubated, there was a paper back in 1984 that showed that there was increased laryngeal injury, that increased steeply between six and 10 days of intubation. So, we kind of feel like by day seven to 10 after being intubated, that area is so vulnerable that that is one of the prime reasons to have scarring. But then, there's so many other elements to this, which is why I think it's a really important topic for other physicians to be keeping in the back of their head, like tube size, cuff pressure, reintubation. There's evidence that reintubating somebody causes fresh trauma and increases the risk of scar development.

And then, there's patient factors. There's things like their overall health, diabetes and acid reflux probably play the biggest roles in contributing to the risk of this forming. And then, female sex has been linked to it, as well as just bigger patients. So, obesity definitely plays a role as well.

Host: Previous health conditions. At the bedside, what should we look for as early warning signs that suggest posterior glottic injury is developing, and how often are these missed or misattributed?

Dr. Manish Shaha: I think that's a really great point, Amanda. I think the classic myth that happens is that somebody was intubated. And then, after they were extubated, they started developing difficulty breathing or some noisy breathing. And then, immediately, they are thought to have anxiety or they're thought to have asthma. And frequently, patients will seem to bounce between pulmonology, psychiatry, for even months before somebody finally puts a camera down their throat. And I think that's to me the classic myth where we think someone got extubated, they had a tube in their throat. So, they're having kind of a vocal cord spasm related to the tube, or they're having asthma symptoms, so it might be asthma. But the truth is this is what needs to be thought of. If you're having trouble breathing or having noisy breathing, we need to think about getting them into somebody who can put a camera down their throat, specifically perform flexible laryngoscopy in a clinic or do a bronch at bedside if they're still in the hospital.

I think other things that I definitely have in my mind are things like voice changes. They don't often happen right after the extubation. Sometimes they do. But things like that can also be a reason that scar has formed and the voice has changed. So, in the outpatient setting, family care, family practitioners who see patients who were intubated after COVID and they're seeing them two or three months later, and the patient is complaining of a hoarse voice, you might want to get them into a specialist sooner rather than later, because this is what could be going on, where the vocal cords are starting to scar together, and it creates major problems in that patient's future.

Host: So, we have to approach it also with a little bit different mindset than in the past by looking for these things and remembering this condition.

Dr. Manish Shaha: Yes, that it's out there. And if you don't know about it, please make my job easier because if you send people to me earlier, there's more I can do.

Host: Right. How can changes in intubation technique, tracheal tube selection, and post-intubation care reduce the risk of posterior glottic stenosis without compromising patient safety?

Dr. Manish Shaha: Where I would like to see most critical care and even family practitioners where their thought processes might be in an acute care setting would be size down your tubes. I think there's a classic thought process that we need big tubes so that patients can do very well on a ventilator. And I think that that is a misnomer and taken from very old anesthesia texts dating back to the '70s and the '80s.

I think realistically, instead of going for size 8 and 9 tubes, which often happens, or if you see a very obese patient, thinking about going to a higher size tube because they'll do better on the vent, I think you're actually getting them ready to get posterior glottic stenosis and have major airway problems in the rest of their life.

So, I often think if you're going to intubate somebody, a 7.0 or a 7.5 is plenty enough space and plenty enough for even very tall patients to be intubated. And the goal is in women maybe a little smaller, you can go 6.0, 6.5. In men, 7.0, 7.5, maximum 8. But the goal is let's have an outer diameter of an endotracheal tube that is going to be 75% or less of the glottic airway.

And these are all estimates because everyone's airway is different. But I generally would say those sizes are going to help us reduce the chance of mucosal irritation and erosion. And then, the other part of this is that there have been studies dating back to the '80s that showed that there is continuous erosion as the patient is breathing, that every single time they breathe, the tube is rubbing more and more.

So, keeping evidence of what the cuff pressure is and being vigilant about it, maybe having continuous manometry on the cuff, and targeting maybe 25 to 30 millimeters of mercury as your capillary perfusion standard, that would be a good way to make sure that the cuff is not also causing more erosion or pressure.

I think that maybe us thinking about trachs in an earlier fashion, having a discussion with family maybe around day seven instead of waiting ten to fourteen days, I think that's a very good idea in terms of expediting a trach so that we have less chance of more erosion being caused by the endotracheal tube.

And then, I think there's so much more to be said about re-intubation. You know, a lot of families want to avoid the trach and then potentially have their family member get tried for a trial extubation. But if that patient has to be re-intubated, are we really potentially causing fresh trauma to an already injured posterior commissure? So, maybe thinking about steroids before extubation, making sure there's a cuff leak before extubation, which to a lot of people are standard, but if we miss it and we just try to extubate someone and they have to be reintubated, are we potentially leaving them open to having more risk of posterior glottic stenosis? So, I think those are some big things.

Other things that I'd like to say just because they matter to me, even though they might not be in people's minds. But I think tube position is something I often see in the ICU. It's a very difficult job when you have somebody who's intubated and they are supine for a long time, and they have to be turned every few hours to avoid sacral ulcers and pressure issues on their skin.

And when a patient is moved and being cared for in the ICU setting, it's very easy for us to see that the tube is still in place, the vent is still working. But did you notice that maybe the tube shifted from one side of the mouth to the other? Maybe it's on the right side or the left side, and initially when they were intubated, it was in the middle. Well, we're not thinking about the fact that if the tube shifted, even if it's still in the airway, well, now it's putting a lot of pressure on one of the arytenoids, potentially causing more erosion, more irritation, and leaving them open to posterior glottic stenosis.

And then, I think another part of it is controlling reflux while they are intubated. So, making sure they're on prophylactic, obviously, IV pantoprazole or whatever they need to minimize the chance that reflux is also going to add to the picture of mucosal erosion in that postcricoid area.

Host: Those are really helpful suggestions and thoughts to keep in mind to reduce the risk of posterior glottic stenosis. What system level interventions, protocols, education, documentation, or interdisciplinary collaboration are most likely to prevent posterior glottic stenosis from becoming a widespread iatrogenic complication?

Dr. Manish Shaha: I think no matter what, we have to standardize documentation of how we intubate people. What tube size do they have? What cuff pressure were they at? How many attempts it took to get them intubated? What grade of view they had, you know, when you're pulling up the larynx, how easy was it to see their airway? This should all be something that's standardized and something easy that anyone could plug in, even someone who intubated someone in the field. An EMS person can be trained on a standardized template. I think that's number one.

Number two, I think ICU protocols that have hard checkpoints, things like mandatory cuff pressure checks or continuous manometry, daily checks on extubation readiness, not just setting a random timeline three days before we reassess. Instead, just look every day, how does the vent look? Is the patient potentially ready to be extubated earlier? Can we try spontaneous breathing trials, things like that.

One thing that I'm very big on, I also operate at Tampa General Hospital as a Medical Director of Inpatient Speech and Airway services. And one of the things we're building here is an interdisciplinary trach and airway rounds. So, ENT, pulmonology, critical care, speech language pathology, respiratory therapy coming together for rounds that traditionally these specialties wouldn't do rounds, but there's complicated patients. Let's walk the unit, see them, and develop identification of laryngeal injury before it becomes a fixed scar.

I think anesthesia education on tube sizing would be really helpful, mainly because it's kind of just a change in culture and mentality. A lot of residency programs default to higher sized tubes by reflex and by old mentalities. So, they favor 7.5, 8.0 tubes when I think direct teaching of the anesthesia culture on the larynx injury that can happen could really shift practice to help us prevent this more often.

And then, there's a few other things like, after extubation, knowing if there's any of these warning signs with changes in voice or a little noisy breathing, getting them to an ENT for a scope as soon as you can, can keep them still at a lower grade posterior glottic stenosis versus them coming to me four to six months down the line and having a grade 4 stenosis, which is essentially where nothing is moving, and now their airway is a slit and, only 1 millimeter wide.

Host: Well, Dr. Shaha, thank you for these insights into the complexities of intubation and for explaining the many ways we can lower the risks of posterior glottic stenosis. And thank you also for getting the word out to the medical community

Dr. Manish Shaha: Oh, thank you so much for having me. It's definitely something I'm passionate about and appreciate just having a venue to hopefully get some people to be on our team, so that we don't have to deal with it as much as we do at this time.

Host: That was Tampa General Hospital laryngologist Dr. Manish Shaha. Thank you for listening to MDCast by Tampa General Hospital, which is available on all major streaming services for free. To collect your CME, please click on the link in the description. For other CME opportunities, including live webinars, on-demand videos, and local events offered to you by Tampa General Hospital, please visit cme.tgh.org. Thank you.