Do LMAs increase the risk of aspiration compared to ETTs? Part II

Welcome back to Depth of Anesthesia. This is a podcast that critically explores our clinical practices. I'm David Hao, and I'm an anesthesiologist at the Massachusetts General Hospital. Well, you know it's been a while when you pull out the microphone and there's a layer of dust on it. Uh my apologies for the delay and uh here again is my annual reaffirmation that I'll be aiming for less time between episodes.

So this is part two of two of our episode that's exploring the claims and evidence regarding aspiration in laryngeal mask airways. Our guests, as you might have forgotten, are Dr. Chris Di Capua, who is a CA1 in our department here. I've actually had the pleasure of working with Chris several times in the ORs, and he certainly has a bright future. Our second guest is Dr. Brian Glezerson. Brian is a neuroanesthesiologist in Montreal, Canada, and he's been an active participant in this podcast series in the past.

So I'll go through the case again and briefly recap what we touched on with the first episode. So our case was that of a 60-year-old woman with a history of type 2 diabetes and elevated BMI who was undergoing an elective laparoscopic cholesteromy. The med student on the anesthesia rotation suggested an LMA for the case, but the attendee responded that LMAs, while are while they are useful devices, are somewhat limited because of the increased risk of pulmonary aspiration. So the team instead elects to secure the airway with an endotracheal tube. So in the first episode, we explored the primary claim, which was that an LMA represents an unprotected airway. thus increasing a patient's risk of pulmonary aspiration compared to an endotracheal tube.

We started with some early studies using dye like methylene blue and esophageal lumin pH electrodes, which were used as surrogates for reflux. We then touched on a cadaveric model that compared the seal across seven superglodic airways, and we finished up with two meta-analyses that compared the rates of aspiration with LMAs and endotracheal tubes. And finally, Dr. Glezerson and Dr. Baker taught us about the statistical concept of rule of three and how to apply that concept to the evidence in this space. So, today's episode will focus on the secondary claim, which is that specific patient populations are at higher risk of aspiration with an LMA, and in these groups or circumstances, LMAs are thus contraindicated. This includes patients who are receiving positive pressure ventilation, patients undergoing laparoscopic surgeries with abdominal insufflation, obese patients, and pregnant patients.

So here's Dr. Christi Capua kicking us off with his findings in the positive pressure ventilation group. Exactly, Dr. Howe. So in the subgroup of positive pressure ventilation, I'll draw our attention to three separate articles. The first was published by Keller et al. in the Canadian Journal of Anesthesia in 1998. This study involved 164 ASA-1 to 2 patients who were scheduled to undergo peripheral musculoskeletal surgeries in the supine position.

Each of these patients was randomized to one of four groups. Group 1 included patients who were getting isoflurane with positive pressure ventilation. Group 2, isoflurane and spontaneous ventilation. Group 3, Sevoflurane and positive pressure ventilation, and group 4, Sevoflurane and Spontaneous Ventilation. Note here that all the patients in each of the groups had their airway secured with a laryngeal mask.

So the objective here was actually to see if rates of complications varied based upon ventilation mode and or the type of anesthetic gas used to maintain anesthesia throughout the case. Patients were excluded from the study if they had some underlying respiratory tract pathology, had a BMI greater than 30, or were deemed, and I quote here, at risk for aspiration. Unfortunately, the authors don't provide us with any information on what constitutes at risk for apparition, so we're sort of left to wonder here what that means. Regarding the LMA use, size 4s were used in females and size 5 were used in males, and positive pressure ventilation was applied with tidal volumes between 6 to 8 milliliters per kilogram. and the authors set parameters such that the peak airway pressure would be limited to fifteen centimeters of water.

In their methods, the authors specified that epigastric auscultation would be used to detect gastric insufflation in these patients. In the results, they didn't see any evidence of gastric insufflation in the patients in this study. They also didn't notice any differences in airway complications like laryngospasm, bronchospasm, regurgitation, or aspiration between any of the four study groups. So the authors subsequently concluded, and I'm going to take a quick quote here from their their paper and their discussion. They state, these data suggest that positive pressure ventilation With the LMA is comparable to spontaneous ventilation in non-paralyzed adult patients, end quote.

But I think it's important to look at a couple of the different limitations of this study. First off, they limited peak airway pressures to 15 cm of water, which is relatively low. There are often cases where the anesthesiologist must apply peak airway pressures above 15 cm of water to achieve adequate tidal volumes On top of that, the authors themselves state that based upon their understanding of the literature, gastric insulation is unlikely to occur with peak airway pressures less than 20 cm of water So we're not even looking at area pressures that we usually expect to result in gastric insuflation. Also, epigastric auscultation is an imperfect method for monitoring for gastric insuflation. And then lastly, I'll say the sample size in this study was relatively small, with an end value of only 164 patients.

So I think any astute reader will look at this article and squint a little bit because admittedly an imperfect tool used to detect something that's unlikely to happen. in a small sample size with four in uh intervention groups is not really a study that you can place much faith in, I would say, not to disparage any of the authors if they are still active in academia. But I think that it's just worth taking this article with a grain of salt so that we don't necessarily place much weight in the statement that use of positive pressure ventilation does not increase your risk of aspiration by some metric. Brian, I think that's well said. And one thing that I pick up time and time again as I read primary literature is that the conclusions which are prominently displayed in abstracts and often quoted from clinician to clinician, uh usually don't reflect the limitations of a study.

And I think that speaks to the need for us to communicate with a bit more nuance and language that tends to hedge on some of the results uh that are conveyed in these studies. So Dr. Chris Takapua, let's move on to the second paper here The next study I'll bring up was published by Bernardini et al. and was published in Anesthesia in 2009. I think this study adds some additional value to our discussion for a number of different reasons. First off, it was a retrospective analysis of prospectively collected data on over 65,000 patients, so far more patients in the previous study we just discussed. And on top of that, the investigators looked specifically at risk of pulmonary aspiration as the primary endpoint of their interest, and they aimed to compare this endpoint in patients receiving positive pressure ventilation through an LMA versus through an endotracheal tube One limitation, however, right off the bat, is that they restricted their analysis to the classic LMA only, so no further generations of LMA devices were actually included in this study In their methods, they defined an event as pulmonary aspiration if gastric contents, bilious fluids, or other non-respiratory secretions were suctioned from the trachea. or two if dyspnea, hypoxia, oscillatory abnormalities, and or new infiltrates were identified on chest x-ray after appearance of gastric contents or non or other non-respiratory secretions were seen in any part of the LMA or in the oropharynx during the case.

They evaluated the association between LMA use or endotracheal tube use and the incidence of pulmonary aspiration through odds ratios, and they utilize propensity scores to try to adjust for baseline differences between either of the sample groups. In the end, they arrived at 65,712 procedures that they included in this study, and the LMA was used in 38,200 of those, which corresponded to 38% Further hospital policy, use of the LMA was contraindicated in patients that were non-fasted, had any evidence of intestinal obstruction, pregnancy, unplanned surgery, airway surgery, or were placed in a prone position Shifting now to their results, their univariate analysis identified that the LMA had an odds ratio of 0.36 for pulmonary aspiration when compared with the tracheal tube.

This result wasn't significant. The 95% confidence interval was 0.09 to 1.4 for a p-value of 0.141 Once they factored in the effect of the propensity score, the adjusted odds ratio increased from 0.36 to 1.06. This, however, also was not clinically significant. The p-value was 0.945 here. In other words, they didn't identify any statistically significant difference in rates of aspiration with either airway device, even after adjusting the regression analysis with propensity scores.

Interesting study for sure. Um one thing I'll point out is that the ventilator setting was volume control with tidal volumes of eight to ten cc per kilogram of actual body weight. So just something to keep in mind. So it sounds like we have a prospectively collected data set on more than sixty-five thousand patients. Odds ratio with univair analysis was 0.36 , but that was not statistically significant.

They then uh apply propensity scoring, which as a quick reminder is a uh statistical strategy to correct for differences in baseline characteristics, uh often when uh the data set is in observational or non-randomized studies. But even after propensity scoring, uh, there was still no statistically significant difference seen in the rates of aspiration with either airway device. And I think that's probably the most obvious limitation of this trial, which is that the patients in the LMA and endotracheal groups were fairly different. Uh those in the tracheal tube group were older on average, there were higher rates of unplanned surgeries, longer surgeries, and in general were more likely to be scheduled for major abdominal or laparoscopic surgery than those in the LMA group.

Again the investigators attempted to account for this by using propensity scorings, but it's always difficult to say whether this uh adequately adjusted for the differences. The authors also uh conducted a power analysis um based on the incidence of aspiration of one in thirteen thousand eight hundred nineteen in patients with tracheal intubation. They calculated that to demonstrate an increase in 25 % uh in the rate of pulmonary aspiration with LMAs, they would have to randomize over three million patients uh per group. And I think that speaks to the challenges of uh conducting studies that examine rare events. And in situations like this, we're often limited to observational studies and meta-analyses.

Alright, Dr. Dickapwell, let's move on to the next study. So let's change gears now to the question of LMA use during laparoscopic surgeries. And here I've highlighted four different articles for us to talk about. the first of which was published by Maltby et al. in the Canadian Journal of Anesthesia back in 2000. Their design included the 101 ASA 1 to 2 adults who were scheduled to undergo Lapcoles electively They were randomized to have the airway managed with either the LMA classic or an endotracheal tube. Individuals were excluded from the study if they had a BMI greater than 30, had a known hyatal herdia, or a history of GERD.

Prior to the start of each case, an OG tube was passed to decompress the stomach before insertion of the LMA or endotracheal tube. Neuromuscular blockers were also given to each of the patients in either of the groups. and they were maintained at a level of one trinophore twitch during laparoscopy. And in all of the cases, the surgeon was also told to maintain peritoneal insuflation at a pressure of 15 millimeters of mercury. Tidal volumes were set in either of the groups at 10 mL per kilogram. In the case of the LMA group, this translated to an average airway pressure of 16 plus or minus 4 cm of water at baseline. which subsequently increased to twenty-one plus or minus four centimeters of water during peritoneal insuflation.

The surgeon was blinded to the airway device that was being used. and they were told to score the degree of gastric extension on a zero to ten scale at different time points, the first of which was after insertion of the laparoscope, and then again immediately before removal at the end of the surgical procedure With this scale, zero was defined as an empty stomach, and 10 was defined as distention that interfered with the surgical exposure. In the results, the authors found that clinically relevant rates of gastric distention were no different in either group They subsequently concluded that the risk of gastric distention was similar for both devices during laparoscopic surgeries that required abdominal insuflation. Okay, so to summarize, about a hundred patients uh presenting for elective lap coli.

Patients were randomized to endotracheal tubes or LMAs, but everyone got near muscular buckade. And then we have blinded surgeons who are scoring the degree the degree of gastric distention. And the results showed that the overall incidence and change in gastric distention was similar between groups. Alright, what else do you got? Another really interesting study was performed by Kim et al. And this was published in Nature in 2021, very recently.

This was a single center, single-blinded randomized controlled trial that was done at the medical center in South Korea. Here they looked at living liver donors over 18 years old who were scheduled to undergo elective living liver donor hepatectomies. Patients were excluded from the study if they had an ASA score greater than or equal to three, a BMI over thirty, were on H two blockers or PPIs for GERD. had a documented upper airway deformity, recent upper respiratory tract infection, a history of any major oral laryngeal surgery, or had a mouth opening less than three centimeters. Patients were randomized one-to-one to either the LMA group or the endotracheal tube group. The LMA group included 45 patients using the Protector LMA, while the endotracheal tube group included 43 different patients.

Participants ended up being induced with thiopentol and vectoronium and were maintained with remifentinol and isoflurane. In the LMA group, after the device was inserted, the cuff was inflated and the oropharyngeal leak pressure was measured A gastric drainage tube was inserted after confirming effective ventilation. In the endotracheal tube group, the cup pressure was maintained at 25 cm of water. For each of the groups, the tidal volume was kept at 8 milliliters per kilogram of ideal body weight, and PEEP was set at 6 cm of water. In the results, the authors found no cases of pulmonary aspiration in either of the groups that were studied Also, in both of those groups, the arrow devices were maintained for approximately 280 to 290 minutes throughout the duration of the case.

So one important comment when understanding this study is that it wasn't designed to determine differences in pulmonary aspiration rates in either group. The number of subjects in this study was actually based on a power analysis relating to the primary outcome, which in fact was the level of CO2 in the blood. But this doesn't change the underlying fact that no LMA patients had aspiration events during this prolonged laparoscopic surgery involving positive pressure ventilation. It's interesting to examine this study through the lens of North American practice because at least if my center is like your center doing a laparoscopic hepatectomy with an laryngeal mask airway would be extremely unusual. But nonetheless, I think a study like this gives us at least the flavor that perhaps it's not as or shouldn't be as unusual as it is.

Another study was published by Parik et al. in 2017. This study was a prospective randomized trial of 60 ASA-1 to 2 patients who were scheduled to undergo elective laparoscopic surgeries under general anesthesia Individuals were excluded if they had a mouth opening less than two centimeters, were anticipated to have a difficult airway by the anesthesiologist. Had a BMI greater than 30 a r a prior upper respiratory tract infection, had an increased risk of aspiration, which was determined by the presence of GERD, a known hiatal hernia, or pregnancy status, or had a cervical spine fracture or other kind of instability Those included ended up getting randomized to two different groups. Thirty were included in the ProSeal LMA group, and another thirty in the endotracheal tube group I think it's important to note that the Pro Seal is a double lumen device.

The double lumen allows for a separate passage for regurgitated fluids, and the cuff is specially designed to allow for an improved glottic seal Got it. So elective laparoscopic surgery and randomization to ProSeal LMA or endotracheal tube. And I'll also point out here that everyone got pantoprazol uh intravenously before induction. uh in addition to neuromuscular buckade which was achieved with atricurium and then positive pressure ventilation was performed with tidal volumes of eight cc's per kilogram All right, Chris, what were some of the strengths and uh findings of this study? Yeah, I think one of the particular strengths of the study is it's table one. The authors saw no differences in baseline characteristics through either group, and regarding the primary outcome, regurgitation of gastric contents to the drain tube wasn't seen in any of the patients, and there was no case of pulmonary aspiration in either of the two groups Okay, so again, very small numbers here, but uh some initial data suggesting no cases of uh gastric regurgitation or aspiration um when comparing endotracheal tubes versus the ProSeal LMA uh in a uh specific population, which in this case is appropriately fascist patients for elective laparoscopic surgery with muscle relaxation.

Exactly. A separate study was published by Park and al in 2016. Here they conducted a systematic review and meta-analysis of randomized controlled trials That compare the performance and the risk of complications associated with superglottic area devices and endotracheal tubes in patients receiving laparoscopic surgeries under general anesthesia. They ended up looking at 17 different studies for a total of 1433 patients. Two of those studies measured the oropharyngeal leak pressure using a manometric stability technique.

I'm just gonna quickly jump in here. Oral pharyngeal leak pressure is typically used to quantify the uh f efficacy of an airway seal with superglottic airway devices. Um manometric stability is just one technique to measure this. Other options to evaluate leak pressure include things like listening for audible noise or uh observing keepnography. All right, Chris, carry on In the results, six of the studies commented specifically on rates of gastric insufflation.

The pooled rates between the groups were not significantly different. The relative risk here was measured as. 9, with a ninety five percent confidence interval of. 48 to one point seven one. Regurgitation was looked at in five of the 17 studies, and aspiration was compared in four of those studies. And in none of those studies were any events of regurgitation or aspiration identified. The authors go on to say in their discussion, and I'm going to pull a quick quote here from their article, and I'm quoting now.

This finding supports the use of superglodic airway devices in laparoscopic surgeries from the perspective of providing a reliable airway. This finding is also consistent with that of a recent study demonstrating that superglottic airway devices could ensure efficient or pharyngeal leak pressures to seal the airway in laparoscopic surgeries. One of the things I love about this paper that has nothing to do with methodology and everything to do with scientific communication is that they limit their conclusions to those which are supported by the data that they present. They state, as you said, that the findings here support the use of superglottic airway in laparoscopic surgery from the perspective of providing a reliable airway. And indeed, that's what they showed.

If you look at fifty almost 1,500 patients and you don't have any deaths related to hypoxemia in the group, then presumably it is at least in most cases a reliable airway. And so I think that that's a reasonable conclusion. That as I said is supported by the data. Importantly, they don't mention this notion of safety Because I think that the authors are presumably insightful enough to realize that fifteen hundred patients is actually not a very large group when you consider the totality of airway management that's occurring on the planet. So, all that to say that good scientific communication has a relatively restrained set of conclusions that is usually a lot less bold and confident than you sometimes see.

Well put again. So that leads us to our final two patient populations, pregnancy and obesity. It looks like we have two fairly robust articles to discuss. Is that right Yeah, Doctor Howe, we do. It seems like the story surrounding these two last populations is very similar to what we've been discussing so far in the episode The first study I'll get into was published recently in A in twenty twenty by White et al. and it was titled The Comparison of Superglottic Airway Devices with Endotracheal Intubation in Low Risk Patients for Caesarean Delivery, a systematic review and meta-analysis.

This article included 14 different studies for a total of 2,236 patients. Per the inclusion criteria in the study, articles were required to report on first cesarean delivery cases, two, placement of SGA devices, and lastly, comparison to an endotracheal tube. The primary outcome in this article was first attempt success and timed successful insertion of the airway device. Other secondary outcomes they looked at included rates of difficult insertion, which was defined as an insertion requiring greater than one attempt. Insertion failure, peak airway pressures required to achieve adequate ventilation, aspiration, bronchospasm, hypoxia at the time of induction, rates of laryngospasm, blood on the device at the time of removal, and incidence of a sore throat after the surgery.

Another strength of this study is that it included multiple different types of LMAs. An important takeaway is that for all the studies that investigated aspiration, bronchospasm, and hypoxia, the incidence for each of these outcomes was zero for both the SGA and intubation groups. So this is an interesting article for a number of reasons, and I think it's worthwhile extracting a citation from the article directly because it's phrased quite well. The authors state, there was no incidence of aspiration in the present meta-analysis. Between these studies, and here they're referring to a number of other studies that examined the use of superglodic airway , There are greater than eight thousand parterrients with only one reported aspiration event.

In addition, in the National Audit Project 4, the NAP 4, which I mentioned before. There was one reported aspiration during cesarean delivery associated with the use of a superglottic airway device. This aspiration occurred following three failed intubation attempts. They continue and they offer there are several possible reasons for such low aspiration rates reported in the literature. These include the use of nasogastric tube, minimal fundal pressure and the use of a rapid sequence intubation technique to insert the superglatic airway without face mask ventilation.

I think it's worth In response to this paper, to examine one's own practice. I know personally, I have never used a laryngeal mask airway in a pregnant lady, in a pregnant woman. And I suspect that many anesthesiologists and anesthesia providers in North America similarly have not used laryngeal mask airways electively or even emergently in patients of this sort. And so it's sub it was surprising to me anyway to see such a low incidence of adverse events when you consider the total rarity of its use for fear of those very same events in our practice. One of the other important points that was brought up by the authors is that the majority of the patients in this study and others like it were presumably well fasted.

They were not in active labor. And so their fasting status, though certainly different from a non-pregnant individual, is perhaps optimized. Yeah, I I'm likewise surprised by their ability to aggregate over 1400 patients for this analysis. And I've gotta say I'm actually pretty reassured by their measured approach um to their conclusions. They comment that despite a reasonable safety profile demonstrated in this meta-analysis, the analysis remains underpowered and therefore inconclusive, which I think is quite appropriate.

The study has some limitations which include low patient numbers and significant heterogeneity not only in the superglotic airway devices used, but also the patient cohorts and clinician familiarity with these devices. uh specifically in the obstetric population. Now before we continue, I do want to briefly touch on a study that was mentioned but not ultimately included in this meta-analysis because it did not include a comparison with endotracheal tubes. But as of today, I believe it represents the largest patient population that's been studied for use of LMAs in elective C-sections. It also has a very interesting study design, so I think it's worth talking about. So this study was published in 2010 and conducted in Jordan.

ASA 1 in 2 patients were enrolled who presented for elective C-section and chose general anesthesia. Patients who had uh reflux, uh obesity, or risk factors or history of known difficult intubation were excluded from the study. All patients were fasted for a minimum of eight hours and given rhinitidine before the operating room. They underwent a modified RSI with propofol and then roculonium with application of cricoid pressure. A size 4 ProSeal LMA was then inserted.

Now, this is where it gets interesting. They use a very specific technique for LMA insertion, which is something I've never heard of before. They first load a 14 French gastric tube uh slightly beyond the distal tip of the drain port of the LMA They then conducted laryngoscopy with a Macintosh blade after induction, and then they used a McGill forcep to help guide the gastric tube into the esophagus. Once the gastric tube was in the appropriate position in the esophagus, they then used uh the gastric tube as a railroad for the LMA to ultimately seat the LMA into place. So their primary outcome was regurgitation or aspiration.

Regurgitation was defined as gastric contents identified in the mouth at any time and they uh assess gastric contents by measuring the pH less than four suggesting gastric etiology. And uh the pH of the inner bowl of the LMA was also measured uh after the surgery. So in terms of the results of the study, there was only one case of regurgitation of gastric contents. Uh this occurred during fundal pressure at the delivery of one uh neonate. Gastric fluid was seen to emerge from the inner drain tube as well as the uh outer drain tube with some spilling into the oral cavity.

But uh the patient was followed and ultimately there were no uh clinical or imaging findings of aspiration in the subsequent twenty-four hours. Uh but otherwise in this large group of 3,000 patients there were no other complications, including no patients with oxygen desaturation less than 93 % or any patients who had a pH of the inner bowl with a mask less than four after surgery, suggesting lack of gastric uh contents surrounding that structure. So definitely an interesting study, and I think this adds to a growing end, but as the authors of the meta-analysis suggest, the takeaways that the evidence currently available is most likely insufficient to conclusively confirmed that a superglottic airway has the equivalent safety profile compared to endotracheal intubation.

Alright, let's head into the last group we're going to take a look at today. The study we're going to look at is a Cochrane systematic review that was conducted by Nicholson et al. in 2013. Yeah, thank you, David. This study was comprised of randomized controlled trials, including patients greater than 16 years of age with BMIs greater than 30 undergoing general anesthesia. Through their search, they identified two eligible studies for inclusion, both of which compared the ProSeal LMA with endotracheal tubes.

In the end, this resulted in a study population of 232 different patients Breaking these two studies apart, one of those study populations underwent laparoscopic surgeries and included morbidly obese patients. The other study population involved obese patients that were scheduled to undergo various routine procedures that did not include abdominal surgeries. The primary outcomes in the study were rates of failed airway device placement, the incidence of hypoxia between induction and full recovery Serious respiratory complications including lower respiratory tract infections within 30 days of anesthesia, rates of pulmonary aspiration, and even mortality within 30 days Fortunately, the researchers did not identify any cases of pulmonary aspiration of gastric contents, mortality, or serious respiratory complications in either of the two studies included.

One thing I'll say about this subgroup is that it's particularly hard to find studies that look specifically at obese patients. In a lot of the available literature, comparing LMAs and endotracheal tubes, obese patients are excluded explicitly As they are traditionally thought to be particularly high risk. This limits the n value in the systematic review, as only two small trials fit the population inclusion criteria However, one particularly telling element of his paper is that of the two trials, one of those trials included patients who were both morbidly obese and undergoing laparoscopic surgeries. That's two different groups previously thought to be at particularly high risk. One interesting aspect I want to point out about this study is that the authors included an important qualifier to the results.

With about 3 to 5% of patients in these studies, they were unable to have a superglottic airway device successfully placed. And in these instances, the device actually needed to be exchanged out for an endotracheal tube Uh this poses an inherently risky situation which may or may not predispose to aspiration, but it does highlight a potential risk of LMA use in this group. Okay, so between this episode and the last, I think we've covered a ton of literature that has spanned almost 35 years. Dr. Di Capua, do you want to take a crack at trying to summarize some of the literature we've touched on? Yeah, absolutely.

Here were a couple of my key takeaways from doing this literature search. You know, some of these initial fears surrounding LMA use and aspiration. are really based on some literature done back in the early 1990s, which showed that these devices might be associated with drops in lower esophageal sphincter pressures through a reflex mechanism. And that this may thereby translate to more instances of gastric reflux. However, there's little evidence in these studies that this reflux is predictive of tracheal aspiration In addition, cadaver studies have shown that LMAs provide variable protection against aspiration by creating a protective seagull over the airway, even in the event of elevated esophageal pressures. Some larger clinical studies have been done, and while they have notable limitations, they have shown that rates of aspiration with an LMA are similar to that seen with an endotracheal tube.

Also, some of the available evidence does not point towards a higher aspiration risk in LMA patients historically believed to be at a greater aspiration risk, such as obese or pregnant patients, or those undergoing positive pressure ventilation or laparoscopic surgeries. Nonetheless, a lot of the literature in these populations is underpowered. Perfect. Thank you, Dr. Di Capua. I'd also like to open it up to Dr. Glezerson if you have any other final thoughts.

So I think that this discussion we've had and and many on this podcast actually are really really interesting for a number of reasons. present us with data that is contrary to our own clinical practice and contrary to our own sense of intuitive judgment. I mean if you were to ask me, if you were to pin me to the wall and say, is your risk of aspiration higher with an LMA than with an inflated endotracheal tube? Intuitively, I would imagine that it is, but in fact, when you look at the evidence, there isn't much supporting that statement. And in fact, when you look at the totality of reports of aspirations that are done in a systematic fashion, It appears as though many aspiration events occur when there is no endotracheal device and no superglottic device present.

And so really we're left with this sort of uncomfortable idea that Although intuitively not having something in the trachea would put you at greater risk, we have little evidence to suggest that strongly. Dr. Glezerson, as always, I appreciate your insights and I appreciate you taking the time to come on the show to provide some commentary on some of the literature and to share some of your perspectives. Thanks so much for having me again. It's really a lot of fun for me and and I hope it's informative for everyone that listens. And Dr. Di Capua, thank you again for all the work that you put into making this episode a reality.

I've personally learned a ton and I guarantee that our listeners will feel the same way. No, thank you so much for allowing me to join. It's been a really great experience. I appreciate the opportunity to be here. To our listeners, thank you for your ongoing support for this show.

We love to hear your ideas and to get feedback on how what we're doing might be changing your practice. As always, stay hungry and keep asking questions.