Does cricoid pressure reduce the risk of pulmonary aspiration?

Welcome back to Depth of Anesthesia. I'm David Hao and I'm an anesthesia resident at the Massachusetts General Hospital. First off, I want to wish everyone a happy and healthy new year. I hope all you guys had a chance to spend some quality time with friends and family. I'm very, very excited to be starting off the 2020 podcast season with one of the most requested topics and luckily enough, one of the most requested guests.

My guest today is Dr. Jerome Crowley. Dr. Crowley is currently an adult cardiothoracic anesthesiologist and intensivist He completed his residency training at UCSF and fellowship training at both UCSF and MGH. Dr. Crowley, welcome to the show. David, happy to be here. Uh excited to uh hopefully stimulate our guests and some interesting thoughts.

So we'll start with our case today, which is that of a healthy 25-year-old man who's presenting as an urgent add-on for a laparoscopic appendectomy. On rapid sequence induction, the attending places his fingers on the patient's neck and applies firm pressure. The resident subsequently intubates the trachea, and the case proceeds. Doctor Crowley, what do you think are some of the claims in this case? In this particular case, the claims are as follows.

One Cricoid pressure reduces the risk of pulmonary aspiration. Two, that the landmark technique is able to accurately identify the cricoid cartilage And three, that cricoid pressure should almost always be administered during a rapid sequence intubation. So to our listeners, what's the level of your agreement with the claims that we just mentioned? And what's the level of evidence for what you believe? So I think we're going to start off this podcast today by kind of discussing the premise and origins of cricoid pressure.

I seem to remember that alternative name for cricoid pressure is the SELIC maneuver. So the first reported data on using something similar to cricoid pressure comes from 1776 where Dr. William Cullen described in the letter what's effectively cricoid pressure to prevent insufflation of the stomach during reinflation of the lungs and drowning victims He said, when blowing is done in a person's mouth or by bellows, a good Dr. Monroe observed that air passes into the stomach. but this may be prevented by pressing the lower part of the larynx backwards upon the gullet. To persons of a little knowledge in anatomy, it is to be observed that the passage should be only on the cricoid cartilage while the passage through the larynx is not interrupted.

It's interesting that in 1776 They effectively describe the same maneuver we're attempting with this patient today. But the Sellick maneuver, named after Dr. Sellick, comes from a paper in 1961 in the Lancet Entitled Cricoid Pressure to control Regurgitation of Stomach Contents During Induction of Anesthesia. The claim in that paper was that temporary occlusion of the upper esophagus by backward pressure on the cricoid ring to prevent stomach contents from reaching the parapharynx should unexpected regurgitation occur. It was a case series of 26 high-risk patients induced with barbiturates and muscle relaxants in a supine position. In 23 of the patients, no regurgitation or vomiting occurred before, during, or after intubation.

In the remaining three Oropharyngeal examination showed gastric or esophageal contents once the cricoid pressure had been released after successful intubation. They also showed in several volunteers that cricoid pressure obliterated the esophageal lumen, as demonstrated with a soft contrast filled latex tube that was placed in the patient's esophagus. at 100 centimeters of water. I will note that the precise application was not standardized. Practitioners received very little training on how to do it. and started with moderate pressure during consciousness and increased refer after anesthesia induction. Selleck's paper obviously has some limitations as an observational study.

But what were some of the key takeaways from his study that we've subsequently applied? So interestingly, despite being just an observational study, the conclusion said cricoid pressure reliably prevents aspiration should be considered in all high-risk patients and should be taught to all providers of airway management. I think what's really fascinating here is that you look at this a conclusion And I think it stems from the fact that aspiration is such a dreaded complication in anesthesia. And we've kind of taken this as the gold standard ever since. I think a lot of things in medicine have origin stories like that, and it's always fascinating to actually be able to review the original papers And my understanding of the mechanism for cricoid pressure is that it assumes that the esophagus is directly posterior to the cricoid cartilage, which is a complete ring.

So the claim is that because it's a complete ring, pressure on the cricoid could compress and therefore theoretically occlude the esophageal lumen thereby preventing aspiration. Does that sound about right? Exactly. I think what people's assumption of the cricoid pressures you're basically interrupting the connection between the oropharynx and the stomach. And then even if the patient attempted to regurgitate, you prevent it.

It's also important to note that this also holds true for avoiding insufflation in the stomach which some airway societies view as the more important purpose of cricoid pressure in the event you have to mass ventilate and emergent airway. Awesome. So let's actually get into a couple of these studies that look at the effect of cricoid pressure on the esophagus through imaging modalities. So the first study that we're going to review is about cricoid pressure and it's an observational study using MRI. So this is a paper in 2003 in anesthesiology. that looked at the cricoid pressure nosophageal displacement using magnetic resonance imaging.

And they had 22 volunteers who had sagittal MRIs without cricoid pressures. with a head position neutrally and they did a two-handed cricoid pressure technique with 20 to 30 newtons of force And the result was the average position of the cricoid is at about C6, C7. It was only clearly visible to see the esophagus at this level in only one subject In the remaining 18 subjects, the crichopharyngeal muscle is the level of the cricoid, which is about a centimeter to a centimeter and a half higher than the esophagus. Wait, so at the level of the cricoid, in only one subject of the 18 was this esophagus even visible? And I think that's It it brings up several important points in some sequence studies here is what you're actually occluding when you apply cricoid pressure.

Because there's certainly data out there saying that cricoid pressure occludes the entrance to the esophagus But is it accomplished by actually compressing the esophagus itself as Select described in his paper, or is it by something else? In this same study in 2003 In about half of the patients without cricoid pressure, the esophagus was lateral. And with cricoid pressure, 91% of the patients had their esophagus later displaced. And it shifted the patients m interestingly mostly to the left rather than the right, probably based on anatomic landmarks. And their conclusion was the two-handed technique of cricoid pressure was associated with a significant increase in the frequency and degree of lateral esophageal displacement um and a one point five increase in the frequency of the esophagus unopposed between the airway and the vertebral body, implying effectively the esophagus was not occluded.

I think that's a really interesting point because I think there's a claim there that snuck its way into this conversation that we didn't necessarily identify up front. And that claim is that crikoid pressure is even compressing the esophagus. We now have another study that actually examines which structure is compressed and whether or not the esophageal position is relevant at all Certainly, I think we actually a couple studies here we can bring up to kind of emphasize your point. So the first is a paper in anesthesia and analgesia in 2009 from Rice et al. Cricoid pressure results in compression of the postcricoid hypopharynx. The esophageal position is irrelevant.

Here they took twenty-four adults with imaging with and without cricoid pressure in three positions. sniffing, neutral, and extended. And they showed there's no lateral movement of the postcricoid hypopharynx And the esophagus wasn't even present at the level of the cricoid parted in any of these images. Which is consistent with our previous trial, shown that at the level of the cricoid, most patients don't have an esophagus at that level. Right. And they showed visible compression of the postchricoid hypopharynx, even though the hypopharynx and rings are lateral to the vertebral body Basically saying that when you pushed down and did cricoid pressure, you still compressed the hypopharynx and interrupted this connection from the stomach to the oropharynx.

And that the hypopharynx and the cricoid ring are an anatomic unit, in the irrespective of the neck position I also want to bring up another small study, the effectiveness of cricoid pressure for occluding the esophageal entrance in anesthesized and paralyzed patients, an experimental and observational glidescope study. This paper is from Anesthesia and Analgesia in 2014. Here, interestingly, they took 79 patients and after induction of anesthesia they used a glidescope and then applied cricoid pressure and tried to see if they were able to pass an oral gastro tube. And they effectively showed that a success rate greater than ninety five percent using a cricoid force of thirty newtons. to include the esophageal entrance , irrespective of the position of the esophageal entrance relative to the glottis, whether it's midline or lateral.

Again implying that while you may not be achieving what Dr. Selleck thought was being done, the effect is still valid. So in terms of a punchline for that study, would you agree that that seemed to provide Uh at least some sort of visual confirmation that regardless of where the actual esophageal entrance is relative to the glottis The cricoid force seemed to occlude the esophageal inlet or whatever inlet sufficient enough that they were not able to pass an orogastric tube. I think that your point's valid there in that they certainly showed the inability to pass the orogastric tube. The caveat though should be is we're kind of coming to this from two different directions. Our goal is to prevent clinically relevant aspiration, and it's unclear that the ability to pass or not pass an oral gastric tube truly represents a risk of aspiration.

I think that's a great point. So, based on the studies that we've now explored, it seems that the esophagus itself may not be what's compressed, but something is being compressed successfully. And one of the concerns I have with this technique is that even though the studies really go to great lengths to attempt to standardize the technique, How do we as practitioners know if we're performing it properly, or if we're even identifying the cricoid cartilage itself properly? And I think that's something that's really common with a lot of procedures if you do in anesthesia, is that if you tell someone this should be standard of care Part of that assumption is that they're applying it properly.

And then is there an objective way that we can determine someone's applying it properly, or is it just kind of subjective opinion, which is a dangerous route to go down in medicine So there's a study here we should worth bring up in Anesthesia, 2018 by Lee et al. which is a multi-center perspective cohort study of the accuracy of conventional landmark technique for cricoid pressure versus using an ultrasound. So in this paper, before induction of anesthesia, patients are placed in the supine position An anesthetic assistant was asked to identify the cricoid cartilage at end expiration using a landmark technique, and a small mark was made The neck was then scanned by an experienced anesthetist using a high-frequency linear probe, and the crikoid car was identified and marked using this image.

And here the height of the anterior cricoid arch varies between half to one centimeter in adult patients. And then they say that While identification of the crichoid cartilage is necessary to achieve potential benefits, application of crichoid pressure at a point more than five millimeters away from the cranial caudal midpoint of the cricoid cartilage will result in a misdirected and therefore likely ineffective maneuver, although that would need further study to confirm Their results show the midpoint was incorrectly identified by a margin greater than 5 millimeters in 41 patients The area is uniformly treated both above and below. There's no significant trend where people either measure too caudal or too cranial. The mean distance into two marks is about two millimeters.

And in 41% of the patients, the midpoint was incorrectly identified by a margin greater than 5 millimeters. And again, this was uniformly distributed around the midpoint of the cricoid cartilage. And their conclusion was that identifying of a cricoid position using a landmark technique Has a high degree of variability and has little correlation with age, sex, or body mass index. And they then further speculate that then some of the negative perceptions of applying caricoid pressure may actually result from the fact that people are doing ineffective cricoid pressure because they're difficult identifying the true location of the cricoid cartilage. And I think this paper draws a lot of corollaries with regional anesthesia and the introduction of ultrasound.

I agree there entirely. That's a great analogy where we know that variation location of the nerves and other structures can vary significantly and isn't easily predicted by simple variables such as age, sex, or BMI, and then we probably become better at ultrasound guided nerve blocks by recognizing these anatomic variations. So this paper seems to suggest that there is certainly a lot of variability in our abil ability to assess the position of the cricoid cartilage. Now what about the actual amount of forces applied? Because in a lot of these papers it's standardized at twenty, thirty newtons.

How will we have any sense of how much that is? No, and I think You bring up two points there. One is this paper may suggest that if cricoid pressure is indicated, that we should be considering using ultrasound to identify our location to optimize it. As far as your question about how much force, I had to plug a small paper that I think shows a really slick way of practicing this. So Flucker et al. in the European Journal of Anesthesiology in 2000 Demonstrated a simple training model.

They take a 50 milliliter syringe, they occlude it at 40 milliliters, and then you are asked to compress it from 40 to 33. And the amount of force it takes is roughly 30 newtons. And this is a simple, inexpensive, and easy way to practice how much pressure to apply the neck. And I think when you have residents and trainees, some people apply probably far too much, and some people not enough force. This is an easy replicatable thing you could do in the operating room with a junior resident you know, during a case as part of a teaching point, plenty of 50cc syringes lying around the operating room.

That's awesome. I'm gonna um I'm gonna definitely try that later. So so one of the other things that I think we should talk about is I've heard plenty of claims with respect to the impact of cricoid pressure on your ability to successfully intubate. What papers or information do we have on whether cricoid pressure makes intubation easier or harder? So there's a couple papers, couple to mention directly, and just some to mention in passing.

So there's several small papers looking at Cricoid Pressure Obstructing the Airway, the one in anesthesia in 2000 by Hart Silver et al. airway obstruction with cricoid pressure, the Journal of Clinical Anesthesia in 1995, the effect of cricoid pressure application of airway patency Then in Anesthesia Analgesia 1992, a paper entitled The Celic Maneuver Causing Complete Airway Obstruction. One in particular I want to mention here is a paper in the Canadian Journal of Anesthesia in two thousand two by Smith et al. and is cricoid pressure decreases ease of tracheal intubation using a fiber optic laryngosphy, which is called the WuScope system, which I will confess is not a laryngoscope system I am familiar with. But I think it's interesting that they standardized with a device that at least had the premise was easier to intubate with.

So in this case, they had 33 patients undergoing elective surgery with general anesthesia, complete neuromuscular blockade ASA 1 through 3 intubated with and without cricoid pressures randomly decided in this prospective trial and excluded if they had a history of difficult intubation, predictors of difficult intubation, or significant risk factors for aspiration. So this was a controlled environment where it probably removed some of the stress of a rapid sequence intubation. And using this fiber optic intubating device, which combined a ridge of the ringgoscope with the flexible fibroscope They applied cricoid pressure with the single-handed technique. The intubator was unaware of the condition being applied. And following the first intubation, the endotracheal tube was removed and it was intubated the second time with either cricoid pressure now applied or not applied.

In the intubation difficulty range from zero to impossible And what they found is that uh 30 of 33 patients without cricoid pressure had an intubation with no difficulty, and 22 of 33 patients with cricoid pressure were intubated without difficulty. So it's a difference ninety-one percent for sixty-seven percent. Cricoid pressure compressed vocal cords in nine patients, and impeded tracheal tube placement in five, and three patients had the pressure it had to be released to be successfully intubated. Did they talk at all about the force or technique applied in this case? So they describe cricoid pressure in the traditional method, which is the thumb and middle finger placed on either side of the cricoid pressure by an experienced anesthesia provider And that the cricoid pressure could be released at the request of the intubation uh clinician.

Um however they don't have a formal measurement of how much pressure or exactly how much training it's required for an experienced provider to be able to provide uh cricoid pressure. I also want to mention briefly the reason for they choosing this WuScope system, which I'm sure many of our listeners are not familiar with This device is designed to aid in the management intubation of patients with known or prior cervical spine injuries. And I think that their belief was that uh this device would be well suited to patients who would often need a rapid sequence intubation. It's comparable to a glidescope maybe? To be honest with you, I it's described as a fiber optic device with a ridge of a ringgoscope and a flexible fibroscope.

You know, I'm looking at Google here what it looks like. And it's different than any device I've ever used, but the concept is you know is pretty slick. I'd be interested to try it I'll throw some uh photos of the the WuScope system up onto the website. Punchline for the study? I think the punchline for the study is that it certainly brings up some idea that y your airway may be more difficult with cricoid pressure.

Particularly if it's not applied correctly, which is not necessarily standardized in all these different trials, but there's definitely a signal out there that cricoid pressure may make it more difficult to intubate. So just to summarize what we've kind of covered up into this point, it seems that cricoid pressure compresses the post-cricoid hypopharynx more than the esophageal position, possibly suggesting that the esophageal position is not as relevant as we might have assumed. And we may have actually more difficulty with identifying the proper cricoid location than previously anticipated, thus translating to possible difficulties with actually practicing this technique properly. So now that we've kind of covered the theoretical and biological plausibility of this whole setup, what do we actually have in terms of quality evidence that looks at the efficacy and clinical benefit of cricoid pressure?

So before we get to kind of the most recent randomized clinical trial, I'm going to bring up a couple caveats. So any study looking clinically at airway management is being complicated by significant variability in both providers. patient's illness, as well as the location of the intubation. Are we talking about intubations in the operating room, the intensive care unit, the emergency department, a coding patient on the floor All places anesthesiologists commonly find themselves being asked to provide airway management, but have differing equipment, supplies, and resources. I think most of those of us listening to this podcast would agree if we were facing the difficult airway, would much rather do that in an operating room with your friendly neighbor and head and ex surgeon nearby than at the floor with just yourself and a bougie So to bring this point up, our emergency department colleagues looked at rapid sequence intubation with a 30 to 40 newton cricoid pressure, and they proposed a trial.

Basically, a randomized provider who is trained would be able to provide cricoid or sham cricoid, and they would look for evidence of aspiration using laboratory assays, which removes some subjectivity. the difficulty of intubation. They wanted to measure the effectiveness of cricoid pressure reducing aspiration. And for our emergency colleagues who may be listening, this is critical, right? Because almost all the intubations happen in the emergency room aren't elective And instead there are people who we consider to be high risk for aspiration. They think they needed 212 patients to see a difference.

Unfortunately, the study was abandoned after only 54 patients was enrolled. They saw macroscopic contamination of the oropharynx in fourteen patients, and due to the counterforce of laryngoscopy, the amount of cricoid force could not be maintained, and they couldn't even do the study. And the conclusion was that cricoid pressure was not feasible in rapid sequence intubations in the emergency department. And it wasn't really a realistic option for people needing emerged intubations. Now the take home points that there's a little bit different.

It's in a non-OR location. Obviously the beds are not as optimally positioned. Some of the equipment may not be as familiar. They may not have as much rescue therapies or equipment And finally, I think it's important to look at this study is how high risk these patients were aspiration. If we consider aspiration to be a very, very rare event, it's going to be difficult to see a clinically significant difference.

Emergency department patients probably err on the side of being high risk, as well as patients who suffer significant consequences from an aspiration. Whereas if we were to do laboratory assays in every patient in the recovery room, there'd probably be some sound aspirations that have no clinical relevance as the patient's lung function is normal and the aspiration is not significant. But I think this segues into probably the trial everyone wants to hear about, which is the iris trial in Jamist Surgery, 2019. So this is called The Effect of Cricoid Pressure Compared with a Sham Procedure and the Rapid Sequence Induction of Anesthesia. It's by Birenbaum et al. It's uh from Jam of Surgery 2019, issue 154, page 9 to 17.

Their clinical question was the application of cricoid pressure prevent aspiration in patients undergoing RSI? And it was a randomized, double-blinded, non-inferiority trial. So they had 3,472 patients at 10 French academic medical centers randomized either cricoid pressure or the sham group. Their inclusion criteria were adults over 18 with a full stomach who had less than six hours of fasting, or one risk factor for pulmonary aspiration, emergency surgery, BMI greater than 30. previous gastric surgery and ileus, early postpartum, diabetic acresis, severe GERD, high hernia. history of preoperative nausea and vomiting or severe pain. Exclusion criteria were refusal to participate, pediatric patients, active pregnancy Lack of national health insurance, or contraindication to the use of suctional choline or cricoid pressure, existing pneumonia, upper restrottle abnormalities, existing coma. or people who are intubated in something other than laryngoscopy.

Before we continue, I think it'd be really helpful for our listeners if you could just cover what exactly a non-inferiority trial is and how we should go about interpreting the results Sure, so a non-inferiority trial rather than a traditional trial trying to show the efficacy of a certain treatment is just trying to show that there's no difference between two groups This has some important statistical consequences. So normally in a randomized trial, we look for something called intention to treat analysis which means that patients are analyzed or subjects are analyzed in the group they're randomized to. And the thought is this reflects real-world conditions. and that if there is a superiority to your treatment, then you would see that because the effect is already minimized by dilution.

So the effect that while if still seen is probably robust and real at the risk that if your treatment is efficacious but not well adhered to, you may not see the benefit. And there's debate here because on one hand, a treatment very poorly tolerated will probably have a low adherence or a treatment of cricoid pressure very difficult. then even if it's efficacious it may not be feasible. I do caution the listeners though that on a non-inferiority trial, what you're looking for is you want to exaggerate differences because you want to prove that this is no difference. between the two groups rather than one superior. In this case a per protocol analysis may actually be beneficial because we really want to see was there a difference in people who truly had cricoid pressure or not We're not studying is cricoid pressure superior.

We're trying to see if doing nothing is the same. And there's a subtle difference there, but it's important because that's the question we're answering. We're not the way we're studying the intervention How much did they go into in terms of how the method was standardized? So they had a pretty robust training program for their Uh people they use that training syringe technique I talked about. Training was repeated every month and only trained and certified providers can provide the cricoid pressure.

They also had training done with a mannequin before the trial started. And so I think they had Probably about the best standardization of cricoid pressure in a study this large that you can really expect. And I have no reason to based on their techniques that their cricoid pressure was ineffective unless you think their actual technique was wrong The sham group, the practitioner applied the same position over the patient, but no pressure. An opaque cover was placed over the practitioner's hand so that the intimidating provider could not see if criko is being provided. And then the cricoid or fake cricoid could be removed at the request of the intubating clinician.

And it's also important to note that all the clinicians intubating uh we had to have significant experience and so you're trying to remove the any bias of having uh junior providers into bailing. And so what was their endpoint for considering the sham procedure non inferior to cricoid pressure? So their endpoint was Uh the sham would be not inferior to caricoid pressure if instance of pulmonary aspiration was not more than 50% higher, or relative risk of 1.5 times. I think it's also important to note that they did a nice job standardizing the intubating conditions with anesthesia and the use of the use of succinylcholine, which has been shown in several meta-analysis to be superior to rocuronium for rapid sequence intubation.

However, they were unable to show the non-inferiority because the incidence of aspiration was very low. It was 0.5 % as opposed to what they expected, 2.8 %. They chucked it up to several factors. Um one is that all their patients were in the operating room so that RSI recommendations weren't strictly followed. Almost every patient got suctional choline as opposed to in other trials only about sixty percent.

And there's some data that suctional choline um provides better intubating conditions than rockarunium and on top of that 90% of the patients of propofol which is also associated with easier intubating conditions than other hypnotics And they had no cardiac arrests. And any of my ICU providers out there of intimate people during CPR can attest the difficulty is significant in adding anything to make the airway more difficult during active chest compressions Um could probably make the area impossible. Alright, so what's the punchline for this study and are there any important caveats to our application of that conclusion? So I think you first look at the study and see that there's really no difference in aspiration rate between the two groups, but the incidence is so low we can't really make a definitive judgment that says you should or shouldn't use the celic maneuver during a rapid sequence of tubation.

What I do want to point out though is they do exclude children and pregnant women, two groups that all have high rates of risk of aspiration, and people were trained as anesthesiologists to be extra vigilant for aspiration. And it's unclear if we may see a different signal in those two patients. And what about time to intubation and Cormac Lahane scores with and without cricoid pressure? Because I think that kind of ties into what we were talking about earlier about ease of intubation and um in terms of their findings was any of that clinically relevant? So there certainly is an improvement in the Cormac Lahaine score when you relieve cricoid pressure um increasing by you know uh roughly one grade.

And there is a statistically significant difference in dubation time about four seconds Although I caution listeners in that that's probably not clinically relevant and that most people would probably trade four seconds longer of intubation time in exchange for avoiding aspiration. So I, while there's certainly a signal here that airway is slightly more difficult with the SELIC group, it certainly is not showing a significant increase in airway failures because of the CELIC maneuver. Got it. So now moving on from that study, just talking a little bit more about the basics of the Celic maneuver, is there any sort of consistency in terms of how to actually perform this technique So no, unfortunately there's certainly no consensus as to proper application of cricoid pressure.

Um there's uh the overall force, the use of thumb index versus index middle versus three-figure occlusion versus two hands Patient positioning horizontal, head up, head down, remains unsettled. There's certainly no randomized trial comparing those. We have seen from imaging studies ways to achieve what appears to be hypofarring seclusion and a relative force of about 30 to 40 newtons. And I want to point out that almost all these are different than the original maneuver described by Selleck in his paper. Now what do the guidelines say in terms of whether or not we should be applying cricoid pressure?

So the first one we'll look at is probably the guidelines to difficult airway society. um which do recommend cricoid pressure for rapid sequence intubation. However, they emphasize the principal benefit is likely preventing gastric insuflation during gentle mass ventilation. And they do recommend immediate abandonment of cricoid pressure if airway is difficult or you do notice evidence of obvious obstruction from the cricoid pressure. The American Heart Association used to recommend CELX maneuver in high-risk patients during ACLS until 2010, but it's no longer part of their guidelines. It's also important to note that in retrospective reviews in the United Kingdom before 1994 and there was no routine use of the Celtic maneuver They had a very rare, but about 54 aspirations reported to their database, and since 1994, sniffing less.

Again, I think this may not just say that cricoid pressure is or isn't the answer. It's just that true clinically catastrophic aspiration is a pretty rare event. And in patients it happens in, it may happen regardless of the airway technique chosen due to the risk of the patient. And probably what really needs to be done is figuring out a better way to stratify who is really at risk for aspiration. I think that's a really solid point, and I think hits a lot of the nuances of trying to dig into the evidence related to such a complicated topic So Dr. Crowley, do you want to summarize some of the evidence that we've explored in this episode today?

Absolutely. So the first to remember is aspiration is a rare event. Even in high-risk patients, most patients do not have any aspiration, and many anesthesiologists will go significant periods of time without even seeing a remote chance of aspiration. There's no significant data saying that cricoid pressure absolutely reduces the instance's aspiration or that it definitively makes airways that much more challenging in the operating room setting. Their iris trial, while well conducted in a large study, failed to show non-inferiority of no-cricoid.

Therefore, we can definitely not say to get rid of cricoid pressure I think what we're kind of left with is the idea that cricoid pressure applied properly may be able to occlude the esophagus. Whether this reduces aspiration is a little bit controversial. But that if the cricoid pressure is interfering with the airway, then it should be released. But I think practitioners should continue to be trained in the application of cricoid pressure. Because another thing we've learned from this review of the literature is that inappropriately provide cricoid pressure likely just makes the area more difficult with any without any significant chance of benefit And so going back to our claims, um the first cricoid pressure reduces the risk of pulmonary aspiration.

The second, that landmark technique is able to accurately identify the cricoid cartilage And the third that cricoid pressure should be routinely applied in any sort of rapid sequence intubation. So again to our listeners, what's the level of your agreement with those claims? And what is the level of evidence for what you believe? Dr. Crowley, thank you for an insightful and thought-provoking discussion, and I look forward to having you back on the show in the future. Dave, thanks for having me here.

This has been great. I hope everyone's having a good start to the year. To our listeners, thanks for joining us on this episode. Please continue to rate and share this podcast It's been an absolute pleasure meeting all of you listeners at various conferences and even at interviews. Keep sharing new ideas with me and hopefully we'll get around to exploring some more claims.

Stay hungry and keep asking questions.