Proteger la salud de los cirujanos de los aerosoles


Creado jueves, 9 de marzo de 2023

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Ronan Cahill  0:01  

One of the interesting things we discovered was that operating rooms are commissioned empty. So the room clearance rates is without any people our equipment in us both actually in an operation you the patient at the center of the room, and you then crowd around that the operating team and really made us focused on local mitigation means of managing those aspects.


Dusty Rhodes  0:27  

Hello there and welcome to Let's talk at clean air our regular look at how clean air can affect the quality process for you and the workplace. My name is Dusty Rhodes On this episode, we're about to look specifically at hospitals, and especially the quality of air in an operating theatre. Recently, the team at UCD University College Dublin in Ireland and one of the city's major hospitals, the Mater hospital, put forward research around reducing the effect of aerosols to help protect the health of the surgeon patients and staff. Joining me to explain more about this research are two of the people very familiar with the subject of Ronan cahill and a Kevin Nolan. I'll start with you a Ronan, can you tell us just a little bit about your professional background.


Ronan Cahill  1:12  

So yeah, hi dusty. I'm a surgeon in the Mater Hospital in Dublin. And I have an academic appointment with UCD as well. And I mean, when COVID kicked off back in March last year, there was a lot of concern in the hospital, by health care staff getting infected from patients that they're coming into contact with. And this was also concerning in surgery where we use a lot of gases to open up spaces for keyhole operations, and that there was now a risk of getting infection of patients and potentially very severe infections. Normally, we wear masks and gowns to stop the patient from getting infected from us or from the environment. But there's a very real chance now of people known to have an even not known to have COVID infecting and knocking out a healthcare team. So there's a lot of uncertainty, a lot of worry about it. And we thought maybe some of this could be measured. So we did a search looking for experts in certain types of airflow technologies. And we're delighted when we saw one person in UCD. very capable, very renowned for doing this. And that's Kevin


Dusty Rhodes  2:28  

grant. So Kevin, then bring yourself into the storyteller. Tell us about your background.


Kevin Nolan  2:34  

So I have a background in experimental stood mechanics. So I did my PhD in University of Limerick. Looking at the genesis of turbulence in wind tunnels. So how do we understand what turbulence is and how do we measure it. And that was done using a technique called particle image velocimetry, where we use cameras and lasers, and we use aerosol to seed the flow. So we're using one micron diameter droplets of oil. And we can create a cloud of those in the room we pass into the wind tunnel. So that lets us see the flow. So I've been on my career, I suppose I've been looking at aerosol inflows using lasers. And and I ended up going through you know, various other roles from them coming to UCD. And at UCD, I use a technique koshland and schlierenis a different technique, it uses mirrors and optics. And it can see the refractive index change almost like a mirage. So if you hold up your hand between these schlieren mirrors, you can see the heat rising from your fingers. It's a really striking almost otherworldly effect, you can see the invisible of it. So combining these two techniques with Roland printer team in the matter, we've been able to, you know, see these invisible risks that that Roland just talked about.


Dusty Rhodes  3:44  

Can you give me an example then thinking of you know, a critical area like an operating theater, where are the aerosols found in there Kevin.


Kevin Nolan  3:55  

The biggest issue is is the distance to source of aerosol is from the high pressure due to the kind of the type of surgery that Roland performs. So this so called keyhole surgery or laparoscopic surgery. What to do, and this is this is a very opening for me I had very little experience working in surgery, I didn't even know much about it. So I learned quite a lot from from watching, watching and learning and what you do is you inflate or deflate the abdomen with co2, which is an inert gas and essentially inflated like a balloon. To put it crudely. And then you access the abdomen via these these trocars are essentially kind of like ports like you have your garden hose you connect your garden hose together and you can connect things together these ports start to tap into small incisions and then the surgeon has room inside to work with is long. These long, slender instruments and cameras and various different tools that we use. This is great because I think it really helps the patient recover quite quickly from having smaller incisions but the problem is down. It's like an aerosol can you have this you know this high pressure environments inside the body, and you have these small ports. And if you break the seal putting in an instrument or if the seal itself starts to wear out over time, from the from the surgical procedure, you get leaks coming out, you get gas leaking out, and that gas can carry aerosol and smoke and other pollutants from inside the body.


Dusty Rhodes  5:17  

So that's why it's so important to be able to control that run and what kind of auto surgeries then will be considered aerosol generating procedures?


Ronan Cahill  5:25  

Well, as it turns out, most of them I mean, there's quite a strict classification of an aerosol generating procedure based on previous pan dynamics, but actually many, many types of interventions to put gas into people the gas does come come out. I mean, sure, they can be, I suppose, obvious surgical type of operations like keyhole, a pen discectomy, or gallbladder operations. But many, many cancer operations are caused like that, too. But interventions like endoscopy, colonoscopy, gastroscopy, bronchoscopy, really everything that gets internal access into a person for the purposes of investigation during their symptoms, and deeds, mostly for this, this treatment of diseases. Use this type of technique.


Dusty Rhodes  6:15  

So, Ronan, when you're looking for a solution to this problem, what kind of situational aspects are you considering?


Ronan Cahill  6:23  

Well, yeah, I mean, it's terribly interesting. I mean, we do work already in positive pressure, ventilated rooms. But one of the things, one of the interesting things we discovered was that operating rooms are commissioned, empty. So the room clearance rates is without any people our equipment in us, but actually in an operation you the patient at the center of the room, and you then crowd around that the operating team and equipment, energy devices, screens, and that causes a relevant, relative stagnation, of airflow just in that operative breathing space, where are the where all these staff are standing. So that was something new for us. And really made us focus on local mitigation means of managing those aspects. So I mean, that can be either reducing the type of gas or smoke that's happening inside the patient, it can be maybe through better design of the type of access ports that are being used, or even local purification methods just in that operative zone. So we've come out this pretty big, illustrating initially, what the problems were. And now we're moving moving into a mitigation face, how to deal with the problems.


Dusty Rhodes  7:42  

So when you're looking for a solution, then are you looking for a solution that's going to treat error in the entire room? Or are you very kind of zoned in on where the patient is, and where the work is happening?


Ronan Cahill  7:53  

Very zoned in on where the patient is. That's where most of the operative stuff risk is. I mean, like you can wear at 95 Masks, we look to using, so very kind of very sophisticated, clean air methods around the person. But all these are sort of just acknowledgments that the risk is there, I would rather deal with the risks better. Now, I should say, we know now that people don't tend to get COVID in these circumstances, but we've become very aware of the pollutant effects that these gases will use cautery inside people, there is smoke in that area, too. And so the product, so the project has really expanded its scope much more from that. From that the initial hypothesis to really trying to improve or clean the air for the benefit to ball operating room teams.


Dusty Rhodes  8:47  

As a surgeon, then is noise an issue for you.


Ronan Cahill  8:53  

Yeah, I think I mean, yeah, things need to be rather quiet. I think most people do already know the noises of an operating room because you hear them on the TV shows. There is that kind of cardiac monitor beep. But generally, it's a rather calm, controlled environment. And people do need to be able to communicate easily and sometimes quickly. So yeah, noise is very important. And face you can't really crowded space with things that aren't usefully doing things. The operative team needs to be able to move to move around. The patient needs to come on and off the table at the start and at the end of us. So doesn't need to we you know, you mostly put the patient in the center and then build up the equipment and people around that person.


Dusty Rhodes  9:42  

So, Kevin, when Ronan came to you then and said, You know, this is the situation that we are in and we need a solution and we need to measure the most effective solution what was going through your head?


Kevin Nolan  9:56  

Well, the first thing was trying to move the equipment from the city to the matter schlieren is quite large and quite bulky space. So schlieren is a very, very old technique it goes back over 100 years, even Lord Kelvin apparently was quite fond of using it. We've all seen a mirage on our on a very warm day when there's delight from a hot rod kind of reflects the sky, we see this kind of mirror shimmering effect that it uses a similar effect to that of a two large parabolic mirrors to about half a meter across, we placed on either side of a room. And then we use a light a light source, in this case, they can add like the light on your phone, we showed that other one mirror, we got a column of light across the room, and then we focused that later with the second marathon. And by blocking some of that light and collecting the result of the camera, we get the schlieren image where we can establish the candle, for example, you will see the hot plume above the flame oscillating above it quite far, you see the heat rising off your fingers. If a hot drink or a cold drink is either heat rising or falling around us it's really visually striking effect. Lovely, but probably seen pictures of it online or some places or various YouTube channels who use it, they look at, you know, guns and shock waves coming off bullets and so forth. The problem with children It is very bulky, it's very cumbersome. And it's very, very sensitive to alignment. So my prior experience has always been in a kind of controlled lab environment, not in surgery. So what we ended up doing was we ended up bringing the system to the monitor instead of get up in the essentially the digital surgery lab, which is the former operating theatres. So the system is currently supposed to be there for a couple of weeks. It's been there for over a year. It's still there, it's and we've been able to do simulated surgery with porcelain cadavers. So essentially does that mean we get apig that's been butchered specifically for surgical work. And by using that, then we can simulate the kind of procedures that occur and get the image get images off of the lakes. So schlierenis very, very, very good for that. But what schlierendoesn't give you it doesn't show you the aerosol in the lake and shows you the gas. So we ended up doing that was we used a laser which expands through a particular lens, which expands the beam into like a long, kind of a fan or as she says two dimensional slice, the laser is easy, it's quite small, we can move it around on a little trolley, and then we use a camera so we rock the cat in Ireland to get a one of their pre release cameras, the Canon r five, which has the record video on 8k resolutions as 1000. By 2000 pixels is enormous pixel density. By using the laser and this camera and some very, very nice lenses, we can resolve aerosol particles down to about two microns. So we use the laser technique in live surgery with patients so that when I was to move the laser move the camera quite safely around the room and then image directly the aerosol. So by combining these datasets together, then we have a view of where the leaks occur. And where in those leaks is where air is or aerosol is or smoke.


Dusty Rhodes  12:57  

So rather than when you saw the results of where the leaks occur, and the airflow does this surprise you to be actually able to see it?


Ronan Cahill  13:05  

He has astonishing. It's absolutely as tarnishing and not just me but the rest of the operative team and East, nurses, porters. It's really quite incredible. I mean, I've been very complacent about this. Previously in my current career, which I think is reflective of most, most operating surgeons to do, you know, we kind of know in theory that these things exist. But because we don't see us our heroes, we don't tend to really think it's a very important aspect to us. The nursing organizations, though have been very clear over the past couple of decades that there is occupational hazard in being exposed to operating gases and smoke but it's really feel bad about how complacent I was born you can see us dusty 3d quite incredible. These are beautiful pictures you're seeing in real time. So can't really be disputed. And we've really seen a number of specialties and specialists looking to get their own techniques and procedures investigated. And Kevin will will I think the whole hospital now knows Gavin from the physiotherapists to Speech Language therapists, dentists, everyone has been trying to use that type of technology to make sure that the best patient care can happen. Despitethings like societal pandemic,


Dusty Rhodes  14:32  

tell me Ronan, you obviously, were aware that there were aerosols in the room and probably more than then you needed. Were you kind of shocked to the results to see how much aerosol was there for sure,


Ronan Cahill  14:44  

because we do trust that the room ventilation, you know, serves its purpose to know absolutely. And, you know, we wear masks and we kind of think, Well, you know, we're pretty well equipped in the traditional way to deal with these type of things. But actually It's really, it's really illuminating, to see this type of stuff. And of course, once you can see it, then you can do something about it. And nearly everyone, Kevin, who's kind of seen, your analysis instantly starts to come up with ideas to mitigate those those risks. It's really I mean, it's so instant, the kind of the feedback that you can't not be drawn in. And the area is so important, really, everyone who looks at us does start to kind of, you know, give up themselves to come forward with, with, with, with suggestions and, and ways to help us.


Dusty Rhodes  15:34  

So tell me then about what ideas you came up with to control that.


Kevin Nolan  15:39  

So, I mean, obviously, we could do is some sort of vacuum, right, you have some sort of suction that you can you can use to capture these leaks as they occur. The problem is, and I was told by a mentor long time ago, this notion that you cannot look at a candle, right, you can blow out a candle across the room, you can have a good chance of over a meter away blowing out a candle, you try, inhale, there's no way you can do that, because the airflow has been pulled in from all directions equally. That's why we use a vacuum cleaner, we bring it down close to the surface as possible. So we control the direction of the flow. So soaking up a high speed jet coming out of a port is very, very difficult and requires a lot of thought into how the geometry of the device would be designed. And that's what our partner and Galway Pele are doing with our Hs 2020 project. So we've funded European project to design devices that can be cleverly designed to try and mitigate that source as much of the material as possible. Other aspects we're looking at are ways to control the curvature of the port. So during various fluid mechanics effects that try to involve my students as much apart as possible in this work, so during my lectures for the year, I will be showing some of our videos, just to remind them, you know, this is why you need to wear your mask, this is why your hairstyle is risky. So how to get several more students in their final year projects and so forth involved in this work. So one student I worked with, we looked at this, this idea of decline the effect, so he have a curved surface flow will tend to follow the curvature of that surface due to friction. So if you get a if you get a spoon with a turnip turn on your kitchen sink, tap at a fairly low flow rate, and you put the back of the spoon against the stream, you see the flow kind of hugs the curvature of the spills. So if you need to do something similar to the outlet geometry of these trocars, they're designed a certain way. But for the most part, the exit geometry is not that important. It's really just to facilitate the surgeon to insert instrument. So if I were to incorporate a similar curvature into the exit port, we could actually encourage the jet to actually have the surface be diverted to the ground rather than off into people's faces. So that's kind of add to source kind of ways of dealing with this demo we're looking at is to deal with this, this this problem that Roland talked about how when people are crowded around the room, ventilation is not doing its job. And as for the camfil technology comes in, we can place one of these devices in the operating space, and then start to pull away that material and encourage you to move out of a airflow direction, that's, that's more furtherfield away, that's about half a meter away or so forth. That's not in the surgeons way. But we can still encourage the flow to move away from face.


Dusty Rhodes  18:14  

So tell me that about the solution then that you did find with air cam felt.


Kevin Nolan  18:19  

Sothe guys in Camfil contacted us based on the work that we've alreadyperformed. And they were eager to see if their device could have some effect. So they have a number of different devices, they were showing to us for different applications, because ventilation is usually a part of ventilation, not just in surgery, but also in schools and offices, and if any place where people have to congregate are very, very important. So they had this particular device to this to city age, which has an extendable arm on it, which means it's quite portable, and quite adaptable to the surgical environment. So by using that we were able to, again, do some do some experiments, we use the laser, she's thehigh resolution camera. And we did some sort of simulated surgery on a porcelain cadaver. And we were able to show using that device that yes, indeed it can effectively from over half a meter to almost a meter away, it can actually encourage the theairflow in that region tobe effectively vacuumed up to be pulled away quite well, without having to close that it gets to the surgeons way. So that was that was a really important part that it has that that range of effect, because of the size and because of this design.


Dusty Rhodes  19:34  

And then Relman speaking about the size, and the noise, as we mentioned is required to unit


Ronan Cahill  19:40  

Yeah, yeah, it is. I mean, there's different settings for us, but even at the highest level, it's really it's really very fitted and very well alongside the rest of the audio footprint of an operation. Yeah, it really I mean it wasn't built specifically for this but it's looks like it was terrific.


Dusty Rhodes  19:57  

How do you find thesize of the extraction arm is that does this fit in with your workflow?


Ronan Cahill  20:02  

Yeah, it's pretty good. Maybe maybe the faceplate could be a little bit smaller, perhaps. But it's very easy to move us as it can be positioned around. I mean, there's certain times in the operation when the risks are higher, like when you're using electric cautery. So operation tend to be very standardized. And there's certain times when you know, there's going to be certain things being beingdone. So I think, yeah, I think this was, I think this is very practical. I guess there's always a couple of small and things that you might like to evolve. But you really need to use things dusty before you can really be sure about what needs to be done or not need needs to be done. So it's great to have an off the shelf capability that can then be put into different situations. And then with some use, people could start to really make sense about what could be maybe, you know, an optimized configuration for far, far the use case. But I must say, I was really impressed. This did work straight out of the box.


Dusty Rhodes  21:01  

Well, what was the reaction of all the people within the surgeon community when you were telling them about this?


Ronan Cahill  21:07  

Yeah, it's really interesting, because people had been sort of thinking that they needed the whole room redesign of the operating room. But it's no small thing to try and move from positive pressure to negative pressure are to change, you know, where the beams and the positions of the room are. So it's really quite kind of marvelous. That, you know, there's the kind of the combination of Kevin's technological illustrations of us to know the real time visibility of the smoke, and itsits dynamics, and then this kind of lovely, local hoovering up of the action to it. So it is really, it is really rather compelling. Yeah. So, I mean, we've published this experience in Europe's most prestigious surgical journal. So, you know, it's about maybe moving that conversation to, to include other people and, and views. And education is a big thing in this cafe. And you know, as I said, I've been very complacent and ignorant about this in the past, and it's really terrific to get educated.


Dusty Rhodes  22:11  

Well, I have included some links into the show notes of the podcast. If you listen to this right now, just look into the show description, and you'll see links, giving more detail about all of the research and the effects. But for now, Ronan Cahill and Kevin Nolan, thank you very much for chatting with us. And I should also note that the links below also include contact details and anything else that you might need to get more information on our topic today. Our podcast was produced by camfil, a world leader in the development and production of air filters and clean air solutions. To stay up to date on how clean air can affect the quality process for you and the workplace. do click follow in your podcast player right now. So you get our next show automatically, under them for myself does yield thank you as always for listening and take care.