Episode 23: Intraosseus access

Hello and welcome to Femcast. Hello and welcome to this month's podcast and today's theme is... Interestious Access. This has come up a number of times within our local service recently and we realised that... Even though we knew a bit about this subject area, and to be honest, assumed we knew quite a lot about this subject area, a number of our contributors have put us right. So we thought it'd be really nice to be able to share some of that knowledge and share some of that thinking.

Yeah, there's some top tips coming up. Some really interesting stuff about how interosseous developed and where it came from and why it's now such an important part of our practice. And also some... lessons i think to learn about how to put them in and perhaps when not to so we've got some i hope some really exciting things which you'll really enjoy so we've got tony keogh

talking about his time using IO in Afghanistan. Yep, and then the anatomy professor from the surgical skills course in the Midlands. going through the humoral anatomy. There was definitely some stuff in there that I didn't know before. And then we've got the EZIO rep talking through some salient points from his experience.

So let's get on with the interviews and Tony Keough is up first. So first of all, Tony, thanks very much for coming to Femcast. If you could introduce yourself. Hi, I'm Tony Keough. I'm an emergency physician. And I've been a practitioner in pre-hospital care with London Hems. And then when I was still in the military with Mert. And I've done some children's retrieval with cats from London as well.

All services which have, for different reasons and at different times and with different indications, relied quite heavily on IO access in difficult cases. Okay, so can you give us a bit of...

Your knowledge then of the history of the development of interosseous? Well, I don't know that much about how they were originally developed. But my experience, I guess, has been around the evaluation and implementation of... I.O. devices in adults because from many, many years, decades, we know that people have been using the I.O. routine children when access is very, very difficult with the Cook I.O. needle.

And I'm sure many of your listeners have had their hands on that or at least tried it maybe on life support courses. In real life, it felt a pretty brutal thing to do. It certainly didn't seem a very refined technique. And that probably explains why it was never really popular in adults.

you would probably expect it's going to be generally easier to get IV access. And I think most of the services I've worked in wouldn't have occurred to them to revert to IO access when things were difficult. However, I think I was at London on two occasions. I did the physician response unit job there, which was, if you like, an apprenticeship for HEMS proper.

So I did that in 2005 and then came back as a Real Hems Reg in 2007. And it was around that period that Hems as a Service started adopting IO access in adults too. And what was very interesting at the time is that there were at least three competing devices on the market. And nobody knew which was going to work best or which was going to be the most useful or the easiest to use. And so London Hems were probably a service that was a good choice to try and evaluate it.

So we had the easy IO, but we also had a thing called the bone injection gun, which is a spring-loaded harpoon that you fire. And then we had the fast one, which is a external IO device. And I think we went... There was a degree of formality in how we evaluated them, but mainly it was feedback on how easy they were to use. It became apparent pretty soon that their bone injection gun was downright dangerous.

Certainly the one we had to test, you could reload and fire at each other across the doctor's office. That didn't seem particularly safe in our hands. The Fast One worked okay, but it was slightly erratic in when it would fire. The original Fast One device had a series of small needles. They looked like needles.

they weren't the actual interosseous needle. So when you unsheathe the device, these needles were all kind of pressure gauges, pressure sensors. And when you had all of those loaded with equal pressure... then the harpoon would fire from the middle. So we found it quite hard, actually, to get all the pins lined up with pressure so that it was uniform throughout to make it fire. Plus, when it did fire, it was a bit of a shock.

Okay. And instinctively, you sort of recoiled from the discharge, which I think meant that some of them went in quite superficially. Whereas the easy IO was... Seemed pretty safe, pretty reliable. It was easy to put in. You could see and feel as it was going in. So you felt pretty, it felt pretty reliable that you had got to the right place.

During the original evaluation phase, the manufacturer had only produced the pink one and the blue one. As far as I know, they're the same internal diameter. The only difference is the length of it.

And we were encouraged to use the pink one in children and the blue one in adults. And I think the particular clinical scenario that this revolutionized for us was traumatic cardiac arrest. It was part of the Hems philosophy was that rather than just transferring a really difficult scene into an emergency department, if you could be...

quite genuinely confident that the patient wasn't going to respond to resuscitative measures, then you could declare the patient dead on scene. And actually that was... I think, a good outcome for the health system. But to do that, one of the reversible causes you have to address in some way is hypovolemic shock.

In the absence of blood products, because nobody at that stage that I was aware of in UK practice was taking blood products forward, we used crystalloid. But we would use a generous crystalloid challenge. Many patients with traumatic cardiac arrest have arrived at that point through hypovolemia, terribly shut down, really, really difficult to get access in. And I suppose many of our high energy trauma cases also have quite distorted anatomy.

So having an IO needle, but particularly one that you could use flexibly in a variety of different sites, was a real boon for the service. And I think it enabled us to get on early and correct. potentially reversible causes and if there was a response that's great but if there's no response then I think you can confidently turn around to the police officer next to you and pronounce life extinct.

So the sites that we started using, and at this stage, I think the manufacturer was only offering us the proximal tibia as a kind of bona fide. anatomical site to use that's not much use in a motorcyclist with a badly disrupted pelvis because we'd be concerned that the fluid is just going straight into the wrong tissues and certainly not the intravascular space. So we started looking at other places that you could sight the needle and the shoulder.

was a really useful place. Now, remember at this stage, we've only got the blue needle, which is still relatively short. Certainly compared to the yellow one that's come on the market since. to use the shoulder, we had to find a way to make the bone relatively superficial.

and then you would have enough depth in the needle to get the end of the needle into the right place. So we found that if you went for the proximal humerus and then you had your hand, your fingers... anteriorly around the bicipital groove and then you internally and externally rotated the humerus with a flexed elbow. moved it in and out, you could feel the bone coming up underneath your fingers, and that seemed to be a useful location. So we used it in many...

Many scenarios, we found that you can't usually get flow rates using gravity. What you need to do is introduce a pump into the circuit, which typically would be a 15-inch syringe with a three-way tap. But with one of those, you could quite comfortably infuse a litre of crystalloid in a period of five to ten minutes, which in traumatic cardiac arrest is, I think, the most reasonable fluid challenge we could offer at the time.

Another location that we certainly tried, and I think with some success, although it was a little bit harder to know, was the pelvis. Clearly not when we suspected that there was pelvic fracture. The anterior superior neck spine is another place. Clearly that's where we do bone marrow aspirates, isn't it? It's a good superficial place to get access into the skeleton.

You have to be able to visualize, though, the shape of the bone underneath and then place your needle in such a way that you are going between the two cortices of the iliac crest. It anchors the IO needle beautifully when you get it in. It's a really, really solid insertion point. One of the potential drawbacks of the humeral head as an insertion point is that the arm is very mobile.

And once you've inserted a needle, any movement of the arm subjects the shaft of the needle to quite strong shearing forces or quite strong leverage forces which can bend and keep the needle in the pelvis that was never a problem because it's never moving and it was always rock solid again you could you could get a reasonable volume of fluid into someone. Whether it was definitely going to the circulation, I don't feel you would be able to appreciate if it was extravasating.

in the same way that you would from the human head, where it's just maybe a little bit more obvious if there's a swelling in the soft tissues of the shoulder. I know there are some nice videos that you can see online of how... dye enters the central circulation really quite quickly. Well, we kind of saw that in vivo as well, particularly in cases who had had a thoracotomy that we were transfusing crystalloid into.

you could feel the heart fill in your hands as you were doing internal massage. So it was very clearly getting into the right space pretty quickly. Yeah, and we'll put some links on the blog to those videos because they are worth looking at some really interesting... We're using an x-ray dye, isn't there, to see how quickly it gets into the circulation. Okay, so and then was your next experience then the use of interosseous when you were working with MERT, a military setting? Yeah.

We worked at full deployments around 2008-2009, and it had clearly become quite widely known that Bitproximal Humerus was a good place to try and get access. And the manufacturer by this stage had brought out the much longer yellow needle. But around this time, their recommendation was to use an entirely lateral approach.

just kind of grasping the whole deltoid in your hand, picturing where the center of mass of the human head would be and approaching it laterally. So I had many vociferous arguments with trainers. as part of our pre-deployment training, saying, no, no, no, no, no, that's not a really good way to use it. There's lots of problems with that. Use an anterior approach instead.

It took a little while for the message to get through, but by the time we had deployed, the team we took over from, they had refined the technique for positioning the limb still further. Okay. So, Giles Nordman, who's an army anesthetist. He described placing the patient's hand over their groin.

And if you do that, you get the shoulder into exactly the right position to go straight anterior posteriorly with your needle and get it to the right place. So the team we took over from were already doing it the right way. And in soldiers injured in Afghanistan, the signature injury was from a big IED, so much bigger than military landmines. They seem to be designed to...

to Maine, which takes three or four people out of the fighting unit because then you have to katabak. IEDs in Afghanistan were designed to... kind of blow up and kill. So the force that they generated, the energy was much, much, much greater. So instead of having a relatively discrete hindfoot amputation from a mine strike, you had much more devastating... bilateral high leg amputations often going into the pelvis. There may be an arm involved as well. So patients...

subjected to that kind of injury are critically hypotenuse. And we developed a way of working that was really centered around delivering blood products. And I think... In our philosophy, everything we did was to facilitate the delivery of pull-up products as soon as we could to the casualty. The patients would be loaded onto our airframe.

We would know exactly what we're doing. We'd be set up to do it. And our approach was almost like a pit stop team in motor racing. People would have been drilled, forgive the pun, in exactly what we were going to do. The doctor would typically be at the head end. The patient would be loaded, usually head first. There would be a paramedic on either side and a nurse.

We would usually have some force protection soldiers who we worked with every day and we trained them in first aid as well. And we trained them to be the pump in the system. They were very, very good. It's not a tremendously sophisticated job, but they were really good at it. The patient would be loaded, and our first IO access would be an easy IO straight into the left humerus.

And that would be our access to do the RSI. And for us then, our rationale for doing the RSI was to facilitate blood transfusion. pumping blood or I think anything through an IO is painful. And patients were usually still awake at this stage. So we would get IO access in the left. and deliver the anaesthetic drugs through that, but then can immediately connect the first unit of O negative blood. So the anaesthetic drugs will be chased into the circulation by the first...

unit of red being pumped through with a blood warmer in the system and then the 50-mile syringe and a three-way tap. As soon as the patient was off to sleep we'd intubate and secure the tube. And then we'd roll the patient. And here we were looking for any evidence of bleeding from the back, particularly the pelvis, and we'd be doing what haemorrhage control we could there. Putting on a pelvic splinter that hadn't been done.

And then the patient would be log rolled back onto the back and the second IO access would go into the patient's right tumble head, assuming the upper limbs were intact. And more blood products would go chasing through those. and then so as not to disrupt the flow of resuscitation for ongoing drugs. We used to place the stern line. Now, by this stage, the needles have been replaced by a solid ring, which is easier to get to deploy. I still had a couple of deployment failures.

But anyway, most of the time, once you'd got used to it, we could then reliably, the doctor would do this from kneeling either side of the patient's head and leaning forwards to the sternum.

pop it in there so you have a third access then which is our route for ongoing drugs and using that kind of approach we would regularly normally be able to to deliver two units of O-negative and two units of FFP, some tranexamic acid, usually some calcium as well, and the ongoing anaesthetic drugs in about a 10 to 15 minute flight from the area.

of operations back to Camp Astium. So in my opinion, IO access was the only way on that sort of moving platform under those conditions that we would have been able to get access reliably, quickly, be able to deliver that volume of resuscitation in a short period of time.

And as is the case with loads of the developments in delivery of pre-hospital, particularly trauma care, we've learned a great deal from that military setting regarding the use of intraosseous, but also blood product resuscitation, etc. So it's really good to hear about.

Your experience and how that developed and how much of a game-changer Entrosius was for those patients probably made quite a big difference to survival, I would think. Well, there is a paper, actually. There is a paper and there is no one element that made by itself, I don't think, a significant difference to survival.

The point is that from the very point of wounding all the way through to transfer back to the World War in Birmingham and then ongoing... trauma care there many many many more operations both resuscitative operations and then reconstructive and every item of that Chain of Survival has to be working at the very top of its game to get any kind of decent outcome. So I think we were.

I don't think it was necessarily any more of a game changer than the other links in that chain, which were also developing to the highest level they possibly could be. Tony, thanks very much. It's been really interesting to have an insight into your experience of using Atrocious, which has clearly been quite extensive compared with some of us. I'm very grateful to you for talking to Femcast. Thanks. It's an absolute pleasure. Thanks, Tony.

So we hope you found that chat from Tony useful. I think key points for us was how quickly things have developed in this area and how, for me particularly, I found so exciting how... They built this new technology into a system which really worked for their patients and delivered a bundle of care which is effectively around this ability to deliver IO in a... in a reproducible and mostly successful manner. I think it's amazing how far we've come since Cook Needles. I can remember as...

being a junior doctor and using a cook needle on a child and just being a bit unconvinced by its reliability. And now we've got IO and the easy IO is an excellent device. You know, you just can confidently deliver. really good care to very sick patients. Yeah, I think the kit is where it's at and where the development's been, but the kit won't work unless you know the anatomy. Ba-boom, lead in. Nicely done.

We thought it would be useful to review the anatomy of the shoulder joint. And so I'm joined at the surgical skills course by Richard, who is very kind of going to go through the anatomy that he's just discussed with the candidates here. So perhaps, first of all, you could introduce yourself. And then talk about the anatomy of the...

humorous and how it pertains to intraosseous access, please. Certainly. I'm Professor Richard Tunstall. I'm Head of Anatomy at the University of Warwick Medical School and also Director of Anatomy at the Surgical Training Centre at UHCW Hospital. So we're going to consider the anatomy concerned with intraosseous access, and it's intraosseous access at the proximal humerus.

We'll take a few steps back before looking at shoulder joint anatomy and just consider the anatomy of bone to begin with. Long bones like the humerus have different sections to them and the parts of the bone near to a joint is called the epiphysis. Below that, there's an area called the metaphysis. These regions actually have quite a thin shell of bones surrounding them. Long bones have what's called a cortical shell. Normally, the cortical shell is quite thick.

particularly in the shaft of the bone. But when you're at either the proximal or distal end of a bone, in this metaphysis and... epiphysis region it's much thinner so if you're thinking about drilling through the bone it's a logical place to do it because the bone's thin there the drill will easily penetrate that bone if you try to do it on the shaft of a bone it's much thicker

And to be honest, you won't get through it with the drill setups that we use for intraosseous perfusions. The reason bone is such a good place to put fluid is you're actually targeting the medullary cavity of the bone. And bones have an extensive vascular network within them. They have an incredibly rich blood supply. And anyone who breaks a bone may know that

they get considerable bruising afterwards and swelling. And some of that's because of the bleeding and because of the hematoma that forms. So putting fluid into the centre of a bone is a logical choice because there's a large vascular network into which it can be absorbed. Also, what may not be known is that the medullary space within the bone actually generally has a higher pressure within it than there is in the venous system. So there's a pressure gradient also there for fluid absorption.

Great. Okay. And there's a really good video, which I'll link to in the show notes, that demonstrates how quickly the fluid passes out into the circulation. It is instantaneous, really, isn't it? Absolutely. Yeah, it's very quick. We've done demonstration dissections here on Fresh Calibre.

tissue that allow us to visualize the axillary vein. That's the main vein draining the upper limb. And when we flush fluid into an intraosseous line, you can see the vein dilate almost instantly. And that's in the cadaveric specimen.

So we'll have a think now and think about the anatomy of the shoulder region. And when we're in this region, the humerus articulates with the scapula at the shoulder joint. But there are some bony features in this region that can be felt and palpated. And these are really important features to feel. They're landmark features that allow us to identify the correct site for needle insertion.

The target we're aiming for with a proximal humeral intraosseous needle is actually the greater tubercle. It's the greater tubercle of the humerus. sits at the top end of the humerus and it's located in a lateral position. We'll start just by talking about some of the features we can feel of the scapula. With the clavicle, you can divide it into thirds. It's got a medial third. a middle third and a lateral one third. And if you palpate or have a feel just below that lateral one third,

you should be able to feel a prominence of bone just pointing out towards you. It might feel like the end of your thumb, so just a firm prominence. And that's known as the coracoid process. So that's a bony feature of the scapula. If you now just drop your fingers off the lateral side of the coracoid process and press quite deeply through the deltoid muscle, you'll actually have your fingers now on the lesser tubercle.

The thing to do now is keep that pressure on and immediately rotate your shoulder joint. And when you immediately rotate the shoulder joint, the tubercle will move across your fingers and your fingers should then drop down into a groove. And that groove is the bicipital groove or the intertubecular groove. So the bicipital or intertubecular groove houses a tendon, and it's the tendon for the biceps muscle.

So that's one of the structures that must be avoided in this region. If you continue now to medially rotate the shoulder joints, your fingers should rise up out of the groove and onto the greater tubercle. So that's a large bony feature and it's the large bony targets that we'll be drilling into for this procedure.

And what we'll do is, obviously it's quite difficult to visualise these types of things when we're discussing them in an auditory sense, but we'll put some pictures and some diagrams on the blog post and put a couple of videos on, which hopefully will help people to... visualize exactly what you're describing yeah absolutely so the the greater tubercle is a considerable size target and the reason it's such a big piece of bone is that it's got muscles inserting into it

And the muscles that insert into it are actually three of what we know as the rotator cuff muscles, these being muscles that come off the scapula and insert into the proximal end of the humerus. And the three that insert into... The superior and posterior aspects of the greater tubercle are concerned with laterally rotating the shoulder joint and also helping you lift the shoulder joint upwards in what we know as abduction action.

We do know, though, where these muscles insert, and actually the lateral aspect of the greater tubercle is the region of the bone that doesn't have any muscle insertion, and that's why it's a safe region to drill into. The greater tubercle will be covered by the deltoid muscle. And deltoid is a considerable size muscle that comes off the lateral part of the clavicle, the acromion, and what we know is the spine of the scapula.

and its fibres coalesce and insert into the lateral aspect of the humerus. So during this procedure, the deltoid will have to be passed through, but even in quite... quite fit younger people with a good muscle bulk, the deltoid actually isn't that thick, and particularly where you'll be drilling, so it's easily passed through. Something else that's worth considering in the region as well...

is some of the neurovascular structures that you might be concerned about. Thankfully, the big neurovascular supply to the upper limb actually sits medial to where the coracoid process is and the muscle called coracobrachialis. So as we're going to be doing this procedure lateral to that muscle and lateral to the coracoid process, we know that we're not in danger of damaging structures like the median nerve, the ulnar nerve, the radial nerve.

There is one nerve though that must be borne in mind and that's the axillary nerve. And the axillary nerve is a very important nerve supply to the deltoid muscle. The axillary nerve can be positioned quite easily because it follows a route around the surgical neck of the humerus. And the surgical neck of the humerus is the slightly thinner section of the humerus that sits below the articular head.

So really it's where the top end of the humerus begins to taper in and join to the shaft. Many people will actually be able to palpate that, and if they were to squeeze their shoulder joint, the lateral side of their shoulder with a finger and thumb, and then move distally,

they'll actually be able to feel the bone narrow off, and that's quite a good way of locating where the surgical neck sits. If that's not possible, the other way to visualise this is the axillary nerve sits approximately 5 to 6 centimetres. below the acromion.

The acromion is the bony shelf that you can easily feel over the top of your shoulder. If you just put your hands over the top of your shoulder area, laterally, even in very fit people with big muscle bulk, you'll be able to feel the bony shelf of the acromion. Follow that laterally and it will drop off into the softer deltoid muscle. So if you visualize an area between five to six centimeters inferior to that acromion, that's where the axillary nerve...

And some important arteries called the circumflex humeral arteries run. So if you're actually above that point, then that's the relative safe zone for needle insertion. Okay, great. And we should be quite a lot higher than that when we're doing this as long as we're in the right place.

which should be quite a bit higher than where that circumflex artery sits. Absolutely, yeah. Providing the correct landmarking has been done for this procedure, then you'll be above the level of the axillary nerve. Just to point out, if the axillary nerve... were to be damaged, then there would be a weakness of deltoid. So depending on where the axillary nerve is injured...

then will dictate how much weakness or paralysis of deltoid you would get. If you had a full damage to the axillary nerve, then there would be a full paralysis of deltoid. And for your patients, it would then make it very difficult for them to actually use it. their shoulder. Deltoids needed for quite a wide range of moving to the shoulder which include things like flexion, extension and abduction so they wouldn't be able to reach up, comb their hair.

They'd also have problems actually lifting the upper limb to get their hand in a pocket of a pair of trousers. So it's a really important nerve. Richard, thanks very much for taking us through that anatomy. It's really helpful. You're very welcome. Thank you.

So we've had a romp through the anatomy in relation to this procedure and I think this is where it goes wrong most of the time nowadays. The kit seems to work pretty much every time. People know how a drill works. from their home DIY, and they tend to know how to get the system flushed and the freeway taps going. But the failures, I think, are coming from getting it in the wrong place.

Yeah, I think so. And we'll put on the blog post some pictures of the anatomy because it does help to just visualize some of that stuff that Richard was talking about. It doesn't perhaps come quite across as well as a podcast as when you can see it. And there'll also be some links from some videos. that Tom recommends in his interview when he's talking about top tips about how to use the device. So moving rapidly on here's Tom.

Tom, thanks very much for joining us on Femcast. I've asked Tom to speak to us about interosseous and I'll let him introduce himself so that you know why. Hi, my name is Tom Humphreys. I'm a clinical specialist for Teleflex, who are the makers of the EZIO. My background is 12 years pre-hospital as a paramedic. I'm still a registered paramedic and do bank shifts for the NHS. So I've used EZIO for real.

on real patients and we met at the surgical skills course at coventry which you're quite integrally involved in um and you certainly taught me some really good tips about introsis insertion, which I thought would be really useful to share with people. So would you mind going through that for us? Yes, I think there's kind of three points I'd like to cover today. First point being early recognition.

of when to use IO access and definitely the patients presenting with difficult IV access. I think I've seen... 11 attempts at IV access before it was eventually considered. And I think that's probably excessive. And I think everyone listening to this will probably agree that's an excessive amount of IV attempts.

So I think with your critically unwell, time-critical peri-arrest, arrest patients, it's very easy to get task-focused. There's always somebody saying, I need to get IV access. And there's a lot of tapping the veins. on both sides of the body, sometimes feet. And I think that's the point when you should be recognising as a clinician. Actually, maybe you need to be considering another option. And it's another tool in the arsenal. And so...

Considering it early on, I think is a good idea. And I think there's a lack of confidence in using I.O. People don't get to do it frequently. And there's always this kind of stigma of... drilling a needle into someone's bone. And I think sometimes understanding exactly how it works and how quickly it works is another thing that people need to consider early on. Secondly, correct landmarking.

is another thing that I like to teach people to improve confidence of using it. I think you're absolutely right. I think there is that fear. you know we are unfamiliar potentially with it we don't use it very often and probably we might have originally had a little bit of training like this is how you use it crack on potentially from people who weren't that familiar with it themselves and it seems as if

Certainly the training I've attended more recently is much better than it used to be. I think the detail that's available, some of the videos that I'll link to from the blog post are really good.

How do you think we can get more confident? How can we reassure people and say, look, it really is a good thing to do? Teleflex provides free on-site training so people like me can turn up and do teaching. And I think from my experience... I feel I was taught badly and I want to go out and teach people better about landmarking and how to do it correctly. We also have an app which is available on the App Store. Again, it's all completely free.

which will talk you through needle selection, site identification, landmarking and insertion technique, which is all out there. So these things are available. And like I said, I'd like to put a link at the end of this. to link towards our education website which is okay all free landmarking the humoral head is is is probably the thing that i'm most keen about getting people more confident doing it's not difficult it was always

the option for me when I was taught it was, well, you can go humeral head or proximal tibia. Well, proximal tibia is easiest, so let's just go for the proximal tibia. But I think, especially pre-hospitaly... Humeral head makes more sense, has increased flow rate, faster to get the medications towards the heart. And if you've got a patient responding to pain, reported to be less painful on insertion as well.

And access, from my point of view, on an ambulance, I'd rather I was all on the head end. And I think most helicopters that people are working on, I don't think you can get to the tibia. Yeah, I think that's a fair comment. So tell us about how you would recommend approaching the humeral introsis insertion. So the rule we teach in landmarking the human head is the 45 rule. So anyone who's 40 kilograms and above.

Use the 45 millimeter needle, the yellow needle. You approach the patient 45 degrees across the plane of the body. So from the humerus you're landmarking, 45 degrees across the body to the opposite iliac crest. with a 45 degree angle from the floor effectively or the bed for the patient one. So 90 coming straight down, zero is level with the floor and a 45 degree angle in between those two.

That puts the needle into that intermodulary space sitting below the growth plate, which no big deal going through the growth plate, but there's a much better flow for your medication in that spongy bone. in that intermedullary space. So we're not saying that every single time you should be using the proximal humerus, you should be using clinical judgment on each patient and deciding, but the proximal humerus is becoming the site of choice.

And I think what you're saying is it shouldn't be a sight to be frightened of as long as you approach it with that 45 degree rule and make sure you've positioned the patient correctly. Yeah. Should be onto a winner. Exactly. I suppose I didn't mention about the positioning of the patient, but putting the arm across the abdomen or rotating the hand, the thumb down, immediately rotates that joint and presents the greater tubicle on the humerus, which is our target area.

People sometimes get a bit scared about being quite exact, but they say it's about the size of a 50p coin on an adult of a target area. So it's actually a bigger area than most people think. So one of the questions I'm asked quite frequently is which needle should I be using? They come in three different sizes. It's pink, blue and yellow. The pink is anything from three kilograms and above. Blue, three to 39 kilograms and yellow is 40 kilograms and above.

Some people like to call the pink needle the paediatric needle. And I'd much prefer to just say, just use your clinical judgment. From my point of view, I tend to use the blue needle in paediatrics. And pink on neonates and newborns, so very young children. And that's about where the black line sits, isn't it? So when you drill the bone, the black line still needs to be outside the skin.

Is that right? Oh, okay, great. So tell me. Right, that's a good point. Good. I was taught that as well. Okay, there you go. So once you've selected the appropriate needle, the way to gauge the depth of the needle is once you've attached the needle to the end of the driver, push it through the skin to touch the bone.

and there are little black lines on the needle and the last line is five millimeters away from the hub. You need to be able to see that black line pre-insertion because all the sites that we're going for have got an average of five mils cortical bone. Okay. So pre-insertion, if you can see that fibromyalgia line, you'll have enough needle to get through the cortex to get the needle into that intermodulary space. All right, so let me get this right.

You're going to push the needle through the skin until you hit the bone without using the drill. And at that point, you should still be able to see that last black line. And then you drill. And that might mean the black line goes through the skin. It does indeed. Okay, got it. Yeah. So that was the thing that I think was initially taught the people.

were told they had to see that line but actually we're saying you can see more than that black line you just need to be able to see at least that one so after insertion the needle could be touching the skin it could be slightly a little bit of daylight underneath the skin what we're trying to say is try not to indent the skin and cause potentially friction burns or pressure wounds underneath so thirdly insertion technique as we've talked in that previous one about selecting the right needle size

There's sometimes this temptation to want to use the drill as you're going through the skin. There's no need to do that because the end is such a sharp needle that you just push it through to touch the bone. So push through and then we say light to moderate pressure. and let the driver do the work. And it will. It's got a cutting tip that will cut through the bone. So you don't need to lean on it and push down, which I sometimes see people approaching patients with.

Feel the change of resistance. So once you've gone through that cortex, there should be a change of resistance. For the humerus, we say go all the way down to touch the skin, to short of the skin. But with the tibia, and especially on paediatrics, when you feel like a change of resistance.

You've gone through that cortex and into that spongy, cancerless bone, where you should get a change of resistance. Then after the insertion, the driver is disconnected with the magnetic tip, so you just pull it away. You can hold the hub.

unscrew the needle out the middle and then you would put a stabiliser dressing over the top to hold it in place but at this point I wouldn't seal it down. Connect up a primed connector which screws onto the top and then you can connect your flush.

So two to five mils for kids and five to ten for adults as a flush. At this point if you wanted to check that you're in the right place you can aspirate back to see if you get a little flash of blood or marrow back into the connector which is a kind of confirmation to be in the right place and then you deliver your rapid flush.

And the theory behind that, I think, or the teaching used to be that that would open up the cavity to try and make it easier to get the fluids in. Is that the case? So that cavity is filled with a thick fibrin mesh, which you need to break down without flush. And one of the things we teach people is no flush, no flow. So if you don't flush that cavity open, you're not going to get the expected flow rates. There's anecdotal evidence out there that if you...

Put an IO into the humerus and then put up a bag of fluids. You may get some drips of it flowing through, but you're never going to get expected flow rates. It's kind of five litres an hour and upwards. So once you flush the catheter to open up that intermodullary space, broken down that fibre mesh, you also need pressurised flow. 300 millimetres of mercury in a pressure bag to get the expected flow rates.

Or you can also use a three-way tap and a 50mm syringe and just have that continuous. Yeah, definitely. That's my experience. So connect the three-way tap up and then prime the connector and a 50mm syringe to deliver 50mm bonuses fluid, definitely. And I think it's just worth bringing you back to that because I know in the heat of the moment, so I've used introsseus recently on a three and a half kilo baby who was peri-arrest. And it was...

I've used a fair amount of intros, yes, but it was still quite a frightening moment. And as I put the needle in, I was like, right, make sure you put the dressing on before you put the connector. Because if you don't, you can't put it on afterwards, can you? So that's just a top tip for people. That's a very good point. And I will hold my hands up and say I've been guilty of doing that in the past. Yeah. You can do it, but the...

the chances of then introducing some form of air emboli is a lot higher. So we do suggest, yeah, put the dressing on first, connect up, deliver the flush, and then if it's not leaking around the site, that's when you stick it down.

and secure in place. So what potential complications could we be having with IO? Needle dislodgement, I think pre-hospitaly is probably the biggest complication because you're moving the patients. If you've done a humeral insertion, If you move the arm much more beyond about 45 degrees, potentially you can bend that needle on the acromion. Potentially fracture, because you're driving a needle into someone's bone. It's a pretty rare complication.

tends to be when people have used a lot of force. So again, another reinforcement of let the driver do the work. Compartment syndrome is one of the known complications that tends to be when people have missed. extravasation so if they've gone through the bone or it's not in the right place then potentially it can lead to compartment syndrome and infections it's an invasive technique so just be aware of signs of infection on the patient

And it's probably worth mentioning at this point is that you would always try and avoid an infected site to insert it in the first place. Yes. One of the contraindications of using EZIO is local infection on the site. The other one being prosthesis. so just be aware of scars over the insertion sites fracture of the target bone you need to be able to landmark it as well so if you can't see any anatomical landmarks then unfortunately you can't guess

And recent IO in the target boat within 48 hours is another one. Because potentially the fluids you put in will just come back out of that other hole. Yeah, and I hadn't thought about that before. But, you know, you can imagine a situation where you sort of have a go.

perhaps it isn't quite right, it feels a bit unstable, so you take it out, but maybe you were in enough. So you really have just got one go in each limb, haven't you? Indeed, yeah. And I think that's one of the things I've seen before.

if someone had a failed insertion and then tried the same site again. So once you've used that site and you've driven into the cortex, you then need to pick a different site. Brilliant. Tom, thank you so much for going through that stuff for us. Is there anything else you want to add?

No, I just like people to, like I said earlier, consider it as an early option. Don't leave it to be a thing that afterwards when you replay the situation in your head, think I should have done IO, maybe consider it earlier as an effective way of delivering medication. Brilliant. Tom, thank you so much. I'll put links to all of the educational resources that you've mentioned in the blog notes. And there's also a great video of the fluoroscopic.

infiltration of fluid into the humeral head which is pretty impressive in terms of flow rate so i'll make sure we share that too thank you thank you very much

So hopefully you've enjoyed our three interviews today. We just wanted to end up by discussing a couple of cases in brief, really. And I think... Getting the balance right, as in all aspects of pre-hospital care medicine, is where the money is here. And we talked about a couple of cases before we sat down to record this. And it's around that definition of a critically ill patient.

So I've got an example. I recently attended a small child who'd been hit by a car and they quite obviously had an isolated lower leg injury. We gave some intranasal medications to kind of... Tied us over. And then there was a couple of failed attempts at intravenous access. At that point, the team I was with were relatively forcibly encouraged to go down the IO route. And then a conversation issued around the proportionality of that. And what are your thoughts, Claire?

Yes, I think you've got to remember that although the actual drilling and the insertion of the enteroseus isn't particularly painful, and you can often do that without local anaesthetic. Infusing fluid into the bone is incredibly painful. And I think that if you've already got one fractured tibbib and you're a frightened child, then having a painful... a procedure such as receiving fluid through an interosseous would be excessive.

It really is that balance between does this patient need a treatment right now that we can't deliver any other way, or can we think about alternative options? Yeah, and I think the opposite side of this is a patient in cardiac arrest or a patient...

uh poly trauma patient who's gcf7 who you're in the process of putting to sleep that to me is failed iv access right i own absolutely And I've had a sepsic patient who was really critically clapped out in the department, actually, who we used introsseus access on, and he was barely conscious.

Even then, when we put the fluid in, he found it incredibly painful. So although there are options around putting local anaesthetic into the bone, I'm not convinced that makes a big difference. So if you're going to do it, you just need to be prepared for that painful stimulus of... giving the fluid if the patient needs it that's fine but just really think do they excellent so i think things from today

Go away and look at the anatomy. It's simple, but can go wrong surprisingly easy, especially when getting the angle of insertion on the humeral head. I think the tibia is simpler and we tend to almost migrate there, but be aware. pelvic injury, abdominal injury, you don't want to just fill up with blood or fluid, something which is already bleeding a lot. It's not going to get to the important bits above the diaphragm.

and also getting the balance right between very early aggressive intervention versus patients where we can perhaps step back a little bit. Probably about it from today. Yeah, I think there's one more thing which we did mention with Tom that I just wanted to emphasise is that once you've put a humeral IO in, if you then have to abduct the arm for any reason, say, for example, a traumatic cardiac arrest where you need to do a thoracostomy, you may well catch the...

needle on the bottom of the acramium and you can knock it out or bend it or even break it. Okay so we need to be aware of that and just kind of build that into our processes and thoughts. Excellent. Well, I hope you enjoyed today. As always, have a look at the blog and let us know any feedback. Bye-bye.