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TAPE STARTS – [00:00]
Speaker: So the next area that I have is it's a real passion for me. This is on the dynamics of compression or another way to say it is what's happening underneath the compression garment or the compression bandage. We often get a lot of lectures on venous leg ulcers. What are they? Compression is the gold standard care, lymphedema all that but I rarely have heard anybody talk about why this compression work and what does it do. So I hope that this will answer some of those questions for you. So we know that compression therapy is the standard therapy for edema that's associated with chronic venous insufficiency, lymphedema or any other types of edema that might be present. It does support the venous blood flow to the heart. It increases healing rates as compared to treatment without compression and it also reduces the risk of recurrent. The risk of recurrence for venous leg ulcers can be as high as 70% because people stop wearing their compression and if we can keep people wearing their compression, their compression stockings or garments or whatever it is that recurrence rate will come way down. So what does compression therapy do or what is it? It's an application of a mechanical force or external pressure to the limb or body part. So in the case of the lower extremity venous ulcers, chronic venous insufficiency, lymphedema, it's that external pressure on that leg that's going to help prevent or it's going to work against -- it's going to resist the expansion of the muscles during activity, during while they are up and walking and it it's a stiff system, it's going to help push that lymphatic flow and venous flow back up to the heart. It's going to support that. It controls edema. It reduces inflammatory mediators.
Because as you are controlling that and as you are pushing allowing the fluid from the interstitial spaces to go back in where that will be reabsorbed into the lymphatic system, it's going to decrease that inflammatory mediators and that's also what a lot of times helps to decrease the pain that patients are feeling. If you get the inflammation down, you can get the pain down. It improves micro-circulation. There is research to support that it does help also with arterial inflow and increases venous ulcer healing. So what's the goal of compression therapy? So your goal with compression therapy is therapeutic compression and what you want to be creating is a stiff and elastic sleeve. The stiffer the garment, the stiffer the bandage wrap or what you are using, the better return you are going to have because it's going to resist the movement, the contraction of those muscles and help to promote that blood flow back to the heart. What you want with the stiff and elastic sleeve is even pressure distribution. You want it to be even up the whole limb. You want the maximized effect of the muscle movement. So when you have stiff and elastic sleeve, you are going to get that maximized effect of that muscle movement. It's going to resist it and help to return the lymphatic flow and the venous flow. And then also you want to support the calf muscle pump and venous return. So there are many factors that influence the level of compression and I am going to talk about this a little bit later, but we know that the physical properties of the bandage material does that. Are you working with an elastic system or an elastic bandage or an inelastic bandage and I will go in to some detail with that. What is the number of layers that you have?
The more layers that you put on, the stiffer the device is going to be or the stiffer the bandage is going to be and the better you are going to have control of that edema. The bandage width will influence that, the tension that's applied. And that comes down to who is applying it and I have read many articles that have come back and said that the number one or one of the number one challenges with getting good therapeutic compression is whoever it is that is applying bandage. So they might be pulling too hard and have too much tension on the bandage. A lot of times the appliers have never been taught how to correctly apply the bandage and they just roll it on and then they have ineffective pressures. So that is very much a part of the therapeutic level that you get. You want consistent application, the size and shape of the limb will matter, the location and chronicity of the edema and the activity level of the patient. If you have a patient that's just lying in bed or sitting in their chair and they never move, then they aren't going to have any calf muscle activity going on. So couple of definitions that I wanted to look at was status stiffness index or SSI. So SSI is the difference between that standing and lying or supine sub-bandage pressure and I am going to go through these and I am going to show you some diagrams of what that looks like. The dynamic stiffness index or DSI is the difference between the peak sub-bandage pressure during dorsiflexion and the supine pressure. So it mimics the activity of walking. So it's that difference that you have there and then the amplitude is the difference between the maximal and minimal pressure during dorsiflexion or supine. So it's during that working pressure and the difference that you get there.
So more and more I am hearing and I truly believe that it's about the bandage stiffness that affects the dynamics of compression that you are going to get. It really doesn't matter whether or not you are -- I don't like to talk about graduated compression. I would like to talk about stiffness because stuffiness is going to be what's going to affect that muscle and going to affect the activity. The higher the stiffness results in the greater improvement in the venous return. If they resist that contraction, it will help with venous return. The lower the stiffness such as that you get with elastic type bandages, ACE wrap, self-adherent wraps, that type of stuff, that's going to give you a high resting pressure. If you have a high resting pressure, your patient are going to say that their compression bandage systems are very uncomfortable during sitting or lying down and they are likely to take them off because they hurt. So they will have a high resting pressure and a low working pressure where as inelastic high stiffness compression bandage will give you a low resting pressure, so it's comfortable when they are lying down or sitting but it gives you high working pressure, so that's very therapeutic. The stiffness can be modified by adding or changing the components or the layers of the compression material. So you can add extra layers to your compression systems in order to get more stiffness or maybe if they have a stocking on and they can't tolerate wearing a high level of compression with that stocking. Two stockings on will give it more layers and will give you a higher stiffness or better control of that edema. And then the last thing in regards to stiffness is that the stiffness of the final bandage system determines the performance rather than the individual component. So what I mean by that is if you look at a four-layer system or even a three-layer system, they have different components that are in there.
So they might a long stretch type of bandage in there. They may have a short stretch bandage in there and a lot of them will end with an inelastic bandage or like the self-adherent bandages. What happens is that when you put them all together, they lose their individual properties and so they become a stiff sleeve when they are applied and they act more like an inelastic system than they do what their individual components are. We are going to talk about unna boots. I have a couple of slides on that. So great question. So the dynamics. So what's happening underneath the bandage? So can you see the graphs? Okay good. So the pressure is going to change within the limb with position changes and movement. So we know that as people are up and moving and they are walking or they are on a treadmill or whatever, the pressure within the limb is going up and down and up and down. So the change in pressure is your interface pressure or your sub-bandage pressure. It increases venous and lymphatic return and also helps with reduction of edema. So the first one I want to talk about is your sub-bandage resting pressure. So that is your pressure right here. So that is when you put a garment on, you put a bandage on in a lying down position. First of all, you can put a sensor on like a PicoPress underneath that system so that you can test to see what the pressures are that you are getting the sub-bandage pressure. So in this case, this would have been type of bandage that would provide what they say is 30 to 40 mmHg pressure. That's at rest. That's not the working pressure. It's always at rest. So you can see that the pressure here is 40 or just a little bit above 40. That's a low resting pressure. That will be a comfortable bandaging system to wear at rest.
Then when the patient stands up, you get an increase here that goes from here up to here. That's your SSI. That's that static stiffness index. And inelastic system, which will give you high stiffness is going to have an SSI that's greater than 10 mmHg. It's going to go up at least 10 if not higher. And elastic is going to be less than 10. You aren't going to have high stiffness. You aren't going to get that amplitude that you want. And then finally on this one, you can see that here, this is the activity that's going on. So you can get that walking on a treadmill. When I have tested it, I literally had somebody just act like they are walking in place and you can see the dynamics underneath that bandage happen and that's called the working pressure and what you want is high dynamic working pressure that's going to help with that return and then will ultimately end up decreasing the edema or reducing the edema. So the next what I wanted to talk about was the characteristics of some of the different dressings or the compression material -- the compression bandaging material. So we know that the compression material will give hemodynamic effect. Since all those hemodynamic effect is that it reduces venous reflux, so it helps to close up those valves and prevent that reflux from happening the blood in the fluid from going back into the subcutaneous tissues. And then that will improve your venous pumping function and then also reduce that ambulatory venous hypertension. But all of the research that's has been done states that inelastic material is significantly more effective than elastic material than doing all of that.
The elastic material just does not have enough stiffness to do it. So if we look at a long stretch type of bandage, so long stretch bandage is an elastic bandage. So that can have a maximum stretch of greater than 100%. So you can really pull an elastic bandage and what happens with an elastic bandage is that because of the elastic that's in it, it wants to recoil back to its original length. And so if you are to wrap a leg, an edematous leg, with this product it wants to recoil back and it actually ends up squeezing that limb, which is what causes that high resting pressure and the discomfort. We don't want to squeeze a limb. We want to compress the limb with even distribution of pressure up and down that limb. So it will give you a high resting pressure. It will give you a low working pressure. It's not going to be very effective to accomplish the hemodynamic effects that we wanted to accomplish and it will provide very poor edema management. So if we look at inelastic, inelastic compression are short stretch bandages and you can have a short stretch bandage like that that's used just for lymphedema where they use multiple layers of short-stretch bandages to build that compression all the way up the limb, they are building out the stiffness of it to support the lymphatics. They don't stretch very much. That's as far as this particular short stretch bandage would use and it's applied at full stretch. Another type of short stretch material is also inelastic. It's not as thick as this one. This one is re-useable. Patients will learn how to re-wrap this or it gets reused, washed, reapplied over and over and over again.
This one is not a reuseable product but it still is a short stretch. That's as far as that stretch will go. It's a short stretch, inelastic material and when it's combined with the layer underneath, it forms a stiff and elastic sleeve to support the calf muscle pump. So that's the difference between your long stretch and your short stretch or elastic and inelastic. The textures can vary. I just showed you two different types of textures there. They can be paste impregnated. They can be cohesive. So this one is a cohesive. This one does not have any cohesive material in it. They are applied full stretch. Their extensibility is less than 40%. You saw that I couldn't extend them very much. And again they can be reuseable or single use. So some of the inelastic bandage properties, they don't give way to the muscle volume increase during the contraction. They maintain that hemodynamic effect over time even with significant interface or sub-bandage pressure drop. So I mean by that is when you wrap a limb within the first 24 hours, there is going to be volume reduction. There is going to be fluid that's going to move around and you are going to have that volume reduction that you want to have. That's your goal is to do that. And so you aren't going to have that compression system fitting as tight as it did when you first put it on but the inelastic sleeves will still continue to provide enough resistance there to help with that venous return, to help with that lymphatic return even though the sub-bandage pressures have dropped. Maybe they drop about 10 mmHg within the first 24 hours. They are still going to be effective to do what they were designed to do and an elastic bandage won't do that.
What else here? And also the inelastic bandages can provide a massaging effect that's similar to the intermittent pneumatic pumps and that can be a major factor in the improvement of the calf muscle pump function as well. So multi-component bandages they can be two layers, three layers or four layers and like I said they combine the different properties within those different layers to form a stiff and elastic sleeve. They influence the sub-bandage pressure and pressure stiffness. They can be cohesive or not cohesive. They offer low resting pressure and high working pressure. Not that's what striving for. So you ask about the zinc paste bandages. So the zinc paste bandages are rigid. No stretch bandages that are applied. It's a gauze material with or without stretch fibers that has been impregnated with a zinc paste. There are moist one they are applied and they are dried to semi-rigid sleeve. So they are considered inelastic. They are considered stiff and inelastic. They will provide the short stretch bandage effects of what I just talked about that will give you a low resting pressure, high working pressure. They are most effective with ambulation. Nonambulatory patients can benefit by doing their foot pumps by actually moving their foot and ankle. And they may be soothing for some patient. I know that there is many people that still like to apply a zinc paste bandage because they have a leg that has a lot of stasis dermatitis on and it starts to be cooling and effective. When you see patients with a lot of stasis dermatitis on them or a lot of drainage that's going on, the answer is compression.
Really good therapeutic compression. It's an inside out problem. You decrease the edema, you get rid of the volume that's in the leg and get the calf muscle -- support that calf muscle pump. You are going to see the skin heal and that dermatitis decrease. Regarding zinc paste bandages, there has been some publication recently that talks about the fact that zinc paste bandages are no longer considered optimal for most patients. This is technology that was designed back in 1854 despite the fact that it didn't have a whole lot of clinical evidence to support its use and with the zinc paste bandage it doesn't adjust to the change in leg volume. It just stays the way that it is. That's a soft cast is what it drives to and so it just stays there and it won't support those hemodynamic like I talked about with inelastic bandages. They are messy to apply. There is now considered a potential for allergic reactions or skin reactions to the different types of paste ingredients that are there. There is zinc paste, there is calamine, there is mix of the two and there is potential for skin irritation because of that. Zinc can also create an occlusive environment, which will increase the risk of maceration. We are already trying to deal with the maceration that's there and this could potentially contribute to that. They are unable to handle high exudate levels and oftentimes these legs have high exudate levels. They require more frequent application and they do require a high skill for accurate application and again a lot of people haven't been taught how to put this on. They may not have been taught how to put the others ones on either, but they need to know how to apply these and the publications are saying that these aren't the best choice any longer because of the newer technologies that are available.
So just factors affecting sub-bandage pressure. That's from that one slide that I showed you. So these are the things that can or the factors that can increase the pressure. So the first thing that you have is the high bandage tension. That comes from the applier. Are they taking a bandage that is to be applied at full stretch and actually torquing it as they are really pulling on it or sometimes what I have seen is they are strapping it. So they might be loose on one side and they come around the limb and they really pull it and lay it down. So now you have uneven distribution of the pressures that are in there and it's very high tension on one side and not on the other. Again, it goes back to appropriate education and demonstration of how to apply that compression bandage. Smaller bandage width, so your smaller bandage width is 2-inch -- excuse me 3 cm and the short stretch bandages. The smaller the width in the bandage, the higher the pressure can be. The greater overlap or number of bandage layers. So again I talked about that you can apply more layers and that will increase your sub-bandage pressure, which will increase the stiffness that you are getting from that system that you are using. And then the smaller limb circumference. And if you are wrapping somebody that has a really skinny leg which a lot of times that's not the case but you might be or you have an area that's much smaller. Just the nature of the smaller of the circumference, the pressure is going to be higher in that particular area. Likewise, decreased pressure, you have decreased bandage tension. So somebody that's just rolling on that bandage all the way up and they have no tension on it at all, you are going to have a decrease in the pressure there.
The larger limb circumference. The bigger the limb, the lower the pressure is going to be. And if you think about with padding, I am going to talk about padding just a little bit. If you are building a limb out and putting a whole lot of padding on it, you are going to decrease the effect of pressure that can be applied or that you want to see with that compression bandage the wider the bandage width and padding. So effects of padding. Padding should be used to protect bony prominences. When I am talking about this, I am talking about the use of like the two-layer, the three-layer, the cohesive type of bandage. There are possibly even some of the Velcro wrap and stuff devices that are there. I am not talking about the lymphedema wraps. The padding with the lymphedema, it's a whole system that is built for those particular patients to figure out how to treat that lymphedema. So padding should be used to protect the bony prominences. If your shin is real fragile and real bony, it's an area that can be padded. If you need padding over the ankle area, the malleolus area, you can pad there, but it's not good to just pad everything out because again you are going to decrease the amount of pressure that that patient actually gets. The bandage pressure is going to be lower. The change in pressure and stiffness of the multi-component bandages as the limb size increases, the sub-bandage pressure will decease that's what I just talked about. Also padding can give you uneven distribution of the sub-bandage pressure and if you remember what I talked about is the importance of doing therapeutic compression is to get even distribution of that pressure up and down that whole limb.
Let's see. The skill of the applicator, I talked about that. Many articles that I have read have talked about the fact that there isn't enough education. There isn't enough demonstration of how to appropriately apply compression. So that's really important as you go back to your facilities, invite manufactures to come in and show you how to appropriately apply their compression system. And if they can't, then find somebody that can, because you can do harm if you aren't applying them correctly. You aren't getting high enough. You are getting too high. All the things that I just talked about. Competency and consistency are gained with education and practice and practice and practice and practice. So to summarize inelastic compression is the most effective compression modality to increase the venous ulcer healing rates. They will resist muscle expansion. They give you low resting pressure, high working pressure. They reduce venous reflux. They improve venous pumping and maintain hemodynamic effects over time. So that's it.
TAPE ENDS - [25:16]