Heather Hettrick, PT, PhD, CWS, CLT-LANA, CLWT discusses the basic physiology in regards to the arterial, venous, and lymphatic systems and how pathology in these systems affects patients in the clinical setting.
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Pamela: Dr. Hettrick is going to come up and she is going to do the next part of the program and we’re going to have some fun, ladies and gentleman, and you are going to need to participate. At the end of each section, I get to have the most fun than anybody in this room. I'm going to be leading you in exercises right there at your table and everyone is going to do them. [Laughter] Dr. Hettrick, you are welcome.
Hettrick: [Laughs] Thank you. Okay. Can everyone hear me okay? Alright. It's great to see so many people here, thank you. And I wanted to add one thing into that paper that Dr. Scarborough [phonetic] was just talking about. If you really get into the weeds [phonetic] of that paper, what they found is that there is less than 20 minutes of lymphatic education in medical schools today. Less than 20 minutes, and it's buried in the topics of cardiopulmonary because that’s where they feel it fits. And if you extrapolate that there was a great study done out of the UMDNJ, New Jersey, and they looked at medical education with respect to wound management in the United States and the UK, and I think it's was Germany. And they found out here in the United States it was an average of about nine hours over the course of four years in medical school and it wasn’t even standard of care. It was still kind of more how to pack for hemostasis type approach to wound management. So there is a paucity as far as the education component. And that’s why we get really excited, we have opportunities like this to come just kind of share this information and hopefully have some of the light bulbs go in to this area.
But one of the things that I think is really important we try to appreciate is the relationship between the arterial, the venous and the lymphatic systems. Because, we tend to talk about the arterial and the venous systems and then we kind of talk about the lymphatic system, but what I want to show you is that integration, how they are completely interrelated and we really can’t separate them, especially when we have pathophysiology involved.
But this is interesting. So, if you look at some of these conditions and this is not all inclusive, but some of these are the more common ones we see today in clinical practice. So, things like GI infections and even now talking about Crohn's disease and irritable bowel syndrome, we talk about cancer and some metastasis, chronic infections, inflammation, organ transplantation, autoimmune disease, neuroimmune disorders, metabolic syndrome, diabetes, talking about burn and hemorrhagic shock. All of these different things and lot of the fat disorders that are out there. So lot of these are not related at all, but the common theme that all of these have in common is this, lymphatic dysfunction. Because when you think about what the lymphatic system does, it is there to regulate immunity and inflammation. It is our body’s recycling system. And so when we have these components going on, we kind of forget that maybe the underlying cause or what's really involved with a lot of these down underneath, is lymphatic dysfunction.
And so interesting just a case in point, there is some research going on now where they’re looking to do deep manual lymph drainage in the viscera and down in the abdominal and the omentum area to see if they can manage the symptoms of Crohn’s disease and IBS. Can you imagine, if we could do a manual technique and then get these patients off of their medications and get their systems regulated, just from a manual technique?
So there’s some really interesting things going on here, but I think it's important to highlight why this system is so important, and at the same time, it's just ironic that it doesn’t get the attention it needs. If we’re only giving medical students really 20 minutes in their whole curriculum about the lymphatic system, you think we’re really doing a disservice to the system itself. A. T. Still has been known to say that we strike at the source of life and death when we go to the lymphatics. We wouldn’t be alive if we didn’t have the lymphatic system and it's just that important. Now you can probably say that about any of our body systems, but the problem is, this is kind of like that red-headed stepchild, it just doesn’t get the attention that it deserves.
And so, when you look at the body system, this is hopefully how our body system should be functional. They should all be working in tandem, everything is healthy, everything is functional, everything is operational. But when you have dysfunction of the lymphatics, it's really like a mortar and so as soon as there is lymphatic dysfunction, you're going to start to see complications and a sequela going on in a whole bunch of other conditions and other complications. So, it's really important to appreciate how important the lymphatic system is, just to not only our general health, but to its interrelationship with all the systems. So it's recently being called a nodal centric immunovascular system and it's kind of mouthful, but it makes a lot of sense when you break it down. So nodal centric, it's one system that actually has nodes and these nodes we will about a little bit, but they’re extremely important because that’s how it filters all the lymphatic fluid, that’s what helps to break down metastasis, that’s what help to break down through macrophages, managing the lymphatic bioburden that’s present in that lymphatic tissue. But it is an immunovascular system. It's a vascular system much like our arterial and our venous systems and I’ll show you that in a moment.
But what's interesting too is it's the one that regulates our immune system, and it's even so important to think about that. Even in the surface of our skin and our epidermis, we have Langerhans cells, that’s one of our first line of defense. They are part of our lymphatic system and so when you're putting something on your skin and your putting something on your patient’s skin, those Langerhans cells are there to kind of protect and make sure it's okay. But realize, you absorb 60% of what you put on your skin and where does it go? Your lymphatic system. So your lymphatic capillaries are 3 mm just in the depth of the skin. That’s not a lot, that’s the thickness of your credit card.
And your lymphatic capillaries are everywhere throughout your body except your -- well now, we do know that actually you have glymphatics, you have lymphatics in your dura mater. But we don’t have them in our cornea, we don’t have them in our teeth, we don’t have them in our hair, but they’re really everywhere else. But, in our skin, our lymphatic capillaries are just 3 mm at the surface.
And it's interesting when you think about some of the things we’re doing in wound care, right. And there is evidence now that say that to remove biofilm, what's the depth you need to go to remove biofilm? Any body knows? To sufficiently remove biofilm, how deep do you need to debride to remove biofilm? Three millimeters. What's at three millimeters? Your lymphatic capillaries [Laughs]. So, I think there’s something too that there.
So anyway, it's kind of an interesting thing, that this nodal centric immunovascular system is critically, critically important. And it's only recently that if you look through some of the anatomy text, that they start to show the lymphatic system in the anatomy drawings. Because if you ever look at the skin histology slides, they show everything, right? All the layers of the epidermis, the dermis, all the adnexal structures, epidermal appendages. Very rarely do they include the lymphatic system and now they’re starting to, which is like really, really important because it's very important in that system.
So when we look at this, we know that our arteries and veins are part of a closed blood circulatory system. We’re very familiar with how this system works. But our lymphatic system is considered a half open system, meaning it has these little finger-like projections, you can see them in the green here that project up in the interstitial areas and that’s what collects and absorbs all the extra interstitial fluid. And it's intimately involved, as you can see in this picture between the arterioles and the venules, so they’re all mixed in there together. And what I think is critically important is this picture. This is actually of a chick embryo, but what you can note is this structure here is a vein noted by the V, this is an A for an artery and all this web like material, those are lymphatic vessels. And so look at that interrelationship, look at that, you can’t separate these from one another. And what this is saying is that when you have dysfunction in one these systems, you likely have dysfunction in the other systems and we see that especially with the venous system.
When we see dysfunction in the venous system, we get microangiopathic changes in our lymphatic system. So the two are so intimately involved and connected, we really shouldn’t be talking about them in separate components. They’re too closely interrelated, and you can see that here. They’re just different ways or visuals, but I like this one because it just shows you that interconnection and just how intimately involved these systems are with one another.
And so again, we can see the structure of the lymphatic vessel here and it runs parallel to a blood vessel, but its main role is really to pick up that extra fluid and a lot of that extra fluid is pretty caustic, right? If you have a lot of excess proteins coming out, the only way for those proteins, because they are large, to go back into the venous system is to be picked up by the lymphatic system and brought back in at that venous angle. And every day about 4 L of fluid in an average human is brought back through that venous angle, that’s a lot of fluid. But with that we’ve a lot of other cells, we have cellular debris, we have byproducts of metabolism, we’ve a whole bunch of different things that get picked up. But again, they’re picking it up, they’re bringing it back to regional lymph nodes where it gets processed and circulated and cleansed, and then it's reintroduced back into the venous system; so very, very important.
So, I like analogies, and so one of the things I would like to talk about is the body’s drainage system and so this is just a schematic of your skin, but what it has done is it's really highlighted the lymphatic structures. So right up here, that look like trees, these are your little lymphatic capillaries and these are the ones that are just 3 mm in the surface of the skin. So think of it as all these little tree like structures at the top of the ceiling, okay, and we can manipulate them. These do not have valves and so they allow for bidirectional flow. We can manually direct which way we want that flow to go, by working with these lymphatic capillaries up here. And so to me, these are a lot like the collecting stations or the bathrooms in our homes and our neighborhoods, okay. So they’re going to collect that fluid and those waste products.
And then, what they do is they take that collection and bring them into pre-collectors. So imagine from the ceiling, now you have these pre-collectors coming kind of straight down or at an oblique angle, and so these are the sewage pipes that go from the house down into the main city sewage system, so pre-collectors coming down. And then they’re going to take all those waste products and they’re going to take them into these collectors or these large structures here that are valved, so they allow one-way flow of lymph fluid, much like our veins do, and these collectors now are going to take the waste from the home to the sewage collection system at the water processing plant. And then, ironically, these water processing plants look a lot like lymph nodes, right? Because they’re round and they process the water, they clean the water and they repurpose the water, and our lymph nodes do the same thing with our lymphatic fluid. It recirculates it, it cleanses it, it gets rid of the metabolic waste, all the caustic chemicals that are present, and it helps then reintroduce the clean lymphatic fluid and the healthy proteins and all those other substances back into our water system or into our venous system up at that venous angle. So the venous angle right up here is critically important. Question.
Female speaker: Sorry to interrupt. If the arterial and venous system is closed, then how can you dump back into it?
Hettrick: Excellent question. So the way it works -- so the venous and the arterial system are closed because it's connected with the heart. The way the lymphatic system works, those green finger like projections stick up, they pull all that fluid in and they transport it to regional lymph nodes, usually axillary and inguinal are the main ones, there’s others. And then, what it does is it ultimately transports all of that fluid back into the venous angle, which connects to the venous system. That’s the only way all that fluid gets reintroduced into the venous system is at the venous angle. There’s a left and right venous angle. The left venous angle takes most of the fluid over the course of the day, but if there’s dysfunction in the left venous angle you can actually use the right venous angle. So it's a pretty amazing system, but it's very analogous I think to sewage system and water processing because of the way it cleans and recycles, it's basically our body’s recycling system.
So the main purposes of our lymphatic system, we know it helps regulate immunity, we know it helps with inflammation, but the basic purpose is to drain fluid from those interstitial spaces. How many of you flew here? Okay, did your feet get swollen at the end of the flight? You know, how they say don’t take your shoes off during a flight, okay, because your lymphatic system gets overwhelmed, your feel swell. Or any of you ever been pregnant and towards the end of that third trimester you get very swollen. So, again this is just a situation where your lymphatic system is temporarily overwhelmed, but it's not damaged. And over time, it can kick up itself and not necessarily repair itself, but it can manage that fluid burden and bring it back to a normal level. So, the fluid is constantly circulating in our interstitial spaces and our lymphatic system is what's responsible for picking that up, recycling it and then reintroducing it to our venous system. We also know it acts as a safety valve for fluid overload, so it does help keep edema from forming, but it can get overwhelmed much like transcontinental flight or if you have an ankle sprain or any other type of minor trauma where you end up getting a localized edema, but our system does have a built-in backup system or a safety valve that it can work 10 times more efficiently than what it normally does to offset and prevent that edema from forming.
We also know the homeostasis of extracellular environment is maintained by the lymphatic system because of its immunity component, and so it's constantly picking up metastatic cells, it's constantly picking up cellular debris. It picks up what we call lymphatic loads, so anything you put on your skin ultimately is going to get picked up by your lymphatic system. I always tell my students, one that always gets them, is that if anybody has a tattoo that ink is now -- it was picked up by your lymphatic system. And if you have a tattoo, say in your left arm, your axillary nodes on your left side are going to be the color of that tattoo ink, because it's now a lymphatic load and it stained the lymphatic nodes in that area.
Luckily, now we don’t use caustic chemicals with tattoo ink like we used to do, the blood-based, but they found those on cadaver dissection, so it's very interesting to see very colorful nodes sometimes on cadaver dissection. And the lymphatic system also helps to cleanse the interstitial fluid and provide a blockade to the spread of infection in malignant cells and this is why sometimes when somebody comes in with a cellulitis or an acute attack or anything along that line, we say we hold off on some of our manual lymph drainage techniques because the system is so efficient at mobilizing things, we want to make sure that they’ve had time to be on antibiotic therapy for 24-48 hours before we resume our care. Because we don’t want to mobilize this stuff to other parts of the body, and so we need to give it a little time to work.
But I think this is a fascinating picture. So, this is a cancer cell and this lymphocyte -- it looks almost like it's “using The Force”, right? [Laughs] It's reaching out with its little tendril or whatever you want to call that, and it's going to actually eat and digest the cancer cell. And so, these lymphocytes are critically, critically important and they are throughout our body, but they are concentrated too in things like our nodes and to other areas. So very, very important structures, and again the importance of what our lymphatic system just can’t be underestimated when you think about its role with immunity and inflammation.
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