Burns (DETAILED) Overview - Types, Pathophysiology, TBSA

hello in this video we're gonna talk about burns so we're gonna focus on the different types of burns the most dangerous ones as well as a pathophysiology as well so let's begin by recapping the normal skin anatomy so here's a section of our skin we have three layers of the skin obviously the epidermis on the very top the dermis which is further divided into the papillary layer for your fingerprint prints and then your a reticular layer and then you have the hypodermis also basically what's what's what is known as fat the subcutaneous fat the hypodermis is not really a true skin layer now the epidermis is very thin and interestingly it's only blood supply is at its base the epidermis is what essentially the part of your skin that sheds off every day or sore so what happens here is that the cells at the base of the epidermis which are sitting on the basement membrane receives blood supply from small capillaries from the dermal layer of the skin and so this allows the cells of the epidermis to receive nutrients and to divide while moving up as the cells divide and move up they get less and less blood supply until they die essentially and that is why you have dead skin on the top of your skin other important structures which make up the skin anatomy itself are the hair follicles which help in sensation and indirectly in heat regulation and lubrication the main arteries and veins are that supply the skin really supply the hypodermis and dermis and then the smaller capillaries branch off and supply all the way to the base of the epidermis there are also many sensory nerve endings of the skin important in sensory aspects such as detecting pain heat and pressure finally it is important to mention the glands now glands around the skin help in lubrication as well as releasing antimicrobial substances and heat regulation however it should be pointed out that we normally have what's called opportunistic organisms opportunistic bacterial living on our skin damage to the skin such as a cut can thus introduce bacteria to inside to this area causing problems similarly if a person suffers from a burn injury it can introduce bacteria and other organisms such as fungi easily into the body and can cause significant problems so what are burns well burns are injuries to tissues caused by heat friction electricity radiation or chemicals there are many types of burns such as thermal burns inhalation burns from small particles of smoke cold exposure like frost bites or also burns radiation burns which include UV radiation from the Sun usually people go to hospital for any of the burns mentioned above however there are some burns which which require transfer and referral to a special burns unit because of the complications that may come with them now these types of dangerous burns you can say include chemical burns electrical burns and inhalation burns which are already introduced inhalation burns for example can compromise the Airways and cause significant lung injury so let's learn a bit more about the pathophysiology and the mechanism of disease when a burn occurs on the skin it causes changes within the skin that can be divided into sort of three regions or three zones these zones of a burn were described by Jackson in 1947 and so it is also called the Jackson model the first zone is the zone of coagulation then it's the zone of stasis on the outside and then the furthest part is a zone of hyperemia so the zone of coagulation is essentially the point of maximum damage in this zone there is irreversible tissue loss due to coagulation of proteins thus you get coagulative necrosis surrounding the coagulation zone of necrosis is a zone of stasis now in this zone it's essentially characterized by decreased perfusion this ischemic zone may progress to full necrosis unless the ischemia is reversed at the very outside is the zone of hyperemia in this outermost zone tissue perfusion is increased the tissue here is invariably recovered unless there is severe sepsis or prolonged hypo perfusion again the stasis zone is characterized by ischemia and may progress to full necrosis unless the ischemia is reversed therefore the main aim of burns resuscitation is to increase tissue perfusion here and prevent any further damage any damage becoming irreversible so that is a general pathophysiology or mechanism of disease concept of burns when you accessable it is important to know the cause of the burn as we have learned such as if it's a thermal or radiation burn the other important aspect of a burn assessment is to know the depth of the burn to make it super easy just think of burns as initially being superficial burns or deep burns so let's zoom into the skin here to look at what happens in a superficial burn and what happens in a deeper let's take a look at at a superficial burn first if it's a superficial burn it will cause damage to the epidermis and the upper dermis only so like the papillary layer of the dermis again you have blood vessels here capillaries superficial burns will damage the keratinocytes which are your cells in the epidermis and will also activate an immune response so activate immune cells around the area such as mast cells and macrophages the damaged keratinocytes the mast cells and the macrophages will secrete pro-inflammatory cytokines triggering an immune response the cytokines will stimulate nerve endings around the dermis the sensory nerve endings here can be the ones that detect pain for example and pain is an important feature of superficial some cytokines will cause increase in vascular permeability the increase in vascular permeability will cause fluid to leak out and may lead to interstitial edema as the fluid leaks out it can result in hypotension remember that the increase in vascular permeability causes fluid to leak out the flute can actually accumulate in one area causing a blister on the skin surface the sensitive blister can rupture and release fluid onto the damaged skin surface thus superficial burns have a moist appearance the cytokine secreted by the cells above will also cause concurrent vasodilation causing further hypotension in severe cases the vasodilation contributes to the warmth in the area as well as causing blanching of the skin and erythema blanching means that when you press on the burnt skin surface blood will quickly fill it up because of the increase in blood flow to the area the blanching skin is a feature of superficial burns in deep burns you have more than just damage to the epidermis and the upper part of the dermis you have damage all the way down extends all the way to the hypodermis so it's a pretty deep burn deep burns can thus damage blood vessels in the skin because you have damaged blood vessels everything will leak out you have no blood supply to the area so you eventually get this dry non blanching surface it is dry and inelastic the non blanching dryness is an important feature of deep burns further deep burns extending to the reticular layer of the dermis can destroyed nociceptors and other sensory nerve fibers initially pain can be detected but as a sensory nerve fibers are damaged you get hyper Thessia so you get reduction in sensation loss of sensation is an important feature of deep burns obviously not all your blood supply is damaged or your blood vessels are damaged the functional blood vessels react to the cytokines produced around the area the vessels will increase vascular permeability which will cause fluid to shift out causing interstitial edema so fluid shifts out from the intravascular space so the blood vessel and this will into the interstitial and this huge amount of fluid coming out of the vessels will result in hypotension so circulatory shock even hypotension as a result of this shift of fluid occurs more in deep burns rather than superficial burns so now that we know the pathophysiology of superficial burns and deep burns let us learn a bit more about the classification of the burn depth again burn depth can be broadly divided into superficial and deep burns superficial burns can be further divided into superficial epidermal burns and superficial partial thickness burns in superficial epidermal burns only the epidermis is involved so the very top of the skin the most common cause here is your regular sunburn when you get a dry and red skin which is painful the epidermis layer is the only layer involved on a sidenote superficial burns are not included in the assessment of the total body surface area burn in superficial partial thickness burn you are causing damage all the way to the papillary layer of the dermis so the upper dermis and so because you are going all the way to the upper dermis you are allowing the blood vessels to increase permeability leading to blister formation which then can subsequently rupture the feature of the burn is red moist weeping with rupture and unruptured blisters the burn here is very painful again in superficial partial thickness burns your epidermal and papillary layers of the dermis are involved the important features here are blister formation rupture of blisters causing a weeping moist injury as mentioned before and I'll mention this again superficial burns is characterized by a blanching injury so when you press your finger in the area the area pressured will return to its normal color because of the normal perfusion the other important aspect of superficial burns is that the sensation is still working it is normal and so you feel pain deep burns are totally different deep burns involve all layers of the skin the important feature of deep burns is that it does not blanch with pressure and there is minimal to no pain no sensation due to damage of nerve endings in the area deep burns can be easily divided into deep partial thickness burns and full thickness burns in deep partial thickness burns the burns are partially deep they cause blisters which easily rupture and come off the surface of the skin can be pale if blood supply is lost or red if there is extra masais ssin of red blood cells in partial a deep thickness burns you can get damaged blood vessels which means when you press the skin surface it will be non blanching and also partial deep burns may damage sensory nerve fibers causing a decrease in sensation in partial deep burns the skin layer is involved of the epidermis and all the dermis layer full thickness burns are the worse here all the skin layers including the hypodermis are involved the burn is so extensive that the skin may look waxy white leathery grey or charred black depending on how deep it is duration of the burns etc the burnt area is not wet because no blisters are forming it is usually dry and in elastic the sensory nerves and the blood vessels are definitely destroyed and so you have no sensation and no blanching in full thickness burns you have destruction of all skin layers including the hypodermis there's actually a fifth classification of deep burns but we're not going to talk about it here because I feel like it causes more confusion than help referring a burn to the burns unit is very important we talked about referring certain types of burns to the burns unit such as chemical burns electrical burns and inhalation burns but how about the burn depth well we always refer full thickness burns and also burns greater than 10% of the total body surface area and this does not include the superficial epidermal burns so what does this total body surface area mean when assessing burns it's also important to calculate how much of the body is burnt or the size of the burn or we refer this to the total body surface area a good way to calculate the total body surface area is to use what is called the rule of nines it's a great rapid assessment the rule of nines is where the body is divided into areas of percentage which are divisible by nine with the exception for example you have four point five percent nine percent or 18 percent so if we look at a human from the front and the back the front of the face is four point five percent the back of the head is four point five percent 9 percent front of the chest and nine percent upper back nine percent stomach and nine percent lower back for one leg is 18 percent so nine percent for the front of the leg and nine percent for the back of the leg for the upper limb it's nine percent total so it's four point five percent at the front and four point five percent at the back I hope that makes sense and the genitals and perineum is one percent so to summarize the head and neck total is nine percent the chest front and back is 18% the abdomen all around is 18% one leg is 18% and one arm is 9% and the genitals and perineum is 1% so all should equal 100% if I did it right another quick way to measure total body surface area is by using what's called the Palmer method here the person's palm and fingers will represent 1% total body surface area so for example they have Burton area of their body and their palm and fingers covers this burn this represents 1% total body surface area burnt the Palmer method is useful for small scattered burns so remember we briefly mentioned when to refer burns to the burns unit such as the type of burn as well as the depth of burn so for example full thickness burns or burns greater than 10% of the total body surface area but this does not include superficial epidermal burns so how about some other factors which will make one refer to a burns unit well things that potentially need referring to a burns unit include burns to the very young and very old special areas such as the head major joints genitals hands and feet also need referring to a burns unit burns in pregnancy as well as circumferential burns are very serious circumferential burns especially can progress to what is called compartment syndrome where pressure and edema builds up in the muscular compartments causing diminished neurovascular supply to the area which can lead to irreversible damage and amputation of that limb or area if not saved early I hope you enjoyed this video and burns to learn more about compartment syndrome please click on the link below