0:00 Hello, in this video, we're going to talk about burns, so we're going to focus 0:08 on the 0:08 different types of burns, the most dangerous ones, as well as the pathophys 0:13 iology as well. 0:14 So let's begin by recapping the normal skin anatomy. 0:17 So here's a section of our skin. 0:19 We have three layers of the skin, obviously. 0:21 The epidermis on the very top, the dermis, which is further divided into the 0:25 papillary 0:26 layer, for your fingerprints, and then your reticular layer. 0:31 And then you have the hypodermis, also basically what is known as fat, the sub 0:36 cutaneous fat. 0:38 The hypodermis is not really a true skin layer. 0:43 Now the epidermis is very thin, and interestingly, its only blood supply is at 0:49 its base. 0:51 The epidermis is what essentially the part of your skin that sheds off every 0:55 day or so. 0:56 What happens here is that the cells at the base of the epidermis, which are 1:01 sitting on 1:01 the basement membrane, receives blood supply from small capillaries from the 1:06 dermal layer 1:07 of the skin. 1:09 And so this allows the cells of the epidermis to receive nutrients and to 1:13 divide while 1:13 moving up. 1:15 As the cells divide and move up, they get less and less blood supply until they 1:19 die essentially, 1:20 and that is why you have dead skin on the top of your skin. 1:24 There are important structures which make up the skin anatomy itself, or the 1:28 hair follicles, 1:29 which help in sensation, and indirectly in heat regulation and lubrication. 1:38 The main arteries and veins that supply the skin really supply the hypodermis 1:42 and dermis. 1:43 And then the smaller capillaries branch off and supply all the way to the base 1:48 of the epidermis. 1:50 There are also many sensory nerve endings of the skin important in sensory 1:55 aspects such 1:55 as detecting pain, heat, and pressure. 1:58 Finally, it is important to mention the glands. 2:01 Now glands around the skin help in lubrication, as well as releasing antim 2:05 icrobial substances 2:07 and heat regulation. 2:08 However, it should be pointed out that we normally have what's called opportun 2:13 istic organisms. 2:15 Opportunistic bacteria living on our skin. 2:18 Orange to the skin, such as a cut, can thus introduce bacteria to this area 2:25 causing problems. 2:27 Similarly, if a person suffers from a burn injury, it can introduce bacteria 2:31 and other 2:32 organisms such as fungi easily into the body and can cause significant problems 2:37 . 2:38 So what are burns? 2:40 Well burns are injuries to tissues caused by heat, friction, electricity, 2:45 radiation, 2:45 or chemicals. 2:48 There are many types of burns such as thermal burns, inhalation burns from 2:52 small particles 2:53 of smoke, cold exposure like frost bites or also burns. 2:59 Radiation burns which include UV radiation from the sun. 3:03 Usually people go to hospital for any of the burns mentioned above. 3:07 However, there are some burns which require transfer and referral to a special 3:13 burns unit 3:14 because of the complications that may come with them. 3:19 These types of dangerous burns you can say include chemical burns, electrical 3:25 burns, 3:26 and inhalation burns which are already introduced. 3:30 Inhalation burns, for example, can compromise the airways and cause significant 3:34 lung injury. 3:35 Let's learn a bit more about the pathophysiology and the mechanism of disease. 3:40 When a burn occurs on the skin, it causes changes within the skin that can be 3:45 divided 3:46 into sort of three regions or three zones. 3:50 These zones of a burn were described by Jackson in 1947 and so it is also 3:56 called the Jackson 3:57 model. 3:58 The first zone is the zone of coagulation, then it's the zone of stasis on the 4:04 outside 4:04 and then the furthest part is the zone of hyperimia. 4:10 The zone of coagulation is essentially the point of maximum damage. 4:15 In this zone, there is irreversible tissue loss due to coagulation of proteins. 4:21 Thus you get coagulative necrosis. 4:25 Surrounding the coagulation zone of necrosis is a zone of stasis. 4:28 Now in this zone, it's essentially characterized by decreased perfusion. 4:34 This ischemic zone may progress to full necrosis unless the ischemia is 4:40 reversed. 4:41 At the very outside is the zone of hyperimia. 4:44 In this outermost zone, tissue perfusion is increased. 4:48 The tissue here is invariably recovered unless there is severe sepsis or 4:53 prolonged hypo perfusion. 4:56 Again, the stasis zone is characterized by ischemia and may progress to full 5:01 necrosis 5:02 unless the ischemia is reversed. 5:05 Therefore the main aim of burns resuscitation is to increase tissue perfusion 5:12 here and 5:13 prevent any further damage, any damage becoming irreversible. 5:19 So that is a general pathophysiology or mechanism of disease concept of burns. 5:25 When you assess a burn, it is important to know the cause of the burn as we 5:29 have learned, 5:30 such as if it's a thermal or radiation burn. 5:33 The other important aspect of a burn assessment is to know the depth of the 5:37 burn. 5:38 To make it super easy, just think of burns as initially being superficial burns 5:44 or deep 5:44 burns. 5:45 So let's zoom into the skin here to look at what happens in a superficial burn 5:49 and what 5:50 happens in a deep burn. 5:52 Let's take a look at a superficial burn first. 5:55 If it's a superficial burn, it will cause damage to the epidermis and the upper 5:59 dermis 6:00 only, so like the papillary layer of the dermis. 6:03 Again you have blood vessels here, capillaries. 6:07 Superficial burns will damage the keratinocytes, which are your cells in the ep 6:11 idermis and 6:12 will also activate an immune response. 6:15 So it will activate immune cells around the area such as mass cells and macroph 6:20 ages. 6:21 The damaged keratinocytes, the mass cells and the macrophages will secrete pro- 6:25 inflammatory 6:26 cytokines, triggering an immune response. 6:30 The cytokines will stimulate nerve endings around the dermis. 6:35 The sensory nerve endings here can be the ones that detect pain, for example, 6:39 and pain 6:40 is an important feature of superficial burns. 6:45 Some cytokines will cause increase in vascular permeability. 6:50 The increase in vascular permeability will cause fluid to leak out and may lead 6:54 to interstitial 6:55 edema. 6:59 As the fluid leaks out, it can result in hypertension. 7:04 Remember that the increase in vascular permeability causes fluid to leak out. 7:08 The fluid can actually accumulate in one area causing a blister on the skin 7:14 surface. 7:15 The sensitive blister can rupture and release fluid onto the damaged skin 7:20 surface, thus 7:21 superficial burns have a moist appearance. 7:26 The cytokines secreted by the cells above will also cause concurrent vasod 7:31 ilation causing 7:32 further hypotension in severe cases. 7:37 The vasodilation contributes to the warmth in the area as well as causing bl 7:43 anching of 7:44 the skin and arythema. 7:47 Blanching means that when you press on the burned skin surface, blood will 7:51 quickly fill 7:52 it up because of the increase in blood flow to the area. 7:57 The blanching skin is a feature of superficial burns. 8:02 In deep burns, you have more than just damage to the epidermis and the upper 8:07 part of the 8:08 dermis. 8:09 Damage all the way down extends all the way to the hypodermis so it's a pretty 8:15 deep burn. 8:17 Deep burns can thus damage blood vessels in the skin. 8:21 Because you have damaged blood vessels, everything will leak out. 8:25 You have no blood supply to the area so you eventually get this dry non-blanch 8:31 ing surface. 8:33 It is dry and inelastic. 8:36 The non-blanching dryness is an important feature of deep burns. 8:41 Further deep burns extending to the particular layer of the dermis can destroy 8:46 no-ceceptors 8:47 and other sensory nerve fibers. 8:50 Initially pain can be detected but as a sensory nerve fibers are damaged, you 8:55 get hypoesthesia 8:57 so you get reduction in sensation. 9:00 Loss of sensation is an important feature of deep burns. 9:05 Obviously, not all your blood supply is damaged or your blood vessels are 9:09 damaged. 9:10 The functional blood vessels will react to the cytokines produced around the 9:15 area. 9:16 The vessels will increase vascular permeability which will cause fluid to shift 9:21 out causing 9:21 interstitial edema. 9:24 So fluid shifts out from the intravascular space, so the blood vessel, into the 9:29 interstitial, 9:30 and this huge amount of fluid coming out of the vessels will result in hypot 9:37 ension. 9:38 So circulatory shock even. 9:41 Hypotension as a result of the shift of fluid occurs more in deep burns rather 9:45 than superficial 9:45 burns. 9:47 So now that we know the pathophysiology of superficial burns and deep burns, 9:51 let us 9:52 learn a bit more about the classification of the burn depth. 9:57 Again, burn depth can be broadly divided into superficial and deep burns. 10:05 Superficial burns can be further divided into superficial epidermal burns and 10:10 superficial 10:10 partial thickness burns. 10:16 In superficial epidermal burns, only the epidermis is involved, so the very top 10:21 of the skin. 10:22 The most common cause here is your regular sunburn when you get a dry and red 10:26 skin which 10:27 is painful. 10:29 The epidermis layer is the only layer involved. 10:32 On a side note, superficial burns are not included in the assessment of the 10:38 total body 10:39 surface area burn. 10:42 In superficial partial thickness burn, you are causing damage all the way to 10:47 the papillary 10:48 layer of the dermis, so the upper dermis. 10:51 And so because you are going all the way to the upper dermis, you are allowing 10:56 the blood 10:56 vessels to increase permeability leading to blister formation which then can 11:01 subsequently 11:03 rupture. 11:05 The feature of the burn is red moist weeping with rupture and unroptured bl 11:13 isters. 11:14 The burn here is very painful. 11:18 Again in superficial partial thickness burns, your epidermal and papillary 11:22 layers of the 11:23 dermis are involved. 11:25 The important features here are blister formation, rupture of blisters, causing 11:29 a weeping moist 11:30 injury. 11:32 As mentioned before, and I will mention this again, superficial burns is 11:36 characterized 11:37 by a blanching injury. 11:39 So when you press your finger on the area, the area pressured will return to 11:43 its normal 11:44 color because of the normal perfusion. 11:48 The other important aspect of superficial burns is that the sensation is still 11:53 working. 11:53 It is normal and so you feel pain. 11:55 Deep burns are totally different. 11:57 Deep burns involve all layers of the skin. 12:01 The important feature of deep burns is that it does not blanch with pressure 12:06 and there 12:06 is minimal to no pain. 12:09 No sensation due to damage of nerve endings in the area. 12:14 Deep burns can be easily divided into deep partial thickness burns and full 12:19 thickness 12:20 burns. 12:23 When deep partial thickness burns, the burns are partially deep. 12:27 They cause blisters which easily rupture and come off. 12:31 The surface of the skin can be pale if blood supply is lost or red if there is 12:36 extra sensation 12:37 of red blood cells. 12:39 In partial deep thickness burns, you can get damaged blood vessels which means 12:44 when you 12:45 press the skin surface, it will be non-blanching. 12:51 And also partial deep burns may damage sensory nerve fibers causing a decrease 12:59 in sensation. 13:01 In partial deep burns, the skin layers involve the epidermis and all the dermis 13:06 layer. 13:07 Full thickness burns are the worst. 13:09 Here, all the skin layers including the hyperdermis are involved. 13:15 The burn is so extensive that the skin may look waxy white, leathery gray or 13:20 charred black, 13:21 depending on how deep it is, duration of the burns, etc. 13:26 The burn area is not wet because no blisters are forming, it is usually dry and 13:32 inelastic. 13:33 The sensory nerves and the blood vessels are definitely destroyed and so you 13:37 have no sensation 13:38 and no blanching. 13:40 In full thickness burns, you have destruction of all skin layers including the 13:44 hyperdermis. 13:46 There is actually a fifth classification of deep burns, but we are not going to 13:50 talk 13:50 about it here because I feel like it causes more confusion than help. 13:56 Referring a burn to the burns unit is very important. 14:00 We talked about referring certain types of burns to the burns unit, such as 14:04 chemical 14:04 burns, electrical burns and inhalation burns, but how about the burn depth? 14:10 Well, we always refer full thickness burns and also burns greater than 10% of 14:16 the total 14:17 body surface area and this does not include the superficial epidermal burns. 14:23 So what does this total body surface area mean? 14:27 When assessing burns, it's also important to calculate how much of the body is 14:31 burnt 14:32 or the size of the burn or we refer this to as the total body surface area. 14:39 A good way to calculate the total body surface area is to use what is called 14:43 the rule of 14:44 nines. 14:45 It's a great rapid assessment. 14:50 The rule of nines is where the body is divided into areas of percentage, which 14:55 are divisible 14:56 by 9, with the exception, for example, you have 4.5%, 9% or 18%. 15:04 So if we look at a human from the front and the back, the front of the face is 15:09 4.5%, the 15:11 back of the head is 4.5%, 9% front of the chest, 9% upper back, 9% stomach and 15:18 9% lower 15:19 back. 15:21 For one leg is 18%, so 9% for the front of the leg and 9% for the back of the 15:27 leg. 15:28 For the upper limb, it's 9% total, so it's 4.5% at the front and 4.5% at the 15:34 back. 15:35 I hope that makes sense. 15:37 And the genitals and perineum is 1%. 15:42 So to summarize, the head and neck total is 9%, the chest, front and back is 18 15:50 %. 15:51 The abdomen all around is 18%. 15:56 One leg is 18%, and one arm is 9%. 16:01 And the genitals and perineum is 1%. 16:05 So all should equal 100% if I did it right. 16:11 Another quick way to measure total body surface area is by using what's called 16:15 the pama method. 16:17 Here the person's palm and fingers will represent 1% total body surface area. 16:23 So for example, they have burnt an area of their body and their palm and 16:27 fingers covers 16:27 this burn. 16:29 This represents 1% total body surface area burnt. 16:33 The pama method is useful for small, scattered burns. 16:37 So remember we briefly mentioned when to refer burns to the burns unit, such as 16:42 the type 16:43 of burn, as well as the depth of burn. 16:46 So for example, full thickness burns or burns greater than 10% of the total 16:52 body surface 16:53 area. 16:54 But this does not include superficial epidermal burns. 16:58 So how about some other factors which will make one refer to a burns unit? 17:03 All things that potentially need referring to a burns unit include burns to the 17:07 very 17:07 young and very old, special areas such as the head, major joints, genitals, 17:15 hands and 17:15 feet also need referring to a burns unit, burns in pregnancy as well as circumf 17:20 erential 17:20 burns are very serious. 17:23 Circumferential burns especially can progress to what is called compartment 17:27 syndrome, where 17:28 pressure and edema builds up in the muscular compartments causing diminishing 17:33 your vascular 17:34 supply to the area which can lead to irreversible damage and amputation of that 17:38 limb or area 17:39 if not saved early. 17:41 I hope you enjoyed this video on burns. 17:43 To learn more about compartment syndrome please click on the link below.
