BURNS
In terms of the etiology of burn wounds, there are five major types of burn wounds, namely: Thermal, Chemical, Mechanical, Electrical and Radiation. However, in terms of the severity of symptoms, burn wounds can also be classified as Mild, Moderate and Severe or as 1st-degree, 2nd-degree and 3rd-degree burns.
1st-degree burns are characterized by soreness, swelling, redness of the skin, pain and warmth to touch. 2nd-degree burns are subdivided into two: Superficial and Deep 2nd-degree burns. Superficial 2nd-degree burn ( i.e., Superficial partial thickness ) primarily affects the epidermis and the dermis. It is characterized by blisters, pain, swelling and a red or dark pink skin. Deep 2nd-degree burn ( i.e., Deep partial thickness ) on the other hand, affects the deep dermal partial tissues but pores and sweat glands are not damaged. Its symptoms include dry, pale color skin, blisters, serum leakage and severe pain. In a 3rd-degree burn, all of the epidermis, dermis, pores and sweat glands are completely damaged. The fat layer, fascia, muscle, bone and nerves are also damaged.
Whenever there is a burn injury, three distinct concentric zones are discernable. The Zone of Coagulation occurs at the vicinity of maximum damage to the skin. Platelets aggregate and coagulation factors are released in order to stop the attendant bleeding. Next is the Zone of Stasis. This zone is characterized by a decrease in tissue perfusion. Zone of Hyperemia surrounds the Zone of Stasis. It is reversible, it has adequate perfusion and redness may occur because of increased vascular permeability.
Recovery from a burn injury naturally occurs in phases. Four phases have been delineated. The first one is the Hemostatic phase. It is characterized by platelet aggregation. The aggregated platelets not only stop the bleeding from the injury, they also release Platelet Factor 4 ( PF4 ) and such growth factors as Platelet-derived Growth Factor ( PDGF ), Transforming Growth Factor-beta ( TGF-beta ), Epidermal Growth Factor ( EGF ) and Insulin-like Growth Factor-1 ( I-LGF-1 ). These growth factors promote healing.
The second phase of wound healing is the Inflammatory phase. During this phase, the aggregated platelets secrete a chemo-attractant which attracts Monocytes, Macrophages and Neutrophils to the site of injury. Enzymes secreted by the cell membrane of these platelets stimulate the synthesis of such pro-inflammatory substances as Prostaglandins ( PGs ) and Leukotrienes ( LTs ). Mast cells secrete histamine which causes vasodilation and, along with such clotting products as Kinins and Thrombin, increases capillary permeability with a resultant edema stemming from the leakage of fluid into the interstitial space. Angiogenesis factors ( e.g., TGF-beta ) released in phase 1 now start stimulating the growth of new capillaries. In the Inflammatory phase, growth factors from the Hemostasis phase increase the synthesis of Fibroblasts which migrate to the center of the burn wound.
The third phase of burn healing is referred to as the Proliferation phase. It occurs 3 days to 4 weeks after the burn injury. The release of Angiogenetic factors e.g., Vascular Endothelial Growth Factor ( VEGF ), basic Fibroblast Growth Factor ( bFGF ) and TGF-beta, is initiated by a drop in oxygen tension, a decrease in pH and an increase in lactate levels. Those new Angiogenetic factors facilitate neovascularization. The final step in the Proliferation phase is Re-epithelialization. In this step, EGF and TGF-beta are produced by the Platelets, Macrophages and Keratinocytes. The keratinocytes cover the skin surface , proliferate and migrate across the wound, covering it with new epidermal cells.
and collagen rearrangement are processed at this stage. The epithelium regenerates and connective tissue fibrosis ensues.
The repair of damaged tissues often involves stimulating growth factors, increasing blood flow to the tissue ( i.e., oxygen boosters ), ………………………………………