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MECHANISMS OF INJURY

MECHANISMS OF INJURY. THERMAL INJURIES.

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MECHANISMS OF INJURY

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  1. MECHANISMS OF INJURY

  2. THERMAL INJURIES • SCALDS —70% of burns in children;They also often occur in elderly people. Water at 140°F (60°C) creates a deep partial-thickness or full-thickness burn in 3 seconds. At 156°F (69°C), the same burn occurs in 1 second. Scald burns from grease or hot oil are usually deep partial-thickness or full-thickness burns, as the oil or grease may be in the range of 400°F (200°C).

  3. THERMAL INJURIES • FLAME — often associated with inhalational injury and other concomitanttrauma. Flame burns tend to be deep dermal or full thickness.Flame burns are the second most common mechanism of thermal injury. • CONTACT—In order to get a burn from direct contact, theobject touched must either have been extremely hot or the contactwas abnormally long. Burns from brief contact with very hot substances are usuallydue to industrial accidents. Contact burns tend to be deep dermalor full thickness.

  4. THERMAL INJURIES • FLASH - Explosions of natural gas, propane, butane, petroleum distillates, alcohols, and other combustible liquids, as well as electrical arcs cause intense heat for a brief time period. Flash burns generally have a distribution over all exposed skin, with the deepest areas facing the source of ignition. Are typically epidermal or partial thickness, their depth depending on the amount and kind of fuel that explodes

  5. ELECTRICAL INJURY • Some 3-4% of burn unit admissions are caused by electrocutioninjuries (US data, 2005). • Mechanism: • An electric current will travel through the body fromone point to another, creating "entry" and "exit" points. • Thetissue between these two points can be damaged by the current. • The amount of heat generated, and hence the level of tissuedamage, is equal to 0.24x(voltage)2xresistance. • The voltageis therefore the main determinant of the degree of tissue damage

  6. CHEMICAL INJURY • Chemical injuries are usually results of industrial accidentsbut may occur with household chemical products. • These burnstend to be deep, as the corrosive agent continues to cause coagulativenecrosis until completely removed. • Alkalis tend to penetratedeeper and cause worse burns than acids. • Cement is a commoncause of alkali burns. Chemical burn due to spillage ofsulphuric acid

  7. BURN PATHOPHYSIOLOGY

  8. The body’s response to a burn. • Burn injuries result in both local and systemic responses

  9. Local response • Zone of coagulation—point of maximum damage., irreversible tissue loss due to protein coagulation • Zone of stasis—with decreased tissue perfusion, tissue potentially salvageable • Zone of hyperemia—outermost zone tissue perfusion is increased

  10. Clinical image of burn zones. Thereis central necrosis, surrounded by the zones of stasis and ofhyperaemia

  11. LOCAL RESPONSE • Loss of tissue in the zone of stasis will lead to the wound deepening as well as widening

  12. SYSTEMIC RESPONSE • release of cytokines and other inflammatory mediators at the site of injury has a systemic effect once the burn reaches 30% of total body surface area

  13. SYSTEMIC RESPONSE

  14. Electrical injuries • electric current travels through the body from one point to another, creating “entry” and “exit” points. • tissue between these 2 points can be damaged by the current • amount of heat generated = level of tissue damage • Voltage determines the degree of tissue damage

  15. Electrical Injuries (Type) • Domestic Electricity (Low Voltage): cause small, deep contact burns at the exit and entry sites • True” high tension injuries:voltage ≥1000V • extensive tissue damage, often limb loss • large amount of soft and bony tissue necrosis • Flash injuries: tangential exposure to a high voltage current arc but no current flow through the body

  16. Classification of Burn Depths • Partial thickness burns: do not extend through all skin layers • Superficial—affects the epidermis but not the dermis (such as sunburn), epidermal burn • Superficial dermal: extends through the epidermis into the upper layers of the dermis, associated with blistering • Deep dermal—extends through the epidermis into the deeper layers of the dermis but not through the entire dermis. • Full thickness burns: extend through all skin layers into the subcutaneous tissues

  17. Classification of Burn Depths

  18. Assessment of Burn Depth

  19. ASSESMENT OF BURN AREA

  20. WALLACE RULE OF NINES

  21. Lund and Browder chart

  22. RESCUSCITATION REGIMEN

  23. RESCUSCITATION REGIMEN • The starting point for resuscitation is the time of injury, not the time of admission • High tension electrical injuries require substantially more fluid (up to 9 ml×(burn area)×(body weight) in the first 24 hours) and a higher urine output (1.5-2 ml/kg/hour) • regimens should be continuously adjusted • according to urine output and other physiological parameters (pulse, blood pressure, and respiratory rate)

  24. CRITERIA FOR REFERRAL TO A BURN CENTER • Second- and third-degree burns greater than 10% TBSA in patients under 10 or over 50 years of age • Second- and third-degree burns greater than 20% TBSA in other age groups • Second- and third-degree burns that involve the face, hands, feet, genitalia, perineum, and major joints • Third-degree burns greater than 5% TBSA in any age group • Electrical burns, including lightning injury

  25. CRITERIA FOR REFERRAL TO A BURN CENTER • Chemical burns • Inhalation injury • Burn injury in patients with pre-existing medical disorders that could complicate management, prolong recovery, or affect mortality • Any patients with burns and concomitant trauma (e.g., fractures, blast injury) where burn injury poses the greatest risk of morbidity or mortality. • Burn injury in children who will require special social/emotional and/or long-term rehabilitative support, including cases involving suspected child abuse or substance abuse

  26. REFERENCES • Initial management of a major burn: II—assessment and resuscitation. ShehanHettiaratchy, Peter Dziewulski. BMJ VOLUME 329 10 JULY 2004 • Pathophysiology and types of burns. ShehanHettiaratchy, Peter Dziewulski. BMJ VOLUME 328 12 JUNE 2004 • American Burn Association. Hospital and Prehospital Resources for Optimal Care of Patients with Burn Injury: Guidelines for Development and Operation of Burn Centers. Journal of Burn Care and Rehabilitation. 1990; 11: 98-104.

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