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BURN PATHOPHYSIOLOGY. The body’s response to a burn. Burn injuries result in both local and systemic responses. Local response. Zone of coagulation —point of maximum damage., irreversible tissue loss due to protein coagulation
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The body’s response to a burn. • Burn injuries result in both local and systemic responses
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
LOCAL RESPONSE • Loss of tissue in the zone of stasis will lead to the wound deepening as well as widening
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
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
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
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
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)
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
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
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.