Clinical meaning
Burn injury causes tissue destruction in concentric zones: the Zone of Coagulation (center, irreversible necrosis), Zone of Stasis (surrounding area with compromised but potentially salvageable tissue), and Zone of Hyperemia (outermost area with increased blood flow that typically recovers). The depth classification includes: Superficial (1st degree) involving epidermis only with erythema and pain; Superficial partial-thickness (2nd degree) involving epidermis and superficial dermis with blisters, moist appearance, and severe pain; Deep partial-thickness (2nd degree) extending into deep dermis with mottled appearance and decreased sensation; Full-thickness (3rd degree) involving entire dermis, appearing white/charred/leathery with absent pain; and Subdermal/4th degree extending into fascia, muscle, or bone. Burns >20% TBSA trigger a massive systemic inflammatory response: capillary permeability increases dramatically within minutes, causing fluid shifts from intravascular to interstitial space (burn edema). This creates two distinct phases: the Emergent/Resuscitative Phase (0-48 hours) characterized by massive fluid loss, hypovolemic shock, hyperkalemia (from cellular destruction), and risk of renal failure from myoglobinuria; and the Acute/Wound Care Phase (48 hours to wound closure) characterized by infection risk (loss of skin barrier), hypermetabolic state (metabolic rate increases 100-200%...