Topic Four: Pathophysiology
Whatever the mechanism, burn injuries cause a local response and, in complex burns, a systemic response.
Local response
The local response to a burn injury consists of inflammation, regeneration and repair.The burn can be divided into three zones:
Zone of coagulation and necrosis
- At the centre of the wound
- No tissue perfusion
- Irreversible damage due to coagulation of proteins
Zone of stasis
- Surrounds the central zone of coagulation
- Decreased tissue perfusion
- Some chance of tissue recovery with optimal damage
Zone of hyperaemia
- At the periphery of the wound
- Good tissue perfusion
- Tissue recovery likely
(International Best Practice Statement, 2014; Jeschke et al., 2018)
The usual process of repair occurs around the edges and at the superficial edges. After 3-4 days, loss of tissue viability in the zone of stasis will cause the burn wound to become deeper and wider.
Systemic response
In more complex burns of more than 20-30% total body surface area (TBSA), there is also a systemic response due to the extensive release of inflammatory mediators to the injury site. The effects include systemic hypotension, hypovolemia, vasoconstriction, hemolysis (requires a blood transfusion), bronchoconstriction, and a threefold increase in the basal metabolic rate, and a reduced immune response (Jeschke et al., 2018).