Topic Progress:

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).