- Most of fluid (in first 24-36 hr) leaks out of blood vessels.
- As the capillaries begin to regain their integrity, burn shock resolves and fluid returns
to the vascular compartment.
- As fluid is reabsorbed from the interstitial tissue into the vascular compartment, blood
volume increases.
- If renal and cardiac function is adequate, urinary output increases.
- Diuresis continues for several days to 2 weeks.
Fluid shift
Local edema occurs if burn area is less that 25% TBSA
Generalized edema if burn area is more than 25% TBSA Maximal edema is after 24 hours. Begins to resolve 1 to 2 days after the burn and usually is completely resolved
within 7 to 10 days. As edema increases, pressure on small blood vessels and nerves in the distal
extremities causes an obstruction of blood flow and consequent ischemia.
This complication is similar to a compartment syndrome. The physician may need to perform an escharotomy , a surgical incision into the
eschar (devitalized tissue resulting from a burn), to relieve the constricting
effect of the burned tissue- Circulating blood volume decreases during burn shock.
- Evaporative fluid loss through the burn wound may reach 3 to 5 L or more over a 24-
hour period until the burn surfaces are covered.
- Usually, hyponatremia is present.
- Immediately after burn injury, hyperkalemia results from massive cell destruction.
Hypokalemia (potassium depletion) may occur later with fluid shifts and inadequate
potassium replacement.
Fluid Remobilization
- Occurs after 24 hours
- Capillary leak stops
- See diuretic stage where edema fluid shifts from the interstitial spaces into the
vascular space