Pathogenesis of edema formation in burn injuries

One of the obvious acute features of cutaneous thermal injury is the swelling of the involved tissue. This swelling is caused by a fluid shift from circulating plasma. Along with the evolution of intravenous fluid therapy in trauma and surgery, the implementation of such therapy to burn victims has improved survival. Edema generation aggravated by fluid therapy may, however, represent a source of increased morbidity. This paper presents a review of the literature on postburn edema generation, focusing mainly on fluid physiology. It is well documented that fluid is lost from the circulation into burned tissue because of a moderate increase in capillary permeability to fluid and macromolecules and a modest increase in hydrostatic pressure inside the perfusing microvessels. Recently it was discovered that a very negative interstitial pressure develops in thermally injured skin. This pressure constitutes a strong "suction" adding markedly to the edema generating effect of increased capillary permeability and pressure.