Role of thermal injury-induced hypoproteinemia on fluid flux and protein permeability in burned and nonburned tissue.

We studied the role of hypoproteinemia, induced by a major burn injury, on the edema process in burned and nonburned tissues including the lung in the adult sheep. We used lymph flow (QL) and the lymph-plasma (L/P) protein ratio as indicators of the rate of fluid and protein flux across the microcirculation and into the interstitium. We compared the response after a full-thickness burn to 30% of total body surface plus resuscitation by means of lactated Ringer's solution (n = 8) with a comparable degree of hypoproteinemia produced by plasmapheresis with vascular hydrostatic pressure and cardiac output kept constant. We measured lung QL and soft tissue (prefemoral) QL from both the burned and nonburned areas. A twofold increase in QL and a decrease in the L/P ratio was seen in both lung and nonburned tissue in both burn and plasmapheresis animals, indicating the postburn response to be due to hypoproteinemia with no increase in protein permeability. The QL in burned tissue was increased five to ten times with an increase in the L/P ratio. Four burned sheep were resuscitated with pooled plasma. Restoration of plasma proteins eliminated the increase in QL in lung and nonburned tissue but had no effect on the burn response. In summary, burn-induced hypoproteinemia plays a major role in the edema process in nonburned tissues and is corrected by restoration of plasma proteins. Edema in burned tissue does not appear to be related to this process.