Effect of dextran-70 on increased microvascular fluid and protein flux after thermal injury

The effect of a colloid (dextran-70) infusion on increased microvascular fluid and protein flux after thermal injury was compared with that seen with a crystalloid infusion. Lymph flow (Q̇(L)) and lymph/plasma (L/P) protein content were used to monitor microvascular fluid flux and protein permeability in the lung and in burned and nonburned soft tissue, namely, skin and subcutaneous tissue, for 72 h in 13 sheep given a 30% TBS full-thickness burn. Vascular pressures were maintained constant with dextran in saline or lactate Ringer's. Mean fluid requirements for dextran were one-half that for crystalloid during the 24-h resuscitation period. However, plasma proteins decreased by 50% with dextran compared to 30% with crystalloid. An increase of 2-2.5 fold in Q̇(L) was seen during resuscitation in the lung and nonburned soft tissue with crystalloid while the L/P protein ratio decreased, indicating no change in protein permeability. This Q̇(L) response was prevented during dextran infusion. A rebound increase in soft tissue Q̇(L) occurred after discontinuation of dextran, probably as a result of the severe residual hypoproteinemia. Burn Q̇(L) and L/P were markedly increased during the entire 72-h period, indicating increased permeability. Dextran infusion accentuated the Q̇(L) response in the burn microcirculation. We conclude that dextran decreases edema in nonburned tissue, but appears to increase the protein loss from burn tissue.