Effect of fluid resuscitation from endotoxin shock on lung transvascular fluid and protein exchange

The hypothesis that volume expansion during septic shock produces a greater transvascular protein flux than volume expansion alone was tested in anesthetized sheep by giving a high dose of endotoxin (40 micrograms/kg) intravenously. After 0.5 h of systemic hypotension, Ringer lactate, equivalent to 8% body wt, was infused followed by an additional 4 h of lymph collection. The results were compared with those from control animals receiving only Ringer lactate. The changes in plasma total protein with time were similar between groups. The increases in lymph flow and lymph protein flux were greater in the endotoxin-challenged group compared with the control group receiving Ringer lactate during the first 2 h but were similar thereafter. The interstitial volume was greater in the endotoxin-challenged animals compared with controls. The extravascular masses or apparent tissue concentrations for albumin or immunoglobulin G did not change in either group receiving Ringer lactate. The pulmonary edema following resuscitation from septic shock with Ringer lactate could be accounted for by either the pulmonary hypertensive effects of endotoxin or an initial, transient increase in microvascular protein permeability but not a sustained increase in microvascular permeability.