Sepsis Produced by Pseudomonas Bacteremia Does Not Alter Plasma Volume Expansion After 0.9% Saline Infusion in Sheep

Abstract

Clinicians generally consider sepsis to be a state in which fluid is poorly retained within the vasculature and accumulates within the interstitium. We hypothesized that infusion of 0.9% saline in conscious, chronically instrumented sheep with hyperdynamic bacteremic sepsis would be associated with less plasma volume expansion (PVE) and greater interstitial fluid volume expansion than in conscious, nonseptic sheep. Six conscious adult sheep received an IV infusion of 25 mL/kg of 0.9% saline over 20 min (1.25 mL.kg(-1).min(-1)) in a control nonseptic state and during early and late sepsis (4 and 24 h, respectively, after initiation of a standard infusion of live Pseudomonas aeruginosa). The distribution and elimination of infused fluid were studied by mass balance (after measurement of plasma volume using Evans blue dye) and volume kinetic analysis. Mass balance demonstrated no significant differences in the time-course of PVE between control, early sepsis, and late sepsis. At the end of the infusions, which averaged 1050 +/- 125 mL in sheep weighing an average of 42 +/- 5 kg, calculated PVE was 312 +/- 50 mL, 386 +/- 34 mL, and 400 +/- 51, respectively. Volume kinetic analysis was similar in all three protocols. In both nonseptic and septic sheep, infusion of 0.9% saline resulted in similar peak PVE and resolution of PVE over a 3-h interval and similar kinetic parameters. Contrary to clinical impressions and to our hypothesis, the distribution of 0.9% saline in this animal model was not changed by bacteremia produced by infusion of Pseudomonas aeruginosa.

Hypoproteinemia does not alter plasma volume expansion in response to a 0.9% saline bolus in awake sheep

“…It appears that small molecular fluids in this setting shift in a more physiologic way unaffected by the protein level. Likewise, in a sheep study during early and late sepsis over a 3-hr interval, there were no differences in distribution or elimination of infused crystalloids found neither by mass balance analysis nor volume kinetic analysis (16).…”

Isoproternenol Increases Vascular Volume Expansion And Urinary Output After a Large Crystalloid Bolus in Healthy Volunteers

“…Chappell et al further summarize that the endothelial glycocalyx can bind free plasma and they form together the endothelial surface layer and that an oncotic gradient seems to be present directly across the endothelial surface layer, that defines finally vascular integrity, so that the presence of this layer should be the basic requirement for a physiologic barrier function (21). Additionally Svensen et al, (22) showed that in septic and burn-injured sheep that the intravascular retention of infused fluid is paradoxically maintained despite increased microvascular protein permeability and a reduced plasma-to-tissue oncotic gradient (22). Thus, isotonic crystalloid components due to their small size can leak regardless of the state of the endothelial barrier.…”

Haemodilution induced by hydroxyethyl starches 130/0.4 is similar in septic and non‐septic patients

“…In a cat model of trauma with capillary leakage, dextran or albumin induced greater volume expansion than did HES 130/0.4 or saline, and no differences were noted between HES 130/0.4 and saline over a 3‐h period (12). In a sheep model, plasma volume expansion in response to 0.9% saline was similar in animals with and without sepsis (26). Our study suggests that HES 130/0.4 may remain within the intravascular space even in patients with capillary leak syndrome.…”