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

Abstract

In contrast to our hypothesis, severe acute hypoproteinemia does not reduce plasma volume expansion in response to 50 mL/min 0.9% saline infusion in nonspleenectomized sheep when compared with the resultant plasma volume expansion after a 50 mL/min of 0.9% infusion in the euproteinemic state.

Understanding Volume Kinetics: The Role of Pharmacokinetic Modeling and Analysis in Fluid Therapy

“…The distribution and elimination of IV fluids have been investigated under the influence of inhalant anesthesia (36,38,42), various fluid infusion rates and duration (37,39), hemorrhage (41), hypoproteinemia (44), sepsis (34,40), and use of vasoactive agents (43,45) in sheep, rabbit, and pig models. Aside from the aforementioned studies performed by the same group of researchers, there is only one veterinary study that investigated real-time IV fluid dynamics using a different method in healthy anesthetized dogs (20).…”

“…This study also revealed that markedly supraphysiologic infusion doses exceed the limits of linearity of a VK model. In 2010, Brauer et al (44) found that severe acute hypoproteinemia induced by plasmapheresis does not reduce the PV expansion of isotonic crystalloid infusion (27 mL/kg 0.9% NaCl over 20 min) in non-hemorrhaged, non-splenectomised sheep. The depletion of mean total protein concentration from 5.4 to 2.5 g/dL following plasmapheresis resulted in a parallel reduction in mean plasma COP from 20 to 9.6 mmHg (44).…”

“…Intravenous fluids can now be studied like pharmaceutical drugs, leading to improved understanding of their time-volume effects or elimination half-life on plasma and interstitial fluid compartments (30), making evidence-based approaches to fluid therapy possible. Although this concept originally served as a research model for humans (30)(31)(32)(33), a handful of experimental studies have been performed in animals including rabbits (34), pigs (35), and sheep (36)(37)(38)(39)(40)(41)(42)(43)(44)(45).…”

Intraoperative fluid losses revisited

“…If the level of protein inside the vessels falls, as during trauma and surgery, it implies further shifting of fluid out of the vasculature. Smaller molecules, such as crystalloids, are probably not much effected since they escape through the barrier anyway 20,21 . During normal conditions it will, however, only lead to a moderate shift and accumulation of fluid since both an increased lymph flow and interstitial hydrostatic pressure in combination with diluted amount of interstitial protein will limit any excess accumulation of fluid interstitially.…”

“…Smaller molecules, such as crystalloids, are probably not much effected since they escape through the barrier anyway. 20,21 During normal conditions it will, however, only lead to a moderate shift and accumulation of fluid since both an increased lymph flow and interstitial hydrostatic pressure in combination with diluted amount of interstitial protein will limit any excess accumulation of fluid interstitially. During normal circumstances there is also an escape of albumin of about 5% of the intravascular albumin rate per hour.…”