Reflection coefficient for albumin and capillary fluid permeability in catcalf muscle after traumatic injury

Surgery and traumatic injury are often followed by tissue oedema and a low plasma albumin concentration, indicating leakage of fluid and proteins from the intravascular to the interstitial space. Transcapillary leakage can be referred to as an increase in capillary hydraulic conductance and/or a dec rease in the reflection coefficient for plasma macromolecules. This study e valuates if time-dependent variations in the reflection coefficient for alb umin and capillary hydraulic conductance can be confirmed experimentally fo llowing a surgical trauma using a blood perfused cat skeletal muscle in viv o preparation. The hydraulic conductance was estimated by the capillary fil tration coefficient. and was used to evaluate variation in capillary fluid permeability. According to the Starling fluid equilibrium, the ratio betwee n the reflection coefficients for albumin on two occasions can be calculate d from the maximum osmotic absorption rates induced by a fixed intravenous bolus infusion of albumin (0.5 g kg(-1)) and from the capillary filtration coefficients. We found a decrease in the reflection coefficient of about 30 % up to 10 h after the preparation. The capillary filtration coefficient sh owed no significant change over time, but decreased by 5-10% following the albumin infusion. We conclude that: (1) the reflection coefficient for albu min is reduced after a trauma, whereas the effects on the capillary fluid p ermeability are small. (2) albumin in plasma contributes to preserve normal capillary fluid permeability and, (3) the model seems to be useful for eva luation of relative variations in the reflection coefficient for albumin.