Increased plasma viscosity prolongs microhemodynamic conditions during small volume resuscitation from hemorrhagic shock

Abstract

Systemic and microvascular hemodynamic responses to hemorrhagic shock resuscitation with hypertonic saline (HTS, 7.5% NaCl) followed with a small volume of plasma expander were studied in the hamster window chamber model to determine the role of plasma expander viscosity in the acute resuscitation outcome. Moderate hemorrhagic shock was induced by arterial controlled bleeding of 50% of blood volume (BV) and the hypovolemic state was maintained for one hour. Volume restitution was performed by infusion of HTS, 3.5% of BV followed by 10% of BV plasma expanders. Resuscitation was followed for 90 min. The experimental groups were named based on the plasma expanders infused after the HTS, namely: [Hextend], Hextend® (6% Hetastarch 670 kDa in lactated electrolyte solution, 4 cp), [Hextend+V], Hextend® with viscosity enhanced by the addition of 0.4% alginate, 8 cp, and [NVR] no volume resuscitation as control group. Measurement of systemic parameters, microvascular hemodynamics and capillary perfusion were performed during hemorrhage, shock and resuscitation. Restitution with Hextend yielded the higher mean arterial pressure (MAP), followed by Hextend+V and NVR. Increasing plasma viscosity did not increase peripheral vascular resistance. Functional capillary density (FCD) was higher for Hextend+V than Hextend and NVR. The level of restoration of acid-base balance correlated with microvascular perfusion and was significantly improved with Hextend+V when compared to Hextend and NVR. These results suggest the importance of restoration of blood rheological properties through enhancing plasma viscosity, influencing the re-establishment of microvascular perfusion during small volume resuscitation from hemorrhagic shock.

Improved Resuscitation From Hemorrhagic Shock With Ringer's Lactate With Increased Viscosity in the Hamster Window Chamber Model

“…Therefore, our results confirm previous findings showing that the increase in blood and plasma viscosities are associated with increased tissue perfusion after acute anemia and hemorrhagic shock. 29 High-viscosity RL increased FCD by comparison with RL, an effect that was sustained for 90 minutes and which is significant as a gauge of the benefit derived for using RL-HV because FCD, an indicator of local tissue perfusion, 8 is a comprehensive marker for microvascular function and an early predictor of survival. 6 Mechanistically, the increase in plasma viscosity improves tissue perfusion by increasing/maintaining the A-V capillary pressure gradient and elevating capillary pressure, which is the critical factor determining FCD as shown in studies of extreme hemodilution (11% Hct).…”

Two-dimensional lattice Boltzmann study of red blood cell motion through microvascular bifurcation: cell deformability and suspending viscosity effects

“…In recent experiments looking at volume restitution using a plasma expander, Cabrales et al (2008), Vàzquez et al (2009) noticed that plasma viscosity might also be a determinant for the hematocrit distribution in microcirculation.…”

“…In this study, the 2D IB-LBM algorithm (Zhang et al 2007) will be further employed to study RBC dynamics in a bifurcation model similar to those adopted in previous studies (Hyakutake et al 2008;Barber et al 2008). In addition to an improved RBC representation, here effects of cell deformability as well as the suspending plasma viscosity will be investigated for their importance in clinical and biomedical applications (Stoltz et al 1999;Cabrales et al 2008). …”

Regulation of blood viscosity in disease prevention and treatment

“…Using the severe experimental hemorrhagic shock model based on the infusion of hypertonic saline, Golden Syrian Hamsters were randomly infused with Hextend (6% Hetastarch in lactated electrolyte solution, 4 mPa s) or viscosity-enhanced Hextend (Hextend + 0.4% alginate, 8 mPa s). Resuscitation with Hextend resulted in higher MAP, but viscosity-enhanced Hextend showed better results in terms of improved functional capillary density, microvascular perfusion, and the restoration of acid-base balance [86].…”