The choice of volume expander for fluid resuscitation in hemorrhagic shock is still debated. Changes in plasma viscosity (PV) are barely investigated while PV modulates functional capillary density, microcirculation and organ function. The present study evaluated the impact of 2 strategies of fluid resuscitation in hemorrhagic shock in pigs. Ten pigs were subjected to hemorrhagic shock and randomly assigned to a low viscosity fluid regimen (Lactated Ringer's, LR) group or a high viscosity regimen (hypertonic-hydroxyethyl starch, HES) for volume resuscitation. Sublingual microcirculatory flow and tissue oxygen tension were assessed together with macro- and microcirculatory, biochemical and rheological variables at baseline, 30 minutes after hemorrhagic shock, immediately after reaching resuscitation endpoints (R-0), and 60 minutes after resuscitation (R-60). PV decreased similarly in both groups following resuscitation (from 1.36 [1.32-1.38] to 1.21 [1.21-1.23] for LR, and from 1.32 [1.31-1.32] to 1.20 [1.17-1.21] mPa.s for HES). No differences were found between the groups for other rheological variables, microcirculatory flow or tissue oxygen tension at R-0 and R-60. Despite a 6-fold difference in the volumes required to achieve blood flow endpoints, commercially available volume expanders had similar effects on rheological and microcirculatory variables, irrespective of their viscosity. Our findings are consistent with the absence of clinically relevant differences between crystalloid and colloid resuscitation of hemorrhagic shock.
Keywords: Hemorrhagic shock; functional capillary density; microcirculation; pigs; plasma viscosity; volume expander.