Renal Microcirculation and Function in a Pig Model of Hemorrhagic Shock Resuscitation with Norepinephrine

Rationale: Norepinephrine (NE) is commonly used in combination with fluid during resuscitation of hemorrhagic shock, but its impact on kidney microcirculation, oxygenation, and function is still unknown in this setting. Objectives: During hemorrhagic shock resuscitation, does a combination of fluid and NE affect kidney oxygenation tension, kidney microcirculatory perfusion, and 48-hour kidney function, as compared with fluid alone? Methods: Hemorrhagic shock was induced in 24 pigs, and 8 pigs were included as a sham group. Resuscitation of hemorrhagic shock was performed, using a closed-loop device, either by fluid alone (0.9% NaCl; fluid group) or associated with the administration of NE at two doses (moderate dose: mean rate of 0.64 μg ⋅ kg^-1 ⋅ min^-1; high dose: mean rate of 1.57 μg ⋅ kg^-1 ⋅ min^-1) to obtain a target systolic arterial pressure of 80 to 90 mm Hg. Resuscitation was followed by transfusion of the withdrawn blood. Measurements and Main Results: The amount of fluid required to reach the target systolic arterial pressure was lower in the NE groups than in the fluid group, with subsequently less hemodilution. NE restored kidney microcirculation, oxygenation, and function in a manner comparable to that achieved with fluid resuscitation alone. There were no histologic differences between animals resuscitated with fluid and those resuscitated with NE. Conclusions: In pigs with hemorrhagic shock, resuscitation with a combination of NE and fluid restored kidney microcirculation and oxygenation, as well as renal function, in a manner comparable to fluid resuscitation alone and without differences between the two NE doses. NE administration led to a fluid volume-sparing effect with subsequently less hemodilution.