Improved Hemodynamic Stability in Experimental Trauma/Hemorrhagic Shock by Red Blood Cell‐containing Resuscitation Fluids Secondary to Preserved Diastolic Blood Pressure

Abstract

ObjectiveFluid resuscitation with blood products is standard of care in the current management of trauma/hemorrhagic shock (T/HS). However, the availability of whole blood is rare in civilian prehospital care, and thus blood component therapy and other fluid replacement options are required. This study sought to differentiate and compare the effects of lactated Ringer’s solution (LR), plasma, washed red blood cells (RBC), and whole blood (Control) as resuscitation fluids for hemodynamic restoration after T/HS.MethodsWister male rats (400g) were randomly divided into four groups: LR, Plasma, RBC, and Control, anesthetized with isoflurane and subjected to experimental T/HS. A mid‐line laparotomy incision was made, and blood was slowly withdrawn to maintain a mean arterial blood pressure (MAP) of 35–40 mmHg for 90 minutes. After the 90‐min shock period, intravenous fluids corresponding to the experimental group were started with the goal of achieving a MAP ≥ 65 mmHg, the clinical target for adequate pressure. Animals were monitored for 120 minutes following start of reperfusion. Vital signs were continuously measured, as well as arterial blood gases, lactate, and hemoglobin.ResultsMAP in animals that received RBCs was similar to that of the whole‐blood Control group (70.4 ± 4.0 mmHg vs 83.0 ± 5.8 mmHg, RBC vs Control, NS), and significantly greater than MAPs of Plasma (59.9 ± 4.4 mmHg, p=0.03) and LR (45.6 ± 4.8 mmHg, p<0.001) groups. As systolic blood pressure (SBP) was not significantly different between RBC, Plasma and Control groups, the higher MAP seen in the RBC group compared to Plasma was due to increased diastolic blood pressure (DBP) (55.5 ± 3.1 mmHg vs 38.6 ± 3.2 mmHg, RBC vs Plasma, p=0.01). The RBC and Control groups were able to achieve a higher MAP with decreased volume resuscitation percentage (RBC: 50.7 ± 13.6%; Control: 39.3 ± 5.1%) compared to the Plasma and LR groups (81.1 ± 4.4% and 190.5 ± 10.6%, respectively). Animals given blood products also displayed significantly lower lactate levels compared to those given LR (Control: 2.3 ± 1.2 mM; Plasma: 4.8 ± 0.9 mM, RBC: 4.3 ± 1.3 mM, vs LR: 10.7 ± 3.5 mM, p=0.004 all groups compared to LR). Ending hemoglobin in RBC animals was significantly greater than in other groups (p<0.001 compared to all groups). However, blood gas analysis revealed that the RBC group also had the lowest O2 saturation (88.3 ± 0.5% vs. LR: 93.9 ± 4.7%, Plasma: 94.8 ± 0.6%, WB: 93.5 ± 4.5%), yet PaO2 was comparable between groups.ConclusionIn our model of experimental T/HS, reperfusion fluids carrying red blood cells substantially improved hemodynamic stability by returning the mean arterial blood pressure to survivable values. The efficacy of RBC and whole blood resuscitation may be largely the result of improvements in diastolic blood pressure, suggesting increased contribution from systemic vascular resistance in these groups.Support or Funding InformationDOD W81XWH‐17‐2‐0047