Background: Hemorrhagic shock remains a leading cause of early death among severely injured in both civilian and military settings. As future military operations will require strategies allowing prolonged field care of the injured, we sought to develop an in vivo model of prolonged hypotensive resuscitation (PHR) and to evaluate the role of plasma-based resuscitation in this model. We hypothesized that resuscitation with fresh frozen plasma (FFP) would mitigate lung injury when compared with Hextend in a rodent model of PHR.
Methods: Mice underwent laparotomy and hemorrhagic shock (mean arterial blood pressure, 35 ± 5 mm Hg × 90 minutes) followed by PHR with either FFP or Hextend to maintain a mean arterial blood pressure of 55 mm Hg to 60 mm Hg for 6 hours. Sham animals underwent cannulation only. At the end of 6 hours, animals were euthanized, and lung tissue harvested for measurement of histopathologic injury, inflammation and permeability using hematoxylin and eosin staining, myeloperoxidase immunofluorescence staining and Evans Blue dye. Pulmonary syndecan-1 immunostaining was assessed as an indicator of endothelial cell integrity.
Results: All animals in the FFP, Hextend, and sham groups survived to the end of resuscitation. Resuscitation with FFP mitigated lung histopathologic injury compared with Hextend (histologic injury score of 4.38 ± 2.07 vs. 7.5 ± 0.93, scale of 0-9, p = 0.002) and was comparable to shams (histologic injury score of 4.0 ± 1.93, scale of 0-9, p = 0.99). Fresh frozen plasma also reduced lung inflammation (0.116 ± 0.044 vs. 0.308 ± 0.054 relative fluorescence of myeloperoxidase, p = 0.002) and restored pulmonary syndecan-1 (0.514 ± 0.061 vs. 0.059 ± 0.021, relative syndecan-1 fluorescence, p < 0.001) when compared with Hextend. Consistently, FFP mitigated lung hyperpermeability compared with Hextend (7.30 ± 1.34 μg vs. 14.91 ± 5.55 μg Evans blue/100 mg lung tissue, p = 0.005).
Conclusion: We have presented a novel model of PHR of military relevance to the prolonged field care environment. In this model, FFP maintains its pulmonary protective effects using a PHR strategy compared with Hextend, which supports the need for further development and implementation of plasma-based resuscitation in the forward environment.
Level of evidence: Basic science.