Background: Generation of reactive oxygen species (ROS) is an important mechanism of ischemia-reperfusion injury. Abrupt reoxygenation compared with slow reoxygenation has been known to increase ROS generation. Thus, slow and stepwise reperfusion can reduce ROS generation and subsequent ischemia-reperfusion injury. This study investigated the effect of slow reperfusion by blood pressure-targeted stepwise resuscitation (PSR) in hemorrhagic shock.
Methods: Pressure-controlled hemorrhagic shock was induced in male Sprague-Dawley rats for 1 hour. Rats were then allocated to one of three groups (no-resuscitation group, n = 14; PSR group, n = 15; rapid normalization of blood pressure (RR) group, n = 15). Survival time and hemodynamic changes were recorded and compared. Blood samples and liver tissue were harvested after 6 hours of resuscitation in surviving rats.
Results: All of the rats in the no-resuscitation group were expired before the end of the 6-hour observation period. Survival times were significantly longer in the PSR group than in the RR group (survival rates, 11 of 15 vs. 5 of 15, log rank p = 0.032). Plasma amino alanine transferase, histologic liver injury, and ROS generation in the liver tissue were significantly lower in the PSR group than in the RR group (all findings significant, p < 0.05). In addition, PSR significantly decreased plasma nitric oxide, liver interleukin 1β, and liver interleukin 6 compared with rapid resuscitation in addition to augmenting Akt survival pathways (all p < 0.05).
Conclusion: Slow reperfusion by PSR decreased mortality, ROS generation, and liver injury in rats undergoing hemorrhagic shock. Stepwise resuscitation also decreased inflammatory cytokine production and augmented Akt survival pathways.