Blood pressure–targeted stepwise resuscitation of hemorrhagic shock in a swine model

Preperitoneal pelvic balloon tamponade-an effective intervention to control pelvic injury hemorrhage in a swine model

Objective: This study aimed to estimate the effects of the volume of preperitoneal balloon (PPB) on arterial and venous hemorrhage in a swine pelvic fracture model. Methods: Twenty-four swine were randomized into 0-mL, 500-mL, 800-mL, and 1000-mL intra-hematoma PPB groups. They were subjected to open-book pelvic fracture and reproducible injuries in the external iliac artery and vein. The pelvic binder and IH-PPBs with different volumes of fluid were applied to control the active hemorrhage after arterial and venous injuries. The survival time and rate during 60-min observation and digital subtraction angiography (DSA) images were the primary endpoints in this study. Secondary endpoints included survival rate within 70 min, peritoneal pressure, hemodynamics, blood loss, infusion fluid, blood pH, and lactate concentration. Results: Our results indicated that the 800-mL and 1000-mL groups had a higher survival rate (0%, 50%, 100% and 100% for 0, 500, 800, and 1000-mL groups respectively; p < 0.0001) and longer survival time (13.83 ± 2.64, 24.50 ± 6.29, 55.00 ± 6.33, and 60.00 ± 0.00 min for 0, 500, 800, and 1,000 groups respectively; p < 0.0005) than the 0-mL or 500-mL groups during the 60 min observation. Contrastingly, survival rate and time were comparable between 800-mL and 1000-mL groups during the 60-min observation. The IH-PPB volume was associated with an increase in the pressure of the balloon and the preperitoneal pressure but had no effect on the bladder pressure. Lastly, the 1000-mL group had a higher mean arterial pressure and systemic vascular resistance than the 800-mL group. Conclusion: IH-PPB volume-dependently controls vascular bleeding after pelvic fracture in the swine model. IH-PPB with a volume of 800 mL and 1000 mL efficiently managed pelvic fracture-associated arterial and venous hemorrhage and enhanced survival time and rate in the swine model without evidences of visceral injury.

Reoxygenation speed and its implication for cellular injury responses in hypoxic RAW 264.7 cells

BACKGROUND

Ischemia/reperfusion injury is characterized by excess generation of reactive oxygen species (ROS). The purpose of this study is to test the effect of reoxygenation speed on ROS production and the cellular injury responses in hypoxic macrophages RAW 264.7 cells and its potential mechanisms for the generation of ROS.

MATERIALS AND METHODS

After hypoxic exposure of RAW 264.7 cells for 20 h, reoxygenation was performed for 6 h by stepwise increase in oxygen concentration (0.8% increase of oxygen every 15 min) in the slow reoxygenation (SRox) group or by moving the culture flasks quickly to a normoxic incubator in the rapid reoxygenation (RRox) group. To identify the potential effect of reoxygenation speed on the generation of ROS, the cells were pretreated with apocynin, VAS2870, and MitoTEMPO before the induction of hypoxia.

RESULTS

SRox significantly decreased cell death and cytotoxicity compared with RRox (P < 0.05). RRox resulted in significantly more generation of ROS, interleukin-1β, interleukin-6, and nitric oxide than SRox (P < 0.05). SRox also increased the expression of prosurvival proteins and decreased apoptosis. In cells pretreated with VAS2870 or MitoTEMPO, the reduced ROS generation by SRox was maintained. However, pretreatment with apocynin abolished the effect of reoxygenation speed on ROS generation.

CONCLUSIONS

SRox compared with RRox decreased cellular injury in hypoxic RAW 264.7 cells by decreasing ROS and inflammatory cytokine production and decreasing apoptosis.