• Akira Takasu, Shinichiro Iwamoto, Satoshi Ando, Yusuke Minagawa, Misato Kashiba, Yorihiro Yamamoto, and Toshihisa Sakamoto.
• Department of Traumatology and Critical Care Medicine, National Defense Medical College, Namiki, Tokorozawa, Saitama, Japan. atakasu@ndmc.ac.jp
• Resuscitation. 2009 Jul 1;80(7):826-31.

ObjectiveTo test the hypothesis that a fractional inspired oxygen (F(I)O(2)) of 1.0 compared to 0.4 during hemorrhagic shock (HS) and fluid resuscitation (FR): mitigates tissue dysoxia; however, enhances the oxidative stress; therefore, offsets the benefit on survival.MethodsThirty rats underwent: HS for 75min, during which 3.0mL/100g of blood was withdrawn, followed by FR for 75min, during which 1.0mL/100g of shed blood and 3.0mL/100g of crystalloid solution were infused. Ten rats were randomized into one of three F(I)O(2) (0.21 vs. 0.4 vs. 1.0) groups, and observed for survival until 72h in each group. Hemodynamics, liver tissue PO(2) (P(T)O(2)), and, plasma antioxidants levels were also monitored.ResultsOxygen inhalation increased mean arterial pressure (MAP) and decreased heart rate (HR) during HS and FR. Liver P(T)O(2) was less than 10Torr in all groups throughout HS; while it increased to average 26-35Torr in oxygen groups during FR, it remained at 10Torr with F(I)O(2) 0.21 (P<0.01). MAP, HR, and P(T)O(2) did not differ significantly between oxygen groups. Plasma antioxidants levels did not differ among the three groups. All rats treated with oxygen, but eight of 10 rats with F(I)O(2) 0.21 survived up to 72h (NS).ConclusionsSupplemental oxygen does not mitigate tissue dysoxia during HS, but does reduce tissue dysoxia without enhancing oxidative stress during subsequent FR. Increased F(I)O(2) appears to prolong survival. These beneficial effects of supplemental oxygen do not differ between an F(I)O(2) of 0.4 and 1.0.

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