Effects of arterial oxygen content on oxidative stress during resuscitation in a rat hemorrhagic shock model.

OBJECTIVE

To examine whether reactive oxygen species (ROS) production is affected by arterial oxygen content (CaO(2)) in attempted resuscitation to restore blood pressure from hemorrhagic shock (HS) or not.

METHODS

Under light anesthesia and spontaneous beating, 16 rats underwent HS for 80min, during which 3.0mL/100g of blood was withdrawn, followed by resuscitation attempt for 70min. At 80min, rats were randomized into a high-CaO(2) group (Group 1, transfusion under fractional inspired oxygen (F(I)O(2)) of 1.0, n=8) or a low-CaO(2) group (Group 2, fluid administration under F(I)O(2) of 0.21, n=8). In each group, either blood or lactate Ringer's (LR) solution was infused to maintain mean arterial pressure ≥75mmHg under each F(I)O(2) concentration. CaO(2), O(2) utilization coefficient (UC) and plasma %CoQ9 were compared between groups.

RESULTS

Mean infused volume for attempted resuscitation was 7.6±1.0mL of blood in Group 1, and 31.4±5.5mL of LR solution in Group 2. At the end of resuscitation, CaO(2) was 18.5±1.2 vol% in Group 1, almost double the 9.1±0.8 vol% in Group 2 (P<0.01). O(2) UC and %CoQ9 in all rats increased from baselines of 0.25±0.12 and 7.6±1.8% to 0.44±0.13 and 9.7±1.8% after resuscitation, respectively (P<0.05 vs. baseline for each), but did not differ significantly between the groups.

CONCLUSION

In a rat HS model, attempted resuscitation to restore blood pressure increased O(2) UC as well as %CoQ9. However, the magnitude of %CoQ9 increase that represents ROS production is not affected by CaO(2) during resuscitation from HS.