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

Abstract Objective To examine whether reactive oxygen species (ROS) production is affected by arterial oxygen content (CaO2 ) 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Under light anesthesia and spontaneous beating, 16 rats underwent HS for 80 min, during which 3.0 mL/100 g of blood was withdrawn, followed by resuscitation attempt for 70 min. At 80 min, rats were randomized into a high-CaO2 group (Group 1, transfusion under fractional inspired oxygen (FI O2 ) of 1.0, n = 8) or a low-CaO2 group (Group 2, fluid administration under FI O2 of 0.21, n = 8). In each group, either blood or lactate Ringer's (LR) solution was infused to maintain mean arterial pressure ≥75 mmHg under each FI O2 concentration. CaO2 , O2 utilization coefficient (UC) and plasma %CoQ9 were compared between groups. Results Mean infused volume for attempted resuscitation was 7.6 ± 1.0 mL of blood in Group 1, and 31.4 ± 5.5 mL of LR solution in Group 2. At the end of resuscitation, CaO2 was 18.5 ± 1.2 vol% in Group 1, almost double the 9.1 ± 0.8 vol% in Group 2 ( P < 0.01). O2 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 O2 UC as well as %CoQ9. However, the magnitude of %CoQ9 increase that represents ROS production is not affected by CaO2 during resuscitation from HS.