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

ObjectiveTo 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.MethodsUnder light anesthesia and spontaneous beating, 16 rats underwent HS for 80 min, during which 3.0 mL/100 g of blood was withdrawn, followed by resuscitation attempt for 70 min.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 (FIO2) of 1.0, n = 8) or a low-CaO2 group (Group 2, fluid administration under FIO2 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 FIO2 concentration. CaO2, O2 utilization coefficient (UC) and plasma %CoQ9 were compared between groups.ResultsMean 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.ConclusionIn 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.