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 (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Under light anesthesia and spontaneous beating, 16 rats underwent HS for 80min, during which 3.0mL/100g of blood was withdrawn, followed by resuscitation attempt for 70min.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 &#x2265;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&#xb1;1.0mL of blood in Group 1, and 31.4&#xb1;5.5mL of LR solution in Group 2. At the end of resuscitation, CaO(2) was 18.5&#xb1;1.2 vol% in Group 1, almost double the 9.1&#xb1;0.8 vol% in Group 2 (P<0.01). O(2) UC and %CoQ9 in all rats increased from baselines of 0.25&#xb1;0.12 and 7.6&#xb1;1.8% to 0.44&#xb1;0.13 and 9.7&#xb1;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.