Hyperoxia during one lung ventilation: inflammatory and oxidative responses.

BACKGROUND

It is common practice during one lung ventilation (OLV) to use 100% oxygen, although this may cause hyperoxia- and oxidative stress-related lung injury. We hypothesized that lower oxygen (FiO(2) ) during OLV will result in less inflammatory and oxidative lung injury and improved lung function.

METHODS

Twenty pigs (8.88 ± 0.84 kg; 38 ± 4.6 days) were assigned to either the hyperoxia group (n = 10; FiO(2)  = 100%) or the normoxia group (n = 10; FiO(2)  < 50%). Both groups were subjected to 3 hr of OLV. Blood samples were tested for pro-inflammatory cytokines and lung tissue was tested for these cytokines and oxidative biomarkers.

RESULTS

There were no differences between groups for partial pressure of CO(2) , tidal volume, end-tidal CO(2) , plasma cytokines, or respiratory compliance. Total respiratory resistance was greater in the hyperoxia group (P = 0.02). There were higher levels of TNF-α, IL-1β, and IL-6 in the lung homogenates of the hyperoxia group than in the normoxia group (P ≤ 0.01, 0.001, and 0.001, respectively). Myeloperoxidase and protein carbonyls (PC) were higher (P = 0.03 and P = 0.01, respectively) and superoxide dismutase (SOD) was lower in the lung homogenates of the hyperoxia group (P ≤ 0.001).

CONCLUSION

Higher myeloperoxidase, PC, and cytokine levels, and lower SOD availability indicate a greater degree of injury in the lungs of the hyperoxia animals, possibly from using 100% oxygen. In this translational study using a pig model, FiO(2)  ≤ 50% during OLV reduced hyperoxic injury and improved function in the lungs.