Oxygenation, inflammatory response and lung injury during one lung ventilation in rabbits using inspired oxygen fraction of 0.6 vs. 1.0

Maintaining adequate oxygenation during one-lung ventilation (OLV) requires high inspired oxygen fraction (FiO2). However, high FiO2 also causes inflammatory response and lung injury. Therefore, it remains a great interest to clinicians and scientists to optimize the care of patients undergoing OLV. The aim of this study was to determine and compare oxygenation, inflammatory response and lung injury during OLV in rabbits using FiO2 of 0.6 vs. 1.0. After 30 minutes of two-lung ventilation (TLV) as baseline, 30 rabbits were randomly assigned to three groups receiving mechanical ventilation for 3 hours: the sham group, receiving TLV with 0.6 FiO2; the 1.0 FiO2 group, receiving OLV with 1.0 FiO2; the 0.6 FiO2 group, receiving OLV with 0.6 FiO2. Pulse oximetry was continuously monitored and arterial blood gas analysis was intermittently conducted. Histopathologic study of lung tissues was performed and inflammatory cytokines and the mRNA and protein of nuclear factor kappa B (NF-кB) p65 were determined. Three of the 10 rabbits in the 0.6 FiO2 group suffered hypoxemia, defined by pulse oximetric saturation (SpO2) less than 90%. Partial pressure of oxygen (PaO2), acute lung injury (ALI) score, myeloperoxidase (MPO),tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), mRNA and protein of NF-кB p65 were lower in the 0.6 FiO2 group than in the 1.0 FiO2 group. In conclusion, during OLV, if FiO2 of 0.6 can be tolerated, lung injury associated with high FiO2 can be minimized. Further study is needed to validate this finding in human subjects.