High oxygen concentration exacerbates cardiopulmonary bypass-induced lung injury

Objective: To investigate the effect of ventilation with 100% oxygen on lung injury associated with surgery involving cardiopulmonary bypass (CPB). Design: A prospective randomized study. Setting: University hospital. Participants: Thirty patients undergoing coronary artery bypass graft surgery with CPB. Interventions: Patients were randomized to receive 100% oxygen (Oxygen group) or 50% oxygen (Air group) throughout surgery. During CPB, patients' lungs in the Air group were flushed with air and in the Oxygen group with 100% oxygen. Measurements and Main Results: Lung injury was evaluated by arterial oxygen tension-inspired oxygen concentration (PaO₂-F₁O₂) ratio and cytokine levels (tumor necrosis factor-α and interleukin-8) in blood and bronchoalveolar lavage fluid measured before and after CPB. The lowest PaO₂-F₁O₂ value was observed after 40 minutes following the completion of CPB in both groups. PaO₂-F₁O₂ values 6 hours after CPB were not different from baseline in the Air group but remained lower (359 ± 63 mmHg and 298 ± 78 mmHg; p = 0.013) in the Oxygen group. Blood cytokine levels rose during surgery in both groups. Bronchoalveolar lavage levels of interleukin-8 did not change, whereas tumor necrosis factor-α increased only in the Oxygen group (p = 0.035). Conclusions: A significant decrease of oxygenation was observed in the early post-CPB period in both groups of patients, with delay in recovery in patients treated with 100% oxygen. A larger increase of the proinflammatory cytokines was found in patients treated with 100% oxygen. High oxygen concentrations during surgery with CPB should be used only when specifically required. Copyright (C) 2000 by W.B. Saunders Company.