Low versus High Fraction of Inspired Oxygen During Lung Separation in Thoracic Surgery: A Randomized Controlled Trial

OBJECTIVES: To investigate whether a lower fraction of inspired oxygen (FiO2) during the early phase of lung separation is able to improve overall oxygenation of the blood assessed by the arterial partial pressure of oxygen (PaO2)/FiO2 ratio, and to investigate its effect on lung collapse and postoperative pulmonary complications (PPC). DESIGN: Prospective, nonblinded, randomized controlled trial. SETTING: Single-center trial at a university hospital. PARTICIPANTS: Patients scheduled for thoracic surgery requiring one-lung ventilation (OLV). INTERVENTIONS: Study participants received either a low and then increasing oxygen concentration after lung separation or pure oxygen and then a decreasing oxygen concentration. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was the PaO2/FiO2 ratio 30 minutes after the start of OLV. Secondary endpoint included lung collapse defined as none, partial, or complete during the early phase of OLV and incidence of PPC. A total of 55 patients were enrolled, 53 of whom were included in the analysis. The primary endpoint, PaO2/FiO2 ratio, was comparable in the 2 groups, and the secondary endpoint, lung collapse, was similar. However, the incidence of PPC was significantly reduced with a low oxygen content strategy (19% vs 48%; p = 0.042). CONCLUSIONS: A strategy of low FiO2 before and after lung separation did not improve the oxygenation capacity of the lungs, and lung collapse was comparable in the 2 study groups. However, the occurrence of PPC was significantly reduced in the group treated with low FiO2.