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

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).

Prospective, nonblinded, randomized controlled trial.

Single-center trial at a university hospital.

Patients scheduled for thoracic surgery requiring one-lung ventilation (OLV).

Study participants received either a low and then increasing oxygen concentration after lung separation or pure oxygen and then a decreasing oxygen concentration.

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).

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.