30% FiO2 during mechanical ventilation may not reduce postoperative atelectasis volume compared with 60% FiO2

This study, “Effects of 30% vs 60% inspired oxygen fraction during mechanical ventilation on postoperative atelectasis: a randomised controlled trial”, is published in BMC Anesthesiology, and the co-author is Songbin Liu.

Wang et al. and other researchers explaining the study background said one of the ongoing debates over the effect of inspired oxygen fraction (FiO2) during mechanical ventilation on postoperative atelectasis needs more elucidation and data.

The primary purpose of this study was to compare the effects of low (30%) and moderate (60%) FiO2 on postoperative atelectasis.

To investigate the background, we hypothesised that 30% FiO2 during mechanical ventilation may reduce postoperative atelectasis volume compared to 60% FiO2.

We included 120 patients in our study and assigned them to 30% or 60% FiO2 during mechanical ventilation in a ratio of 1:1, they noted.

The main points of conclusion from this study are:

• One hundred thirteen patients completed the study, including 55 subjects in 30 % and 58 in 60% FiO2 groups.
• There was no difference in the percentage of postoperative atelectasis volume between the groups.
• They noted no significant difference in the atelectasis volume between the two groups.
• Also, the groups had no significant differences in the volumes of the over-aeration, normal-aeration, and poor-aeration regions.
• Between the two groups, there were no significant differences in the incidence of clinically considerable atelectasis or oxygenation index at the end of surgery.

They said using 30% FiO2 during mechanical ventilation does not reduce the postoperative atelectasis volume.

They also said It should be noted that the study has limitations.

Further reading:

Jiang, Z., Liu, S., Wang, L. et al. Effects of 30% vs 60% inspired oxygen fraction during mechanical ventilation on postoperative atelectasis: a randomised controlled trial. BMC Anesthesiol 23, 265 (2023). https://doi.org/10.1186/s12871-023-02226-6