The Takeaway
The results of this study suggest a unique sensitivity to alveolar hyperoxia at the time of lung reinflation and raise the possibility that restricting the inspired oxygen fraction during lung reinflation could reduce injury and related sequelae. Our findings imply that a 10% increase in FiO2 during the reinflation period (eg, increasing FiO2 from 80% to 90%) would be associated with 14% greater odds of developing a postoperative pulmonary complication. However, they should be viewed as hypothesis-generating due to the retrospective nature of the study and serve as justification for prospective investigation of this association.
Study Design
- Post hoc analysis focusing solely on the period of lung reinflation
- Study data were derived from 2 integrated perioperative databases
- 2733 procedures included
- Exposure variable was average FiO2 during the 10-minute period beginning 5 minutes before the documented reinstitution of 2-lung ventilation
- Primary outcome in this study was a composite of postoperative pulmonary complications
Physiology Refresh
High concentrations of oxygen can cause absorption atelectasis. Nitrogen in air acts as a “stent” to keep alveoli open. Pure O₂ is quickly absorbed into the blood and leaves nothing to hold alveoli open. Collapsed alveoli don’t exchange gas, potentially leading to development of hypoxia.
Excerpts
we found a significant association between FiO2 during reinflation and postoperative pulmonary complications in this thoracic surgical population.
These findings mean that a 10% increase in FiO2 during the reinflation period (ie, increasing FiO2 from 80% to 90%) is associated with 14% greater odds of developing a postoperative pulmonary complication.
Due to the nature of the study design, we are not able to infer a causative relationship between high FiO2 and PPCs
we cannot eliminate the possibility that an, as yet unidentified, confounding variable such as a specific pulmonary disease condition prompting the delivery of higher FiO2 rather than high FiO2 itself is causally related to increased risk of the primary outcome. We aimed to mitigate this concern through the 3 presented sensitivity analyses; however, the question of whether alveolar hyperoxia during reinflation leads to postoperative pulmonary complications will ultimately require a properly designed prospective study that allows differentiation between the effect of the disease conditions (ie, desaturation) and response (ie, higher administered oxygen concentration).
While these results should be viewed as hypothesis-generating due to the retrospective nature of our study, they are suggestive of a unique sensitivity to hyperoxia at the time of lung reinflation—a period associated with a number of related and potentially injurious phenomena including
Abstract
Background: A recent multicenter study suggested that the duration of single-lung ventilation, and not the intensity of the hyperoxia (ie, inspired oxygen fraction) during this period, contributes to the development of postoperative pulmonary complications. However, lung reinflation, at the cessation of single-lung ventilation, is a period of particular susceptibility to hyperoxic injury, and the impact of alveolar hyperoxia during this period on postoperative pulmonary complications has not been specifically assessed.
Methods: Clinical practice surrounding the inspired oxygen fraction at lung reinflation and potential clinical implications of alveolar hyperoxia occurring during this period were assessed in this secondary analysis of data from a multicenter retrospective cohort study.
Results: On multivariable logistic regression, average inspired oxygen fraction during the period of lung reinflation was independently associated with postoperative pulmonary complications (adjusted odds ratio [aOR]: 1.14, 95% confidence interval [CI], 1.01-1.29, P = .032; unit: 10% FiO2 increment). The duration of single-lung ventilation (in hours) also remained significant in this model (aOR: 1.21, 95% CI, 1.03-1.42, P = .020).
Conclusions: The results of this study suggest a unique sensitivity to alveolar hyperoxia at the time of lung reinflation and raise the possibility that restricting the inspired oxygen fraction during lung reinflation could reduce injury and related sequelae. Our findings imply that a 10% increase in FiO2 during the reinflation period (eg, increasing FiO2 from 80% to 90%) would be associated with 14% greater odds of developing a postoperative pulmonary complication. However, they should be viewed as hypothesis-generating due to the retrospective nature of the study and serve as justification for prospective investigation of this association.
Citation
Douville NJ, Mathis M, Smolkin ME, Martin LW, Popescu WM, Blank RS. Inspired Oxygen Concentration During the Re-initiation of Two-Lung Ventilation in Thoracic Surgery: A Post Hoc Analysis of Data From the Multicenter Perioperative Outcomes Group. Anesth Analg. 2025 Mar 10. doi: 10.1213/ANE.0000000000007479. Epub ahead of print. PMID: 40063506.
