FiO2 requirements during general anesthesia with dual-lung ventilation: a prospective pilot study

Background Hyperoxemia and prolonged oxygen exposure were common during general anesthesia. However, the relationship between FiO 2 and PaO 2 in patients undergoing general anesthesia with dual lung ventilation remained unclear. This prospective pilot study aimed to explore this relationship. Methods A cohort of 50 patients was recruited for this self-controlled, prospective pilot study. A standardized volume-controlled ventilation strategy was applied, with FiO 2 initially set to 0.3 immediately after tracheal intubation. FiO 2 was then increased in steps of 0.1 until it reached 0.6, followed by an increase to 0.8. Each FiO 2 step was maintained for at least 30 min before blood samples were drawn for blood gas analysis at each point. Results Rmcorr analyses revealed a significant correlation between FiO 2 and PaO 2 ( p < 0.001). The correlation coefficient ( r ) was 0.967 and Model convergence was robust, with a gradient value of 0.00003. At an FiO 2 of 40, 78.0% of patients maintained PaO 2 between 100 and 200 mmHg, while more than 68.0% exceeded 200 mmHg at 50% FiO 2 levels. Rmcorr analysis revealed a weak but statistically significant correlation between FiO 2 and PaO 2 /FiO 2 ( r = 0.290; p < 0.001). Conclusion A significant linear correlation was identified between FiO 2 and PaO 2 during general anesthesia with dual-lung ventilation. In this prospective pilot study, our findings suggested that maintaining 40% FiO 2 was generally sufficient for most patients to achieve PaO 2 levels of 100–200 mmHg, unless specific clinical conditions require otherwise. Importantly, FiO 2 need not exceed 50% in most patients undergoing general anesthesia with dual-lung ventilation. Clinical trial registration http://www.chictr.org.cn , identifier ChiCTR2500095383.