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

## TL;DR

This study found that 40% oxygen is usually enough to maintain safe blood oxygen levels during general anesthesia with dual-lung ventilation.

## Contribution

The study provides new empirical evidence on optimal FiO2 levels during dual-lung ventilation in general anesthesia.

## Key findings

- 40% FiO2 maintained PaO2 between 100-200 mmHg in 78% of patients.
- FiO2 exceeding 50% was unnecessary for most patients.
- A strong linear correlation was found between FiO2 and PaO2.

## Abstract

Hyperoxemia and prolonged oxygen exposure were common during general anesthesia. However, the relationship between FiO2 and PaO2 in patients undergoing general anesthesia with dual lung ventilation remained unclear. This prospective pilot study aimed to explore this relationship.

A cohort of 50 patients was recruited for this self-controlled, prospective pilot study. A standardized volume-controlled ventilation strategy was applied, with FiO2 initially set to 0.3 immediately after tracheal intubation. FiO2 was then increased in steps of 0.1 until it reached 0.6, followed by an increase to 0.8. Each FiO2 step was maintained for at least 30 min before blood samples were drawn for blood gas analysis at each point.

Rmcorr analyses revealed a significant correlation between FiO2 and PaO2 (p < 0.001). The correlation coefficient (r) was 0.967 and Model convergence was robust, with a gradient value of 0.00003. At an FiO2 of 40, 78.0% of patients maintained PaO2 between 100 and 200 mmHg, while more than 68.0% exceeded 200 mmHg at 50% FiO2 levels. Rmcorr analysis revealed a weak but statistically significant correlation between FiO2 and PaO2/FiO2 (r = 0.290; p < 0.001).

A significant linear correlation was identified between FiO2 and PaO2 during general anesthesia with dual-lung ventilation. In this prospective pilot study, our findings suggested that maintaining 40% FiO2 was generally sufficient for most patients to achieve PaO2 levels of 100–200 mmHg, unless specific clinical conditions require otherwise. Importantly, FiO2 need not exceed 50% in most patients undergoing general anesthesia with dual-lung ventilation.

http://www.chictr.org.cn, identifier ChiCTR2500095383.