# Effects of varying inhaled oxygen concentrations on lung function in older adult patients undergoing laparoscopic gastrointestinal surgery under general anesthesia: protocol of a prospective multicenter clinical study in China

## TL;DR

This study compares the effects of low and high inhaled oxygen levels on lung function in older adults undergoing laparoscopic surgery in China.

## Contribution

The study introduces a large, multicenter clinical trial to evaluate the impact of different oxygen concentrations on postoperative pulmonary outcomes in elderly patients.

## Key findings

- The primary outcome will assess the 48-hour postoperative oxygenation index between low and high FiO2 groups.
- Secondary outcomes include blood gas analysis, pulmonary complications, and 30-day mortality rates.
- Results may clarify the optimal oxygen concentration for reducing postoperative pulmonary complications in older adults.

## Abstract

Postoperative pulmonary complications (PPCs) are severe and are of particular concern in older adult patients undergoing laparoscopic gastrointestinal surgery. Both 40% and 80% fraction of inspired oxygen (FiO2) are commonly used for anesthesia. Presently, whether 40% FiO2 can increase the oxygenation index of patients 48 h postoperatively and reduce PPCs remains controversial. Moreover, no clear consensus exists for older adult patients. Therefore, this study aims to compare the effects of low FiO2 (40%) and high FiO2 (80%) levels on postoperative pulmonary function in older adult study participants undergoing laparoscopic gastrointestinal surgery.

This multicenter, prospective, parallel-cohort, randomized controlled clinical trial will include 1098 older adult participants aged ≥ 65 years old undergoing laparoscopic gastrointestinal surgery, from 16 clinical trial sites across China. Participants will be randomized, as per a 1:1 ratio to two cohorts, the “L” and “H” cohorts, to receive low FiO2 (40%) and high FiO2 (80%) levels, respectively. The primary outcome measure is the 48-h postoperative oxygenation index between the two cohorts. The secondary outcome measures include the other blood gas analysis results, PPCs within 7 days, and 30-day mortality rate.

This study of elderly patients undergoing laparoscopic gastrointestinal surgery with different intraoperative oxygen concentrations at high risk for pulmonary complications. All subjects were followed up for up to 30 days for pulmonary function, postoperative complications, etc. Randomization was performed separately at 16 sites.

ClinicalTrials.gov NCT06359106. Registered and posted on April 11, 2024.

The online version contains supplementary material available at 10.1186/s13063-026-09471-3.