New Zealand Study Provides Detailed Insights into Intraoperative Oxygen Levels and Surgical Outcomes

A retrospective cohort study led by Dr Daniel Frei, Honorary Fellow at the Medical Research Institute of New Zealand (MRINZ), has revealed crucial insights into the impact of liberal intraoperative oxygen levels on surgical outcomes. The Associations between the intraoperative fraction of inspired intraoperative oxygen administration and days alive and out of hospital after surgery study spans 2012 to 2020 and analyses data from 15,449 adult patients undergoing elective surgeries lasting more than 2 hours.

The primary objective of the study was to investigate how average oxygen levels during surgery affect recovery and complications afterward. The findings, which challenge previous assumptions in the field, emphasise the need for further research that could enable personalised oxygen management strategies tailored to different patient profiles and surgical procedures.

The study found no major link between the average fraction of inspired oxygen (FiO2) levels during surgery and how long patients stayed alive and out of the hospital 90 days after surgery. This indicates that changes in oxygen levels during surgery didn't notably affect patients' overall recovery after 90 days. FiO2 is the oxygen fraction in the air or gas mixture a person breathes, and is used in medical settings to describe how much oxygen is given during oxygen therapy or mechanical ventilation.

However, the study revealed associations between FiO2 levels and specific post-operative complications. Lower FiO2 levels were linked to an increased risk of surgical site infection, while higher FiO2 levels showed a dose-dependent association with respiratory complications and the need for  admission to the intensive care unit.. These findings underscore the complex interplay between oxygen management during surgery and various post-operative outcomes.

During the study period, there was a noticeable decrease in the average levels of FiO2 used during surgery each year. This observation suggests that there may have been changes in how doctors and medical teams are administering oxygen during surgeries, which could have important consequences for future research and the development of medical guidelines.

Dr Frei highlighted the significance of the study's findings, stating, “Our study provides insights into the complex effects of intraoperative oxygen levels on post-operative outcomes. It highlights the need for further investigation into personalised oxygen management strategies tailored to different patient profiles and surgical procedures.”

 The study’s implications for clinical practice suggest a move towards tailored oxygen management strategies that consider individual patient factors and specific risks associated with varying FiO2 levels. Further research, including large-scale clinical trials would be needed to support these findings and develop evidence-based guidelines for optimal oxygen management in surgical settings.