Intraoperative Mechanical Power: Comment

We read with great interest the article by Elefterion et al.1 titled “Intraoperative Mechanical Power and Postoperative Pulmonary Complications in Noncardiothoracic Elective Surgery Patients: A 10-Year Retrospective Cohort Study” published in the March 2024 issue of Anesthesiology. The study found that lower tidal volume of predicted body weight, decreased dynamic respiratory system compliance, and increased mechanical power, as well as decreased pulse oxygen saturation, are independently associated with postoperative pulmonary complications. We appreciate the authors’ great work. However, we also have a question, and we would like to raise it with the investigators for discussion.The article collected the fractional inspired oxygen tension as one of ventilation parameters in the section of “Exposures.” However, the study did not indicate whether the difference in intraoperative fraction of inspired oxygen (Fio2) between the two groups was statistically significant or considered Fio2 as a confounding factor for adjustment by using a logistic regression in statistical analysis. There have been so many studies suggesting that high Fio2 was associated with the increasing rate of absorption atelectasis and damaging pulmonary gas exchange, which may cause postoperative pulmonary adverse events, and we did not think it should be omitted if it could be available.2–4However, because some studies failed to find the positive effects of low Fio2 to high, the relationship between Fio2 and postoperative pulmonary complications remains controversial.5 We believe that if the Fio2 was also standardized in the study design as one of the ventilator parameters, the results of this study could have been more informative and conclusive.The authors declare no competing interests.