Critical Considerations on DO2 and Postoperative Outcomes in Cardiopulmonary Bypass

I recently read with great interest the article by Salenger and associates.1 This study presents valuable insights into the relationship between intraoperative indexed oxygen delivery (DO2i) levels, postoperative length of stay, and major postoperative events. However, I would like to seek further clarification and discuss several important aspects of the study that were not addressed but could significantly influence the findings and their interpretation. While the study effectively demonstrates that low DO2i is associated with increased postoperative length of stay and prolonged ventilation, it does not address the role of DO2i in conjunction with other critical parameters such as carbon dioxide production and the oxygen extraction ratio,2 especially during the rewarming phase.