A new study has challenged assumptions about oxygen administration during heart operations
Research conducted by Vanderbilt University Medical Centre (VUMC) found that high and low oxygen levels are safe for cardiac surgery patients.
The research, published in the journal JAMA Surgery, provides new insights into the impact of oxygen administration on post-surgical outcomes, particularly concerning acute kidney injury (AKI).
Acute kidney injury is a significant complication, affecting approximately two out of every ten patients who undergo cardiac surgery.
This condition can lead to more extended hospital stays and increased risks of chronic kidney disease, cognitive decline and heart failure.
Given these risks, the VUMC team, led by Dr Frederic (Josh) Billings, professor of anaesthesiology and medicine, sought to investigate whether hyperoxia – high oxygen concentrations – could contribute.
The study, conducted from April 2016 to October 2020, included 200 randomly assigned participants to receive either high oxygen (hyperoxia) or a lower amount intended to maintain normal blood oxygen levels (normoxia) during surgery.
The researchers monitored several outcomes, including oxidative stress, acute kidney injury, delirium, myocardial injury, and atrial fibrillation.
While the study confirmed that hyperoxia increased oxidative stress during surgery, this effect did not persist postoperatively and did not lead to a higher incidence of AKI.
Overall, the outcomes for patients receiving high oxygen levels were similar to those receiving lower levels.
Dr Billings said: ‘This study broadens the acceptability of various oxygen administration strategies during cardiac surgery.’
Dr Marcos Lopez, associate professor of anaesthesiology and the study’s first author, highlighted the rigorous design of the clinical trial, which aimed to examine the extremes of oxygen administration.
He said: ‘We achieved oxygen treatment goals with meticulous protocol adherence but saw no significant differences in organ injury.’
The findings suggest that traditional concerns regarding hyperoxia may not be as critical as previously thought, at least within the intraoperative period.
However, Dr Billings noted the need for further research to explore the effects of hyperoxia or normoxia during the postoperative period when patients are often on mechanical ventilation.
The study’s results could influence future guidelines on oxygen administration during cardiac surgery, potentially reducing the complexity and costs associated with oxygen management strategies.
