Among those undergoing cardiac surgery, 20% experience acute kidney injury, which can extend their hospital stay and heighten their risk for chronic kidney illness, memory issues, and heart failure.
A study conducted by Vanderbilt University Medical Center (VUMC) investigated a potential contributor to these complications: the use of hyperoxia, or high levels of oxygen supplied to patients during surgery, compared to oxygen levels closer to what is found in the air. Recently published in the journal JAMA Surgery, the research found that hyperoxia did heighten oxidative stress during the procedure; however, this increase was temporary and did not result in a higher incidence of acute kidney injury post-surgery.
The findings indicate that both high and low oxygen levels can be safely used during cardiac surgical procedures, according to the study’s corresponding author, Dr. Frederic (Josh) Billings IV, who is a professor of Anesthesiology and Medicine.
“This research expands the range of acceptable oxygen administration options during cardiac surgery,” remarked Billings.
Conducted between April 2016 and October 2020, the clinical trial included a one-year follow-up and was based entirely at VUMC. Participants were randomly assigned to receive either high levels of oxygen (hyperoxia) or a reduced level intended to maintain normal oxygen levels in the blood (normoxia).
Two hundred participants were monitored for various outcomes, including oxidative stress, acute kidney injury, delirium, heart damage, atrial fibrillation, and other secondary issues. Aside from increased oxidative stress, those who received hyperoxia displayed outcomes comparable to those receiving normoxia.
Dr. Marcos Lopez, the first author and an associate professor of Anesthesiology, stated, “The purpose of the study was to analyze oxygen administration at both high and low levels to increase the chances of identifying any effects from oxygen treatment. We consistently met our oxygen treatment targets, yet found no significant differences in organ damage.”
Billings highlighted that this study focused solely on the surgical phase and proposed that further investigations could explore the effects of continuing either hyperoxia or normoxia after surgery. This postoperative period, during which cardiac surgery patients may be on mechanical ventilation, could benefit from different strategies for administering oxygen, he proposed.
Other contributors to the study included Matthew Shotwell, PhD, Cassandra Hennesey, MS, Mias Pretorius, MBChB, David McIlroy, MBBS, Melissa Kimlinger, MD, Eric Mace, MD, Terek Absi, MD, Ashish Shah, MD, and Nancy Brown, MD.
