Maximizing or minimizing patient oxygenation during cardiac surgery may not affect postoperative organ injury: JAMA

Liberal oxygen administration also known as hyperoxia is commonly used in the surgical setting to ensure adequate oxygenation. However, the consequence of such hyperoxia on the mechanisms of organ injury in the perioperative period has recently come into question. Thus, the current study investigated the effects of intraoperative hyperoxia versus normoxia on post-cardiac surgery oxidative stress, kidney injury, and other organ dysfunctions.

The objective of this randomized clinical trial was to assess the effect of intraoperative hyperoxia versus normoxia on oxidative stress, kidney injury, and other organ dysfunctions following cardiac surgery.

This participant and assessor-blinded, randomized clinical trial was conducted from April 2016 to October 2020 at a single tertiary care medical center. Adult patients (≥18 years) scheduled for elective open cardiac surgery were eligible for inclusion, provided they did not have preoperative oxygen requirements, acute coronary syndrome, carotid stenosis, or were on dialysis. Out of 3919 patients assessed, 2501 were eligible, and 213 consented to participate. After exclusions, 200 patients were randomized to either hyperoxia, where fraction of inspired oxygen was set to a value of 1.00, or normoxia, which maintained a minimum FiO2 to keep oxygen saturation within the range of 95% to 97% during surgery.

Patients were assessed for oxidative stress by F2-isoprostanes and isofurans, for AKI, delirium, myocardial injury, atrial fibrillation, and other secondary outcomes, with follow-up to one year after surgery.

Results

• This was a prospective cohort study of 200 patients with a median age of 66 years (IQR 59 to 72), including 140 men and 60 women, and 82 (41%) had diabetes.

• Oxidative stress markers, F2-isoprostanes and isofurans, were higher during surgery from a median baseline value of 73.3 pg/mL to 85.5 pg/mL at ICU admission.

• Levels were 9.2 pg/mL higher (95% CI, 1.0-17.4; P = .03) in the hyperoxia group.

• The primary clinical endpoint, change in serum creatinine from baseline to postoperative day 2, showed a median change of 0.01 mg/dL (IQR, −0.12 to 0.19) in the hyperoxia group versus −0.01 mg/dL (IQR, −0.16 to 0.19) in the normoxia group (median difference, 0.03; 95% CI, −0.04 to 0.10; P = .45).

• AKI occurred in 21 participants (21%) in each group.

• Hyperoxia did not affect additional acute organ injuries, safety events, or long-term kidney, neuropsychological, and functional outcomes at one year.

This study, therefore, is an indication that while intraoperative hyperoxia increases the level of oxidative stress, it neither results in kidney injury nor other organ dysfunctions in adults going through cardiac surgery. The results suggest that the maintenance of normoxia might be sufficient and could avoid unnecessary risks of hyperoxia.

Among adults undergoing cardiac surgery, intraoperative hyperoxia was associated with increased oxidative stress but did not affect kidney injury or other organ dysfunctions. These findings indicate that hyperoxia may not be necessary and that normoxia might be a safer option for maintaining adequate oxygenation during surgery.

Reference:

Lopez, M. G., Shotwell, M. S., Hennessy, C., Pretorius, M., McIlroy, D. R., Kimlinger, M. J., Mace, E. H., Absi, T., Shah, A. S., Brown, N. J., Billings, F. T., IV, ROCS trial investigators, Deegan, R., Eagle, S. S., Hernandez, A., Gelfand, B. J., Kertai, M. D., Kingeter, M., LeFevre, R., … Wanderer, J. P. (2024). Intraoperative oxygen treatment, oxidative stress, and organ injury following cardiac surgery: A randomized clinical trial. JAMA Surgery. https://doi.org/10.1001/jamasurg.2024.2906