Effects of Oxygen on Perioperative Vascular Function: A Randomized Clinical Trial.

Summary

In a randomized trial of 200 cardiac surgery patients, intraoperative hyperoxia did not change flow-mediated dilation but impaired endothelium-independent vasodilation, likely via soluble guanylyl cyclase heme oxidation. These findings suggest avoiding unnecessary hyperoxia and point to sGC as a therapeutic target to preserve vascular function.

Key Findings

• Randomized 200 elective cardiac surgery patients to hyperoxia vs normoxia.
• Hyperoxia did not change brachial artery flow-mediated dilation (primary endpoint).
• Hyperoxia impaired endothelium-independent vasodilation ex vivo, consistent with soluble guanylyl cyclase heme oxidation.
• Plasma vascular/oxidative stress markers were quantified alongside functional assays.

Clinical Implications

Favor titrating intraoperative oxygen to normoxia rather than routine hyperoxia in cardiac surgery; consider future trials of sGC activators to counteract hyperoxia-induced dysfunction.

Limitations

• Blinding to oxygen strategy is challenging and not described.
• Short-term physiological endpoints without clinical outcome measures.
• Single surgical population (cardiac surgery) may limit generalizability.

Future Directions

Test sGC activators/oxidation-resistant strategies in perioperative settings; assess whether oxygen titration to normoxia improves hard outcomes (e.g., organ injury).