Timing of Redox Imbalances in Cardiac Surgery

Area of Science:

• Cardiology
• Biochemistry
• Oxidative Stress Research

Background:

• Cardiac surgery significantly impacts oxidative metabolism, leading to increased reactive oxygen species (ROS) and diminished endogenous antioxidants.
• Current clinical assessments often rely on indirect markers, necessitating direct measurement of oxidative stress during the perioperative period.

Purpose of the Study:

• To evaluate the feasibility of directly measuring perioperative ROS in cardiac surgery patients using electron paramagnetic resonance (EPR) spectroscopy.
• To investigate the association between vitamin C supplementation and perioperative ROS dynamics in these patients.

Main Methods:

• Direct quantification of highly reactive oxidants via EPR spectroscopy in venous blood of cardiac surgery patients and healthy controls.
• Serial blood sampling at multiple perioperative time points (preoperative, end of surgery, POD 1, POD 7).
• Measurement of serum antioxidants (zinc, selenium, vitamins A, C, E, coenzyme Q10) and comparison between vitamin C supplemented (C+) and non-supplemented (C-) patient groups.

Main Results:

• Cardiac surgery patients exhibited significantly higher preoperative ROS levels compared to controls (p < 0.001).
• A substantial proportion of patients (23-47%) presented with subnormal levels of key antioxidants preoperatively.
• Patients receiving vitamin C supplementation (C+) demonstrated consistently lower perioperative ROS compared to the C- group, with a significant difference observed on POD 1 (p = 0.027).
• A strong inverse correlation was found between serum vitamin C levels and ROS (r = -0.47; p < 0.00001).

Conclusions:

• Direct perioperative ROS measurement using EPR is clinically feasible.
• Cardiac surgery patients face an elevated and worsening preoperative oxidative burden.
• Perioperative vitamin C supplementation is linked to reduced ROS, supporting its use in targeted redox interventions during cardiac surgery.