An observational study on the relationship between plasma vitamin C, blood glucose, oxidative stress, endothelial dysfunction and outcome in patients with septic shock

Abstract

Background. Septic shock is associated with endothelial dysfunction and oxidative stress, against which vitamin C plays a protective role, possibly influencing clinical outcome. Hyperglycaemia may lower vitamin C. Objective. To study plasma vitamin C, oxidative stress, hyperglycaemia, endothelial dysfunction and outcome in septic shock. Methods. In a prospective, observational study of 25 adult septic shock patients, serial blood samples were analysed for vitamin C, thiobarbituric acid-reactive substances (TBARS) (a biomarker of oxidative stress), and soluble vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin (markers of endothelial dysfunction). Blood glucose, Sequential Organ Failure Assessment (SOFA) scores and fluid requirements were monitored. Results. Plasma vitamin C was low, while plasma TBARS were high throughout the 7-day study period. Endothelial dysfunction markers (sVCAM-1 and E-selectin) were high at the baseline. VCAM-1 decreased significantly on day 1 and normalised on day 7. E-selectin was unchanged on day 1 compared with baseline, but increased significantly on day 7. Oxidative stress and endothelial dysfunction were associated with increased SOFA score. Increased oxidative stress was associated with increased requirements for intravenous fluids and prolonged duration of vasoconstrictor support. Nine patients died in hospital. At baseline, levels of TBARS were significantly higher in non-survivors than in the survivors of septic shock. Conclusion. In septic shock, clinically relevant oxidative stress was associated with endothelial dysfunction, low vitamin C and high glucoseto-vitamin-C ratios. Markers of oxidative stress and endothelial damage were increased and correlated with resuscitation fluid requirements, vasoconstrictor use, organ failure and mortality.