Intravenous total parenteral nutrition elevates oxidant production in critically ill patients

Introduction

Critical illness is associated with increased oxidant stress. This is manifested by reduced antoxidant potential and an increase in measured oxidant species (ROS). ROS have the capacity to cause cellular injury and to activate NFKB in inflammatory cells. TPN provides a source of lipid for systemic peroxidation particularly in the presence of reduced antoxidant potential. TPN generally contains inadequate nutrient-antoxidants and precursors to glutathione. Total parenteral nutrition (TPN) is also a source of lipid peroxides which are pro-inflammatory.

Materials and methods

This study was approved by the Committee for Research on Human Subjects of the University of the Witwatersrand. Patients were recruited sequentially if they required TPN. Blood was taken 1 hour pre initiation of TPN, at the time of and 1 hour and 2 hours post initiation of TPN. Urine was also collected at the same times. Vitamin C, glutathione, IL6 and F₂-iso-prostanes were measured in the urine.

Results

There were no changes in the vitamin C levels and no definite trend was seen with IL6. The F₂-isoprostanes in the urine remained constant for the -1, 0 and 1 periods, then increased significantly by 4.24 units (95% CI, 0.03–8.21) at time +2. This was significant (Friedman ANOVA P < 0.01).

Conclusions

Administration of TPN is associated with an increase in lipid peroxide formation which may itself be proinflammatory and account for adverse outcomes of patients on TPN.