Ascorbic acid dynamics in the seriously ill and injured.

Area of Science:

• Biochemistry
• Clinical Nutrition
• Critical Care Medicine

Background:

• Ascorbic acid (vitamin C) is a potent extracellular antioxidant with known roles in wound healing and immune response.
• Previous studies in septic rats suggest high-dose ascorbic acid total parenteral nutrition (TPN) may protect against free radical damage and improve survival.
• This study investigated ascorbic acid levels in critically injured patients and the efficacy of early TPN supplementation.

Purpose of the Study:

• To determine plasma ascorbic acid levels in critically injured patients and those with severe surgical infections.
• To evaluate the effectiveness of early, short-term, high-dose ascorbic acid TPN supplementation in normalizing plasma levels.

Main Methods:

• Ascorbic acid levels were measured in 12 critically injured patients and 2 patients with severe surgical infections.
• Patients received TPN with escalating doses of ascorbic acid over 6 days.
• Plasma and urine ascorbic acid concentrations were analyzed using high-pressure liquid chromatography.

Main Results:

• Baseline plasma ascorbic acid was significantly depressed in critically ill patients.
• Low doses (300 mg/day and 1000 mg/day) of ascorbic acid TPN did not effectively normalize plasma levels.
• A significant increase in plasma ascorbic acid was achieved with 3000 mg/day supplementation.

Conclusions:

• Critically injured patients exhibit severely depleted plasma ascorbic acid levels.
• Supraphysiologic doses of ascorbic acid are required for rapid replenishment in the early post-injury period.
• Optimal repletion necessitates sustained high-dose administration for at least 3 days.