Antioxidant potential of i.v. fluids.

In acute clinical settings where there may be a role for antioxidant therapy, patients receive large amounts of i.v. fluids which may have antioxidant activity. To investigate such effects the antioxidant capacity of nine i.v. fluids was measured (Gelofusine, Haemaccel, 20% mannitol, 4.5% human albumin solution, fresh frozen plasma, aprotinin, N-acetylcysteine and two hydroxyethyl starch solutions). Results are expressed as mean mmol litre-1 Trolox equivalents. Mannitol 20% and the hydroxyethyl starch solutions had no antioxidant activity. Protein-containing solutions (gelatins, albumin and aprotinin) had antioxidant activity 50-66% that of plasma: Gelofusine 0.85 mmol litre-1; Haemaccel 0.78 mmol litre-1; 4.5% albumin 0.95 mmol litre-1; aprotinin 0.80 mmol litre-1; fresh frozen plasma 1.45 mmol litre-1. However, none was nearly as potent an antioxidant as the clinical preparation of N-acetylcysteine, with an antioxidant activity of 502 mmol litre-1. Studies of antioxidant therapy may need to take account of the antioxidant effect of i.v. fluids.