Increased oxidants and reduced antioxidants in irradiated parenteral nutrition solutions may contribute to the inflammatory response.
OBJECTIVE
To measure reactive oxidant production and the decline in antioxidant potential in commercially available, irradiated parenteral nutrition (PN) solutions and the effect that these have on oxidant production in patients in the intensive care unit.


METHODS
Vitamin E and malondialdehyde in irradiated and nonirradiated commercially available, PN solutions were measured. The PBN (alpha-phenyl-n-test-butylnitrone (PBN) spin trap was used to measure free radicals and TEMPOL (2,2,6,6-tetramethyl-4-hydroxy-piperidine-oxyl) was used to assess antioxidant capacity. The irradiated PN was administered (as per unit protocol) to 10 patients with gut failure and plasma and urinary isoprostanes and interleukin-6 (IL-6) were measured 1 hour preadministration, at the time of, and 1 and 2 hours postadministration of PN.


RESULTS
Irradiation reduced vitamin E significantly (P < .0025). Malondialdehyde products were present in both samples, but more so in irradiated samples (P < .0001), as were free radicals measured by PBN spin trapping. Irradiated samples had a higher scavenging capacity of TEMPOL free radical due to depletion of antioxidants in irradiated samples. Urinary isoprostanes increased at time 2 by 6.3 units relative to time 0 and by 5.23 units relative to time 1(Friedman ANOVA: P < .01413).


CONCLUSIONS
Lipid hydroperoxides are formed in PN solutions and increase further following irradiation. This is associated with a significant reduction in vitamin E and antioxidant potential. The increase in urinary isoprostanes indicates a potentially proinflammatory effect of irradiated PN.
Intensive Care Unit, Johannesburg Hospital and University of the Witwatersrand, Johannesburg, South Africa. guy.richards@wits.ac.za
Guy A
GA
Richards
Hayden
H
White
Heidi
H
Grimmer
Caiphus
C
Ramoroka
Kalavati
K
Channa
Mark
M
Hopley
Heidi
H
Fickl
Mary
M
Gulumian
D000328:Adult; D000975:Antioxidants / Q000032:analysis*; D003497:Cyclic N-Oxides / Q000032:analysis; D005609:Free Radicals / Q000032:analysis; D006801:Humans; D007249:Inflammation / Q000209:etiology*; D007362:Intensive Care Units; D028421:Isoprostanes / Q000652:urine; D008054:Lipid Peroxides / Q000032:analysis; D008315:Malondialdehyde / Q000032:analysis; D008875:Middle Aged; D016877:Oxidants / Q000032:analysis*; D010288:Parenteral Nutrition; D012996:Solutions / Q000737:chemistry / Q000528:radiation effects; D013113:Spin Labels; D014810:Vitamin E / Q000032:analysis
D000975:Antioxidants; D003497:Cyclic N-Oxides; D005609:Free Radicals; D028421:Isoprostanes; D008054:Lipid Peroxides; D016877:Oxidants; D012996:Solutions; D013113:Spin Labels; D014810:Vitamin E; D008315:Malondialdehyde; C001803:tempol