Free radical formation in infants: The effect of critical illness, parenteral nutrition, and enteral feeding

Background/Purpose: An increase in free radical activity has been observed in patients suffering from a variety of illnesses and has been correlated w ith disease severity. Free radical production is increased by the administr ation of total parenteral nutrition (TPN) and may be linked to its adverse effects. Some of the complications of TPN can be ameliorated by partial ent eral feeding. The aim of this study was to investigate free radical activit y during critical illness and during the administration of parenteral nutri tion. Methods: Three groups of surgical infants were studied: (1) control infants (n = 8) before minor surgery, (2) stable infants on the ward recovering fr om a major operation (n = 24), (3) critically ill infants in the neonatal i ntensive care unit (NICU, n = 28). Fourteen patients in the ward and 17 pat ients in NICU were receiving parenteral nutrition. Of the 31 patients on TP N, 9 were also receiving minimal enteral feeding (3% to 24% of total calori e intake). Plasma malondialdehyde (MDA), an index of free radical activity, was measured in all 60 infants. The Paediatric Risk of Mortality (PRISM) s core was obtained on NICU patients. The cytokines tumor necrosis factor (TN F-alpha) and interleukin 6 (IL-6) were measured in 25 patients. Results: Plasma MDA was significantly higher in (1) the stable patients on the ward compared with control patients (P < .001) and (2) patients in NICU compared with stable patients in the ward (P < .001). Parenteral nutrition was associated with higher levels of plasma MDA both in stable patients in the ward and critically ill infants in NICU. There was no correlation betw een the PRISM score and MDA. In patients not receiving TPN there is a corre lation between MDA and TNF-alpha (r = 0.54, P = .02) and between MDA and IL -6 (r = 0.74, P = .001). The level of free radical activity in patients on TPN is not changed by partial enteral feeding. Conclusions: Critical illness causes a rise in free radical production. Par enteral nutrition causes a significant elevation in free radical activity i n both stable infants in the ward and critically ill infants in NICU. The a ddition of minimal enteral feeding to parenteral nutrition does not reduce free radical activity. We hypothesize that the parenteral nutrition solutio n directly initiates free radical production. J Pediatr Surg 34:1091-1095. Copyright (C) 1949 by W.B. Saunders Company.