Chapter 4

### INTRODUCTION

Inflammation and the generation of free radicals is the hallmark pathology of critical illness. Micronutrients with antioxidant properties have received much attention due to their role in these reactions. Reactive oxygen species, produced by leukocyte aerobic metabolism and free radical generation from nitric oxide metabolism, facilitate the release of nuclear transcription factor kappa B (NFκB). Cytoplasmic NFκB translocates to the nucleus, where it binds to DNA and increases acute-phase mediators like tumor necrosis factor α (TNFα), interleukin 2 (IL-2), and IL-2 receptors. Micronutrients such as selenium act to down-regulate NFκB.1,2 Micronutrient deficiency may be due to suboptimal premorbid intake; redistribution from the circulation to tissues; and excessive losses from the kidneys, gastrointestinal (GI) tract, skin, and drains. Iron, selenium, zinc, vitamin D, and water-soluble vitamins are decreased in critical illness, whereas copper and manganese levels may be increased. Administration of micronutrients during illness is an area of great interest. Trace elements and vitamins that support antioxidant function—particularly high-dose parenteral selenium, alone or in combination with other antioxidants—are reportedly safe and may be associated with a reduction in mortality in critically ill patients.2 Studies investigating the role of supplementation with selenium, vitamin E, and vitamin C in the critically ill have shown promising results, although there are still a number of unanswered questions.3 Systematic reviews and meta-analyses in adults have shown that micronutrient supplementation may be associated with a decrease in overall mortality and specifically 28-day mortality. Decreased mortality seems to be mainly associated with combination products rather than any single micronutrient. However, supplementation does not affect infectious complications or length of stay in the intensive care unit (ICU) or hospital. The majority of trials have reported no adverse effects from micronutrients, with the exception of one study, which reported a worse outcome in patients with severe acute pancreatitis.4

### TRACE ELEMENTS

Current daily recommendations for pediatric trace elements and vitamins are provided in Table 4-15 and Table 4-2, respectively, for reference, and the commoner manifestations of deficiency states are shown in Table 4-3. A brief description of the role of individual micronutrients and a summary of the literature related to their supplementation during pediatric illness are provided in this chapter.

Table 4-1.

Suggested Daily Pediatric Parenteral Trace Element Provision

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