Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition
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Critical illness can be viewed as consisting of 4 distinct stages: (1) acute critical illness (ACI), (2) prolonged acute critical illness, (3) chronic critical illness, and (4) recovery. ACI represents the evolutionarily programmed response to a stressor. In ACI, substrate is shunted away from anabolism and toward vital organ support and inflammatory proteins. ⋯ It is at this point that nutrition and metabolic support become integral to the care of the patient. This paper (1) delineates and develops the 4 stages of critical illness using current evidence, clinical experience, and new hypotheses; (2) defines the chronic critical illness syndrome (CCIS); and (3) details an approach to the metabolic and nutrition support of the chronically critically ill patient using the metabolic model of critical illness as a guide. It is our hope that this clinical model can generate testable hypotheses that can improve the outcome of this unique population of patients.
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During critical illness, the stress response causes accelerated gluconeogenesis and lipolysis, leading to hyperglycemia and elevated serum triglyceride levels. The traditional nutrition support strategy of meeting or exceeding calorie requirements may compound the metabolic alterations of the stress response. Hypocaloric nutrition support has the potential to provide nutrition support without exacerbating the stress response. ⋯ Providing adequate dietary protein has emerged as an important factor in efficacy of the hypocaloric regimen. Although it is inconclusive, currently available research suggests that a nutrition support goal of 10-20 kcal/kg of ideal or adjusted weight and 1.5-2 g/kg ideal weight of protein may be beneficial during the acute stress response. Well-designed, randomized, controlled studies with adequate sample size that evaluate relevant clinical outcomes such as mortality, ICU LOS, and infection while controlling for factors such as glycemic control, severity of illness, incorporation of calories from all sources, in addition to feeding regimens, are needed to definitively determine the effects of hypocaloric nutrition support.