Feeding critically ill patients: What is the optimal amount of energy?

Abstract

Hypermetabolism and malnourishment are common in the intensive care unit. Malnutrition is associated with increased morbidity and mortality, and most intensive care unit patients receive specialized nutrition therapy to attenuate the effects of malnourishment. However, the optimal amount of energy to deliver is unknown, with some studies suggesting that full calorie feeding improves clinical outcomes but other studies concluding that caloric intake may not be important in determining outcome. In this narrative review, we discuss the studies of critically ill patients that examine the relationship between dose of nutrition and clinically important outcomes. Observational studies suggest that achieving targeted caloric intake might not be necessary since provision of approximately 25% to 66% of goal calories may be sufficient. Randomized controlled trials comparing early aggressive use of enteral nutrition compared with delayed, less aggressive use of enteral nutrition suggest that providing increased calories with early, aggressive enteral nutrition is associated with improved clinical outcomes. However, energy provision with parenteral nutrition, either instead of or supplemental to enteral nutrition, does not offer additional benefits. In summary, the optimal amount of calories to provide critically ill patients is unclear given the limitations of the existing data. However, evidence suggests that improving adequacy of enteral nutrition by moving intake closer to goal calories might be associated with a clinical benefit. There is no role for supplemental parenteral nutrition to increase caloric delivery in the early phase of critical illness. Further high-quality evidence from randomized trials investigating the optimal amount of energy intake in intensive care unit patients is needed.

Optimizing Nutrition in Intensive Care Units: Empowering Critical Care Nurses to Be Effective Agents of Change

“…At least 6 current evidence-based guidelines developed through professional organizations and reputable researchers are available, and although this number presents choice, it may also introduce confusion C ritically ill patients have increased metabolic requirements 1 and rely on the administration of nutritional feedings to meet increased demands. Observational studies [2][3][4] have revealed that, compared with patients who receive more nutrition, patients who receive less are more likely to experience adverse events such as increased infectious complications and higher mortality. Despite recognition of the importance of nutritional feedings, the delivery of optimal nutrition remains difficult to achieve in most intensive care units (ICUs).…”

Metabolic and Nutrition Support in the Chronic Critical Illness Syndrome

“…89 Therefore, the paradigm of combined modality EN/PN to assure adequate nutrition and prevent underfeeding-associated catabolism still seems rational and should be reexplored. 90 Average energy intakes of critically ill patients are reported at 49 -70% of calculated requirements, 91 consistent with a general trend toward underfeeding. Nutrition can be classified according to the proportion of the REE supplied: hypocaloric (0.5-0.9 ϫ REE), isocaloric (1.1-1.3 ϫ REE), and hypercaloric (Ͼ 1.5 ϫ REE).…”

“…91,94 However, a possible bias in these studies is that more severely ill patients are less likely to tolerate or receive uninterrupted EN and more likely to require a longer ICU course with more complications. 91 In sum, the above data are not convincing with respect to optimal nutrition support in the CCI patient. This means that CCI physicians need to exercise rational decisionmaking with close monitoring and poise to adjust their nutritional prescriptions with any indications of detrimental under-or overfeeding.…”

Nurse to Bed Ratio and Nutrition Support in Critically Ill Patients

“…The total calorie goal was 20 to 25 kcal/kg in the acute phase of injury and 25 to 30 kcal/kg during I nadequate intake of calories and protein is a common problem in intensive care units (ICUs) [1][2][3][4] and results from a combination of a hypercatabolic state and a reduction in the nutrient supply. 5,6 The reduced nutrient supply may be due to an underestimation of the amount of calories and protein needed [7][8][9][10] or to the difference between the number of calories prescribed and the number received. The percentage of prescribed calories that is actually received varies between 51% and 99%.…”