Full or hypocaloric nutritional support for the critically ill patient: is less really more?

The Caloric Necessities of Critical Care Patients During the First Week of Admission

INTRODUCTION

 The nutritional needs of critically ill patients have been the subject of intense controversy. In accordance with international guidelines, it is advocated to optimize a nutritional intake based on the following recommendation: 25-30 kcal/kg body weight per day. However, there still are authors who recommend permissive underfeeding in the first week of hospitalization. Nevertheless, energy expenditure (EE) and necessity are influenced by the catabolic phase of critical illness, which may vary over time on a patient and from patient to patient.

OBJECTIVE

The objective of this study is to assess if the energy needs of critically ill patients admitted in our intensive care unit (ICU) in the first week of hospitalization are in line with those recommended by the European Society for Clinical Nutrition and Metabolism (ESPEN) international guidelines.

METHODS

A prospective cross-sectional study was carried out from September to December 2019. The energy needs were evaluated by indirect calorimetry and by the Harris-Benedict equation. Stress variables were evaluated, namely, the type of pathology, hemodynamic support, sedation, temperature, sequential organ failure assessment (SOFA) score, and state at discharge.

RESULTS

Forty-six patients were included in this study, with an average energy expenditure by indirect calorimetry of 19.22 ± 4.67 kcal/kg/day. The energy expenditure was less than 20 kcal/kg/day in 63% of the measurements. The concordance rate did not show the relationship between the Harris-Benedict equation and the values of indirect calorimetry. Stress variables were analyzed, with the SOFA score as the only variable with values close to statistical significance.

CONCLUSION

In our ICU, the energy needs of critically ill patients in the first week of hospitalization are lower than the intake recommended by the guidelines.

Energy, Protein, Carbohydrate, and Lipid Intakes and Their Effects on Morbidity and Mortality in Critically Ill Adult Patients: A Systematic Review

The guidelines for nutritional support in critically ill adult patients differ in various aspects. The optimal amount of energy and nutritional substrates supplied is important for reducing morbidity and mortality, but unfortunately this is not well known, because the topic is complex and every patient is individual. The aim of this review was to gather recent pertinent information concerning the nutritional support of critically ill patients in the intensive care unit (ICU) with respect to the energy, protein, carbohydrate, and lipid intakes and the effect of their specific utilization on morbidity and mortality. Enteral nutrition (EN) is generally recommended over parenteral nutrition (PN) and is beneficial when administered within 24-48 h after ICU admission. In contrast, early PN does not provide substantial advantages in terms of morbidity and mortality, and the time when it is safe and beneficial remains unclear. The most advantageous recommendation seems to be administration of a hypocaloric (<20 kcal · kg^-1 · d^-1), high-protein diet (amino acids at doses of ≥2 g · kg^-1 · d^-1), at least during the first week of critical illness. Another important factor for reducing morbidity is the maintenance of blood glucose concentrations at 120-150 mg/dL, which is accomplished with the use of insulin and lower doses of glucose of 1-2 g · kg^-1 · d^-1, because this prevents the risk of hypoglycemia and is associated with a better prognosis according to recent studies. A fat emulsion is used as a source of required calories because of insulin resistance in the majority of patients. In addition, lipid oxidation in these patients is ∼25% higher than in healthy subjects.

Relevance of non-nutritional calories in mechanically ventilated critically ill patients

Background/Objectives:

Overfeeding in critically ill patients is associated with many complications. Propofol, dextrose infusion and citrate dialysis provide non-nutritional calories (NNCs), potentially causing overfeeding. The relevance of NNCs for total caloric intake has not been systematically studied.

Subjects/Methods:

We retrospectively studied adult mechanically ventilated intensive care unit (ICU) patients receiving enteral nutrition with or without supplemental parenteral nutrition. Primary outcome was the proportion of NNCs (from dextrose, propofol and trisodium citrate) to the total energy intake during the first 7 days after ICU admission. In addition, NNC intake groups were compared.

Results:

In total, we identified 146 patients: 142 patients with NNC median value of 580 kcal (interquartile range 310–1043 kcal) over 7 days and 4 patients without NNC intake. The mean proportion of NNCs was larger during the first days after ICU admission (30.7–36.1%), because of the start-up phase of the nutrition. In the ‘propofol' group and the ‘dextrose' group this proportion levelled off at 6% on day 4. A more stable proportion of 18% was found during the first 7 days of ICU admission in the ‘citrate' group.

Conclusions:

The mean proportion of NNCs in patients who receive dextrose and/or propofol is low (6%); however, in individual patients it may comprise one-third of the total daily calories. Patients receiving trisodium citrate have higher mean non-nutritional intakes (18%). As NNC intake can be marked in individual patients, close monitoring is warranted when administering high-dose propofol or trisodium citrate anticoagulation to prevent overfeeding.