Modelling of Protein Breakdown During Critical Illness

Preview Step 3/4 print version Topic: 12.1. Metabolism, endocrinology and nutrition clinical studies Title: A MODEL OF CHANGES IN ENERGY EXPENDITURE TO SPECIFY DAILY CALORIC INTAKE TARGETS IN SEPSIS AND TRAUMA PATIENTS Author(s): U. Pielmeier1, M.L. Rousing1, S. Andreassen1 Institute(s): 1Aalborg University, Center for Model-based Medical Decision Support, Aalborg, Denmark Text: INTRODUCTION European intensive care nutrition guidelines recommend caloric intake close to measured energy expenditure. The daily supply during the first days should not exceed 20-25 kcal/kg body weight (BW). During recovery, 2530 kcal/kg BW/day is recommended. OBJECTIVES We hypothesized that specific daily caloric targets can be defined based on modeled changes in measured energy expenditure (MEE) on consecutive ICU days. METHODS We searched the literature for clinical data of MEE by indirect calorimetry on consecutive ICU days. We limited our search to patients with sepsis, trauma, or sepsis and trauma. We excluded studies without daily measurements and studies without data to predict resting energy expenditure (pREE). We estimated daily averages of the increase from pREE by calculating the mean values (± standard error of the mean (SEM)) of the ratio of MEE to pREE on each day and constructed a model of the changes in energy expenditure by a mathematical fit to the mean values of the ratios. RESULTS We found three studies with daily measurements in seven [1], eight [2], and thirteen [3] patients (mean age 38±20, 60±16, 63±16 years, respectively). The patient numbers for the analysis of MEE/pREE ratios on consecutive ICU days differed between 9 (day 14 and 15) and 25 (day 7). Fig. 1 shows the mean MEE/pREE ratios (± SEM) by study on consecutive ICU days and a model of the time course for changes in MEE/pREE ratio based on a parabolic fit to the mean values. The model indicates an increase in MEE/pREE ratio during the first week and a peak after 9 days. To estimate daily caloric needs, the MEE/pREE model value is read from the curve and multiplied with the pREE of a patient. For example, at a predicted basal metabolic rate of 1500 kcal/day, the caloric target is 1680 kcal (1.12 x 1500 kcal) on day 2 and increases to 1995 kcal on day 9 (1.33 x 1500 kcal). [Fig. 1 mean MEE/pREE ratios (±SEM) and model fit] CONCLUSION Changes in energy expenditure over the course of critical illness are evident from daily measurements. Optimized caloric intake close to energy expenditure is recommended. The modeled time course of changes in MEE/pREE ratio may be a method to define specific daily caloric targets in the absence of indirect calorimetry. We proposed a model for sepsis and trauma patients based on data from three studies. More studies with MEE and pREE on consecutive ICU days and detailed patient care information are needed to validate this approach. REFERENCES Figure 3.8: The figure shows a fit of data on the ratio of energy expenditure measured by indirect calorimetry (MEE) and predicted energy expenditure (pREE) over the course of ICU stay. A distinct increase in energy expenditure can be seen when entering the flow phase [Pielmeier et al., 2014].