Course of measured energy expenditure over the first 10 days of critical illness: A nested prospective study in an adult surgical ICU

Various factors can cause significant daily fluctuations in energy expenditure among critically ill patients. This nested, prospective study in a trauma surgical ICU aimed to track the progression of energy expenditure over the first 10 days of critical illness and identify the factors influencing it.

Indirect calorimetry was conducted on alternate days from ICU Day 3 ± 1 to Day 10 ± 1, using the Q-NRG+ metabolic monitor. Linear mixed regression, with two fractional polynomial terms to account for non-linear responses, was used to model the mean daily measured energy expenditure, respiratory quotient, and total energy delivery as a percentage of measured energy expenditure.

This study enhances our understanding of metabolic changes in the first 10 days of critical illness in a trauma surgical ICU. Measured energy expenditure showed a significant non-linear response, increasing over the first 4 days peaking on day 5 then plateauing. The variability observed highlights the complexity of managing critically ill patients and emphasizes the need for personalized monitoring and adjustments to nutrition and therapy. Recognizing this variation is key to providing tailored energy support, avoiding both overfeeding and underfeeding. Future studies should explore factors influencing energy expenditure variability, potentially by stratifying patients based on characteristics like surgery type or illness severity, and using advanced models to predict energy needs.