Post-ICU nutrition: the neglected side of metabolic support

This review will focus on the neglected side of metabolic support in ICU survivors: nutritional therapy after critical illness. Knowledge of the evolution of the metabolism of patients that survived critical illness will be bundled, and current practices will be investigated. We will discuss some studies conducted to determine resting energy expenditure in ICU survivors and which identified barriers that cause interruptions in the feeding process based on published data between January 2022 and April 2023.

Resting energy expenditure can be measured using indirect calorimetry, as predictive equations have proven to fail in their attempt to have good correlations with measured values. No guidelines or recommendations are available on post-ICU follow-up, including screening, assessment, dosing, timing, and monitoring of (artificial) nutrition. A limited number of publications shared treatment adequacy between 64-82% for energy (calories) and 72-83% for protein intake in a post-ICU setting. Loss of appetite, depression, and oropharyngeal dysphagia are the most prominent physiological barriers responsible for decreased feeding adequacy.

Patients may be in a catabolic state during and after ICU discharge, with several factors impacting metabolism. Therefore, large prospective trials are needed to determine the physiological state of ICU survivors, determine nutritional requirements, and develop nutritional care protocols. Many barriers causing decreased feeding adequacy have already been identified, but solutions are scarce. This review depicts a variable metabolic rate among ICU survivors and a significant variation in feeding adequacy in-between world regions, institutions, and patient sub-phenotypes.