This study focuses on understanding how well patients who have recovered from an ICU stay absorb nutrients when receiving enteral (tube) feeding. Proper nutrition is crucial for recovery, but we don't fully understand how efficiently enteral feeding works in ICU survivors. The study will use advanced techniques like bomb calorimetry to measure the energy content of stool, and indirect calorimetry to measure patients' resting energy expenditure (REE). This will help assess the effectiveness of enteral feeding in these patients, providing valuable information about their metabolic needs and nutritional status.

The study will also look into the environmental impact of enteral feeding, particularly food waste. By understanding how much of the nutrition is absorbed versus excreted, the study hopes to suggest more sustainable feeding practices and reduce unnecessary waste in hospitals.

Key Goals:

• Primary Goal: Measure how much energy from enteral feeding is absorbed by patients post-ICU by analyzing their stool and energy expenditure.
• Secondary Goal: Assess how enteral feeding can be made more sustainable, with less waste generated from unused nutritional products.

This research will help improve nutritional care for ICU patients, enhance recovery, and potentially lead to more environmentally friendly healthcare practices.

This study investigates the absorption efficiency of enteral nutrition in patients recovering from an intensive care unit (ICU) stay. Nutritional support is critical in the recovery of ICU patients, and enteral feeding is commonly used due to its benefits in preserving gut integrity and reducing infection risks. However, there is limited data on the actual absorption of nutrients in these patients, particularly in terms of how much of the provided energy is utilized versus excreted.

The primary focus of this study is to quantify the caloric intake and the caloric content of excreted stool to determine the efficiency of nutrient absorption in post-ICU patients. This will be done using bomb calorimetry, which measures the energy content in stool samples, and indirect calorimetry to assess the patients' resting energy expenditure (REE).

The study design is prospective, interventional, and single-center, involving 20 post-ICU patients who meet the inclusion criteria. Detailed tracking of caloric intake, including both enteral feeding and supplemental infusion calories, will be performed daily. Stool samples will be collected for three days, with the nonabsorbable blue dye marker method used to track the specific stool produced during this period. These stool samples will be freeze-dried, formed into pellets, and analyzed using the Parr 6200 Isoperibol Calorimeter to measure their energy content.

The secondary objective is to evaluate the sustainability of enteral feeding practices by assessing the amount of waste generated, such as unused nutritional formulas and tubing. This includes quantifying food waste in the hospital, focusing on nutrition that is not consumed, absorbed, or excreted.

By understanding the actual energy absorption in ICU survivors, this study aims to provide insights that will optimize nutritional strategies, improve patient recovery, and contribute to cost-effective, environmentally sustainable healthcare practices.

Inclusion Criteria:

• age of 18 years or older
• minimum ICU stay of 7 days
• fully dependent on enteral feeding (nasogastric or PEG-tube)
• ability of the patient or representative to understand and sign written informed consent in Dutch, French or English

Exclusion Criteria:

• known inflammatory bowel disease
• known malabsorptive gastrointestinal disease
• history of small bowel resection
• concomitant use of serotoninergic or sympathomimetic medications (oa. setrone, tryptans, antidepressants, methylphenidate, monoamine oxidase inhibitors, tramadol)