Resting Energy Expenditure by Gastrointestinal Functional Status

Overview

This prospective, comparative interventional study will evaluate resting energy expenditure in adults with different gastrointestinal functional status. A total of 92 participants aged 18 to 65 years will be included: 30 healthy adults with normal gastrointestinal function and 62 patients with clinically confirmed intestinal failure. The intestinal failure group will include patients with short bowel syndrome and patients with other causes of intestinal failure. Participants will be assigned to one of two protocol-defined groups according to their gastrointestinal functional status. Each participant will attend one study visit lasting approximately 90 to 120 minutes. The research procedures will include measurement of resting energy expenditure by indirect calorimetry after an overnight fast, assessment of body composition by dual-energy X-ray absorptiometry and bioelectrical impedance analysis, and blood sampling for inflammatory markers. The primary objective is to compare resting energy expenditure between healthy participants and patients with intestinal failure and to determine whether resting energy expenditure differs according to the underlying cause of intestinal failure. Secondary objectives are to evaluate the associations between resting energy expenditure, lean body mass, fat mass, phase angle, and inflammatory markers. The results may contribute to more individualized nutritional management of patients with intestinal failure.

Intestinal failure is a condition in which the gastrointestinal tract is unable to provide adequate digestion and absorption of nutrients, electrolytes, and fluids. Patients may therefore require partial or complete parenteral nutrition. Their resting energy expenditure may be affected by the underlying cause of intestinal failure, changes in body composition, nutritional and metabolic status, and systemic inflammation. Accurate assessment of energy requirements is important for planning individualized nutritional support. This is a prospective, comparative interventional study with two non-randomized, protocol-defined groups. Group A will include 30 healthy adults with normal gastrointestinal function. Group B will include 62 clinically stable patients with confirmed intestinal failure. Within Group B, approximately 38 participants will have short bowel syndrome and 24 will have other causes of type II or type III intestinal failure, including chronic intestinal dysmotility or extensive disease of the small intestinal mucosa. The study intervention consists of metabolic, body-composition, and laboratory assessments performed according to a standardized research protocol. Each participant will complete the study during one visit at the Institute of Oncology Ljubljana. The visit will last approximately 90 to 120 minutes. Resting energy expenditure will be measured in the morning, after fasting, in a thermoneutral environment using indirect calorimetry. The indirect calorimetry measurement will last approximately 30 minutes and will determine oxygen consumption and carbon dioxide production. Body composition will be assessed using dual-energy X-ray absorptiometry to measure lean body mass, fat mass, and bone mineral density. Bioelectrical impedance analysis will also be performed to determine phase angle as an indicator of cellular integrity and function. A blood sample will be collected to assess inflammatory markers, including C-reactive protein and calculated neutrophil-to-lymphocyte, platelet-to-lymphocyte, and lymphocyte-to-monocyte ratios. Resting energy expenditure will be evaluated as an absolute value in kilocalories per day and in standardized forms, including adjustment for lean body mass, age, and sex. The primary analyses will compare resting energy expenditure between healthy participants and patients with intestinal failure and between patients with short bowel syndrome and patients with other causes of intestinal failure. Secondary analyses will examine the associations between resting energy expenditure and body-composition parameters, phase angle, and inflammatory markers. The study is intended to improve understanding of metabolic requirements in intestinal failure and to support the development of more individualized nutritional recommendations for these patients.