Metabolism and the impact of protein intake in Chronic critically ill adult patients: Protocol for a unicentric prospective cohort study (MetaChronic Study)

BACKGROUND: Survival of acutely critically ill patients has improved, resulting in a growing population of chronic critically ill (CCI) patients with prolonged organ dysfunction, mechanical ventilation, and high morbidity. While nutritional guidelines during the acute phase of critical illness are well defined, our understanding of metabolism and nutritional needs in CCI patients is limited. Persistent inflammation may influence the metabolic response and nutritional uptake, highlighting the need for prospective studies in this area. METHODS: The MetaChronic Study is a single-center, prospective cohort study of metabolism in patients with CCI. Adult ICU patients with invasive mechanical ventilation ≥48 h and ICU stay >7 days are eligible. Patients are followed for up to 42 days after ICU admission, with final outcomes assessed at 90 days. Resting energy expenditure is measured weekly by serial indirect calorimetry. Weekly protein and calorie intake are recorded and inflammation is assessed using serum C-reactive protein and procalcitonin measurements. Patients are categorized according to high or low protein intake (>1.3 g/kg/day vs. ≤1.3 g/kg/day after the first week). The primary objective is to characterize longitudinal metabolic trajectories. Secondary objectives include subgroup analyses (septic, trauma, neurocritical patients), assessment of the interaction between inflammation and metabolic rate, and exploratory analyses of the association between protein intake and clinical outcomes. ETHICS AND DISSEMINATION: The study has been approved by the institutional ethics committee. Findings will be disseminated through peer-reviewed journals and scientific conferences.