Role of malnutrition on clinical outcomes of patients with hypercapnic respiratory failure treated with non-invasive mechanical ventilation

This PhD project investigated the role of malnutrition on clinical outcomes in patients with hypercapnic respiratory failure treated with non-invasive respiratory support (non-invasive mechanical ventilation, NIMV, or high-flow nasal cannula, HFNC). Malnutrition is highly prevalent among hospitalized patients and is associated with impaired respiratory function, prolonged hospital stay, and increased mortality. This multicenter observational study included 127 patients admitted to sub-intensive care units between 2023 and 2025. Nutritional status was assessed using six validated screening tools (MNA, MNA-SF, NRS-2002, MUST, SNAQ, MST), while malnutrition was diagnosed according to the GLIM criteria. Additionally, sarcopenia and diaphragmatic function were evaluated using clinical assessment and thoracic ultrasound. Results showed a high prevalence of malnutrition (58.3%), which was associated with worse clinical conditions, longer hospital length of stay, and significantly higher three-month mortality. Among the screening tools, the Mini Nutritional Assessment (MNA) demonstrated the best diagnostic performance in identifying malnutrition. Furthermore, the MNA-SF score emerged as an independent predictor of three-month mortality, whereas biochemical markers such as albumin and total protein levels did not show independent prognostic value. Regarding secondary outcomes, sarcopenic patients exhibited significantly reduced diaphragmatic function, including lower diaphragmatic excursion and thickening fraction, suggesting a link between respiratory sarcopenia and ventilatory impairment. However, diaphragmatic ultrasound parameters were not independently associated with major clinical outcomes after adjustment for confounding factors. In conclusion, this study highlights the importance of early nutritional screening in patients with acute respiratory failure and supports the use of MNA-based tools for improved risk stratification. Integrating nutritional assessment with evaluation of respiratory sarcopenia may help identify high-risk patients and guide personalized therapeutic interventions.