The goal of this observational study is to determine the association of gastrointestinal dysfunction through the Gastrointestinal Dysfunction Scale (GIDS) tool and serum concentrations of citrulline and Intestinal fatty-acid binding protein (I-FABP) with primary [calories received, protein received, parenteral nutrition requirement and 28-day mortality in the intensive care unit (ICU)] and secondary (development of pneumonia, surgical and cardiovascular complications in the ICU, length of hospital and ICU stay, duration of mechanical ventilation) clinical outcomes in critically ill patients undergoing aortic surgery.

The treatment of choice for various cardiovascular diseases often involves cardiac surgery, including aortic surgery, which is performed to correct conditions related to this major vessel, such as aneurysms, stenosis, aortic dissections, as well as issues affecting the aortic valve. With the increasing prevalence of non-communicable chronic diseases, a 46% increase in demand for cardiac surgeries is projected by 2025. The post-surgical period, commonly in the intensive care unit (ICU), increases the risk of complications, especially in patients with pre-existing risk factors. In this regard, gastrointestinal (GI) dysfunction affects up to 63% of patients, being associated with complications and a mortality rate of 55% to 60%. Early detection of GI dysfunction allows for the implementation of management strategies. Additionally, the administration of appropriate nutritional therapy is essential for recovery, and GI dysfunction may limit nutrient absorption. Inadequate caloric intake has been linked to increased morbidity and mortality. Tools such as GIDS (Gastrointestinal Dysfunction Scale) and biomarkers like citrulline and I-FABP enable early evaluation of GI function, advancing monitoring and management. Identifying changes before serious complications arise allows for early and personalized interventions. Early detection not only prevents complications and improves quality of life but may also reduce mortality. This research project aims to address these gaps by early assessing GI dysfunction in post-aortic surgery patients. Utilizing the GIDS tool and biomarkers such as citrulline and I-FABP, the goal is to identify GI dysfunction early and its impact on nutrition administration.

Inclusion Criteria:

• 18 years of age or older.
• Patients after surgical interventions (elective or urgency) on the aorta with cardiopulmonary bypass.
• Invasive mechanical ventilation expected to be required more than 48 hours.
• Signed informed consent.

Exclusion Criteria:

• Patients under mechanical ventilation with pre-existing gastrointestinal issues.
• Diagnosis of adult congenital heart disease.
• Ongoing pregnancy or lactation period.
• Simultaneous participation in another clinical study involving experimental therapy.
• Presence of chronic intestinal disease.
• Previous gastrointestinal conditions detected during nutritional screening.

Adult patients following aortic surgery necessitating invasive mechanical ventilation and an intensive care unit stay of ≥ 48 hours.