Introduction and assumptions of the research project:

Patients treated in intensive care units (ICUs) require comprehensive treatment. Nutrition is an important and integral part of this therapy. Both insufficient and excessive calorie intake are associated with poorer prognosis and increased mortality in ICU patients. Furthermore, the caloric requirements of patients in life-threatening conditions in the ICU are characterized by periods of hypo- and hypermetabolism, which, if nutrition is not optimized, expose patients to overfeeding or underfeeding. Therefore, monitoring resting energy expenditure (REE) using indirect calorimetry has become the "gold standard" in the ICU. Previous methods based on mathematical formulas for calculating REE were characterized by insufficient correlation with actual demand. Indirect calorimetry uses measured exhaled carbon dioxide and the concentration of oxygen administered. Then, taking into account patient-dependent parameters such as gender, height, and weight, it indirectly calculates energy expenditure, which corresponds to caloric demand. By dividing the volume of CO2 released by the volume of O2 absorbed, investigators can obtain the respiratory quotient (RQ). This quotient is related to the type of diet and is, for example, 0.7 for fats, 0.8 for proteins, and 1.0 for carbohydrates. Its value also changes with nutritional status. High values may suggest an excessive energy supply (relative to demand), while low values may indicate a calorie deficit. Some authors suggest that the RQ ratio could potentially be used to further optimize nutritional status. Currently, however, due to insufficient research, it is mainly used in clinical practice to assess the accuracy of recording and monitoring calorimetry. This study, is trying to assess the usefulness of RQ for optimizing nutrition in patients treated in the ICU.

Methodology:

Study group:

This will be a randomized study with a study group and a control group in patients treated in the ICU. All patients participating in the study are patients who, at the time of qualification, are mechanically ventilated and treated in the ICU. These will be patients of both sexes, aged 18-85 years. The control group will be fed under the supervision of indirect calorimetry and REE, in accordance with current ICU nutrition guidelines. In the study group, nutritional preparations will be additionally systematized and selected for each patient depending on their RQ value, and caloric requirements will be controlled by indirect calorimetry and REE, as in the control group. Regular assessments of albumin, total protein, total cholesterol, LDL, HDL, iron, glycemia, Na+, K+, and triglycerides will be conducted, collected along with the routine test package. In addition, typical endpoints for patients treated in the ICU will be assessed, such as length of stay in the ICU, length of mechanical ventilation, number of days without a ventilator, 28-day survival, and survival to hospital discharge.

Expected duration of the study: October 2024 to October 2026 (2 years) Conditions for inclusion in the study: patients > 18 years of age, treated in the ICU, mechanically ventilated, covered by universal health insurance Conditions for exclusion from the study: ECMO therapy, the need for mechanical ventilation with an oxygen concentration in the breathing mixture FiO2 > 60%, patients breathing independently without the aid of a ventilator, critically ill patients who are not expected to survive the next 48 hours, pregnant women, patients < 18 years of age or > 85 years of age

Reasons for discontinuing the study:

1. if, during the course of the study, there are clear indications that one of the groups will experience or worsen final outcomes such as mortality, 28-day mortality, length of stay in the ICU - which would suggest a clear advantage of one of the chosen strategies, along with an increase in the number of patients included in the study, a regular analysis of the current effects of both strategies will be conducted,
2. the patient develops hypersensitivity/intolerance to nutritional preparations, with no possibility of switching to another preparation used in the study,

Expected results and their planned subsequent use:

Patients from the control group, should achieve faster stabilization of nutritional parameters and fewer episodes of underfeeding and overfeeding. This should translate into improved endpoints such as mortality, length of stay in the ICU, and shorter mechanical ventilation time. In addition, the systematization and algorithms for the use of nutritional products developed during the study can be further used in department of the study and other departments around the world.

Inclusion Criteria:

• patient treated in the ICU
• mechanically ventilated
• covered by universal health insurance

Exclusion Criteria:

• ECMO therapy
• mechanical ventilation with an oxygen concentration in the breathing mixture FiO2 > 60%
• breathing independently without the aid of a ventilator
• critically ill patients who are not expected to survive the next 48 hours
• pregnant women