In general, malnutrition in surgical patients is associated with a higher risk of postoperative infections, decreased immune response, more cardiac complications, prolonged mechanical ventilation , and a higher rate of reimportation due to several other complications than lead to an increase in morbidity and mortality, a prolongation of the total hospitalization time in the ICU[intensive care unit ] and the chamber, and a delay in the healing of the surgical trauma .

The presence of a low percentage of lean mass, as calculated by the technique of bioelectric conductivity, practically means a small percentage of muscle tissue. However, muscle tissue is an important, if not the only source of amino acids for both protein synthesis and gluconeogenesis in stress conditions, such as surgery and the first postoperative days. Thus, post-operative patients in general, and cardio-operated patients, in particular, having a low lean mass have minimal reserves to the stress requirements, resulting in an increased risk of complications.

In the last few years, the most reliable indicator of malnutrition- in addition to the lean mass index - began to be considered the phase angle, which is also calculated when measuring the bioreduction of electrical conductivity, although there is a very recent challenge . The phase angle expresses the relationship between the electrical reactance, i.e. the state of the cell membrane, to resist the permeability and the resistance, i.e. the restriction to the flow of the electrical current through the body, mainly related to the water of the tissues . Like the FFM[fat-free mass]- index, the phase angle uses the total water of the tissues, and thus also reflects the cell mass. In addition, however, it also measures the resistance of cell membranes, so it also evaluates their quality and is therefore considered to be a reliable indicator of poor nutritional status , although some also maintain demur due to the possible poor distribution of extracellular fluid in cardiological patients.

From all of the above, it appears that there are some gaps in the evaluation of the patients who are going to undergo cardiac surgery regarding their nutritional status, both because the classic nutrition control indicators are not fully documented as being reliable for these patients, and there are no studies to monitor and compare body composition directly to any other index postoperatively.

The study protocol-mandated baseline data will include demographics, comorbidities, EuroSCORE[European System for Cardiac Operative Risk Evaluation] II, C-reactive protein, left ventricular ejection fraction (by transthoracic echocardiography) and peak expiratory flow rate (assessed by spirometry). Physical performance status will be assessed by APACHE [Acute Physiology And Chronic Health Evaluation] II score. Furthermore, SOFA [Sequential [Sepsis-related] Organ Failure Assessment] score will be assessed preoperatively and up to 7th postoperative day.

Preoperatively and on the 7th postoperative day, the following parameters will be calculated or measured and then recorded:

• Anthropometric data including body height, weight and waist circumference measurement, estimation of waist/circumference ratio and calculation of body mass index [BMI].
• Nutritional status will be assessed by MUST[Malnutrition Universal Screening Tool] score
• Body composition analysis using bioelectrical impedance analysis [BIA], will be performed for the calculation of FFM [fat-free mass] and fat mass [FM] indicators, intracellular, extracellular and total water [ICW, ECW, TBW] and phase angle parameter [PhA]. Additionally, muscular power will be assessed by handgrip strength [HGS], the upper third triangle perimeter and skin fold thickness will be measured.
• Daily calorie and protein needs of each patient will be calculated

During hospitalization, the following parameters will be recorded:

• Type of diet [parenteral, intestinal, oral]
• Post-operative infections involving respiratory system, medieval space, sternum trauma, lower limb trauma (if present) and endocarditis.
• The occurrence of organ dysfunction or sepsis. Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. For clinical operationalization, organ dysfunction will be represented by an increase in the Sequential [Sepsis-related] Organ Failure Assessment (SOFA) score of 2 points or more, which will be associated with an in-hospital mortality greater than 10%.
• Thromboembolic events such as stroke, peripheral venous thrombosis and pulmonary embolism.
• Acute renal failure.
• Re-operation for bleeding.
• Need for inotropic or vasoactive support.
• Hospitalization data (intubation> 24 hours, duration of mechanical ventilation and ICU stay, duration of hospital stay, in-hospital mortality

Inclusion Criteria:

• age >18 years
• planned introduction for cardiac operation with CPB[cardiopulmonary bypass]
• coronary artery bypass surgery
• heart valve surgery [heart valve surgery]

Exclusion Criteria:

• non-consent of the patient
• urgent admissions - operations
• pacemaker exist
• congenital heart disease
• recent [<3-month] open-heart surgery

Patients scheduled to undergo cardiac surgery for coronary revascularization or valvular heart disease