The Efficacy of Early Postoperative Enteral Immunonutrition in Low-Risk Cardiac Surgery Patients

Inclusion Criteria: * Age ≥18 years; * Elective cardiac surgery with cardiopulmonary bypass: * coronary artery bypass grafting surgery (CABG); * aortic valve replacement; * mitral valve replacement; * mitral valve repair; * tricuspid valve repair; * combined operations (CABG and valve surgery); * Phase angle \<5.5⁰ (phase angle was evaluated one day prior to surgery using bioelectrical impedance analysis (InbodyS10 device). Exclusion Criteria: Preoperative: * previous cardiac surgery; * left ventricle ejection fraction \<40%; * use of preoperative intra-aortic balloon pump (IABP); * critical preoperative state; * pulmonary artery mean pressure \>55 mmHg; * diagnosis of infectious endocarditis; * pacemaker; Operative: * complicated intraoperative course (unplanned intervention or low cardiac output syndrome in the operating theatre: failure to wean from cardiopulmonary bypass (CPB) or intraoperative insertion of IABP or infusion of two or more inotropic medications with a cumulative dose of 0.2 mcg/kg/min); * surgery time \>6 h; * unplanned intervention; Postoperative: * disturbance of dietary rules.