**8. Nutritional support in liver transplant recipients**

Post-LT nutritional support in ICU is an essential adjunct to transplant recovery. Malnutrition, which characterizes many patients with ESLD being evident at rates of up to 80%, deteriorates with the progression of liver failure, and affects the patients' outcome [80]. On the other hand, it is associated with prolonged ICU and hospital stay, infections, respiratory complications, graft impairment, and mortality. Sarcopenia, defined as severe muscle wasting, is also a determining factor of the outcome, and it can be easily diagnosed with bioelectrical impedance. Patients with cirrhosis often present carbohydrate, fat, and protein disorders, characterized by elevated levels of aromatic amino acids and methionine while lowering plasma levels of branched-chain amino acids are detected [81, 82]. The immediate postoperative energy demands are increased, especially in patients with a high MELD score [82]. Factors such as operational stress, release of catabolic hormones, administration of immunosuppressants, mainly corticosteroids, as well as ICU factors including mechanical ventilation and hemodialysis, contribute to increased metabolic needs. For the above reasons, the aim is to ensure adequate intake of protein and calories in addition to protein breakdown protection [81]. An increase in nonprotein calories, estimated at 25–35% kcal/kg per day, is recommended when indirect calorimetry is not available. It should always be in accordance with the metabolic and inflammatory status, and it should be reviewed in hemodynamically unstable patients [83]. Due to elevated protein catabolism, it is necessary to obtain 1.5–2 g/kg of protein. Enteral nutrition (EN) has the edge over the parenteral one, assisting in maintaining intestinal integrity, by supporting the diversity of the microbiome, and helping the immune and metabolic response. The rapid onset of EN even 12 h after LT is recommended by some authors. It has been reported to reduce viral infections and contribute to a better N2 balance. If postoperative encephalopathy remains, the amount of protein intake is not reduced but the type of nutrition is altered by the addition of branched-chain amino acid (BCCA) enriched formulae, while the administration of immunonutrition remains under discussion. Frequent screening of electrolytes is required to prevent and correct disorders, while re-feeding syndrome is also considered a risk factor for these disorders [83].
