Perioperative nutritional support: guidelines of the All-Russian public organization “Federation of Anesthesiologists and Reanimatologists” and their key differences from the previous 2021 version

Perioperative malnutrition and protein-energy wasting remain key modifiable risk factors for complications, prolonged hospital stay, and increased costs in surgical patients. The updated 2026 FAR guidelines on perioperative nutritional support systematize evidence from 2021–2025 and present a comprehensive multidisciplinary approach to diagnosing and correcting malnutrition at all stages of surgical care. In contrast to the 2021 version, the new edition introduces a two-step model for nutritional assessment: expanded risk screening (NRS-2002, MUST, MST, and others) complemented by formal malnutrition diagnosis according to GLIM criteria, incorporating phenotypic and etiologic features as well as instrumental assessment of sarcopenia and clinical frailty. This enables a shift from simple risk stratification to outcome prediction and individualized selection of nutritional support strategies. The guidelines emphasize the pivotal role of the preoperative phase, including prehabilitation: correction of nutritional deficits, use of oral nutritional supplements and, when indicated, immunonutrition combined with exercise training and educational interventions. The postoperative section maintains a focus on early enteral nutrition and refines criteria for tolerance, options for direct oral feeding after selected procedures, and indications for supplemental and peripheral parenteral nutrition. For the first time, a distinct post-discharge phase is outlined, with recommendations on continued oral nutritional supplements in high-risk patients. Dedicated sections address the use of specialized formulas (lipid emulsions, omega-3 fatty acids, glutamine, fiber-enriched enteral feeds) and the prevention of refeeding syndrome, including identification of high-risk groups and initial treatment algorithms. The guidelines are fully integrated with ERAS principles, positioning nutritional support as an essential component of the patient pathway rather than an isolated module. The final section provides quality indicators and metrics for the delivery of nutritional and metabolic care, forming a foundation for the development of local protocols, clinical audit, and continuous improvement of practice In Russian surgical wards and intensive care units.