Personalization of ICU nutrition is essential to future of critical care. Recommendations from American/European guidelines and practice suggestions incorporating recent literature are presented. Low-dose enteral nutrition (EN) or parenteral nutrition (PN) can be started within 48 h of admission. While EN is preferred route of delivery, new data highlight PN can be given safely without increased risk; thus, when early EN is not feasible, provision of isocaloric PN is effective and results in similar outcomes. Indirect calorimetry (IC) measurement of energy expenditure (EE) is recommended by both European/American guidelines after stabilization post-ICU admission. Below-measured EE (~ 70%) targets should be used during early phase and increased to match EE later in stay. Low-dose protein delivery can be used early (~ D1-2) (< 0.8 g/kg/d) and progressed to ≥ 1.2 g/kg/d as patients stabilize, with consideration of avoiding higher protein in unstable patients and in acute kidney injury not on CRRT. Intermittent-feeding schedules hold promise for further research. Clinicians must be aware of delivered energy/protein and what percentage of targets delivered nutrition represents. Computerized nutrition monitoring systems/platforms have become widely available. In patients at risk of micronutrient/vitamin losses (i.e., CRRT), evaluation of micronutrient levels should be considered post-ICU days 5–7 with repletion of deficiencies where indicated. In future, we hope use of muscle monitors such as ultrasound, CT scan, and/or BIA will be utilized to assess nutrition risk and monitor response to nutrition. Use of specialized anabolic nutrients such as HMB, creatine, and leucine to improve strength/muscle mass is promising in other populations and deserves future study. In post-ICU setting, continued use of IC measurement and other muscle measures should be considered to guide nutrition. Research on using rehabilitation interventions such as cardiopulmonary exercise testing (CPET) to guide post-ICU exercise/rehabilitation prescription and using anabolic agents such as testosterone/oxandrolone to promote post-ICU recovery is needed.

Nutrition therapy during critical illness has been a focus of recent research, with a rapid increase in publications accompanied by two updated international clinical guidelines. However, the translation of evidence into practice is challenging due to the continually evolving, often conflicting trial findings and guideline recommendations. This narrative review aims to provide a comprehensive synthesis and interpretation of the adult critical care nutrition literature, with a particular focus on continuing practice gaps and areas with new data, to assist clinicians in making practical, yet evidence-based decisions regarding nutrition management during the different stages of critical illness.

Rationale: The long-term effects of delivering approximately 100% of recommended calorie intake via the enteral route during critical illness compared with a lesser amount of calories are unknown. Objectives: Our hypotheses were that achieving approximately 100% of recommended calorie intake during critical illness would increase quality-of-life scores, return to work, and key life activities and reduce death and disability 6 months later. Methods: We conducted a multicenter, blinded, parallel group, randomized clinical trial, with 3,957 mechanically ventilated critically ill adults allocated to energy-dense (1.5 kcal/ml) or routine (1.0 kcal/ml) enteral nutrition. Measurements and Main Results: Participants assigned energy-dense nutrition received more calories (percent recommended energy intake, mean [SD]; energy-dense: 103% [28] vs. usual: 69% [18]). Mortality at Day 180 was similar (560/1,895 [29.6%] vs. 539/1,920 [28.1%]; relative risk 1.05 [95% confidence interval, 0.95–1.16]). At a median (interquartile range) of 185 (182–193) days after randomization, 2,492 survivors were surveyed and reported similar quality of life (EuroQol five dimensions five-level quality-of-life questionnaire visual analog scale, median [interquartile range]: 75 [60–85]; group difference: 0 [95% confidence interval, 0–0]). Similar numbers of participants returned to work with no difference in hours worked or effectiveness at work (n = 818). There was no observed difference in disability (n = 1,208) or participation in key life activities (n = 705). Conclusions: The delivery of approximately 100% compared with 70% of recommended calorie intake during critical illness does not improve quality of life or functional outcomes or increase the number of survivors 6 months later.