Nutritional practices and impact of feeding adequacy on clinical outcomes in Chinese respiratory intensive care units patients: a prospective observational study (ORIENT study)

Background The current status of nutritional support for patients in Respiratory ICU across mainland China remains inadequately characterized. This multi-center study, conducted in RICUs, was designed to investigate nutritional practices in this specific patient population, focusing on initiation timing, energy/protein adequacy, and associations with clinical outcomes. Methods A prospective, observational study enrolled 1,026 patients (ICU stay >48 h) across 68 Chinese RICUs. We analyzed EN initiation rates (24 h/48 h), caloric/protein intake adequacy during the first 7 days, and outcomes via multivariable Cox regression. Results EN initiation occurred in 36.8% (24 h) and 43.4% (48 h) of patients. Excluding patients who could take oral food, the proportion of patients who started EN within 24 and 48 h increased to 86.9 and 95.3%. Among 499 EN-fed patients, 26.1% developed EN complications. Caloric analysis ( n = 317) identified three trajectories: underfeeding (110, 24.3%). Overfeeding independently predicted higher non-social infections and significantly increased mortality risk in patients >50 years (HR = 1.83, 95% CI 1.02–3.28; p = 0.04). Mean protein intake was 0.9 g/kg/day, with no 28-day mortality benefit at higher thresholds (≥1.2 g/kg: p = 0.31; ≥1.3 g/kg: p = 0.42). Conclusion This multicenter study demonstrates optimal early EN initiation rates in Chinese RICUs. Energy overfeeding was associated with increased mortality risk only in patients >50 years and non-social infections risk, whereas protein adequacy showed no outcome associations. Protocolized EN delivery balancing adequacy and overfeeding risks is urgently needed in RICUs. Clinical trial registration Identifier, NCT04958447.