Association between energy surplus and intensive care unit length of stay in critically ill patients: A retrospective cohort study

Background Patients experiencing persistent critical illness have poor short-term and long-term outcomes and consume disproportionate amounts of health care resources. Nutrition optimization may improve outcomes, though few data exist on resting energy expenditure and nutrition requirements. We hypothesized that increased energy surplus per day is associated with increased intensive care unit (ICU) length of stay (LoS) in critically ill patients.Methods Patients from a single ICU at Royal London Hospital were included in this retrospective cohort study. Exposure: energy surplus measured by serial indirect calorimetry (IC) and nutrition intake. Inclusion criteria: mechanical ventilation of >= 3 days and expected to remain ventilated. Primary outcome: ICU LoS.Results Across 30 patients (median LoS 21 days), increased ICU LoS was associated with actual daily energy intake surplus to resting energy expenditure (REE) (R-2 0.16; P < 0.005). Median REE was less than predicted energy requirements: 24 kcal per day per kilogram of ideal body weight (IBW) (interquartile range [IQR], 20-28) vs 28 kcal/day/kg IBW (IQR, 26-29) (P < 0.001). Patients with COVID-19 had a median energy surplus (actual intake- REE) + 344 kcal/day (IQR 35-517) vs -57 kcal/day (IQR -324 to 211) in other patients (P = 0.011); however, they had a median LoS of 44 days (IQR 26-58) vs 10 days (IQR 7-24), respectively (P < 0.001). Patients with obesity had a median energy deficit of -32 kcal/day (IQR -384 to 335) vs +234 kcal/day (IQR -79 to 499) for nonobese patients (P = 0.021).Conclusion Overfeeding represents an easily modifiable factor to improve outcomes in patients experiencing persistent critical illness, for which IC may be useful.