Metabolic rate and energy requirements by indirect calorimetry versus predictive formulas in mechanically ventilated patients on full very high protein-to-energy polymeric formula: A retrospective study.

BACKGROUND & AIMS: In ventilated critically ill patients, both overfeeding and underfeeding can be harmful. Determining energy expenditure is challenging due to various factors. Accurate estimation of nutritional requirements is essential for optimal care. This study compared resting energy expenditure in patients on full-dose high protein-to-energy tube feeding, using indirect calorimetry (IC) and the Roza & Shizgal (R&S) formula. It also examined the effects of sex, age, BMI, primary diagnoses, and non-intentional energy intake, and assessed adherence to European Society for Clinical Nutrition and Metabolism guidelines on protein intake.

METHODS

A retrospective cohort study included 178 ventilated ICU patients who received ≥7 days of full-dose high-protein enteral tube feeding between June 2019 and December 2022. IC was compared to the R&S formula, and 24-h nutritional intake data, including non-intentional sources, were analysed. Multivariate regression identified predictors of energy expenditure differences.

RESULTS

A significant difference of -146.64 kcal (SD = 276.38) was found between measured and estimated resting energy expenditure, with severe or morbid obesity and COVID-19 pneumonia as significant predictors. This difference increased when non-intentional energy intake in the preceding 24 h was considered (M = -514.51; SD = 326.37). When excluding non-intentional energy intake, patients achieved the ESPEN daily protein target of ≥1.3 g/kg actual or adjusted body weight/day, with averages of 1.3-1.5 g/kg using both indirect calorimetry and the Roza & Shizgal formula.

CONCLUSION

The Roza & Shizgal formula for estimating resting energy expenditure can overestimate or underestimate, so caution is needed, especially in severely to morbidly obese patients. Monitoring energy intake is important, particularly in tube feeding. Protein targets per international guidelines are generally met, except in patients with high non-intentional energy intake.