Energy expenditure early after liver transplantation: Better measured than predicted

Objective: There is no consensus on how to estimate energy requirements after liver transplantation (LT). The aim of this study was to compare measured resting energy expenditure (REE) with predictive equations and fixed factors, and evaluate whether clinical variables were associated with REE.

Methods: During the period of 2011 through 2018, REE measured with indirect calorimetry and predicted by the Harris and Benedict (HB) equation was compared in patients during the first 30 postoperative days after LT. The fixed factors 25 kcal/kg, 30 kcal/kg, or 35 kcal/kg were used to calculate energy requirements. The accuracy of HB and fixed factors were evaluated with a Bland-Altman analysis and Lin's concordance correlation coefficient. The associations of pre- and postoperative clinical variables with REE were evaluated in a multivariate regression analysis.

Results: A total of 143 patients were evaluated and had indirect calorimetry performed on postoperative day 6 (interquartile range: 3) in median. The mean measured REE was 1950 ± 461 kcal (range, 720-3309 kcal) or 24.5 ± 6.1 kcal/kg body weight. Large limits of agreements were observed in the Bland-Altman analyses for both HB and fixed factors. HB was closer than fixed factors with a positive concordance (concordance correlation: 0.350; 95% confidence interval, 0.248-0.445) and Pearsons r² = 0.261. Measured REE was significantly associated (P < 0.05) with age, sex, Model for End-Stage Liver Disease score before LT, surgery time, and graft cold ischemia time according to the multiple regression analysis.

Conclusions: The low accuracy of HB and fixed factors suggests risks of both under- and overfeeding of individual patients if energy requirement is only based on calculation. REE measurement is recommended after LT to secure accurate and safe nutritional therapy.