Comparison of Measured Energy Expenditure Using Indirect Calorimetry Versus Predictive Equations for Liver Transplant Recipients

BACKGROUND To assess the appropriate energy expenditure requirement for liver transplant (LT) recipients in South Korea, four commonly used predictive equations were compared with indirect calorimetry. METHODS A prospective observational study was conducted in the surgical ICU of an academic tertiary hospital between December 2017 and September 2018. The study population comprised LT recipients expected to remain in the ICU > 48 hours postoperatively. Resting energy expenditure (REE) was measured 48 hours after ICU admission using open-circuit indirect calorimetry. Theoretical REE was estimated using four predictive equations (Simple weight-based equation (25 kcal/kg/day), Harris-Benedict, Ireton-Jones [ventilated], and Penn state 1988). Derived and measured REE values were compared using an intraclass correlation coefficient (ICC) and Bland-Altman plots. RESULTS Of 50 patients screened, 46 were enrolled, were measured, and completed the study. The Penn state equation showed 65.0% agreement with indirect calorimetry (ICC: 0.65); the simple weight-based equation (25 kcal/kg/day), Harris-Benedict and Ireton-Jones equations showed 62.0%, 56.0% and 39.0% agreement, respectively. Bland-Altman analysis showed that all four predictive equations had fixed bias, although the simple weight-based equation (25 kcal/kg/day) showed the least. CONCLUSION Although predicted REE calculated using the Penn state method agreed with the measured REE, all four equations showed fixed bias and appeared to be inaccurate for predicting REE in LT recipients. Precise measurement using indirect calorimetry may be necessary when treating liver transplant recipients to avoid underestimating or overestimating their metabolic needs. This article is protected by copyright. All rights reserved.