Development and Validation of a New Cardio-Specific Resting Energy Expenditure Equation for Adults

Background: This study tested the accuracy of resting energy expenditure (REE) equations among patients who underwent cardiopulmonary bypass and developed/validated a more accurate cardio-specific equation (CSE). Materials and Methods: Prospective observational cohort of 240 adults (derivation data set, 170 patients; validation data set, 70 patients). REEs were calculated with 6 equations—Penn State 2003a, Penn State 2003b, Ireton-Jones, Swinamer, Faisy, and American College of Chest Physicians—and results were compared with indirect calorimetry (IC). Multivariable linear regression analysis was used to develop the CSE. Agreement between measured and calculated REEs was assessed with Lin’s concordance correlation coefficient (LCCC), Bland-Altman plot, and regression analysis. Results: LCCCs present poor agreement between measured and calculated REEs: 0.24 (95% CI, 0.19–0.29), for the Faisy equation; 0.15 (95% CI, 0.1–0.19), Ireton-Jones; 0.31 (95% CI, 0.25–0.37), Swinamer; 0.17 (95% CI, 0.13–0.21), Penn State 2003a; 0.19 (95% CI, 0.14–0.23), Penn State 2003b; and 0.11 (95% CI, 0.07–0.15), American College of Chest Physicians. Based on the derivation data set, REEs are explained by the following equation: CSE = 616 − 8 × age in years + 13 × weight in kilograms + 450 if on ventilator + 159 × MV in liters + 145 if on inotropes. Based on the validation study results, the LCCC between IC and the CSE was 0.82 (95% CI, 0.73–0.88). Conclusion: The CSE has adequate precision and could be used for REE estimation for patients undergoing cardiopulmonary bypass if IC is unavailable.