title: Are Predictive Energy Expenditure Equations in Ventilated Surgery Patients Accurate?
abstract: While indirect calorimetry (IC) is the gold standard used to calculate specific calorie needs in the critically ill, predictive equations are frequently utilized at many institutions for various reasons. Prior studies suggest these equations frequently misjudge actual resting energy expenditure (REE) in medical and mixed intensive care unit (ICU) patients; however, their utility for surgical ICU (SICU) patients has not been fully evaluated. Therefore, the objective of this study was to compare the REE measured by IC with REE calculated using specific calorie goals or predictive equations for nutritional support in ventilated adult SICU patients.
  A retrospective review of prospectively collected data was performed on all adults (n = 419, 18-91 years) mechanically ventilated for >24 hours, with an Fio2≤ 60%, who met IC screening criteria. Caloric needs were estimated using Harris-Benedict equations (HBEs), and 20, 25, and 30 kcal/kg/d with actual (ABW), adjusted (ADJ), and ideal body (IBW) weights. The REE was measured using IC.
  The estimated REE was considered accurate when within ±10% of the measured REE by IC. The HBE, 20, 25, and 30 kcal/kg/d estimates of REE were found to be inaccurate regardless of age, gender, or weight. The HBE and 20 kcal/kg/d underestimated REE, while 25 and 30 kcal/kg/d overestimated REE. Of the methods studied, those found to most often accurately estimate REE were the HBE using ABW, which was accurate 35% of the time, and 25 kcal/kg/d ADJ, which was accurate 34% of the time. This difference was not statistically significant.
  Using HBE, 20, 25, or 30 kcal/kg/d to estimate daily caloric requirements in critically ill surgical patients is inaccurate compared to REE measured by IC. In SICU patients with nutrition requirements essential to recovery, IC measurement should be performed to guide clinicians in determining goal caloric requirements.
authors.affiliation: 1 Division of Acute Care Surgery (Trauma, Burns, Critical Care, Emergency Surgery), Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Tignanelli
authors.affiliation: 2 Respiratory Care, University of Michigan Health System, Ann Arbor, MI, USA.
authors.forename: Allan G
authors.initials: AG
authors.lastname: Andrews
authors.affiliation: 1 Division of Acute Care Surgery (Trauma, Burns, Critical Care, Emergency Surgery), Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Kurt M
authors.initials: KM
authors.lastname: Sieloff
authors.affiliation: 3 Department of Pharmacy Services, University of Michigan Health System, Ann Arbor, MI, USA.
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Pleva
authors.affiliation: 4 Division of General Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Reichert
authors.affiliation: 5 Nutrition Services, University of Michigan Health System, Ann Arbor, MI, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Wooley
authors.affiliation: 1 Division of Acute Care Surgery (Trauma, Burns, Critical Care, Emergency Surgery), Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Lena M
authors.initials: LM
authors.lastname: Napolitano
authors.affiliation: 1 Division of Acute Care Surgery (Trauma, Burns, Critical Care, Emergency Surgery), Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Jill R
authors.initials: JR
authors.lastname: Cherry-Bukowiec
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002153:Calorimetry, Indirect / Q000379:methods*; D016638:Critical Illness; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008432:Mathematical Computing; D008875:Middle Aged; D009751:Nutritional Requirements; D011184:Postoperative Period; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000706:statistics & numerical data*; D012146:Rest; D012189:Retrospective Studies; D055815:Young Adult
keywords: Harris-Benedict equations; indirect calorimetry; metabolic cart; resting energy expenditure; surgical critical care