title: Energy expenditure in mechanically ventilated patients: The weight of body weight!
abstract: Optimal nutritional care for intensive care unit (ICU) patients requires precise determination of energy expenditure (EE) to avoid deleterious under- or overfeeding. The reference method, indirect calorimetry (IC), is rarely accessible and inconstantly feasible. Various equations for predicting EE based on body weight (BW) are available. This study aims at determining the best prediction strategy unless IC is available.
  
  
  
  Mechanically ventilated patients staying ≥72 h in the ICU were included, except those with contraindications for IC measurements. IC and BW measurements were routinely performed. EE was predicted by the ESPEN formula and other predictive equations using BW (i.e. anamnestic (AN), measured (MES), adjusted for cumulated water balance (ADJ), calculated for a body mass index (BMI) of 22.5). Comparisons were made using Pearson correlation and Bland & Altman plots.
  
  
  
  85 patients (57 ± 19 y, 61 men, SAPS II 43 ± 16) were included. Correlations between IC and predicted EE using the ESPEN formula with different BW (BWAN, BWMES, BWADJ, and BWBMI22.5) were 0.44, 0.40, 0.36, and 0.47, respectively. Bland & Altman plots showed wide and inconsistent variations. Predictive equations including body temperature and minute ventilation showed the best correlations, but when using various BWs, differences in predicted EE were observed.
  
  
  
  No EE predictive equation, regardless of the BW used, gives statistically identical results to IC. If IC cannot be performed, predictive equations including minute ventilation and body temperature should be preferred. BW has a significant impact on estimated EE and the use of measured BWMESor BWBMI 22.5is associated with the best EE prediction. Clinical trial registration number on ClinicalTrial.gov: NCT02552446. Ethical committee number: CE-14-070.
authors.affiliation: Clinical Nutrition Unit, Geneva University Hospitals, Switzerland; Division of Intensive Care, Geneva University Hospitals, Switzerland. Electronic address: severine.graf@hcuge.ch.
authors.forename: Séverine
authors.initials: S
authors.lastname: Graf
authors.affiliation: Clinical Nutrition Unit, Geneva University Hospitals, Switzerland. Electronic address: claude.pichard@hcuge.ch.
authors.forename: Claude
authors.initials: C
authors.lastname: Pichard
authors.affiliation: Clinical Nutrition Unit, Geneva University Hospitals, Switzerland. Electronic address: laurence.genton@hcuge.ch.
authors.forename: Laurence
authors.initials: L
authors.lastname: Genton
authors.affiliation: Clinical Nutrition Unit, Geneva University Hospitals, Switzerland. Electronic address: oshima.taku@hcuge.ch.
authors.forename: Taku
authors.initials: T
authors.lastname: Oshima
authors.affiliation: Division of Intensive Care, Geneva University Hospitals, Switzerland. Electronic address: Claudia.Heidegger@hcuge.ch.
authors.forename: Claudia Paula
authors.initials: CP
authors.lastname: Heidegger
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001831:Body Temperature; D001835:Body Weight; D002153:Calorimetry, Indirect; D003422:Critical Care; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012121:Respiration, Artificial
keywords: Body weight; Energy expenditure; Indirect calorimetry; Intensive care unit; Predictive equations