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Energy Expenditure in Critically Ill Obese Patients-A Prospective Observational Study.
Geraldine de Heer1, Christoph Burdelski1, Constantin Ammon1
1Department of Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany.
Nutrients
|July 12, 2025
Summary
Indirect calorimetry revealed similar energy expenditure (EE) in critically ill obese and non-obese patients when using adjusted body weight (ABW). This supports using ABW for nutrition in obese patients when indirect calorimetry is unavailable.
Area of Science:
- Critical Care Medicine
- Nutritional Support
- Obesity Research
Background:
- Critically ill obese patients face risks from both overfeeding and underfeeding, impacting outcomes, particularly in mechanically ventilated individuals.
- Indirect calorimetry (IC) is the gold standard for measuring energy expenditure (EE), but its limited availability and the inaccuracy of predictive formulas pose challenges.
- Accurate EE assessment is crucial for appropriate nutritional management in intensive care settings.
Purpose of the Study:
- To assess and compare energy expenditure (EE) in critically ill obese patients versus non-obese septic controls using indirect calorimetry (IC).
- To evaluate different reference weights (ideal body weight [IBW], adjusted body weight [ABW], total body weight [TBW]) for EE calculation in obese patients.
- To assess nitrogen balance to inform protein requirements in both patient groups.
Main Methods:
- A prospective observational study conducted in a German university medical center.
- Energy expenditure (EE) was measured using indirect calorimetry (IC) at three time points: acute, end of acute, and post-acute phases.
- Nitrogen balance was assessed; various reference weights (IBW, ABW, TBW) were used for EE calculations in 28 obese and 22 control patients.
Main Results:
- Equivalence in EE was observed between obese and control groups when adjusted body weight (ABW) was calculated using 18% of excess body weight (EBW), averaging 24.4 kcal/kg/d.
- Mean EE values at different time points were comparable between obese and control groups, regardless of the phase of illness.
- Both groups presented with negative nitrogen balance, though controls reached nitrogen equilibrium by the post-acute phase.
Conclusions:
- The findings support the European Society for Parenteral and Enteral Nutrition (ESPEN) recommendation to use adjusted body weight (ABW) with 20% of excess body weight (EBW) for nutrition in critically ill obese patients when IC is unavailable.
- Further research is warranted to optimize protein supplementation strategies and their timing to improve clinical outcomes in critically ill obese populations.
- Accurate energy expenditure estimation is vital for guiding nutritional therapy in complex patient populations.
