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Assessment of Physical Activity Intensity with Accelerometers and Oxygen Consumption
Published on: June 20, 2025
A comparison between ventilation modes: how does activity level affect energy expenditure estimates?
Jorge A Hoher1, Paulo José Zimermann Teixeira, Felipe Hertz
1Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Porto Alegre, Brazil. jah@via-rs.net
JPEN. Journal of Parenteral and Enteral Nutrition
|April 15, 2008
Summary
Accurate caloric intake is vital for mechanically ventilated patients. A 10% activity factor should only be used for assisted ventilation to prevent overfeeding in controlled ventilation patients.
Area of Science:
- Critical Care Medicine
- Nutritional Support
- Mechanical Ventilation
Background:
- Optimizing nutrition is crucial for mechanically ventilated patients to prevent complications.
- Lack of comparative data on energy expenditure across ventilation modes hinders precise diet prescription.
- This study addresses caloric requirements by comparing estimated and measured energy expenditure in two ventilation modes.
Purpose of the Study:
- To evaluate caloric requirements in mechanically ventilated patients.
- To compare estimated energy expenditure (using Harris-Benedict equation with injury and activity factors) with measured energy expenditure (via indirect calorimetry).
- To assess the impact of a 10% activity factor on energy expenditure estimations for different ventilation modes.
Main Methods:
- Indirect calorimetry was used to measure the 24-hour energy expenditure of 100 intensive care unit (ICU) patients.
- Patients were categorized into assisted or controlled mechanical ventilation groups.
- Measured energy expenditure was compared with Harris-Benedict estimates, with and without a 10% activity factor.
Main Results:
- Mean energy expenditure was 1712.76 kcal/24 h for controlled ventilation and 1867.33 kcal/24 h for assisted ventilation.
- Assisted ventilation showed a statistically significant higher mean total energy expenditure (10.71%, P < .001) compared to controlled ventilation.
- Harris-Benedict estimates with injury and activity factors overestimated measured expenditure for controlled ventilation (8.2%, P = .012) but underestimated for assisted ventilation when the activity factor was omitted (10.7%, P = .001).
Conclusions:
- A 10% activity factor should be applied exclusively to assisted ventilation.
- Using an activity factor for controlled ventilation may result in overfeeding patients.
- Accurate energy expenditure assessment is critical for appropriate nutritional management in ICU patients.
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