Title: Indirect calorimetry, non-invasive measurements in practice 
Objectives: To describe and share experience from using indirect calorimetry, non-invasive measurements, in a Burn center. 
Methods and results: Calculation of energy requirements from equations are known to have errors compared to measured resting energy expenditure (REE). Therefore, indirect calorimetry is considered gold standard for assessing energy requirement in (burn) patients.  
The use of indirect calorimetry at least once a week is recommended for all patients with a TBSA > 20 % in one Burn center. Indirect calorimetry can be measured invasively or non-invasively. Non-invasive measurement is done using a hood. REE is measured during 30 minutes in the morning after at least four hours fasting. The patient should be without extra oxygen and be able to lay still during measurement. This makes it difficult to perform in anxious patients and those in pain. Since non-invasive indirect calorimetry measurements represent REE for 30 minutes an assessment of physical activity must be added to the measured value to estimate the total energy requirement. The physical activity level can be assumed to be at least 1.2 for patients in bed but must be increased for patients with higher physical activity.  
In a Burn center, strategies identified to make it easier to use non-invasive indirect calorimetry on a regular basis are: 
local recommendations on how and when to use indirect calorimetry 
trained personnel 
decision on when to measure indirect calorimetry during rounds documented in the patients’ records and on patients´ activity board at the ward 
prepare patient the day before measurement 
measurement early in the morning  
Conclusion: Indirect calorimetry, non-invasive measurements can be difficult but are possible to perform on a regular basis in a Burn center.

7 - Indirect calorimetry, non-invasive measurements in practice