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Study objectives: Nutritional support of ICU patients is usually guided by estimations of their caloric needs. However, recent studies have shown that energy expenditure (EE) of critically ill patients is not as high as previously thought. The goal of this study was to measure EE in ICU patients, compare it with estimated EE and evaluate nutritional support.

Methods: Energy expenditure was measured with indirect calorimetry in a broad group of ICU patients requiring mechanical ventilation >48hours. In comparison EE was estimated with the Harris-Benedict equation. Nutritional support during ICU stay was registered.

Results: Mean measured EE of 56 patients was 1820 ± 419 kcal/day or 22 kcal/kg/day. The Harris- Benedict equation underestimated EE by 11%, but adding a stress factor resulted in 15% overestimation. Mean nutritional support was 1175 ± 442 kcal/day or 67% of EE. The energy deficit was greatest during the first week of ICU stay. Mean protein administration was 0,44 g/kg/day.

Conclusion: Measured EE of ICU patients was less than nutritional support recommended by international guidelines. These results are in accordance with recent studies. Nutritional support was only 67% of measured energy expenditure and protein content less than recommended. Further studies are needed as it has not be shown how this might influence outcome.

Icel Med J 2009; 95: 491-7