The British journal of nutrition
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To assess energy balance in very sick medical patients requiring prolonged acute mechanical ventilation and its possible impact on outcome, we conducted an observational study of the first 14 d of intensive care unit (ICU) stay in thirty-eight consecutive adult patients intubated at least 7 d. Exclusive enteral nutrition (EN) was started within 24 h of ICU admission and progressively increased, in absence of gastrointestinal intolerance, to the recommended energy of 125.5 kJ/kg per d. Calculated energy balance was defined as energy delivered - resting energy expenditure estimated by a predictive method based on static and dynamic biometric parameters. ⋯ Using receiver operating characteristic curve analysis, the best deficit threshold for predicting ICU mortality was 5021 kJ per d. Kaplan-Meier analysis showed that patients with mean energy deficit > or =5021 kJ per d had a higher ICU mortality rate than patients with lower mean energy deficit after the 14th ICU day (P = 0.01). The study suggests that large negative energy balance seems to be an independent determinant of ICU mortality in a very sick medical population requiring prolonged acute mechanical ventilation, especially when energy deficit exceeds 5021 kJ per d.