[Energy requirements in the ICU. Calorimetry and expert opinion]

To compare the method for calculating the energy requirements in critical patients as calculated by our computer software with those measured using calorimetry and using the recommendations of experts in nutritional support. REFERENCE POPULATION: 18 critical patients with mechanical ventilation and admitted to our ICU during 1998.

Indirect calorimetry was carried out over a 24 hour period in critical patients with mechanical ventilation and their requirements were calculated using computer software. Ten of the measurements were placed on Internet web pages in order to receive the comments and recommendations of nutritional support experts. Those responses which fell into the range between 80% and 120% of the calorimetric measurement were considered correct.

Calorimetric determinations were effected on 31 occasions in 18 patients, with an average APACHE score of 19 +/- 3. The energy requirements measured by calorimetry were 34 +/- 3 kcal/kg/day with 0.34 +/- 16 g/kg/day of nitrogen in urine, whereas the recommendations of the computer programme were 31 +/- 1 kcal/kg/day and 0.28 +/- 0.04 g/kg/day of nitrogen in urine, i.e. 92 +/- 8% of the former values. The responses by the experts to 10 of these measurements came very close to those of the programme, with 33 +/- 6 kcal/kg/day and 0.29 +/- 0.06 gr/kg/day of nitrogen, with a percentage of correct responses of around 68%.

The method for calculating the energy requirements used by our computer software constitutes around 92% of the calorimetric measurements in critical patients with mechanical ventilation and the responses are very similar to the average of the responses given by experts in nutritional support.