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24-Hour Indirect Calorimetry in Mechanically Ventilated Critically Ill Patients![]() ![]()
* Division of Nutritional Sciences and Dietetics,
Julius Centre for Health Sciences and Primary Care, University Medical Centre
Utrecht, The Netherlands; Correspondence: Correspondence: Nicole M. de Roos, PhD, Division of Nutritional Sciences and Dietetics, UMC-Utrecht, internal mail G01.111, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. Electronic mail may be sent to n.deroos{at}umcutrecht.nl.
Background: Energy imbalance in critically ill, mechanically
ventilated patients may lead to medical complications. The nutrition care team
needs accurate, noninvasive, rapid methods to estimate energy requirements. We
investigated whether brief measurements of indirect calorimetry at any time of
the day would give valid estimates of 24-hour energy expenditure (EE).
Methods: EE of 12 mechanically ventilated critically ill patients (6
men, 6 women, mean ± SD age 67 ± 18 years, weight 70.2 ±
8.8 kg) was recorded every minute during 24 hours by indirect calorimetry. All
patients were continuously fed enteral nutrition. Results: Mean
± SD EE was 1658 ± 279 kcal/d (6941 ± 1167 kJ/d). Within
patients, EE during the day fluctuated by 234 kcal in the most constant
patient to 1190 kcal in the least constant patient, with a mean fluctuation of
521 kcal (12 patients). No statistically significant difference (p =
.53) in mean EE between morning (6–12 hours, 1676 kcal), afternoon
(12–18 hours, 1642 kcal), evening (18–24 hours, 1658 kcal), and
night (0–6 hours, 1655 kcal) was found. A 2-hour instead of a 24-hour
measurement resulted in a maximal error of 128 kcal (536 kJ), which was
<10% of the average EE. The maximal error decreased with longer time
intervals. Conclusions: In mechanically ventilated critically ill
patients, 24-hour indirect calorimetry measurements can be replaced by shorter
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Nutrition in Clinical Practice, Vol. 22, No. 2,
250-255 (2007) |
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2 hours) measurements. Time of day did not affect EE. 