Preventing Caloric Deficits
How to define caloric goals for ICU patients
The risks arising from a caloric deficit
Without an adequate nutrition, a patient can develop a caloric deficit, worsening his/her overall outcome. If a caloric deficit is maintained over time, this can lead to severe malnutrition and impair the patient’s recovery.
In ICU patients who accumulate caloric deficits during the first days of admission, it is difficult to compensate these deficits later on, which can impair their outcome.1,2 Research shows that in critically ill patients with a cumulated caloric deficit of approximately 5,000 – 9,000 kcal within the first ICU week or >100 kcal/kg BW/d infectious complications occur more often.1,3,4 Furthermore, early nutritional deficits are associated with an increase in antibiotic use, mechanical ventilation, ICU stay and mortality.5,6,7
An increased ICU mortality for example has been observed in mechanically ventilated patients with a mean negative cumulative energy balance of approximately 3,550 (± 4,591) kcal.8
Therefore, in order to achieve adequate nutritional support, nutrition management should be started as early as possible.
According to Professor Pierre Singer MD, Chairman of ESPEN and director of the general intensive care department, Rabin Medical Center, in Tel Aviv (Israel), many observational studies have shown that bigger caloric deficits lead to more complications.9 Nevertheless, he calls to attention that providing too much energy can result in complications as well. Hence, it is necessary to individually adjust energy support as good as possible.
Estimation of energy requirements
Today, indirect calorimetry is the preferred method for estimating a patient’s energy requirements.10 However, this method is not always feasible. One alternative is an estimation of the requirements based on a patient’s caloric target using the following formula:10,11
- < 20-25 kcal per kilogram (kg) of body weight per day in the early acute phase of critical illness
- 25-30 kcal/kg of body weight per day in the recovery phase / stabilized patients
A patient’s individual energy needs can also be evaluated by either directly measuring the resting energy expenditure (REE) or by using an equation that calculates the REE, such as the Harris-Benedict equation:
Activity or trauma factors must then be considered to account for increased energy requirements due to physical activity and metabolic stress related to the underlying disease:12
Why energy expenditure increases in critical ill patients
The REE is the amount of energy a person needs under normal physiological conditions during phases of rest, for example breathing and cardiac function. In situations when the body is experiencing physiological stress, such as in cases of surgery or serious illness, energy requirements differ.13
During a period of simple starvation, the body conserves energy stores by reducing energy expenditure. The purpose of this is to keep normal physiological processes functioning until nutritional intake is restored. During physiological stress however, the body reacts differently. The body’s stress response involves various changes in hormone levels causing an increase in REE and therefore energy requirements during critical illness. Patients in catabolic state rapidly break down all their body’s nutrient stores to ensure an immediate supply of nutrients, such as glucose, to provide energy, raise body temperature and induce fever to fight infection.13
Protein stores are broken down to convert them into essential proteins. To avoid that protein is misused as energy by the body, both glucose and protein need to be supplied in parallel to the patient. Protein break down and the absence of protein synthesis are two reasons why muscle loss occurs in critically ill patients.14
Due to these processes it is important that critically ill patients are adequately fed and caloric deficits are avoided by providing sufficient calories.
- 1. a. b. Villet S, Chiolero R, Bollmann M et al. Negative impact of hypocaloric feeding and energy balance on clinical outcome in ICU patients. Clin Nutr 2005;34:502-509.
- 2. Singer P, Pichard C, Heidegger CP et al. Considering energy deficit in the intensive care unit. Curr Opin Clin Nutr Metab Care 2010;13(2):170-176. doi: 10.1097/MCO.0b013e3283357535.
- 3. Dvir D, Cohen J, Singer P. Computerized energy balance and complications in critically ill patients: An observational study. Clin Nutr 2006;25:37-44.
- 4. Faisy C, Candela Llerena M, Savalle M et al. Early ICU Energy Deficit Is a Risk Factor for Staphylococcus aureus Ventilator-Associated Pneumonia. Chest 2011;140(5):1254-1260. doi:10.1378/chest.11-1499.
- 5. Alberda C, Gramlich L, Jones N et al. The relationship between nutritional intake and clinical outcomes in critically ill patients: results of an international multicenter observational study. Intensive Care Med 2009;35:1728–1737.
- 6. Petros S, Horbach M, Seidel F et al. Hypocaloric vs Normocaloric Nutrition in Critically Ill Patients: A Prospective Randomized Pilot Trial. JPEN April 3, 2014.
- 7. Rubinson L, Diette GB, Song X et al. Low caloric intake is associated with nosocomial bloodstream infections in patients in the medical intensive care unit. Crit Care Med 2004;32:350-357.
- 8. Singer P, Anbar R, Cohen J et al. The tight calorie control study (TICACOS): a prospective, randomized, controlled pilot study of nutritional support in critically ill patients. Intensive Care Med 2011;37(4):601-609.
- 9. Singer P. Clinical consequences of energy deficit in ICU. Retrieved from http://www.espen.org/education/electronic-video-library/pearls-of-knowle....
- 10. a. b. Singer P, Hiesmayr M, Biolo G et al. Pragmatic approach to nutrition in the ICU: Expert opinion regarding which calorie protein target. Clin Nutr 2014 Apr;33(2):246-251.
- 11. Kreymann KG, Berger MM, Deutz NE et al. ESPEN Guidelines on Enteral Nutrition: Intensive Care. Clin Nutr 2006;25(2):210-223.
- 12. Austrian Society of Clinical Nutrition (AKE). Recommendations for enteral and parenteral nutrition in adults. Vienna 2008.
- 13. a. b. Fletcher J. Giving nutrition support to critically ill adults. Nursing Times 2015;111:12-16. Retrieved from http://www.nursingtimes.net/home/specialisms/nutrition/giving-nutrition-....
- 14. Schefold JC et al. Intensive care unit-acquired weakness (ICUAW) and muscle wasting in critically ill patients with severe sepsis and septic shock. Journal of Cachexia, Sarcopenia and Muscle 2010;1(2):147-157.