Protein requirements, morbidity and mortality in critically ill patients: fundamentals and applications.

Recent evidence suggests that a negative protein balance secondary to severe disease is associated with increased morbidity. A loss of total body protein is inevitable in this scenario, even with an aggressive nutritional approach, primarily due to the catabolism of skeletal muscle fibers. The ubiquitin-proteasome system is the primary metabolic and biochemical mechanism involved in this process; paradoxically, this system consumes adenosine triphosphate as its energy source.

Assessement of resting energy expenditure of obese patients: comparison of indirect calorimetry with formulae.

Background & Aims: Determining the caloric expenditure of overweight (Body mass index - BMI from 25-29.9 kg/m(2)) or obese (BMI> or =30 kg/m(2)) patients is a difficult task. The importance of the measurement using indirect calorimetry (IC) is to avoid the administration of an inadequate caloric load, which can increase clinical morbidity.

Indirect calorimetry: methodology, instruments and clinical application.

Purpose Of Review: This review aims to identify the basic methods for accurately measuring a patient's energy expenditure in clinical nutrition practice by indirect calorimetry, and the impact upon a disease state of applying the results obtained.

Recent Findings: The open-circuit method is the most widely used in the majority of classical instruments for measuring energy consumption. Advances in gas exchange measurement have made this technique readily and precisely available at the bedside.

Can measured resting energy expenditure be estimated by formulae in daily clinical nutrition practice?

Purpose Of Review: To recognize the fundamental factors that alter energy expenditure on a daily basis and the impact they have on the measurement of caloric consumption by the human body, through respiratory indirect calorimetry, and thus to try to determine which predictive equation best correlates with total energy expenditure generated from energy measurements.

Recent Findings: The most important compartment of the body, for its metabolic activity and influence upon resting metabolic rate, is fat-free mass. Other variables affecting energy expenditure are sex, weight, height, age, body surface area, fat mass and ethnicity.