Body cell mass evaluation in critically ill patients: killing two birds with one stone

Body cell mass (BCM) is the metabolically active cell mass involved in O(2) consumption, CO(2) production and energy expenditure. BCM measurement has been suggested as a tool for the evaluation of nutritional status. Since BCM is closely related to energy expenditure, it could also represent a good reference value for the calculation of nutrient needs. In a recent issue of Critical Care, Ismael and colleagues used bioelectrical impedance analysis parameters and anthropometric variables to evaluate BCM in patients with acute kidney injury, before and after a hemodialysis session. The results of this study suggest that BCM is relatively insensitive to major body fluid shifts, a well known factor interfering with nutritional evaluation/monitoring and energy need calculations in the ICU. Thus, BCM seems to be a more 'stable' nutritional variable, as it is apparently less influenced by non-nutritional factors. The results of this paper emphasize the need to identify biologically sound parameters for nutritional status evaluation and energy need calculation in critically ill patients; in this regard, BCM could fulfill these expectations.