Body Composition Tools for Assessment of Adult Malnutrition at the Bedside

Abstract

Because of the key role played by the body's lean tissue reserves (of which skeletal muscle is a major component) in the response to injury and illness, its maintenance is of central importance to nutrition status. With the recent development of the Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition diagnostic framework for malnutrition, the loss of muscle mass has been recognized as one of the defining criteria. Objective methods to evaluate muscle loss in individuals with acute and chronic illness are needed. Bioimpedance and ultrasound techniques are currently the best options for the clinical setting; however, additional research is needed to investigate how best to optimize measurements and minimize error and to establish if these techniques (and which specific approaches) can uniquely contribute to the assessment of malnutrition, beyond more subjective evaluation methods. In this tutorial, key concepts and statistical methods used in the validation of bedside methods to assess lean tissue compartments are discussed. Body composition assessment methods that are most widely available for practice and research in the clinical setting are presented, and clinical cases are used to illustrate how the clinician might use bioimpedance and/or ultrasound as a tool to assess nutrition status at the bedside. Future research needs regarding malnutrition assessment are identified.

Bedside Ultrasound Measurement of Rectus Femoris: A Tutorial for the Nutrition Support Clinician

“…This new technique holds great promises in the future given its bedside applicability, but it is imperative to follow a standardized protocol to reduce variations and to document changes in measurements performed at different times [23]. …”

Determination of Nutrition Risk and Status in Critically Ill Patients: What Are Our Considerations?

“…The potential use of various technologies for the assessment of body composition such as computed tomography (CT), ultrasound, and bioelectrical impedance analysis has been explored in various studies in recent years . Skeletal muscle quality revealed by CT scan at the third lumbar vertebra was associated with mortality in critically ill patients .…”

“…However, the routine use of such body composition analysis techniques may be impractical in the mechanically ventilated critically ill population. Fluid and electrolyte abnormalities commonly seen in critically ill patients will influenced the accuracy of bioelectrical impedance analysis, and further research is needed to define the optimal way to conduct ultrasound measurement for a better reliability and validity in the ICU …”

“…35 The potential use of various technologies for the assessment of body composition such as computed tomography (CT), ultrasound, and bioelectrical impedance analysis has been explored in various studies in recent years. 36 Skeletal muscle quality revealed by CT scan at the third lumbar vertebra was associated with mortality in critically ill patients. [37][38][39] However, CT scans are costly, require transfer to a radiology unit, and involve a dose of radiation that limits its usage to patients for whom CT is ordered for other clinical reasons.…”

“…Fluid and electrolyte abnormalities commonly seen in critically ill patients will influenced the accuracy of bioelectrical impedance analysis, and further research is needed to define the optimal way to conduct ultrasound measurement for a better reliability and validity in the ICU. 36 Because low skeletal muscle mass is associated with poor clinical outcomes in the ICU and traditional imaging methods are impractical or not yet validated, alternative measures to diagnosing low skeletal muscle mass may be needed. [37][38][39] The SARC-F is a simple and validated questionnaire used to determine sarcopenia (Appendix 5).…”