Place de l'impédancemétrie dans le dépistage de la dénutrition à l'hôpitalBio-impedance analysis: Screening of denutrition in hospitalized patients

The prevalence of malnutrition is high in patients and tends to worsen during the hospital stay. In the absence of one reliable method to evaluate patients, the assessment of nutritional status is based on a global approach. Body composition measurement by bio-impedance analysis (BIA) is one of these approaches. Body composition measurements can detect malnutrition or abnormal hydration. Fat free mass, fat mass, and total body water are the main body compartments that are evaluated. Determination of abnormal body composition can then guide nutritional support. The reliability of BIA depends on the equation used to predict body composition and the parameters included in the formula (weight, height, sex, age, race, etc.). These parameters allow to minimize measurement errors. Thus, formula developed for specific populations allow to evaluate the nutritional status with reasonable error rates. BIA has been found to be inaccurate with abnormal distribution of body compartments (ascites, dialysis, lypodystrophy, etc.) or extreme weights (cachexia, obesity). Multi-frequency or segmental BIA was developed to overcome hydration abnormalities and variations in body geometry. However, these techniques require further validation. The BIA seems to have some limitations. This review aims to assess the reliability of BIA to detect protein-calorie malnutrition at hospital admission or during nutritional follow-up of patients.