Evaluation of the Validity and Reliability of Muscle Ultrasound in the Detection of Undernutrition

In France, the prevalence of undernutrition in hospitalized patients varies from 30 to 50%. Undernutrition is strongly associated with a decrease in the patient's functional abilities and an increase in morbidity and mortality and healthcare expenses. In 2019, the Global Leadership Initiative on Malnutrition (GLIM) published an international consensus report on diagnostic criteria for undernutrition. The diagnostic criteria are numerous, and include etiological criteria such as reduced food intake; an inflammatory setting; symptoms such as anorexia, fatigue; phenotypic criteria such as weight loss, body mass index (BMI), fat to lean mass ratio, fluid retention, and muscle function. Muscle mass is described as a major diagnostic criterion, since it is on the one hand a direct indicator of protein catabolism related to undernutrition, but also a reflection of functional impairment in the patient, as it is directly associated with functional capacities, autonomy and prognosis. Ultrasound is a reproducible method of muscle assessment. It allows the evaluation of muscle thickness or cross-sectional area of a muscle, the reduction of which, a marker of atrophy, is strongly correlated to its loss of strength and to reference measurements. In addition, ultrasound can be used to assess muscle quality, particularly by evaluating the echogenicity of the muscle. The echogenicity increases when the muscle is altered, linked to the presence of fatty infiltrate and fibrous tissue. The use of ultrasound in the evaluation of the patient's nutritional status, as a tool for assessing muscle function, is developing in the ICU and is associated with an increase in the patient's comorbidities. Studies remain limited to a few patient populations, do not report clear cut-off values to define muscle pathological status, and require more precise definition of ultrasound measurement protocols. The investigators hypothesize that muscle ultrasound is reliable and valid in the evaluation of mu