The use of ultrasound in clinical practice is feasible for monitoring muscle mass in critically ill patients. Assessment of muscle mass by ultrasound is clinically relevant and adds value for guiding therapeutic interventions, such as nutritional and physical therapy interventions to maintain muscle mass and promote recovery in critically ill patients.

Critical illness is characterized by substantial hormone- and cytokine-mediated protein metabolism changes in various organs, leading to increased breakdown and decreased synthesis rates. Consequently, a considerable and life-threatening loss of muscle mass occurs. Medical therapeutic measures such as long-term sedation and mechanical ventilation during ICU stay can further enhance this muscle degradation (up to 2 % muscle mass per day leading to clinically relevant symptoms known as ICU-acquired weakness. Nutritional modulation, particularly of dietary amino acids, may have benefits to prevent or attenuate disease-induced muscle wasting. while there are several accurate muscle mass measurement methods and techniques [including computed tomography (CT) scan, bio-impedance analysis and ultrasound], not all are routinely feasible in clinical ICU practice. The use of ultrasound in assessing muscle mass in critically ill patients has gained much attention recently as it is non-invasive and can easily be utilized at the bedside. There are two main goals for the assessment of muscle mass: first, to assess the current muscle mass for the patient as part of (nutritional) diagnosis, and thereby risk stratification and second, to monitor the progression of muscle loss and/or recovery of muscle mass, and create opportunity to examine the effectiveness of therapeutic interventions to reduce muscle loss and/or promote muscle recovery.

Inclusion Criteria:

• all critically ill-patients with Acute Physiologic Assessment and Chronic Health Evaluation II (8) (APACHE II score ) ≥ 25 and could be enterally or parenterally fed in the critical care unit of Assiut University Hospitals.

Exclusion Criteria:

• patients with malabsorption syndrome, previously diagnosed myopathies, traumatic brain injuries, intracerebral hemorrhages and cerebral ischemia.