2021 Volume 55 Issue 6 Pages 273-280
Abstract：Skeletal muscle mass is an important indicator of clinical outcomes in critically ill patients. However, limb muscle atrophy occurs in approximately 18％ ten days after admission to the intensive care unit. Moreover, atrophy of the respiratory muscles, including the diaphragm, occurs in patients on mechanical ventilation. As muscle atrophy in the acute phase is associated with mortality and impaired physical function, skeletal muscle assessment is important in critically ill patients. Skeletal muscle mass can be assessed using computed tomography （CT）, ultrasound, bioelectrical impedance analysis （BIA）, and biomarkers. CT is useful for accurately measuring the muscle mass and measurement is conducted at the level of the third lumbar vertebra as the gold standard. However, muscle mass assessment using CT is retrospectively conducted because CT accompanies radiation exposure and requires the patients to be transported to the examination room. On the other hand, ultrasound and BIA are noninvasive and available at the bedside, and can be used for longitudinal skeletal muscle assessment. However, these methods require accurate knowledge and skills. Assessments using BIA should be carefully interpreted because critically ill patients exhibit dynamic fluid changes. These methods can be used for qualitative and quantitative skeletal muscle assessments. Furthermore, several biomarkers have been reported to be useful for the assessment of skeletal muscle mass. This review provides appropriate methods for skeletal muscle assessment, thereby widening clinical and research applications to improve the clinical outcomes of critically ill patients.
