Investigating the rate of skeletal muscle atrophy in men and women in the intensive care unit: a prospective observational study

Muscle atrophy greatly affects the prognosis of patients in the intensive care unit, but the rate of change remains unclear. In this prospective observational study, we used ultrasound to measure the change in muscle thickness of the rectus femoris (RF) and vastus intermedius (VI) in 284 patients who were admitted to the SICU of Taoyuan General Hospital between January 1 and June 30, 2020. Patients were excluded if there is a wound at the right thigh which hinders the ultrasonography probe from placing. Daily rates of muscle atrophy were calculated using linear analysis and the ratios of change were plotted against the period of hospitalization. Patient characteristics were adjusted using propensity score matching and differences between men and women were analyzed. A linear mixed model was used to calculate the influence of other factors on muscle loss. The average daily atrophy rates of the RF and VI were 0.84% and 0.98%, respectively. The rate of atrophy was the highest in the third and fourth weeks. Daily atrophy rates of the RF and VI were approximately three times higher in women than in men. Protective factors of muscle atrophy included higher BMI and lower initial thickness of the RF and VI. Our study depicts the trend of muscle atrophy in the ICU and suggests more discussion in prevention to be conducted especially for women.