Ultrasound assessment of muscle mass in critically ill patients: A correlation with nutritional support and clinical outcomes

Background: Critically ill patients are at high risk of Intensive Care Unit (ICU) Acquired weakness, which negatively impacts clinical outcomes. Traditional muscle mass and nutritional status assessments are often impractical in the ICU. Ultrasound offers a promising, non-invasive alternative. This study evaluates the relationship between ultrasound-based muscle assessments, patients' nutritional support, and clinical outcomes in the ICU. Methods: A prospective cohort study was conducted in three ICUs of a tertiary center. Daily nutritional intake, ultrasound measurements of the quadriceps muscle (rectus femoris cross-sectional area - RFCSA - and quadriceps muscle layer thickness - QMLT), and clinical data were collected on days 1, 3, and 7 of ICU. Results: A total of 128 patients were included in the analysis, with a mean age of 65.4 (+/- 18.1) years and a median ICU stay of 6 (4-10) days. QMLT decreased by 5 % and 13 %, and RFCSA decreased by 10 % and 27 % on days 3 and 7, respectively. A significant correlation was found between lower caloric and protein intake and greater muscle mass loss within the initial 3 days of ICU admission. Multivariate logistic regression indicated that QMLT reduction significantly contributed to 28-day mortality (adjusted OR 1.088, 95 % CI: 1.018-1.113, p = 0.015). Lower daily caloric and protein intake was depicted in non-surviving patients (p < 0.001). Conclusions: Our study demonstrates that critically ill patients experience significant muscle mass loss within the first 72 h of ICU. QMLT reduction significantly impacts 28-day mortality, with an 8.8 % increase in the odds of death per 0.1 cm reduction.