ULTRASOUND OF THE THENAR EMINENCE ACCURATELY DETECTS LOSS OF MUSCULAR MASS IN PATIENTS ADMITTED TO A SURGICAL INTENSIVE CARE UNIT.

BACKGROUND & AIMS: Patients admitted to intensive care units (ICUs) often experience rapid and severe muscle wasting, which is associated with increased morbidity and mortality. Traditional methods to assess muscle loss, such as computed tomography, are limited by accessibility and radiation exposure. This study aimed to evaluate whether ultrasonographic measurement of the thenar eminence can detect early muscular loss in critically ill patients. METHODS: A prospective, observational study was conducted in the surgical ICU of a tertiary hospital between 2021 and 2024. Forty-one adult patients expected to remain in ICU for at least 96 hours were included. Ultrasonography was performed within the first 24 hours of admission and repeated 72 hours later to assess changes in the depth and width of the thenar muscles (abductor and flexor pollicis brevis). Statistical analysis included paired t-tests or Wilcoxon tests, and correlation analysis with clinical and laboratory parameters. RESULTS: Significant reductions in muscle size were observed in all ultrasonographic parameters. Longitudinal depth decreased by 11.1% (p < 0.001), transversal depth by 10.7% (p = 0.001), and transversal width by 8.1% (p = 0.01). No significant correlation was found between muscle loss and ICU stay, intubation duration, hospital stay, or mortality. However, serum lactate levels showed moderate inverse correlation with all ultrasound parameters (p < 0.05). CONCLUSION: Ultrasound assessment of the thenar eminence is a feasible and sensitive tool to detect early muscle loss in ICU patients. It may serve as a non-invasive bedside method to monitor muscular deterioration and support nutritional or rehabilitative interventions.