Using bedside ultrasound to screen for sarcopenia in older adults

Sarcopenia, age-related decline of muscle mass, strength, and physical performance, is associated with adverse clinical outcomes and functional disabilities in older adults. Point-of-care ultrasound (POCUS) has emerged as a promising tool for evaluating skeletal muscle mass and quality in recent years. POCUS is advantageous over other commonly used diagnostic methods, such as dual-energy X-ray absorptiometry (DXA) and computed tomography (CT), including greater accessibility, non-invasive nature, low cost, and portability. The objective of this dissertation was to expand the clinical applications of POCUS beyond muscle mass measurement alone. Five separate studies were conducted to evaluate the utility of POCUS-measured muscle thickness (MT), subcutaneous fat thickness (SFT), and echo intensity (EI) in predicting low muscle mass, total body fat percentage, frailty, and length of hospital stay. The key strength of this work was its assessment of multiple muscle sites to identify the most reliable and clinically informative locations. POCUS was used to measure MT and SFT at numerous upper- and lower-limb sites, while muscle strength was assessed using handgrip dynamometry. Outcomes included low muscle mass, total body fat percentage, frailty, and the length of hospital stay. Lastly, data from all three cohorts were pooled to establish reference values for quadriceps MT. Quadriceps and biceps muscles were superior to the triceps and gastrocnemius in predicting low muscle mass and total body fat percentage in both females and males. Quadriceps MT predicted the hospital length of stay among admitted patients, and the results were comparable with the commonly used indicator, the Charlson Comorbidity Index (CCI). EI was associated with Clinical Frailty Scores. Reference values for quadriceps MT were established to support clinical interpretation and future research. Overall, this dissertation provides comprehensive evidence supporting the clinical utility of POCUS for assessing muscle and fat composition, and clinical outcomes in older adults. POCUS represents a practical, bedside tool that may enhance early identification of common geriatric conditions and related risks and inform clinical decision-making in geriatric care.