Acute skeletal muscle loss in surgically treated patients with severe infected necrotizing pancreatitis: a longitudinal ultrasound study

Abstract

Objective – to evaluate perioperative changes in ultrasound‑derived parameters of peripheral muscle mass, using the cross‑sectional area of the rectus femoris muscle as a representative measure, in patients undergoing surgery for severe acute pancreatitis complicated by infected necrosis. Additionally, changes in handgrip strength were assessed, and the association between ultrasound findings and computed tomography–derived muscle mass indices was analyzed.

Materials and methods. This prospective observational study was conducted at two clinical centers and included 28 patients aged 19 – 59 years who underwent surgery for infected necrotizing pancreatitis. The median length of hospital stay was 49 (39 – 59) days. Serial measurements of the cross‑sectional area (CSA) of the rectus femoris muscle were obtained using a portable ultrasound device equipped with a wireless high‑frequency linear transducer, and handgrip strength was assessed with a dynamometer at three clinically defined time points (T1–T3). Serial measurements were obtained at clinically defined time points reflecting the perioperative course of severe acute pancreatitis: the first examination was performed on day 8 (6 – 10) of hospitalization, and the second on day 29 (26 – 31). In a subgroup of 17 patients with available paired computed tomography (CT) scans, skeletal muscle area (SMA) at the L3 vertebral level was assessed, and the association between changes in ultrasound parameters and CT‑derived measurements was analyzed using Spearman’s rank correlation coefficient. Linear mixed‑effects models were applied to evaluate the longitudinal dynamics of skeletal muscle parameters.

Results. A statistically significant progressive decrease in CSA of the rectus femoris muscle (p<0.001) was observed during hospitalization. The total relative reduction in CSA between T1 and T3 was 20.5%. Modeling the length of hospital stay as a continuous variable confirmed an independent association between CSA decline and time (β=–0.025 cm²/day; p<0.001). The reduction in handgrip strength was even more pronounced (p<0.001), with a total relative decrease of 36.7% between T1 and T3. In the subgroup of patients with paired CT scans, ultrasound‑derived changes in CSA demonstrated a moderate positive correlation with changes in skeletal muscle area (SMA) at the L3 vertebral level (ρ=0.65; p=0.005), supporting the concordance between the two assessment methods.

Conclusions. Patients who underwent surgery for infected necrotizing pancreatitis demonstrated progressive deterioration in both morphological and functional skeletal muscle parameters during hospitalization. A more pronounced decline in muscle strength compared with ultrasound‑derived measures of muscle mass may reflect asynchronous functional and morphological changes in skeletal muscle in the context of severe acute pancreatitis complicated by infected necrosis. These findings support the clinical utility of a combined morphological and functional assessment of muscle status for the timely identification of acute secondary sarcopenia and optimizing nutritional and rehabilitation interventions in this patient population.