Assessment of muscle wasting in intensive care unit patients with and without COVID-19 using ultrasound imaging and bioimpedance analysis

Abstract Background Intensive care unit-acquired weakness (ICU-AW) is a common complication among critically ill patients, including those with COVID-19. While viral myopathy and established ICU-related risk factors predispose patients with COVID-19 to muscle dysfunction, few studies have directly compared muscle wasting and weakness between ICU populations with and without COVID-19 using both structural and functional assessment modalities. Methods This was a small, non-concurrent, propensity score–matched ICU study which compared muscle wasting and strength in patients with and without COVID-19 who remained in the ICU for ≥ 7 days. Muscle thickness was assessed using ultrasound (US), body composition using bioelectrical impedance analysis (BIA), and functional strength using handgrip dynamometry. Measurements were performed on ICU days 1, 5, and 7. To reduce baseline differences, propensity score matching was applied using illness severity, nutritional risk, and mechanical ventilation parameters. Results In total, 143 patients were included (101 without COVID-19, 42 with COVID-19). After propensity score matching, 23 pairs were analysed. US revealed significant within-group reductions in muscle thickness over time in both matched cohorts, with no statistically significant between-group differences. BIA-derived phase angle (PhA) values were consistently lower in patients with COVID-19; however, between-group differences in PhA change lost statistical significance after matching. Handgrip dynamometry revealed a significantly higher incidence of muscle weakness in patients with COVID-19 initially, but this difference was non-significant. Absolute and residual strength remained similar between groups. Conclusions ICU patients both with and without COVID-19 experienced comparable degrees of muscle wasting and weakness when adjusted for baseline characteristics. ICU-AW appears more closely associated with the severity of critical illness and ICU treatments than with SARS-CoV-2 infection itself. US measurements appeared less affected by differences in fluid balance, whereas BIA-derived phase angle was more closely related to hydration status. Handgrip dynamometry provided a simple, objective measure of functional muscle strength at ICU discharge.