Acute skeletal muscle wasting in patients with acute kidney injury requiring continuous kidney replacement therapy: A prospective multicenter study

Purpose: Acute kidney injury (AKI) requiring continuous kidney replacement therapy (CKRT) has been hypothesized to increase the risk of developing intensive care unit-associated weakness (ICU-AW), but prospective data are lacking. Materials and methods: This prospective observational study evaluated critically ill adults with AKI requiring CKRT at two U.S. academic hospitals. Using ultrasonography (US), we quantified changes in rectus femoris (RF) muscle mass and quality in the first week after CKRT initiation. At hospital discharge, we assessed for ICU-AW, physical function, and frailty. Results: Twenty-three patients with median age 56 [IQR 47–60] years, BMI 29 [26–36] kg/m², and Charlson Comorbidity Index 3 [1.5–5] were enrolled. The baseline Sequential Organ Failure Assessment (SOFA) score was 9 [7.5–11.5] and CKRT duration was 4 [1–7] days. Six (26 %) patients died in the ICU and one (4 %) transitioned to comfort measures before study completion. Substantial muscle wasting occurred between Day 1 and Day 7: RF muscle thickness (mT) decreased by 10 % [3 %–20 %]; RF cross-sectional area (CSA) decreased by 19 % [12 %–22 %]; and echo intensity (EI) increased (implying worse muscle quality) by 14 % [5 %–25 %]. A significant effect of time within subjects was observed for all three ultrasound measures (CSA: F = 66.2, p < 0.001; mT: F = 27.1, p < 0.001; EI: F = 22.5, p < 0.001). At hospital discharge, 67 % of survivors (n = 10/15) met criteria for ICU-AW. Conclusions: Patients with AKI requiring CKRT experienced significant muscle wasting in the first week following CKRT initiation and had high rate of ICU-AW at hospital discharge. Trial registration: NCT05287204, Registered 20 October 2021.