MUScleNut study

Background: Critically ill patients frequently experience profound skeletal muscle (SM) wasting, to which early detection and effective clinical management remain significant challenges. Ultrasonography (US) provides early objective information about SM compared with usual functional tests. The characteristics of the optimal nutritional support are controversial. This observational study aimed to characterize the SM changes through US in the first week after Intensive Care Unit (ICU) admission and to evaluate the potential interference factors with a focus on nutritional support. Results: A total of 95 patients (age 55.7 ± 16.01 years, 70.5% male) were included. All the ultrasound SM measures tendentially reduced after admission: quadriceps muscle layer thickness (QMLT) 10.03% (0.38 ± 0.73 cm), rectus femoris cross-sectional area (RF-CSA) 10.48% (0.50 ± 1.38 cm2), RF pennation angle (RF-PA) 0.94 ± 4.14 º, RF echogenicity (RF-EG) 1.05 ± 22.33 in echo-intensity gray scale and RF shear wave elastography (RF-SWE) 0.13 ± 1.25 m/s and 3.96 ± 28.10 kPa. A significant association between nutritional risk at baseline and SM changes (QMLT 0.194, p = 0.079 and RF-CSA 0.25, p = 0.027) was observed and confirmed in a linear regression model (1.257 and p = 0.011). No significant associations were found between SM changes and nutritional support. Conclusion: Present findings demonstrate a marked reduction in the SM ultrasound measures evaluated in the first week after ICU admission, mainly in patients at nutritional risk. More evidence on optimal nutritional strategies to attenuate SM wasting is warranted.