Evaluation of Changes in Quadriceps Femoris Muscle in Critically III Children Using Ultrasonography

Objective To measure changes in muscle thickness and echogenicity, reflecting muscle bulk and quality, respectively, of quadriceps femoris (QF), in critically ill children. Methods This study was done on 58 children aged 1–18 y requiring mechanical ventilation, admitted in a pediatric intensive care unit (PICU) of a tertiary care hospital from January 2018 to June 2019. QF thickness was measured twice in longitudinal plane and twice in transverse plane, and an average of these four measurements was used. Muscle quality was assessed using ImageJ software to determine the mean echogenicity, and was calculated separately for vastus intermedius and rectus femoris. These observations were repeated on day 3 and day 7 of the ICU stay. Results The median muscle thickness of QF was 1.58 cm, and vastus intermedius and rectus femoris echogenicity was 35.5 and 25.88 units, respectively in the present cohort, with median age of 6 y. Only 36 of the 58 patients underwent day 7 ultrasonography, as the remainder were either extubated or died. There was no significant change in the muscle thickness over 7 d. Rectus femoris echogenicity increased significantly over 7 d by 16.1% ( p = 0.03). Baseline vastus intermedius echogenicity was significantly higher in patients who subsequently died during the course of their illness ( p = 0.026). Conclusion There was a significant change in rectus femoris echogenicity, but not in QF thickness. Echogenicity rather than muscle thickness may be a more sensitive marker for changes in muscle properties.