The relationship between muscle mass changes and protein or energy intake in critically ill children: A systematic review and meta-analysis

Survivorship after pediatric critical illness is high in developed countries, but many suffer physical morbidities afterwards. The increasing focus on follow-up after critical illness has led to more pediatric studies reporting muscle mass changes (using ultrasound), albeit with different results. A systematic literature review was undertaken examining muscle mass changes, assessed by ultrasound of the quadriceps femoris muscle in children who are critically ill. Secondary objectives were to determine if muscle mass was associated with protein intake and/or energy. Databases were searched in July 2024. Eligible experimental or observational studies, published from January 2010 to July 2024 and including children who are critically ill that were aged between ≥37 weeks' gestational age and 18 years who were admitted to the pediatric critical care unit were included. The Joanna Briggs Institute for observational studies critical appraisal instrument was used to assess studies for methodological quality. One hundred and thirty-five studies were screened, and eight prospective cohort studies were included, involving 411 children. Overall, muscle mass changes reported in seven out of eight of the papers showed a pooled mean muscle mass loss of 8.9% (95% confidence interval [CI] 6.6-11.4) from baseline to days 5-7. Five of the eight publications defined muscular atrophy as a decrease in muscle mass of >10%. Using this cutoff, 92 (49.2%) children developed muscular atrophy during their PICU admission. Overall, muscle mass decreased by nearly 10% during a child's first week in PICU, with almost half of children developing muscular atrophy during their admission.