Ultrasound-Derived Muscle Biomarkers as a Gateway toward Quantitative Pediatric Frailty in Palliative Care.

BACKGROUND

Adult frailty scales rely on performance tests that are rarely feasible in children. Quantitative muscle ultrasound (US) could provide an objective bridge, but its pediatric utility is untested.

OBJECTIVE

To explore whether US-derived biomarkers Z-scores can cluster into recognizable patterns that serve as preliminary building blocks toward a quantitative definition of pediatric frailty.

DESIGN AND

SETTING

Eight-month, single-center exploratory cross-sectional observational study in a pediatric palliative care unit.

PARTICIPANTS

Twenty-four consecutively enrolled children (1-18 years) with advanced but clinically stable, life-limiting conditions (83.5% neurometabolic, 16.5% oncologic), recruited with parental informed consent.

PROCEDURES: Rectus femoris and vastus intermedius were scanned with standardized presets (64 dB gain; 4 cm depth). Age- or weight-adjusted Z-scores for muscle thickness, echo-intensity (EI), and subcutaneous-fat were derived from a published pediatric dataset. Each child was plotted in 3-D "health cubes" (x = muscle-thickness z, y = EI z, z = subcutaneous-fat z).

RESULTS

All patients lay outside the ± 2 SD "normality cube" for at least one reference set.Median (IQR) muscle-thickness z = -4.9 (-5.6 to -4.1); EI z = +3.7 (+2.1 to +5.8).Thickness and EI were inversely correlated (ρ = -0.62, p = 0.002); lower thickness modestly predicted shorter time-to-death (ρ = -0.55, p = 0.01).

CONCLUSIONS

In this modest, single-center cohort, pediatric palliative patients consistently deviated from normative muscle US ranges, forming a distinct cluster outside the "Работает" 3-D zone. While not diagnostic, these patterns support further, larger, longitudinal studies to develop composite US indices and formal cut-points for pediatric frailty. This visual framework may accelerate that process by highlighting multidimensional outliers at the bedside.