Feasibility, reliability, and clinical utility of skeletal muscle assessment with A-mode ultrasonography in hospitalized patients with burns

OBJECTIVES: Amplitude-mode (A-mode) ultrasonography is a promising technique to monitor loss and recovery of skeletal muscle in patients with burns. However, its clinimetric properties are unknown. Therefore, we determined its feasibility, interrater, and intrarater reliability, and clinical utility.

METHODS: Skeletal muscle thickness of upper arms and legs was assessed longitudinally in hospitalized adult patients with ≥ 5 % total body surface area (TBSA) burns, by pairs of two out of five raters. Feasibility was evaluated by % successful assessments, reliability by intra-class correlation coefficients (ICCs), and clinical utility by smallest detectable change (SDC).

RESULTS: Thirty-four patients participated (77 % male; mean age 48 ± 17 y, median TBSA burned 12 % [IQR 7-19]). Images were acquired on 69 % of planned occasions, and 89 % of images could be analyzed. Overall interrater ICCs were ≥ 0.84 (for pairs: 0.63-0.99) and intrarater ICCs were ≥ 0.95 (for pairs: 0.45-0.99). The overall interrater SDC was ≤ 33 % of the measured mean (for pairs: 3-52 %), while intrarater SDC was ≤ 20 % (for pairs: 3-48 %). All five raters could measure legs with moderate to excellent reliability, whereas for arms some demonstrated poor reliability.

CONCLUSION: A-mode ultrasonography assessment of skeletal muscle in patients with burns is feasible. However, reliability and clinical utility are rater-dependent; therefore we recommend assessments by the same rater.