Inter- and intra-observer variability of ultrasonographic arm muscle thickness measurement by critical care physicians

PURPOSE: The aim of this study was to assess inter- and intra-observer variability of arm muscle thickness measured by critical care physicians using bedside ultrasonography (USG). METHODOLOGY: This prospective study included twenty patients admitted with sepsis. Three measurements of thickness of right arm muscles of each patient using B-mode USG were taken by two critical care fellows, independently. Intra- and inter-observer reliability was tested using intraclass correlation coefficient (ICC). RESULTS: The mean 1(st), 2(nd), and 3(rd) measurements of muscle thickness recorded by observer 1 and 2 were 23.620 (±4.171) versus 23.840 (±3.849) mm, 23.235 (±3.620) versus 23.625 (±4.062) mm, and 24.125 (±4.098) versus 23.965 (±3.651) mm, respectively. The average muscle thickness measured by first and second observer was 23.660 (±3.834) mm and 23.810 (±3.674) mm, respectively. ICC for intra-observer variability for observer 1 and 2 was 0.964 (95% confidence interval [CI] 0.924–0.985) and 0.949 (95% CI 0.892–0.978), respectively. ICC for inter-observer variability was 0.995 (95% CI 0.988–0.998). CONCLUSIONS: USG is a reliable tool for assessment of arm muscle thickness by critical care physicians.