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Updated: Apr 8, 2026
Author Spotlight: Assessing Surgical Frailty with Point-of-Care Ultrasound of Quadriceps Muscles
Published on: July 26, 2024
Interobserver Reliability of Quantitative Muscle Sonographic Analysis in the Critically Ill Population
Aarti Sarwal1, Selina M Parry2, Michael J Berry2
1Departments of Neurology (A.S., M.S.C.), Anesthesiology, Section on Critical Care Medicine (A.S.), Biostatistical Sciences, Division of Public Health Sciences (F.-C.H.), and Internal Medicine, Section on Critical Care Medicine (P.E.M., S.D.), Wake Forest School of Medicine, Winston-Salem, North Carolina USA; Department of Physiotherapy, Austin Health, Melbourne, Victoria, Australia (S.M.P., S.B.); University of Melbourne, Melbourne, Victoria, Australia (S.M.P., L.D.); and Department of Health and Exercise Science, Wake Forest University, Winston-Salem, North Carolina USA (M.J.B., M.T.L., N.W.J.). asarwal@wakehealth.edu.
Objectives:
There is growing interest in the use of quantitative high-resolution neuromuscular sonography to evaluate skeletal muscles in patients with critical illness. There is currently considerable methodological variability in the measurement technique of quantitative muscle analysis. The reliability of muscle parameters using different measurement techniques and assessor expertise levels has not been examined in patients with critical illness. The primary objective of this study was to determine the interobserver reliability of quantitative sonographic measurement analyses (thickness and echogenicity) between assessors of different expertise levels and using different techniques for selecting the region of interest.
Methods:
We conducted a cross-sectional observational study in neurocritical care and mixed surgical-medical intensive care units from 2 tertiary referral hospitals.
Results:
Twenty diaphragm and 20 quadriceps images were evaluated. Images were obtained by using standardized imaging acquisition techniques. Quantitative sonographic measurements included muscle thickness and echogenicity analysis (either by the trace or square technique). All images were analyzed twice independently by 4 assessors of differing expertise levels. Excellent interobserver reliability was obtained for all measurement techniques regardless of expertise level (intraclass correlation coefficient, >0.75 for all comparisons). There was less variability between assessors for echogenicity values when the square technique was used for the quadriceps muscle and the trace technique for the diaphragm.
Conclusions:
Excellent interobserver reliability exists regardless of expertise level for quantitative analysis of muscle parameters on sonography in the critically ill population. On the basis of these findings, it is recommended that echogenicity analysis be performed using the square technique for the quadriceps and the trace technique for the diaphragm.
