The Use of Musculoskeletal Ultrasound for Early Detection of Intensive Care Unit-acquired Weakness in Critically Ill Adults: A Prospective Observational Study

Background and aims: Intensive care unit-acquired weakness (ICU-AW) is assessed by the Medical Research Council (MRC) sum score.Ultrasound (US) imaging of limb muscles has emerged as an alternative.This study evaluated the relationship between trends in changes in muscle thickness, echogenicity, and fasciculations during the first 7 days of ICU stay, measured by US, and ICU-AW diagnosed on the basis of MRC sum score among critically ill adult patients.Patients and methods: This was a single academic center, prospective, observational study of patients expected to stay in the ICU for at least 7 days.Medical Research Council sum score and trend of changes in muscle thickness, echogenicity, and fasciculation in all four limbs were evaluated at days 1, 4, and 7 and statistically analyzed to elicit the relationship between the trend of changes in muscle thickness, echogenicity, and fasciculation and ICU-AW.Results: A ≥7.3% reduction in biceps brachii and brachialis thickness predicted ICU-AW at day 7 [sensitivity, 90.9%; specificity, 71.2%; area under the receiver operating characteristic curve (AUROC), 0.87].Grade II echogenicity at tibialis anterior [adjusted odds ratio (aOR): 7.6, 95% confidence interval (CI): 1.21-47.5,p = 0.03] and grade III echogenicity at quadriceps femoris (aOR: 15.4, 95% CI: 1.3-184.3,p = 0.03) were associated with ICU-AW at day 4 and day 7, respectively.Total muscle fasciculation (MF) score ≥3 had a sensitivity of 100% and specificity of 30.1% (AUROC, 0.65) at day 7. Conclusions: Grade II tibialis anterior echogenicity, grade III quadriceps femoris echogenicity, and ≥7.3% biceps brachii and brachialis muscle thickness loss can predict ICU-AW as early as 4-7 days after ICU admission, while low specificity limits the diagnostic value of MFs.