Bedside Ultrasound Predicts ICU-Acquired Weakness Within 4–7 Days, Suggests Study

Although intensive care unit-acquired weakness (ICU-AW) affects nearly half of critically ill adults, traditional strength assessment using the Medical Research Council (MRC) sum score is constrained by the requirement for awake and cooperative subjects, creating a clinical gap where alternative modalities like electrophysiology, biopsy, or advanced imaging remain impractical at the bedside. To address this diagnostic challenge, Dr. Sabin Bhandari from the Department of Anaesthesiology and Critical Care at B.P. Koirala Institute of Health Sciences, along with co-authors from Tribhuvan University Teaching Hospital, aimed to evaluate whether serial ultrasound monitoring of limb muscle thickness, echogenicity, and fasciculations during the first week of critical illness could reliably predict subsequent weakness.

Therefore, the single-center prospective study in Nepal evaluated 108 critically ill adults using serial bedside muscle ultrasonography and blinded Medical Research Council sum scoring on days 1, 4, and 7. Investigators tracked changes in muscle thickness, echogenicity, and fasciculations across four limb muscle groups to assess their diagnostic accuracy in predicting intensive care unit-acquired weakness.

Key Clinical Findings of the Study Includes:

• Biceps Thickness Reduction: Investigators demonstrated that a ≥7.3% decrease in biceps brachii and brachialis thickness by day 7 predicted weakness with 90.9% sensitivity, 71.2% specificity, and an AUROC of 0.87.
• Early Tibialis Anterior Changes: Researchers identified that grade II Heckmatt echogenicity in the tibialis anterior independently predicted early weakness at day 4 with an adjusted odds ratio (aOR) of 7.6 (95% confidence interval [CI]: 1.21–47.5, p = 0.03).
• Late Quadriceps Involvement: Authors observed that grade III Heckmat's echogenicity in the quadriceps femoris at day 7 was independently associated with weakness, yielding an aOR of 15.4 (95% CI: 1.3–184.3, p = 0.03).
• Unreliable Fasciculation Score: Scientists found that a total muscle fasciculation score ≥3 provided 100% sensitivity but only 30.1% specificity (AUROC: 0.65) at day 7, demonstrating limited utility as an isolated diagnostic tool.

The results suggest that a ≥7.3% reduction in upper-arm muscle thickness alongside elevated lower-limb echogenicity—specifically grade II in the tibialis anterior and grade III in the quadriceps femoris—can effectively detect ICU-AW between 4 and 7 days after admission.

Bedside musculoskeletal ultrasonography can serve as a practical non-invasive adjunct to routine clinical evaluation, aiding clinicians in early screening for muscle degradation in critically ill patients who cannot undergo voluntary strength assessment.

Although operator dependency, single-center design, and the absence of confirmatory electromyography or muscle biopsy represent notable study constraints, larger multicenter investigations are encouraged to refine standardized sonographic protocols across diverse critical care populations.

Reference

Bhandari S, Shrestha PS, Paneru HR, Shrestha GS, Acharya SP. The Use of Musculoskeletal Ultrasound for Early Detection of Intensive Care Unit-acquired Weakness in Critically Ill Adults: A Prospective Observational Study. Indian J Crit Care Med 2026;30(9):786–792.