Muscle strength assessment in critically ill patients with handheld dynamometry: an investigation of reliability, minimal detectable change, and time to peak force generation

Claire Baldwin, Jennifer Paratz, Andrew Bersten

    Research output: Contribution to journalArticlepeer-review

    59 Citations (Scopus)

    Abstract

    Purpose: Dynamometry is an objective tool for volitional strength evaluation that may overcome the limited sensitivity of the Medical Research Council scale for manual muscle tests, particularly at grades 4 and 5. The primary aims of this study were to investigate the reliability, minimal detectable change, and time to peak muscle force, measured with portable dynamometry, in critically ill patients. Materials and methods: Isometric hand grip, elbow flexion, and knee extension were measured with portable dynamometry. Results: Interrater consistency (intraclass correlation coefficient [95% confidence interval]) (0.782 [0.321-0.930] to 0.946 [0.840-0.982]) and test-retest agreement (0.819 [0.390-0.943] to 0.918 [0.779-0.970]) were acceptable for all dynamometry forces, with the exception of left elbow flexion. Despite generally good reliability, a mean change (upper 95% confidence interval) of 2.8 (7.8) kg, 1.9 (5.2) kg, and 2.6(7.1) kg may be required from a patient's baseline force measurement of right grip, elbow flexion, and knee extension to reflect real force changes. There was also a delay in the time for critically ill patients to generate peak muscle forces, compared with healthy controls (P ≤ .001). Conclusions: Dynamometry can provide reliable measurements in alert critically ill patients, but moderate changes in strength may be required to overcome measurement error, during the acute recovery period. Deficits in force timing may reflect impaired neuromuscular control.

    Original languageEnglish
    Pages (from-to)77-86
    Number of pages10
    JournalJournal of Critical Care
    Volume28
    Issue number1
    DOIs
    Publication statusPublished - Feb 2013

    Keywords

    • Intensive care
    • Muscle strength dynamometer
    • Muscle weakness
    • Quadriceps muscle
    • Skeletal muscle

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