title: Muscle strength assessment in critically ill patients with handheld dynamometry: an investigation of reliability, minimal detectable change, and time to peak force generation.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: Faculty of Health Sciences, School of Medicine, Department of Critical Care Medicine, Flinders University, Flinders Drive, Bedford Park, South Australia, 5042, Australia. claire.baldwin@health.sa.gov.au
authors.forename: Claire E
authors.initials: CE
authors.lastname: Baldwin
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Paratz
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bersten
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D016638:Critical Illness; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D053581:Muscle Strength Dynamometer; D018908:Muscle Weakness / Q000175:diagnosis* / Q000534:rehabilitation; D015588:Observer Variation; D019095:Point-of-Care Systems; D052097:Quadriceps Muscle; D015203:Reproducibility of Results; D016037:Single-Blind Method