Responsiveness of the K-Force Grip Dynamometer in patients with ICU-acquired weakness: a prospective longitudinal study

OBJECTIVE: Handgrip strength is commonly used to assess muscle strength in critically ill patients, including those with intensive care unit-acquired weakness. While the reliability and validity of the K-force grip dynamometer have been established, its responsiveness remains unknown. This study evaluated the responsiveness of handgrip strength measured with the K-force grip dynamometer in intensive care unit-acquired weakness patients. METHODS: In this prospective longitudinal study, intensive care unit-acquired weakness patients were assessed at baseline and after 1 week. Responsiveness was examined using effect sizes and standardized response means. The Medical Research Council sum score was included as a clinical comparator of global measure strength. Changes over time were analysed using Wilcoxon signed-rank tests. RESULTS: Thirty-six patients were included. Dominant handgrip strength increased from 2650 g to 3450 g, with an effect size of r = 0.86 and standardized response means of 0.77 (p < 0.001). Non-dominant handgrip strength increased from 2,700 g to 3,783 g, with an effect size of r = 0.90 and SRM of 0.70 (p < 0.001). Medical Research Council sum score increased from 26.5 to 30.0 (p < 0.001). CONCLUSION: The K-force grip dynamometer demonstrated strong responsiveness in patients with intensive care unit-acquired weakness, supporting its use for detecting short-term changes in handgrip strength in critically ill patients.