Handgrip and inspiratory muscle strength as surrogates for intensive care unit-acquired weakness: A prospective cohort study in Taiwan

Abstract

Objective: The objective of this prospective cohort study was to investigate the incidence of intensive care unit (ICU)-acquired weakness (ICUAW) and compare handgrip strength (HGS) and inspiratory muscle strength, measured by maximum inspiratory pressure (MIP), between critical illness survivors with and without ICUAW. Additionally, we examined whether HGS and MIP could serve as surrogate measures for ICUAW and establish reference cut-off values for both HGS and MIP in Taiwanese ICU survivors.

Methods: A total of 274 ICU survivors aged ≥20 yrs without prior systemic weakness from six medical ICUs at a tertiary care hospital in Taiwan were consecutively enrolled. ICUAW was identified at the time of ICU discharge using standardised manual muscle testing based on the Medical Research Council scale. Simultaneously, HGS and MIP were assessed. A receiver operating characteristic curve analysis was performed to evaluate whether HGS and MIP could serve as surrogate markers for ICUAW and to establish their cut-off values.

Results: Among the 406 enrolled participants, 310 survived their ICU stay, and 274 completed the Medical Research Council test upon ICU discharge. The survivors were predominantly male (65.7%), with a median age of 70 years (interquartile range: 59-80). Acute respiratory failure was the leading cause of ICU admission (52.9%), and 60.2% of patients required mechanical ventilation during their ICU stay, with a median duration of 8 days (interquartile range: 3-8). ICUAW was identified in 23.0% of survivors. Fewer participants in the ICUAW group were able to complete HGS (87.1%) and MIP (45.2%) assessments, likely due to physical limitations. Compared with those without ICUAW, the ICUAW group was significantly older, had higher Acute Physiology and Chronic Health Evaluation scores at admission, required longer mechanical ventilation, had longer ICU stays, and displayed weaker HGS and lower MIP at ICU discharge. The receiver operating characteristic curve analysis demonstrated that both HGS and MIP served as promising surrogate markers with areas under the curve of 0.842 and 0.822, respectively, and optimal cut-offs of 10.9 kg-force for HGS and 22.5 cmH₂O for MIP. Additionally, sex-specific cut-offs were also identified.

Conclusions: HGS and MIP show promise as surrogate markers for ICUAW, with our ICU survivor cohort revealing comparable HGS and lower MIP cut-off values compared to previous recommendations. These results emphasise the importance of tailored cut-offs and screening approaches for different ethnic and geographic regions. Additionally, they provide preliminary reference values for ICU survivors in Taiwan and highlight the need for further studies in the region.

Keywords: Critically ill survivors; Functional ability; Handgrip strength; Intensive care unit–acquired weakness; Maximum inspiratory pressure.