Handgrip strength predicts difficult weaning but not extubation failure in mechanically ventilated subjects

Abstract

BACKGROUND: Muscle weakness, defined by the Medical Research Council scale, has been associated with delay in mechanical ventilation weaning. In this study, we evaluated handgrip strength as a prediction tool in weaning outcome. METHODS: This was a 1-y prospective study in 2 ICUs in 2 university hospitals. Adult patients who were on mechanical ventilation for at least 48 h and eligible for mechanical ventilation weaning were screened for inclusion. Handgrip strength was evaluated using a handheld dynamometer before each spontaneous breathing trial (SBT). Attending physicians were unaware of handgrip strength and decided on extubation according to guidelines. RESULTS: Eighty-four subjects were included (median age 66 [53–79] y, with a median Simplified Acute Physiology Score II of 49 [37–63]). At the first evaluation, median handgrip strength was significantly associated with weaning outcome as defined by international guidelines: simple (20 [12–26] kg), difficult (12 [6–21] kg), or prolonged (6 [3–11] kg) weaning (P =.008). Time to liberation from mechanical ventilation and ICU stay were significantly longer for subjects classified as having muscle weakness according to the handgrip strength-derived definition (P =.02 and P =.03, respectively). In multivariate analysis, known history of COPD (odds ratio [OR] 5.48, 95% CI 1.44–20.86, P =.01), sex (OR 6.16, 95% CI 1.64–23.16, P =.007), and handgrip strength at the first SBT (OR 0.89, 95% CI 0.85–0.97, P =.004) were significantly associated with difficult or prolonged weaning. Extubation failure, as defined by re-intubation or unscheduled noninvasive ventilation within 48 h after extubation, occurred 14 times after 92 attempts, leading to an extubation failure rate of 15%. No association was found between handgrip strength and extubation outcome. CONCLUSIONS: Muscle weakness, assessed by handgrip strength, is associated with difficult or prolonged mechanical ventilation weaning and ICU stay, but not with extubation outcome.