Medical Research Council Scale Predicts Spontaneous Breathing Trial Failure and Difficult or Prolonged Weaning of Critically Ill Individuals.

BACKGROUND: Handgrip strength is an alternative measure to assess peripheral muscle strength and is correlated with the Medical Research Council (MRC) scale, with promising values for diagnosing ICU-acquired weakness (ICUAW). Because ICUAW has been associated with delayed weaning from mechanical ventilation, we hypothesized that ICUAW evaluated with both the MRC scale score and handgrip strength are associated with failure of a spontaneous breathing trial (SBT) and duration of mechanical ventilation weaning. METHODS: We conducted a prospective observational study in 3 general ICUs with a total of 54 beds at 2 academic hospitals. Adult subjects with > 48 h of mechanical ventilation who were eligible for weaning were included in the study. RESULTS: In the evaluation before the first SBT, the MRC score (P < .001) and handgrip strength (P < .001) were significantly different between subjects extubated after a successful first SBT (simple weaning) and those extubated any time after a failed first SBT (difficult weaning). Only the MRC score discriminated between first SBT success or failure (P < .001); in multivariate analysis, the MRC score was significantly associated with first SBT failure (odds ratio 0.91, 95% CI 0.88-0.97, P < .001) and difficult weaning (odds ratio 0.91, 95% CI 0.87-0.96, P < .001). Handgrip strength exhibited good accuracy in identifying ICUAW. CONCLUSIONS: MRC score was independently associated with SBT failure and difficult or prolonged weaning.

Inspiratory muscle training did not accelerate weaning from mechanical ventilation but did improve tidal volume and maximal respiratory pressures: a randomised trial.

QUESTION: Does inspiratory muscle training accelerate weaning from mechanical ventilation? Does it improve respiratory muscle strength, tidal volume, and the rapid shallow breathing index? DESIGN: Randomised trial with concealed allocation and intention-to-treat analysis. PARTICIPANTS: 92 patients receiving pressure support ventilation were included in the study and followed up until extubation, tracheostomy, or death. INTERVENTION: The experimental group received usual care and inspiratory muscle training using a threshold device, with a load of 40% of their maximal inspiratory pressure with a regimen of 5 sets of 10 breaths, twice a day, 7 days a week. The control group received usual care only. OUTCOME MEASURES: The primary outcome was the duration of the weaning period. The secondary outcomes were the changes in respiratory muscle strength, tidal volume, and the rapid shallow breathing index. RESULTS: Although the weaning period was a mean of 8 hours shorter in the experimental group, this difference was not statistically significant (95% CI -16 to 32). Maximal inspiratory and expiratory pressures increased in the experimental group and decreased in the control group, with significant mean differences of 10cmH2O (95% CI 5 to 15) and 8cmH2O (95% CI 2 to 13), respectively. The tidal volume also increased in the experimental group and decreased in the control group (mean difference 72 ml, 95% CI 17 to 128). The rapid shallow breathing index did not differ significantly between the groups. CONCLUSION: Inspiratory muscle training did not shorten the weaning period significantly but it increased respiratory muscle strength and tidal volume.