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.