Is the threshold useful in accelerating weaning from mechanical ventilation?

Introduction

The threshold can be used as a physiotherapy tool in order to increase muscle strength. This effect can be useful in weaning patients. However, there are still controversies considering its advantages during weaning from mechanical ventilation (MV). This study aims to evaluate the effects of the threshold in such situations.

Methods

Patients under MV for more than 48 hours and prone to weaning were randomly assigned to the control group or to the threshold group (trained twice daily). They were followed until extubation, tracheotomy or death. All cardiorespiratory variables, maximal inspiratory and expiratory pressures (MIP and MEP), length of weaning and success or failure were registered. Statistical analysis was performed using ANOVA, Mann–Whitney U test and chi-square test, where appropriate. A level of 0.05 was considered significant.

Results

Eighty-six patients were studied (52% men, mean age 63 ± 17 years, 48% with chronic obstructive pulmonary disease). No differences were observed when comparing initial versus final cardiorespiratory variables in both groups, with the exception of the MIP (varied from -33.72 ± 13.5 cmH₂O to -40.81 ± 12.67 cmH₂O in the threshold group and from -37.67 ± 10.49 cmH₂O to -34.19 ± 10.85 cmH₂O in the control group, P < 0.001), the MEP (varied from 25.47 ± 12.48 cmH₂O to 29.65 ± 12.02 cmH₂O in the threshold group and from 29.65 ± 11.97 cmH₂O to 26.86 ± 11.6 cmH₂O in the control group, P < 0.05) and tidal volume (varied from 386.16 ± 236.56 ml to 436.16 ± 228.39 ml in the threshold group and from 361.91 ± 168.81 ml to 357.14 ± 121.35 ml in the control group, P < 0.05). No differences were observed in the length of weaning (1.36 days in the threshold group versus 1.98 days in the control group, P > 0.05) and weaning success (83.7% in the threshold group versus 76.7% in the control group, P > 0.05).

Conclusion

The threshold during weaning from MV can cause an increase in MIP, MEP and tidal volume. In this group of patients, however, it was not associated with a decrease in the length of weaning or with an increase in weaning success.