Inspiratory muscle strength training improves weaning outcome in failure to wean patients: a randomized trial.

INTRODUCTION: Most patients are readily liberated from mechanical ventilation (MV) support, however, 10% - 15% of patients experience failure to wean (FTW). FTW patients account for approximately 40% of all MV days and have significantly worse clinical outcomes. MV induced inspiratory muscle weakness has been implicated as a contributor to FTW and recent work has documented inspiratory muscle weakness in humans supported with MV. METHODS: We conducted a single center, single-blind, randomized controlled trial to test whether inspiratory muscle strength training (IMST) would improve weaning outcome in FTW patients. Of 129 patients evaluated for participation, 69 were enrolled and studied. 35 subjects were randomly assigned to the IMST condition and 34 to the SHAM treatment. IMST was performed with a threshold inspiratory device, set at the highest pressure tolerated and progressed daily. SHAM training provided a constant, low inspiratory pressure load. Subjects completed 4 sets of 6-10 training breaths, 5 days per week. Subjects also performed progressively longer breathing trials daily per protocol. The weaning criterion was 72 consecutive hours without MV support. Subjects were blinded to group assignment, and were treated until weaned or 28 days. RESULTS: Groups were comparable on demographic and clinical variables at baseline. The IMST and SHAM groups respectively received 41.9 ± 25.5 vs. 47.3 ± 33.0 days of MV support prior to starting intervention, P = 0.36. The IMST and SHAM groups participated in 9.7 ± 4.0 and 11.0 ± 4.8 training sessions, respectively, P = 0.09. The SHAM group's pre to post-training maximal inspiratory pressure (MIP) change was not significant (-43.5 ± 17.8 vs. -45.1 ± 19.5 cm H2O, P = 0.39), while the IMST group's MIP increased (-44.4 ± 18.4 vs. -54.1 ± 17.8 cm H2O, P < 0.0001). There were no adverse events observed during IMST or SHAM treatments. Twenty-five of 35 IMST subjects weaned (71%, 95% confidence interval (CI) = 55% to 84%), while 16 of 34 (47%, 95% CI = 31% to 63%) SHAM subjects weaned, P = .039. The number of patients needed to be treated for effect was 4 (95% CI = 2 to 80). CONCLUSIONS: An IMST program can lead to increased MIP and improved weaning outcome in FTW patients compared to SHAM treatment. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00419458.

Use of inspiratory muscle strength training to facilitate ventilator weaning: a series of 10 consecutive patients.

BACKGROUND AND PURPOSE: We instituted a low-repetition, high-intensity inspiratory muscle strength training (IMST) program and progressively longer spontaneous breathing periods (SBPs) in a group of medically complex patients who were dependent on mechanical ventilation (MV) and had failed to wean. CASE DESCRIPTIONS: IMST was provided to 10 consecutive patients (four men, six women; mean [+/- SD] age, 59 +/- 15 years) who had failed to wean from MV by conventional methods for >or= 7 days. Prior to initiating IMST, patients had received MV support for a mean of 34 +/- 31 days. Daily IMST consisted of four sets of six breaths through a threshold inspiratory muscle trainer that had been set at an intensity to yield an exertion rating of 6 to 8 of a maximal value of 10. At the start of IMST, patients were tolerating 2.1 +/- 3.4 consecutive hours of SBPs. The duration of the SBPs was increased daily, as tolerated. Patients were considered to have been weaned from MV when they were able to breathe without MV support for 24 consecutive hours. OUTCOMES: After 44 +/- 43 days of IMST, 9 of 10 patients were weaned from MV. The initial IMST pressure was 7 +/- 3 cm H(2)O, and it was increased to 18 +/- 7 cm H(2)O (p < 0.05). DISCUSSION: These results indicate that an IMST protocol that produces significant increases in threshold training pressure, in combination with progressive SBPs, aids in weaning patients from MV. Although promising, these preliminary observations must be tested in a controlled trial.