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Open Access Highly Accessed Research

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

A Daniel Martin14*, Barbara K Smith1, Paul D Davenport2, Eloise Harman3, Ricardo J Gonzalez-Rothi3, Maher Baz3, A Joseph Layon345, Michael J Banner4, Lawrence J Caruso4, Harsha Deoghare1, Tseng-Tien Huang1 and Andrea Gabrielli45

Author Affiliations

1 Department of Physical Therapy, University of Florida, 1600 South West Archer Road, PO Box 100154, Gainesville, FL, 32610, USA

2 Department of Physiological Sciences, University of Florida, 1600 South West Archer Road, PO Box 100144, Gainesville, FL, 32610, USA

3 Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine University of Florida, 1600 South West Archer Road, PO Box 100225, Gainesville, FL, 32610, USA

4 Department of Anesthesiology, Division of Critical Care Medicine, University of Florida, 1600 South West Archer Road, PO Box 100254, Gainesville, FL, 32610, USA

5 Department of Surgery, University of Florida, 1600 South West Archer Road, PO Box 100129, Gainesville, FL, 32610, USA

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Critical Care 2011, 15:R84  doi:10.1186/cc10081


See related commentary by Nava and Fasano, http://ccforum.com/content/15/2/153

Published: 7 March 2011

Abstract

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