Respiratory muscle training (RMT) in late-onset Pompe disease (LOPD): A protocol for a sham-controlled clinical trial

Abstract

Introduction:: Morbidity and mortality in adults with late-onset Pompe disease (LOPD) results primarily from persistent progressive respiratory muscle weakness despite treatment with enzyme replacement therapy (ERT). To address this need, we have developed a 12-week respiratory muscle training (RMT) program that provides calibrated, individualized, and progressive pressure-threshold resistance against inspiration and expiration. Our previous results suggest that our RMT regimen is safe, well-tolerated, and results in large increases in respiratory muscle strength. We now conduct an exploratory double-blind, randomized control trial (RCT) to determine: 1) utility and feasibility of sham-RMT as a control condition, 2) the clinically meaningful outcome measures for inclusion in a future efficacy trial. This manuscript provides comprehensive information regarding the design and methods used in our trial and will aid in the reporting and interpretation of our future findings.

Methods:: Twenty-eight adults with LOPD will be randomized (1:1) in blocks of 4 to RMT (treatment) or sham-RMT (control). Assessments will be conducted at pretest, posttest, 3-months detraining, and 6-months detraining. The primary outcome is maximum inspiratory pressure (MIP). Secondary outcomes include maximum expiratory pressure (MEP), 6-minute walk test (6MWT), Gait, Stairs, Gowers, and Chair test (GSGC), peak cough flow (PCF), and patient-reported life activity/social participation (Rasch-built Pompe-specific Activity scale [R-Pact]). Exploratory outcomes include quantitative measures from polysomnography; patient reported measures of fatigue, daytime sleepiness, and sleep quality; and ultrasound measures of diaphragm thickness. This research will use a novel tool to provide automated data collection and user feedback, and improve control over dose.

Ethics and dissemination:: The results of this clinical trial will be promptly analyzed and submitted for publication. Results will also be made available on clinicaltrials.gov.

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Trial registration: ClinicalTrials.gov NCT02801539.

Keywords: Late-onset Pompe disease; Maximum expiratory pressure; Maximum inspiratory pressure; Pompe disease; Randomized control trial; Respiratory muscle training.

Copyright © 2019 Elsevier Inc. All rights reserved.

Figures

Figure 1.

Custom adapters to allow inspiratory muscle training using expiratory-type RMT devices including the Threshold PEP (top) and EMST 150 (bottom). Includes one-way gas valve to allow expiration without resistance before initiating inspiratory repetitions.

Figure 2.

RMT Monitor shown interfacing with the EMST 150 device (covered in heat-shrink tubing) for expiratory muscle training. The device allows automated data collection, provides user feedback after each repetition, and enhances control over RMT dose.

Figure 3.. Study Overview.

PSG = polysmnography, RMT Tx = on-site RMT or sham therapy visits, Phone Check = RMT clinician telephone check.