Inspiratory Muscle Training in Myotonic Dystrophy type 1: a pilot study.

Rationale: In case of hypercapnic respiratory failure in Myotonic Dystrophy type 1 (DM1) patients, the only optional treatment is home mechanical ventilation (HMV). However, HMV is frequently used insufficient and survival benefits are not clear. So, new treatments are needed. Inspiratory muscle training (IMT) has shown positive effects in other neuromuscular disorders. We hypothesize that an IMT program, using POWERbreathe devices, of 12 weeks at home will improve inspiratory muscle strength and endurance capacity in DM1 patients.
Objective: The primary objective is to analyse the effects of IMT on respiratory muscle strength and endurance capacity after a 12 week IMT training schedule at home.
Study design: A prospective intervention pilot study of 10 DM1 patients. Results of inspiratory muscle strength and endurance capacity after the 12 week training program will be compared with results at baseline.
Study population: Adult (≥ 18 year) DM1 patients (diagnosis DNA proven) with vital capacity and maximum inspiratory muscle strength < 80% of predicted, who are not using HMV or when HMV is not indicated yet.
Intervention: a 12 week IMT program at home consists of two training sessions per day (one session is 30 breaths) and at least five days per week, using a digital inspiratory muscle trainer (POWERbreathe KHP2). Intensity of the threshold will be programmed individually for every patient, based on individuals’ maximum inspiratory muscle strength. Every two weeks a supervised training will be performed and threshold will be increased based on a predefined schedule in combination with training results.
Main study parameters/endpoints: Difference in respiratory muscle strength and endurance capacity after 12 weeks of IMT training at home compared to results at baseline.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Patients have to perform at least ten sessions per week. One session exist of 30 breaths using the POWER breathe (which will take circa 3 min). Patients can experience some myalgia and dizziness due to the training. Patients could benefit of the training by strengthening their respiratory muscles and probably by secondary positive effects of decreasing pneumonia risks and in case of continuing therapy the development of respiratory failure can be delayed (and subsequently needs for HMV). In general, no adverse events of training in DM1 are described. To better understand the effects of training on the respiratory muscles in a neuromuscular disorder, additional tests with pulmonary function and diaphragm tests will be performed. Indirect benefits might be achieved as well, because at a group level we will learn more about training effects of respiratory muscles to develop novel treatment options for patients with DM1 and respiratory failure.

We hypothesize that IMT training in DM1 patients will improve respiratory muscle function, which probably could prevent the development of atelectasis and pneumonia or even delay the need for HMV.

Study start (expected): 1-4-2020
Start inclusion: 1-5-2020
Study period: 1,5 years
End inclusion period: 01-09-2020

12 weeks program of IMT.