EFFECTS OF INSPIRATORY MUSCLE TRAINING ON RESPIRATORY RELATED FUNCTION AND QUALITY OF LIFE IN INDIVIDUALS WITH SPINAL MUSCULAR ATROPHY

H.-Y. Wang¹, W.-M. Lee²

Background: Spinal muscular atrophy (SMA) is a recessive genetic disorder, which results in progressive muscle weakness and motor dysfunction. Recurrent lung infections often occur in individuals with SMA due to insufficient respiratory muscle strength. Some studies on respiratory muscle training (RMT) for individuals with neuromuscular diseases has been reported, and found that it can help to delay the occurrence of respiratory complications and also to improve health-related quality of life (HRQoL) of these individuals. However, studies investigating the effects of RMT intervention specifically for individuals with SMA are still lacking.

Purpose: The purpose of this study was to investigate the effects of a 6-week inspiratory muscle training intervention by using a breathing training device on the respiratory related function and HRQoL for individuals with SMA.

Methods: A total of 10 individuals with SMA were recruited and assigned into two groups (Group A and B). The Dofin™ breathing device is a hand-held equipment designed for breathing training and can be set to different levels of inspiratory loading. For the A group (mean age 30.2±11.5 years, 3 males/2 females), the starting inspiratory training loading was set to 30% of the individual’s maximal inspiratory pressure (MIP), and the loading was increased weekly by 5% up to the 50% of their MIP. In the B group (mean age 21.80 ± 8.28 years, 3 males/2 females), the inspiratory loading was maintained at 30% of their MIP during training period. The period of intervention for both groups was 6 weeks, 5 days/ week, two times a day, 30 repetitions of inspiratory training movements per time. The primary outcomes were MIP, maximal expiratory pressure (MEP), and peak expiratory flow rate (PEFR). The larger values indicate better the breathing function. The secondary outcome was the score of HRQoL by using the Short Form 36 Quality of Life Questionnaire (for>18 year-old ), or the PedsQL™ 3.0 Neuromuscular Module Health-Related Quality of Life Questionnaire (for 13~18 year-old), higher the scores indicate better HRQoL. All the outcome measures were conducted before (pre-test) and after (post-test) the period of training intervention.

Results: In group A, the findings of MIP, MEP, and PEFR on post-test were all significantly greater than those on the pre-test (p＜.05) ; whereas in group B, only significant difference in MEP (p＜.05) between the pre-test and post-test was found. Regarding the secondary outcome of the subjects, there was no significant difference in the HRQoL score between the pre-test and post-test.

Conclusion(s): For individuals with SMA, the 6-week inspiratory training program, which was assigned to have constant inspiratory loading or to gradually increase the loading, could effectively promote respiratory muscle strength or/and expiratory flow rate. About the finding of no significant change in the HRQoL scores, it may be due to the training time was being only 6 weeks.

Implications: This study displayed that hand-held breathing device is a useful device for improving respiratory function for individuals with SMA. Future studies with larger sample sizes and longer periods of intervention are needed to provide further evidence of training programs in clinical settings.

Funding, acknowledgements: This study had no grants or funding supported.

Keywords: Spinal muscular atrophy, Inspiratory muscle training, Quality of life

Topic: Disability & rehabilitation

Did this work require ethics approval? Yes

Institution: Kaohsiung Medical University Chung-Ho Memorial Hospital

Committee: Institutional Review Board of the KMUH

Ethics number: KMUHIRB-SV(1)-20190041