Respiratory muscle training may improve respiratory function and obstructive sleep apnoea in people with cervical spinal cord injury

Abstract

Study design: This is a double-blind crossover case study series.

Objectives: The objective of this study was to assess the feasibility of respiratory muscle training (RMT) as an effective intervention to improve lung function and obstructive sleep apnoea (OSA) in cervical spinal cord injury (SCI) patients.

Setting: This study was conducted in Australia.

Methods: Three adults (C5-6, AIS A-C) participated in this study. They trained with an RMT device (active or sham) for 4 weeks followed by 2 weeks of rest, and then trained with the alternate device for 4 weeks. RMT occurred twice daily, 5 days a week, and it consisted of three sets of 12 inspirations and three sets of 12 expirations. Training intensity commenced at 30% maximal inspiratory pressure (MIP) and 30% maximal expiratory pressure (MEP), which was increased every second day by 10%. Spirometry, MIP, MEP, polysomnography and Epworth Sleepiness Scale (ESS) were measured before and after every 4 weeks of training.

Results: After active RMT, vital capacity and inspiratory capacity improved from baseline in all participants (by 44%, 60% and 18% and by 18%, 46% and 5%, respectively); MIP improved by 40 and 17% from baseline in two subjects; and MEP improved in all participants. Two participants had OSA, and after active training their obstructive apnoea-hypopnoea index improved from 30 to 21events per hour and from 72 to 18 events per hour, and ESS marginally improved. Sham RMT resulted in minimal changes in all measures.

Conclusion: RMT is feasible and likely effective to increase respiratory muscle strength, to improve lung function, and to reduce the severity of OSA and sleepiness in people with cervical SCI. A randomised controlled trial is planned to validate these findings and to examine respiratory-related morbidity and quality of life.

Figure 1

Individual data from three participants with cervical SCI: participant 1—square, participant 2—triangle, and participant 3—circle. Pre- and post-training values are connected by a line. Order of respiratory muscle training is presented along the x axis: active training in the middle panel and sham training in the left panel for participant 1 and right panel for participants 2 and 3. Graph a: obstructive apnoea–hypopnoea index (central events excluded); graph b: vital capacity; graph c: maximal inspiratory pressure; and graph d: maximal expiratory pressure.