"More air-better performance-faster recovery": study protocol for randomised controlled trial of the effect of post-stroke inspiratory muscle training for adults

Abstract

Background: Stroke results in varying physical, cognitive, emotional and/or social disabilities in the short and long term alike. Motor impairments are important, persistent consequences of stroke and include, among others, decreased respiratory muscle function, decreased ability to expand the thorax and postural dysfunction. These deficits affect the patient's ability to perform daily activities, produce fatigue and reduce endurance and quality of life. Inspiratory muscle training (IMT) aims to improve the strength and endurance of the diaphragm and the external intercostal muscles. The objectives of this study are to investigate the effect of 3 weeks of IMT on (i) maximal inspiratory pressure (MIP) in adults having suffered a stroke, as well as (ii) functional activities and expiratory measurements.

Methods/design: This is a randomised controlled trial (RCT) comparing IMT with conventional neurorehabilitation (usual practice). The trial will include 80 patients with reduced MIP hospitalised at a specialised neurorehabilitation hospital in Denmark. The intervention group will receive IMT sessions, exercising at 30% of MIP. Patients in the intervention group will perform two daily sessions (one session of IMT with Threshold IMT consisting of two times 15 inspirations at normal breathing rhythm (5-10 min)), 7 days a week for 3 weeks. Training can be with or without physiotherapist supervision.

Study outcomes: MIP assessed by the Power Breath, Functional Independence Measurement, The 6-min walk test, the Fatigue Severity Scale and average voice volume. Expiratory function will be assessed using spirometry. All assessments will be conducted at baseline and 3 weeks (at termination of the intervention) and 3 months after the intervention has concluded.

Discussion: IMT is a promising and partly self-managed tool for rehabilitation to improve respiratory function. The introduction of IMT in combination with traditional physical therapy may enhance faster recovery after stroke and may at the same time demand little personnel resources to increase training intensity. This trial will provide further evidence of IMT to clinicians, patients and health managers. Hereby, this study accepts the call for further research.

Trial registration: ClinicalTrials.gov NCT04686019 . Registered on 28 December 2020.

Keywords: Activity of daily living; Endurance in gait; Fatigue; Inspiratory muscle training; Peak expiratory flow; Spirometry; Stroke; Voice volume and phonation.