Effects of Inspiratory Muscle Training in Patients With Bronchiectasis

The purpose of this study is to determine whether inspiratory muscle training could improve and/or prevent the deterioration of inspiratory muscle strength, clinical cardiopulmonary outcome, systemic immunologic responses and quality of life in patients with bronchiectasis.

Inspiratory muscle training is reportedly beneficial in patients with diverse chronic cardio-pulmonary diseases. It can increase inspiratory muscle strength and endurance, improves exercise capacity and quality of life (QOL), and decreases the perception of dyspnea (POD) for adults with stable chronic obstructive pulmonary disease (COPD). Though the pathophysiology in COPD and bronchiectasis are different, there are some similarities in clinical presentation. In COPD patients, lung hyperinflation induces functional weakness of the inspiratory muscle and increases elastic load to breathing and intrinsic positive end expiratory pressure. Patients with bronchiectasis shows reduced ratio of FEV1/FVC, reduced FEV1, and normal or slightly reduced FVC, which indicate that airways are blocked by mucus. However, there has been no study that used IMT as a training modality to determine its effect in bronchiectasis. The clinical relevance of increased respiratory muscle strength per se by IMT alone is unknown. This study tried to evaluate the feasibility and effectiveness of home-based threshold training and examined if the effects of IMT extends to clinical outcomes such as activities of daily living and QOL in bronchiectasis patients.

A pressure threshold device (Threshold® IMT HS730, RESPIRONICS Inc, Cedar Grove, NJ, USA) was used for the inspiratory muscle training program. The individualized training program was started at an intensity of 30% MIP, which was increased by 2 cmH2O each week, but the maximal intensity did not exceed 50% of MIP. Patients were encouraged to perform IMT for 30 minutes per day, at least 5 days a week for 8 weeks.

MEP was measured after maximal inspiration,while MIP was measured after maximal expiration with each subject seated and wearing a nose-clip. An experienced respiratory therapist strongly urged the subjects to make maximum inspiratory and expiratory efforts at or near residual and total lung capacity, respectively. Determinations were repeated until two technically satisfactory measurements were recorded, with the highest value used for calculations.

The 6-min walk test (6 MWT) is a submaximal exercise test that entails measurement of distance walked over a span of 6 minutes. The 6-minute walk distance (6 MWD) provides a measure for integrated global response of multiple cardiopulmonary and musculoskeletal systems involved in exercise.

The 6-minute walk work (6Mwork) value was calculated as body mass distance covered during the 6-minute walking test.

Inclusion Criteria: Bronchiectasis confirmed by clinical history, pulmonary function test, and high resolution computed tomography Exclusion Criteria: Had recent exacerbation within six weeks Use of corticosteroid With poor consciousness level Have cerebro-vascular or neuro-muscular disorders