Minimal important difference in field walking tests in non-cystic fibrosis bronchiectasis following exercise training.

BACKGROUND: The 6-min walk distance (6MWD) and incremental shuttle walk distance (ISWD) are clinically meaningful measures of exercise capacity in people with non-cystic fibrosis (CF) bronchiectasis, but the change in walking distance which constitutes clinical benefit is undefined. This study aimed to determine the minimal important difference for the 6MWD and ISWD in non-CF bronchiectasis. METHODS: Thirty-seven participants with mean FEV1 70% predicted completed both field walking tests before and after an 8-week exercise program. The minimal important difference was calculated using a distribution-based and anchor-based method, with the global rating of change scale used. RESULTS: The mean change in 6MWD in participants who reported themselves to be unchanged was 10 m, compared to 36 m (small change) and 45 m (substantial change) (p = 0.01). For the ISWD, the mean change in participants who reported themselves to be unchanged was 33 m, compared to 54 m (small change) and 73 m (substantial change) (p = 0.04). The anchor-based method defined the minimal important difference for 6MWD as 24.5 m (AUC 0.76, 95% CI 0.61-0.91) and for ISWD as 35 m (AUC 0.88, 95% CI 0.73-0.99), based on participant's global rating of change. The distribution-based method indicated a value of 22.3 m for the 6MWD and 37 m for the ISWD. There was excellent agreement between the two methods for the 6MWD (kappa = 0.91) and the ISWD (kappa = 0.92). CONCLUSIONS: Small changes in 6MWD and ISWD may represent clinically important benefits in people with non-CF bronchiectasis. These data are likely to assist in the interpretation of change in exercise capacity following intervention.

Relationship between body composition, peripheral muscle strength and functional exercise capacity in patients with severe chronic obstructive pulmonary disease.

The influence of body composition and peripheral muscle strength on 6-minute walk distance was assessed by performing dual energy X-ray absorptiometry scanning, spirometry and dynamometry testing in 13 men and 13 women with severe chronic obstructive pulmonary disease. Multivariate modelling showed that 76% of the variance in 6-minute walk distance could be explained by an equation incorporating lung function, quadriceps strength and lean leg mass. These findings indicate an important role for lower limb strength measures in pulmonary rehabilitation training programmes.

Six-minute walk test: observed adverse events and oxygen desaturation in a large cohort of patients with chronic lung disease.

BACKGROUND: The 6-min walk test (6MWT) is widely used to assess patients with chronic lung disease (CLD). Anecdotal reports and studies in small numbers of patients with CLD suggest that complications associated with the 6MWT are rare. This study reports the incidence of observed adverse events during the 6MWT in patients referred to an outpatient pulmonary rehabilitation service. METHODS: Seven hundred and forty-one patients with stable CLD (chronic obstructive pulmonary disease (COPD), n= 572) completed the 6MWT in accordance with a standardized protocol that included continuous monitoring of oxygen saturation (SpO(2)) and heart rate (Polar). RESULTS: Adverse events occurred in 43 tests (6%). One 6MWT was terminated by the tester because of chest pain and one patient developed persistent tachycardia and irregular pulse immediately following the test. In 35 tests, the tester instructed the patient to stop walking because of profound oxygen desaturation (SpO(2) < 80%). Six patients prematurely terminated the 6MWT because of symptoms. Forty-seven per cent (n= 345) of patients exhibited significant oxygen desaturation (≥4% fall in SpO(2) to <90%). Pre-exercise SpO(2) was a significant predictor of desaturation in the COPD (1.79, 1.54-2.08, adjusted odds ratio (OR), 95% confidence intervals) and ILD (OR 1.40, 1.11-1.77) cohorts with FEV(1) (forced expiratory volume in 1 s) also a predictor in COPD (OR 3.02, 1.77-5.15). CONCLUSION: Profound oxygen desaturation is the most common adverse event observed during the 6MWT in patients with stable ILD and COPD. We propose that the American Thoracic Society 6MWT guidelines are revised to recommend continuous monitoring of SpO(2) during the 6MWT in patients with ILD and COPD.

High-intensity inspiratory muscle training in COPD.

The aim of the present study was to investigate the effects of an interval-based high-intensity inspiratory muscle training (H-IMT) programme on inspiratory muscle function, exercise capacity, dyspnoea and health-related quality of life (QoL) in subjects with chronic obstructive pulmonary disease. A double-blind randomised controlled trial was performed. Sixteen subjects (11 males, mean forced expiratory volume in one second (FEV(1)) 37.4+/-12.5%) underwent H-IMT performed at the highest tolerable inspiratory threshold load (increasing to 101% of baseline maximum inspiratory pressure). Seventeen subjects (11 males, mean FEV(1 )36.5+/-11.5%) underwent sham inspiratory muscle training (S-IMT) at 10% of maximum inspiratory pressure. Training took place three times a week for 8 weeks and was fully supervised. Pre- and post-training measurements of lung function, maximum inspiratory pressure, maximum threshold pressure, exercise capacity, dyspnoea and QoL (Chronic Respiratory Disease Questionnaire; CRDQ) were obtained. H-IMT increased maximum inspiratory pressure by 29%, maximum threshold pressure by 56%, 6-min walk distance by 27 m, and improved dyspnoea and fatigue (CRDQ) by 1.4 and 0.9 points per item, respectively. These changes were significantly greater than any seen following S-IMT. In conclusion, high-intensity inspiratory muscle training improves inspiratory muscle function in subjects with moderate-to-severe chronic obstructive pulmonary disease, yielding meaningful reductions in dyspnoea and fatigue.

The active cycle of breathing techniques--to tip or not to tip?

The active cycle of breathing techniques (ACBT) in gravity-assisted drainage positions is an effective airway clearance regimen for individuals who produce excess bronchial secretions. This study compared the ACBT in positions with and without a head-down tilt. Nineteen subjects (11 men), mean age 37.1 years (range 18-76 years), with bronchiectasis who produced more than 20 g of sputum per day and had a mean forced expiratory volume in 1 s (FEV1) of 56.9% predicted (range 23-90% pred.) were studied. There was no significant difference in the wet weight of sputum expectorated when using the ACBT in gravity-assisted drainage positions with or without a head-down tilt. Mean (SD) score for perception of breathlessness, measured on a visual analogue scale, increased significantly following treatment with a head-down tilt [2.3 (1.6) to 3.3 (2.0) cm, P = 0.02]. There was no significant difference in oxygenation or lung function (FEV1). Eighteen subjects preferred the ACBT without a head-down tilt. The ACBT in the horizontal position is a simple airway clearance regimen suitable for individuals who produce greater than 20 g of sputum per day. Subjects were less breathless and preferred the ACBT in the horizontal position, thus providing a treatment alternative that may improve adherence in individuals who are required to carry out daily airway clearance treatments.