Reducing Dynamic Hyperinflation Through Breathing Retraining

Dynamic hyperinflation limits exercise tolerance in chronic obstructive pulmonary disease
(COPD). To limit dynamic hyperinflation during exercise and thus improve exercise
tolerance, we successfully developed a visual-auditory ventilation-feedback system. The
system retrains patient's breathing pattern during exercise. The goal of the current
proposal is to develop a user-friendly ventilation-feedback technique with a novel auditory
feedback system. We reason that the proposed feedback system plus exercise training will be
superior to exercise training alone while having the potential for an easier application
into clinical practice. Hypotheses: The primary hypothesis is that the exercise duration
of patients with moderate-to-severe COPD who successfully complete a 12-week program of
breathing retraining plus exercise will be longer than that of patients who complete a
12-week program of treadmill exercise training alone. We also hypothesize that the primary
predictor of improved exercise duration will be a reduction in dynamic hyperinflation and to
a lesser extent, improvement in peripheral muscle function. Lastly, we hypothesize that
dyspnea will be reduced in patients assigned to breathing retraining plus exercise when
compared to exercise training alone. Methods: The proposed study is a randomized
controlled clinical trial. 246 patients with moderate-to-severe COPD will be enrolled and
randomized into breathing retraining plus exercise or exercise training alone. Both groups
will receive 12-weeks of treadmill exercise training three times weekly. The breathing
retraining plus exercise group will also receive auditory feedback to decrease respiratory
rate and prolong exhalation. The goal of breathing retraining is to reduce exercise-induced
dynamic hyperinflation. Follow-up testing will be completed at 6, 12, and 24 weeks.
Testing will include a pulmonary function test, symptom-limited and constant workrate
treadmill tests, six-minute walk, dyspnea measurements, testing of respiratory muscle
strength and endurance, and quadriceps muscle endurance testing. Analysis: Measures of
central tendency will be used to describe the study sample. A two-sample t-test ( = 0.05)
will be used to analyze changes from baseline to 12-weeks between the breathing retraining
plus exercise group and exercise training alone group. In data analysis, intention-to-treat
principles will be used. Since several measures will be taken on each patient, mixed-models
analysis will be used to compare changes over time between the two groups. Multiple
regression analysis will be employed to determine the predictors of improved exercise
performance.

Inclusion Criteria:

- 40 yr of age

- FEV1 70%

- FEV1/FVC < 70%

- RV/TLC 120%

- mean SpO2 90% at peak exercise (w/ or w/o O2)

- Able to hear metronome sounds Lives near Hines, IL (Chicagoland area)

Exclusion Criteria:

- Respiratory infection/exacerbation within the previous four weeks

- Exercise limiting heart disease (+ stress test or other indicators of heart disease
or complaints of angina during the stress test)

- Primary asthma

- Congestive heart failure (New York Heart Association Class III or IV)

- Exercise-limiting peripheral arterial disease (stops exercise due to intermittent
claudication)

- Stops exercise due to arthritic pain in the knee or hips (self-report)

- Inability to walk on the treadmill

- Pregnancy

- Any unforeseen illness or disability that would preclude exercise testing or training

- Participation in a formal exercise program within the previous 12 weeks