Influence of the VitaBreath on Exercise Tolerance in COPD

People with COPD have more air in their lungs than other people (this problem with high lung volumes is called "hyperinflation"). Unfortunately this is unhelpful as breathing at higher lung volumes requires more effort and contributes to breathlessness. When anyone exercises, they breathe more quickly. People with COPD have narrowed airways, which makes breathing out difficult. When they breathe more quickly they may not be able to breathe out fully before they need to take the next breath in. This means that the volume of air in their lungs tends to increase further during exercise, which makes breathing even more difficult. This problem is called "dynamic hyperinflation".

Pulmonary rehabilitation is one of the most helpful interventions for people with COPD and most of the benefit gained is from exercise. Anything that helps people increase the amount of exercise they can perform should lead to further improvements.

Non-invasive positive pressure ventilation is a method of supporting a person's normal breathing. The ventilator delivers a flow of air at low pressure as you breathe out, which helps patients to breathe out more completely. The device also detects when patients start to breathe in and delivers a stronger flow of air at a higher pressure, helping them to take a deeper breath in. Previous research studies have shown that when people with COPD use non-invasive ventilation during exercise they are able to exercise for longer and are less breathless. The purpose of this study is to assess whether a new portable non-invasive ventilation device, called the VitaBreath, helps people with COPD recover from breathlessness during the exercise breaks more quickly (by reducing "dynamic hyperinflation", described above) and to exercise for longer overall. The VitaBreath device is small and light, weighing 0.5 kilograms (just over one pound). It is handheld and battery powered.

In patients with chronic obstructive pulmonary disease (COPD) dynamic hyperinflation (DH) and the concurrent mechanical constraints on tidal volume expansion during exercise increase work of breathing and perceived respiratory discomfort, limiting endurance. An additional consequence of DH and the concomitant high mean intrathoracic pressure swings, cardiac performance and, hence, supply of oxygenated blood to the malfunctioning peripheral muscles is further compromised. This contributes to perceived leg discomfort and exercise intolerance.

Bronchodilator therapy is associated with a reduction in operating lung volumes, leading to improvements in perceived breathlessness and exercise tolerance. Heliox (helium and oxygen) is less dense and generates less airway resistance than air. Heliox breathing has been shown to improve exercise tolerance in COPD. A recent study demonstrated that compared to room air, breathing heliox during constant-load exercise (CLE) (continuous) increased inspiratory capacity (IC), and lessened DH, breathlessness and leg discomfort at isotime and at the point of exercise limitation. In addition, heliox breathing increased stroke volume, cardiac output and hence locomotor muscle oxygen delivery. However, the main drawback of heliox supplementation is the high cost, especially when it is used for long periods of time. Previous studies using inspiratory pressure support have shown improvements in dyspnoea and exercise capacity by reducing the work of breathing, as well as improved central hemodynamic responses and peripheral muscle oxygenation.

In comparison to traditional noninvasive ventilators, the Vitabreath device, which provides positive inspiratory pressure, is compact, light and inexpensive. Ease of operation, portability and battery life support use to aid relief of breathlessness, including away from the patient's home. This should facilitate maintenance of, and improvement in, activity. Vitabreath may also prove to be a useful tool to increasing exercise tolerance and the intensity of training, and hence the magnitude of physiological adaptations by mitigating DH during rehabilitative exercise training.

Eligibility Criteria:
Inclusion Criteria:

1. Male or female aged 40 years or older.
2. Current or previous smoking history: 10 or more pack years.
3. Spirometry confirmed stable COPD (GOLD stages II-IV) under optimal medical therapy.
4. Exhibit substantial exercise-induced dynamic hyperinflation (ΔIC baseline \> 0.15 L)

Exclusion Criteria:

1. Orthopaedic, neurological or other concomitant diseases that significantly impair normal biomechanical movement patterns, as judged by the investigator.
2. Moderate or severe COPD exacerbation within 6 weeks.
3. Unstable cardiac arrhythmia.
4. Unstable ischaemic heart disease, including myocardial infarction within 6 weeks.
5. Moderate or severe aortic stenosis or hypertrophic obstructive cardiomyopathy.
6. Uncontrolled hypertension.
7. Uncontrolled hypotension (SBP\<85mmHg).
8. Uncontrolled diabetes.
9. Intolerance of the VitaBreath device.