Acute Effects of a Flutter Device in COPD

Chronic obstructive pulmonary disease (COPD) is characterised by airflow limitation that is not fully reversible. This limitation is usually progressive and associated with an abnormal inflammatory response of the lungs to noxious particles or gases.

Patients suffering from COPD may show pathologic changes not only in the large but also in the small airways, which are defined as less than 2mm in diameter. Airway inflammation may cause increased thick mucus secretions which can narrow the airways increasing the resistance to the airflow.

Physiotherapy to remove secretions is indicated for patients with COPD who have regular sputum or those with thick secretions and various techniques and physiotherapy devices can be applied for the removal of secretions. The flutter is a simple and small device shaped like a pipe that creates a positive expiratory pressure (PEP) and high frequency oscillation as expired air passes through it. These vibrations and PEP are thought to mobilise airway secretions facilitating their clearance and improving airflow.

The effects of the flutter device have been studied in different patient groups, but especially in lung diseases characterised by mucus hypersecretion such as COPD, cystic fibrosis and bronchiectasis. In COPD, even though the flutter device increases the volume of expectorated secretions, its beneficial effects on pulmonary function as assessed by spirometry and plethysmography are inconclusive. However, these standard lung function tests (such as spirometry) asses the large airways, but do not provide an accurate estimate of the small airways which have been described by some authors as "the silent zone".

The investigators hypothesise that the use of impulse oscillometry (IOS), a non-invasive technique that provides information on small airway resistance during normal breathing, may reveal the effect of the flutter device which may have not been accurately measured by spirometry in previous studies.

In addition, the investigators would like to measure exhaled nitric oxide (NO) levels which reflect airway inflammation and may therefore be useful to determine the association between small airway disease and inflammation.

In summary, the symptoms of patients with COPD improve following breathing exercises with a flutter device, however, the effect of this device on lung function is unclear. The investigators hypothesise that the combined use IOS and NO, would help understand and quantify the effects of the flutter device on the small airways disease in COPD.

The main objective of this study is to measure the effect of a 30 minutes breathing exercise with a flutter device on airway resistance as assessed by impulse oscillometry in patients with COPD.

The secondary objective is to investigate the association between inflammation, airway resistance and volume of secretions in COPD patients.

Inclusion criteria

• patients with COPD meeting the Global Initiative for Obstructive Lung Disease (GOLD) guidelines, with forced expiratory volume in the first second of expiration (FEV1) <80% predicted, FEV1/FVC ratio <70% predicted (FVC= forced vital capacity), and total lung capacity (TLC) >80% predicted), with or without sputum, will be included.

The severity of COPD will be classified according to GOLD criteria:

Stage I: mild FEV1/FVC<0.70 and FEV1>80% predicted; Stage II: moderate FEV1/FVC<0.70 and 50<FEV1<80% predicted; Stage III: severe FEV1/FVC<0.70 and 30<FEV1<50% predicted; Stage IV: very severe FEV1/FVC<0.70 and FEV1<30% or FEV1<50% predicted plus chronic respiratory failure,

Exclusion criteria

Patients with:

• Upper respiratory tract infection within the previous 28 days
• Treatment with antibiotics within 4 weeks prior the study
• Acute dyspnoea or hemoptysis
• Chest pain or recent history of rib fracture or pneumothorax
• Acute cardiovascular events in the previous 3 months
• Any history or evidence of renal, gastrointestinal or hepatic disease
• Any history and evidence of neuropsychiatric disease
• Alcohol, drug abuse or any other condition associated with poor compliance
• Breast feeding
• Pregnancy
• Other complications that hinder the completion of the tests
• Unable to provide written informed consent