The Natural History of Small Airways Physiology in Diseased and Healthy States

Impulse Oscillometry and Airway Inflammation in Asthma and Chronic Obstructive Pulmonary Disease and Airways Physiology in Other Lung Conditions and Healthy Lungs

Spirometry is a useful clinical tool for the assessment and monitoring of lung disease, however, it does not provide information on peripheral airways resistance. On the contrary, impulse oscillometry (IOS) may provide information not only on airway resistance (Rrs) but also on the elastic properties of the lung (Xrs). In addition, multiple breath nitrogen washout (MBNW) utilizes the exhalation of nitrogen gas from the airways to determine changes in lung ventilation and derive small airways indices (that tells us about small airways calibre). This method, like IOS, allows a precise assessment of small airways function.

Even though patients with asthma may show some reduction of the caliber of the small airways these changes are more a feature of patients with COPD. The study team hypothesize that IOS and MBNW measurements may detect these differences and provide different resistance profiles for asthma and COPD. Furthermore, the study team would like to investigate the relationship between airway inflammation and small airway disease by measuring exhaled nitric oxide (NO) at multiple exhalation flow rates. This technique allows the partitioning of NO produced in the central airways from that generated more peripherally in the lung, providing valuable information on the activity of inflammation in different parts of the respiratory system. The study team hope that the combined use of IOS, MBNW and NO will identify a possible correlation between inflammation and small airway dysfunction.

Background

The main objective of this study is to measure the damage of the small airways in lung disease exploring the "silent zone" with methods that have not been used before together in the same patients. Furthermore, because this is a 4 year longitudinal study, the study team will investigate the time related changes of small airway function in lung disease and normal healthy subjects.

The study will also investigate the relationship between small airway resistance and inflammation.

Inclusion Criteria:

• male or female, aged between 18-85 years;
• volunteers who are able to give written informed consent Patients meeting the diagnostic criteria for asthma, COPD, ILD, CF, chronic cough.

Exclusion Criteria:

• upper respiratory tract infection within the previous 28 days
• any history or evidence of renal, cardiovascular, gastrointestinal or hepatic disease
• any history and evidence of neuropsychiatric disease
• treatment with antibiotics within 4 weeks prior to the study
• alcohol, drug abuse or any other condition associated with poor compliance
• breast feeding
• pregnancy
• are unable to provide written informed consent