From sneeze to wheeze: Non-invasive studies on asthma and rhinitis

Asthma and allergic rhinitis are diseases that cause major disability and illness in all ethnic groups and ages. It is well established that allergic rhinitis and asthma are closely linked entities and more than 75 % of the patients with asthma reports concomitant rhinitis. Asthma is also closely associated to bronchial hyperresponsiveness, and a large part of patients with rhinitis alone show a reactive pattern in bronchial provocation tests, even though they have no symptoms of clinical asthma. The fact that patients can react with airway obstruction to bronchial challenge, which is a hallmark of asthma, without experiencing symptoms is curious and could possible be explained by difference in degree and/or geographical distribution of inflammation. In this thesis I wanted to investigate the distribution of inflammation and obstruction in asthmatics compared to patients with allergic rhinitis with or without bronchial hyperresponsiveness. We found that patients with asthma had a greater perception of the obstruction induced during methacholine challenge test compared to patients with rhinitis and bronchial hyperresponsiveness. By using non-invasive techniques such as induced sputum, exhaled nitric oxide and impulse oscillometry in addition to bronchial provocation tests we found signs indicating a higher degree of peripheral airway involvement in the asthmatic group. The transition from allergic rhinitis to clinical asthma is probably a gradual one, with bronchial hyperresponsiveness possibly representing an intermediate step. The geographical distribution of the airway inflammation seems to be a key element in the progress of the airway disease