Variable intrathoracic airways obstruction masquerading as asthma

Chronic upper airways obstruction may be unrecognised or misdiagnosed as asthma or chronic obstructive bronchitis. Clinical features, such as stridor, or the results of pulmonary function tests may lead to a diagnosis. Indeed, there is usually no difficulty in the diagnosis of patients with extrathoracic airway obstruction, when the forced inspired volume in one second (FIV₁), peak inspiratory flow, or maximum mid-inspiratory flow recorded from a flow volume curve is reduced. Conversely such clues do not exist to aid recognition of variable intrathoracic obstruction of the trachea, carina, or main bronchi, when the flow volume curve simply shows expiratory airflow obstruction and the physical signs are similar to those of asthma or chronic obstructive bronchitis - namely, an expiratory wheeze. We report on such a patient in whom asthma was diagnosed erroneously and as a result the definitive investigations and treatment were delayed.