[Therapy-resistant asthma: causes and therapy].

Despite the introduction of new and potent antiasthmatic drugs, a minority of asthma patients, remains without response to therapy. Some of the patients with asthma refractory to therapy actually do not have asthma at all, but suffer from another syndrome mimicking asthma. Asthma may also exist in combination with a syndrome mimicking asthma (e.g. vocal cord dysfunction). Patients may then get treated with high doses of corticosteroids unnecessarily, because the symptoms due to vocal cord dysfunction are misinterpreted as being asthmatic. Sometimes asthma is complicated by an independent factor (e.g. gastroesophageal reflux), which does not respond to antiasthmatic drugs. In all cases of asthma being unresponsive to therapy, the diagnosis of asthma must be questioned, and other complicating factors need to be excluded. The patient's compliance should be encouraged, and correct handling of modern inhalation devices has to be monitored. Patients with refractory asthma should also undergo flexible bronchoscopy to exclude morphologic changes of the bronchial system and to obtain mucosal biopsies.