Pulmonary function testing in bronchial asthma.

: The lung function of asthma is characterized by the following points: - Airflow limitation that reverses after administration of a bronchodilator - Variable airflow limitation Airway hyperresponsiveness, that is, an excessive decrease in airflow in response to an aerosolized provocation that elicits little or no response in a normal person. Airflow limitation from asthma usually demonstrates some degree of reversibility following acute inhalation with a beta-agonist. But patients with mild asthma often do not show this reversibility. Patients can measure peak expiratory flow(PEF) by themselves using a simple device. We can assess the patient's condition by monitoring their PEF. The circadian variation of PEF usually indicates the existence of airway hyperresponsiveness. Airway hyperresponsive- ness is directly measured by bronchoprovocation testing using direct inhalation of meth- acholine or histamine. Indications for bronchoprovocation testing include the accurate diag- nosis of asthma in selected patients, such as patients who do not show airway reversibility, assessment of severity of asthma and assessment of the response to asthma therapy.