The purpose of this study was to examine whether electrical impedance tomography (EIT) was capable of identifying the deteriorated lung function on a regional level during bronchial challenge testing and whether EIT may provide additional information during bronchial challenge testing and identify spatial and temporal heterogeneity of regional lung function.

The content of this study includes:

1. Can EIT identify the uneven ventilation caused by airway contraction in patients during bronchial provocation tests.
2. Can EIT monitor airway contraction in patients before Spirometer examination after inhaling activators.
3. Can EIT observe uneven ventilation caused by airway contraction through tidal breathing after the patient inhales activator.

Inclusion Criteria：

1. Patients suspected of asthma who require bronchial challenge testing.
2. The Bronchodilator responsiveness testing is negative.
3. patients with a pre-bronchodilator FEV1 >60% predicted.
4. No contraindications for bronchial provocation test examination.
5. Fully understand the purpose and significance of this study, and voluntarily participate in the research.

Exclusion Criteria:

1. patients with a pre-bronchodilator FEV1≤60% predicted.

1. Contraindications for bronchial challenge testing.
2. Pregnant or lactating women.
3. After pacemaker surgery.

Patients need to exclude or confirm a suspected diagnosis of asthma through bronchial challenge testing.

Study Protocol and research data.

Within 1 year after the publication of research results.

Can be obtained from the main researcher.