Is airway hyperresponsiveness asthma?

There are many clinical manifestations of asthma, such as dyspnea, vomiting, urinary incontinence, chest pain, high airways, etc. However, some people in life may have manifestations of high airways, but it is not necessarily an asthma reaction, it may also be due to diseases such as bronchiectasis or allergic rhinitis.

Airway hyperresponsiveness Airway reactivity refers to the contraction reaction of the airway to various chemical, physical or drug stimuli. Airway hyperresponsiveness (AHR) refers to the excessive airway contraction reaction of the airway to non-antigenic stimuli that normally do not cause or only cause a mild response. Airway hyperresponsiveness is one of the important characteristics of asthma. AHR often has a familial tendency and is affected by genetic factors, but the role of exogenous factors is more important. It is generally believed that airway inflammation is one of the most important mechanisms leading to airway hyperresponsiveness. When the airway is exposed to allergens or other stimuli, AHR is caused by the participation of various inflammatory cells, inflammatory mediators and cytokines, damage to the airway epithelium and intraepithelial nerves, etc. It is believed that the autocrine and paracrine secretion of endothelin in airway stromal cells, as well as the interaction between cytokines, especially TNFα and endothelin, play an important role in the formation of AHR.

In addition, AHR is related to hypofunction of β-adrenergic receptors, enhanced excitability of choleretic nerves and defective inhibitory function of non-adrenergic non-choleretic (NANC) nerves. Physical and chemical factors such as viral respiratory infections, SO2, cold air, dry air, hypotonic and hypertonic solutions can increase airway responsiveness.

The degree of airway hyperresponsiveness is closely related to airway inflammation, but the two are not the same. It is currently recognized that AHR is a common pathophysiological feature of patients with bronchial asthma. However, not all patients with BHR have bronchial asthma. BHR can also occur in patients with long-term smoking, ozone exposure, viral upper respiratory tract infection, chronic obstructive pulmonary disease (COPD), allergic rhinitis, bronchiectasis, tropical pulmonary eosinophilia and allergic alveolitis. Therefore, the clinical significance of BHR should be fully understood.