Asthma

Asthma is a chronic respiratory condition in which inflamed, sensitive airways narrow intermittently, causing symptoms such as wheezing, breathlessness, chest tightness, and coughing.

Airway hyperresponsiveness: An exaggerated airway narrowing response to stimuli that produce little or no effect in healthy airways. It explains why smoke, cold air, or exercise can trigger disproportionate narrowing.
Spirometry: A lung-function test that measures the volume and speed of air a person can exhale. It can reveal obstructed airflow and improvement after a bronchodilator.
Wheezing: A high-pitched musical sound produced when airflow passes through narrowed airways. It is a familiar symptom, though its presence alone does not establish asthma.
Asthma endotypes: Biologically distinct forms of asthma defined by underlying mechanisms rather than symptoms alone. Different endotypes may explain why the same treatment works unevenly across patients.
Asthma exacerbation: An acute or subacute worsening of asthma symptoms and airflow limitation beyond a person’s usual variation. Exacerbations can require urgent treatment and are a key measure of disease risk.
Bronchoconstriction: Tightening of smooth muscle around the bronchi that reduces airway diameter. This rapid narrowing contributes directly to episodic breathlessness and wheezing.
Peak expiratory flow: The fastest rate of air exhalation measured during a forceful breath out. Repeated measurements can help track changing airflow and worsening asthma.
Dyspnea: The subjective experience of difficult or uncomfortable breathing. Asthma-related airflow limitation can cause this sensation, especially during an episode.
Severe asthma: Asthma that remains uncontrolled despite optimized high-dose treatment or requires such treatment to stay controlled. It exposes limits of standard therapy and motivates targeted treatment research.
Status asthmaticus: A severe, persistent asthma attack that does not respond adequately to initial standard treatment. This emergency illustrates the potentially life-threatening end of asthma worsening.

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