Asthma symptoms are highlighted by the characteristic sudden airway constriction causing difficulty breathing, coughing, and wheezing. These episodes (attacks) are intermittent, variable in severity, and often unpredictable.
Asthma is caused by the involuntary contraction of the muscle within the walls of the two large airways (bronchi) branching left and right from the trachea in the chest.
When the bronchi contract in an asthma attack the airway narrows considerably, the lining of the bronchi become inflamed and swollen, and mucus is produced. All of these factors contribute to a drastic reduction in the amount of air that may pass from the mouth and nose to the lungs.
Often some stimulus promotes the constriction of the airways preceding an asthma attack. In many cases the stimulus may not be identifiable. Some known, common stimuli are dust, pollen, specific foods, animal dander, and cigarette smoke.
Typically with time or with treatment the conditions subside and the attack ends and normal breathing is possible. Some individuals experience a basal continual dry cough and/or wheezing between episodic attacks.
- sudden difficulty breathing
- coughing (possibly with clear sputum)
- tightness in the chest
- increased heart rate
- loss of consciousness
Diagnosis is typically through observation of the characteristic presenting symptoms. Respiration testing allows for confirmation of diagnosis and determination of the severity of an attack. Often it is not possible to determine which simuli induce an attack for any given individual.
Treatment and prevention are typically with anti-inflammatory and/or bronchodilating drug administration. These drugs can either be taken orally, inhaled, or injected. Avoiding known triggering stimuli is important to prevent attacks from reoccurring.