Asthma III: Clinical Manifestations

Wheezing is a high-pitched whistling sound heard during exhalation and sometimes inhalation, caused by turbulent airflow through narrowed, mucus-filled airways. It results from bronchoconstriction and mucus hypersecretion that obstruct normal airflow. In severe asthma, wheezing may become loud and fail to respond to short-acting bronchodilators.

A persistent, dry cough is one of the most common early features of asthma and tends to worsen at night or in the early morning. This pattern reflects circadian variations in airway tone and inflammation, which naturally fluctuate throughout the day and are often heightened during sleep hours.

Chest tightness in asthma is perceived as pressure or constriction that makes deep breathing uncomfortable. It reflects bronchial smooth muscle contraction and increased airway resistance. This sensation occurs because narrowed airways limit the ability to ventilate adequately and expand the chest fully.

Shortness of breath, or dyspnea, arises when airflow obstruction limits adequate ventilation. While mild cases are triggered by exercise or allergen exposure, severe asthma can cause dyspnea even at rest. The degree of dyspnea depends on the severity of airway narrowing and mucus accumulation.

During an acute exacerbation, patients develop rapidly worsening dyspnea, persistent coughing, and loud wheezing. Additional physical signs include tachypnea, tachycardia, and use of accessory muscles of respiration such as the sternocleidomastoid and intercostal muscles to support increased breathing effort and maintain ventilation.

An acute asthma attack can be treated with a rescue inhaler, which delivers short-acting bronchodilators to relieve airway constriction. However, if the rescue inhaler fails to resolve severe dyspnea and respiratory distress, hospitalization may be needed to prevent respiratory failure and provide intensive management.

Asthma shares clinical features with chronic obstructive pulmonary disease clinical manifestations, including airway obstruction and respiratory symptoms like coughing and wheezing. However, asthma is characterized by reversible airway inflammation and bronchoconstriction, whereas chronic obstructive pulmonary disease involves progressive, largely irreversible airway damage and obstruction.