Acute-onset bronchial asthma causes wheezing and breathlessness as a result of which of these processes?

Choice A rationale Acute-onset bronchial asthma is fundamentally characterized by airway inflammation, which involves the infiltration of inflammatory cells, such as mast cells and eosinophils, leading to the release of mediators like histamine and leukotrienes. This triggers bronchoconstriction (smooth muscle spasm), mucosal edema, and mucus production, collectively reducing the airway diameter and airflow, which clinically manifests as wheezing and breathlessness. Choice B rationale Alveolar collapse, or microatelectasis, is a consequence of hypoxemia or reduced surfactant, not the primary cause of acute asthmatic symptoms. Acute asthma mainly affects the bronchi and bronchioles by causing inflammation and bronchospasm, which hinders airflow. Alveolar function is compromised secondarily by impaired ventilation, but the obstructive process in the airways is the main source of wheezing. Choice C rationale Compression atelectasis is typically caused by external pressure on the lung tissue, such as a pleural effusion or a large tumor, leading to the collapse of the underlying alveoli. This is not the primary pathophysiologic mechanism in acute bronchial asthma, which is characterized by intrinsic airway obstruction due to inflammation, edema, and bronchospasm within the bronchial walls. Choice D rationale Pulmonary hypertension, characterized by elevated blood pressure in the pulmonary arteries (normal range: systolic 15-30 mmHg), can be a long-term complication of severe, chronic respiratory disease, but it is not the acute-onset process directly responsible for the immediate wheezing and breathlessness in asthma. The acute symptoms are due to airway narrowing from bronchospasm and inflammation.