A patient with asthma is wheezing and has a sudden drop in peak expiratory flow rate. What immediate action should the nurse take?

A. Perform chest physiotherapy: This intervention is designed to mobilize secretions in chronic conditions like cystic fibrosis or bronchiectasis. In an acute asthma exacerbation, the primary issue is smooth muscle constriction, not necessarily mucus plugging. Chest percussion may actually worsen the patient's respiratory distress by increasing agitation. B. Increase oxygen flow rate: While oxygen is supportive, it does not treat the underlying pathophysiology of bronchospasm. Without opening the narrowed airways, increasing oxygen flow may not effectively reach the alveoli for gas exchange. The immediate priority is reversing the mechanical obstruction of the bronchioles. C. Encourage pursed-lip breathing: This technique is more effective for patients with emphysema to prevent airway collapse during expiration. While it may provide some psychological calm, it is not a potent enough intervention to reverse a significant drop in peak flow. It is a supportive measure rather than a rescue treatment. D. Administer a short-acting beta-agonist inhaler: These medications, like Albuterol, rapidly stimulate beta-2 adrenergic receptors on bronchial smooth muscle to induce bronchodilation. This is the first-line "rescue" intervention to increase airway diameter and restore airflow. It directly addresses the physiological cause of wheezing and reduced peak flow.