Chapter 39: Lower Respiratory Disorder Drug Therapy

Lower Respiratory Disorder Drug Therapy establishes the physiological basis of respiration, discussing lung compliance, the function of surfactant in reducing alveolar surface tension, and the neural regulation of ventilation through central and peripheral chemoreceptors sensitive to carbon dioxide, oxygen, and pH levels. The text differentiates between the reversible airway obstruction of asthma—mediated by mast cell degranulation and the release of inflammatory cytokines, histamines, and leukotrienes—and the irreversible structural damage found in chronic bronchitis, emphysema, and bronchiectasis. A significant portion of the chapter details the major drug categories used to treat these conditions, particularly bronchodilators. It explains the mechanism of action for sympathomimetics, specifically selective beta-2 adrenergic agonists like albuterol and salmeterol, which stimulate cyclic AMP (cAMP) production to induce bronchial smooth muscle relaxation. The summary also covers anticholinergic agents such as tiotropium and ipratropium bromide that block muscarinic receptors, and methylxanthine derivatives like theophylline, highlighting the critical need for serum level monitoring due to a narrow therapeutic index and potential for severe toxicity (dysrhythmias and seizures). Furthermore, the chapter explores anti-inflammatory strategies, including leukotriene receptor antagonists like montelukast for asthma prophylaxis, mast cell stabilizers like cromolyn, and the administration of inhaled and systemic glucocorticoids. Key nursing process considerations are integrated, such as teaching proper inhaler technique with spacers, preventing oral candidiasis following steroid use, and managing adverse effects like tachycardia, tremors, and paradoxical bronchospasm.