Pathophysiology and Management of Lung Diseases

Obstructive Lung Diseases

Obstructive lung diseases are defined by difficulty exhaling air from the lungs. Because the airways are narrowed or obstructed, air becomes trapped, often leading to an increased residual volume (RV).

Asthma

Asthma is characterized by airway inflammation and an allergic-type reaction. Triggers such as allergens, cold air, exercise, or perfumes cause the bronchioles to fill with fluid and mucus, leading to the constriction of smooth muscle, known as bronchospasm.

Clinical signs include dyspnea, chest tightness, wheezing, and hypoxia. Management focuses on trigger avoidance, the use of bronchodilators, and corticosteroids to reduce inflammation. Patients should also be taught to monitor their condition using a peak flow meter.

Chronic Obstructive Pulmonary Disease (COPD)

COPD is an umbrella term that includes several progressive diseases, most notably emphysema and chronic bronchitis.

• Emphysema: This involves the destruction of alveolar walls. Enzymes break down these walls, turning the alveoli into fewer, larger, and non-elastic structures called bullae. This leads to air trapping, hyperinflation, and $CO_2$ retention.

  

• Chronic Bronchitis: This is characterized by chronic mucus production, airway edema, and bronchospasm caused by long-term irritants like smoking. The excess mucus serves as a breeding ground for infection.

Management for COPD and asthma includes supplemental oxygen (targeting an $\text{SpO}_2 > 88\%$), bronchodilators, and pulmonary rehabilitation.

Restrictive Lung Diseases

Unlike obstructive diseases, restrictive lung diseases involve a decrease in total lung capacity (TLC) because the lungs cannot fully expand. In these cases, airflow may be normal, but the volume of air the lungs can hold is reduced.

Causes are categorized as:

1. Intrinsic (Lung tissue related): Pulmonary fibrosis, sarcoidosis, and interstitial lung disease (ILD).
2. Extrinsic (Outside lung tissue): Neuromuscular diseases (e.g., ALS, muscular dystrophy), chest wall deformities (e.g., kyphoscoliosis), and obesity.

Patients often present with a dry, non-productive cough, tachypnea (rapid, shallow breathing), and the use of accessory muscles to breathe. Physical assessment may reveal fine crackles upon auscultation.

Diagnosis and Management

Diagnosis is primarily achieved through Pulmonary Function Tests (PFTs), which typically show a decreased TLC but a normal or increased $\text{FEV}_1/\text{FVC}$ ratio. High-Resolution CT (HRCT) is the preferred imaging method to detect "honeycombing" or fibrosis.

Nursing interventions focus on maintaining oxygenation and improving lung expansion. This includes:

• Positioning: Encouraging a high Fowler's position.
• Breathing Exercises: Using incentive spirometry to encourage deep breaths and teaching pursed-lip breathing.
• Medication: Administering antifibrotics or immunosuppressants as prescribed.

Summary of Nursing Interventions and Patient Education

Across all respiratory pathologies, the nurse's role is vital in preventing complications and improving quality of life.

Patient Education Tip: For patients with chronic conditions like COPD or Asthma, education should focus on smoking cessation, proper inhaler/spacer technique, energy conservation, and avoiding environmental triggers.