RGI 10

Importance of Respiratory Diseases

• Respiratory diseases are significant due to their high mortality rates, making them crucial in clinical practice.

• Feedback on the lecture content is welcome since it’s newly introduced this year.

Classification of Respiratory Diseases

Two Main Groups

• Obstructive Diseases: Difficulty in expelling air from the lungs, leading to air trapping.

  • Causes hypoxia (low oxygen) and hypercapnia (high CO2).

  • E.g., asthma, chronic obstructive pulmonary disease (COPD).

• Restrictive Diseases: Difficulty in inhaling air, due to structural lung issues.

  • Results from lung tissue damage or other external factors.

  • Similar exertional dyspnea (difficulty breathing during exercise) in both types.

Diagnostic Measurements

Tools for Diagnosis

• Spirometry: Measures lung function, identifying whether conditions are obstructive or restrictive.

  • Normal tidal volumes may remain intact until exertion.

• Peak Flow Measurements: Provides data on lung function and airflow.

Characteristics of Diseases

• Both obstructive and restrictive diseases can progress or coexist, affecting airflow dynamics.

• Conditions can evolve, such as from obstruction to restriction due to tissue damage (e.g., cystic fibrosis).

Physiological Implications of Lung Diseases

Breathing Mechanics

• Obstructive Diseases: Difficulty getting air out; leads to ineffective gas exchange due to high residual volume.

  • Barrel chest may develop due to trapped air.

• Restrictive Diseases: Difficulty getting air in; marked reductions in lung volume and elasticity due to scarring.

  • Vital capacity is diminished; inspiratory capacity is severely affected.

Key Measurements

• Tidal Volume (TV): Normal amount of air exchanged during breathing.

• Inspiratory Reserve Volume (IRV): Extra air that can be inhaled after normal inhalation.

• Expiratory Reserve Volume (ERV): Extra air that can be exhaled after normal exhalation.

• Residual Volume (RV): Air remaining in the lungs after maximum exhalation.

Vital Capacity (VC)

• The maximum amount of air moved in and out during a breath.

• Obstructive diseases show high residual volume; restrictive diseases reveal reduced total lung volumes.

Peak Flow Monitoring

• Forced Vital Capacity (FVC): Maximum air expelled after maximum inhalation.

• FEV1 (Forced Expiratory Volume in 1 second): Determines how fast air is expelled.

• Comparison of FEV1/FVC ratios distinguishes obstructive from restrictive conditions.

Types of Obstructive Diseases

Include:

• Asthma: Inflammatory response leading to narrowing of bronchi; caused by allergens triggering immune response.

  • Histamine release activates inflammation and bronchoconstriction.

• Chronic Obstructive Pulmonary Disease (COPD): Combination of chronic bronchitis and emphysema.

  • Chronic Bronchitis: Inflammation, mucus overproduction, and narrowing of airways.

  • Emphysema: Loss of elastic tissue due to chronic inflammation and protease overactivity.

Cystic Fibrosis

• Genetic disorder resulting in thick mucus production leading to obstruction and later restrictive problems due to scarring.

• Caused by CFTR gene mutation affecting chloride transport in epithelial tissues.

Types of Restrictive Diseases

Include:

• Tuberculosis: Causes obstructive and restrictive symptoms due to cavitation and fibrotic responses in the lungs.

  • Chronic issue results in reduced elasticity and gas exchange inefficiency.

• Neuromuscular Conditions: E.g., poliomyelitis leading to respiratory muscle paralysis, affecting breathing capacity.

• Myasthenia Gravis: Autoimmune condition limiting muscle contractions, impacting lung expansion.

• Obesity: Excess weight restricts lung expansion, leading to both obstructive and restrictive breathing issues.

• Muscular Dystrophy: Loss of muscle function impairs thoracic movement leading to restrictive lung disease.

External and Environmental Factors

• Environmental Exposures: Long-term exposure to pollutants can lead to lung scarring and fibrosis (e.g., from silica dust or asbestos).

Summary of Clinical Considerations

• Accurate diagnosis utilizing spirometry and peak flow metrics is essential.

• Differentiation between obstructive and restrictive diseases is critical in tailoring treatments and managing patient care effectively.

• Awareness of the interplay between respiratory and cardiovascular systems is key to understanding these diseases.