Respiratory Medicine: COPD Overview

Respiratory Medicine - Obstructive Disease - Airway Diseases - COPD

• Date: 16/10/2024
• Presenter: Dr. Mahad Sadik Mukhtar, Pulmonologist MD, Pulmonary Medicine, MU MBBS A9
• Topic: Chronic Obstructive Pulmonary Disease (COPD)

Lecture Contents

• Case Scenario
• Introduction
• Epidemiology
• Types of COPD
• Causes and Risk Factors of COPD
• Pathophysiology
• Clinical Features
• Diagnosis of COPD
• Management of COPD
• Prevention of COPD

COPD

• A common, preventable, and treatable disease
• Characterized by persistent respiratory symptoms and airflow limitation
• Usually caused by significant exposure to noxious particles or gases
• Influenced by host factors, including abnormal lung development
• Significant comorbidities may affect morbidity and mortality

Proposed New Definition of COPD

• COPD is a heterogeneous lung condition
• Characterized by chronic respiratory symptoms (dyspnea, cough, expectoration)
• Due to persistent abnormalities of the airways (bronchitis, bronchiolitis), alveoli (emphysema), and/or pulmonary vessels
• Confirmed by spirometrically determined airflow limitation and/or objective evidence of structural or physiological pulmonary dysfunction

COPD Risk Factors

• Early life factors and exposures
  • Maternal smoking
  • Respiratory infections
  • Dysanapsis
• Tobacco smoke
  • Nearly 80% of COPD cases attributed to smoking
  • 15-20% of 1 pack per day smokers
  • 25% of 2 pack per day smokers
• Outdoor and indoor pollution
  • Biomass fuel
    • 50% of COPD deaths in developing countries
    • 75% in women
• Occupational exposures
  • Mining
  • Agriculture
  • Textile
  • Paper
  • Wood
  • Chemical
  • Food processing
  • Cadmium fumes (smelting, batteries)
• Socioeconomic status
• Genetic factors
  • Several GWAS linked genetic loci with COPD
  • Best documented in AAT deficiency (SERPINA1 gene mutation)

Epidemiology

• COPD is more common in older people (especially those aged 65 years and older)
• Highest prevalence in World Health Organization (WHO) regions in the Americas
• Lowest prevalence in South-East Asia and Western Pacific regions
• Pooled global prevalence: 15.7% in men and 9.93% in women
• Globally, deaths increased by 23% from 1990 to 2017; currently ~3 million deaths annually from COPD
• Expanding epidemic of smoking and aging population, along with reduced mortality from other causes, suggests over 5.4 million annual deaths by 2060 due to COPD and related diseases

Types of COPD

• Genetically determined COPD (COPD-G)
• COPD due to abnormal lung development COPD (COPD-D)
• Environmental COPD (COPD-E)
  • Cigarette smoking COPD (COPD-C)
  • Biomass and pollution exposure COPD (COPD-P)
  • COPD due to infections (COPD-I)
  • COPD & asthma (COPD-A)
  • COPD of unknown cause (COPD-U)

Pathophysiology

• Oxidant/Antioxidant imbalance
• Emphysema (alveolar wall destruction)
• Mucus hypersecretion
• Enhanced cytokines, chemokines, protease
• Inflammation
• Genetic factors
  • a1-antitrypsin deficiency (decreased a1-antitrypsin results in unopposed breakdown of elastin fibers by elastase)
• Environmental factors (Smoking, biomass burning, and occupational exposure) - recruitment of neutrophils in bronchioles and alveoli, oxidative stress, inflammatory mediator cytokines
• Inflammation (Squamous cell metaplasia or increased goblet cells).

Clinical Features

• Symptoms
  • shortness of breath
  • chronic cough
  • sputum production
  • wheezing
  • chest tightness
• Easy-to-Remember Symptoms:
  • Lack of energy
  • Inability to tolerate activity
  • Nutritional deficit
  • Gas abnormality (respiratory acidosis)
  • Dry or productive cough
  • Accessory muscle use and excessive lung sounds
  • Modification of skin colour
  • Increased anterior/posterior diameter
  • Tripod breathing position
  • Extreme dyspnea

Pulmonary and Systemic Features

• Pulmonary
  • Mucus inflammation
  • Airway wall thickening
  • Peribronchial fibrosis
  • Mucus hypersecretion
  • Goblet cell hyperplasia
  • Mucociliary clearance reduction
  • Luminal mucus obstruction
  • Disrupted alveolar attachments (emphysema)
  • Small airway closure
  • Gas trapping
• Systemic
  • Muscular weakness
  • Increased circulating inflammatory markers
  • Impaired salt and water excretion
  • Peripheral oedema
  • Altered fat metabolism
  • Weight loss
  • Increased prevalence of osteoporosis

Diagnosis

• Symptoms
• Risk factors
• Spirometry
• Other investigations: CBC, Chest X-Ray, HRCT, ABG, ECG, ECHO, Alpha Anti-Trypsin level

COPD Classification and Severity

• GOLD classification (Global Initiative for Chronic Obstructive Lung Disease)
• Mild, Moderate, Severe, Very Severe based on a FEV1/FVC
• Patient assessment using the mMRC and CAT scales
• COPD Assessment Tool (ABE)

COPD Assessment

• Patient with respiratory symptoms that are not explained by heart disease
• Forced spirometry to determine airway obstruction (FEV1/FVC < 0.7)
• Exclude other possible causes (pulmonary hypertension), referral to a specialist if necessary
• Determine clinical response
• Continue treatment or follow-up based on symptoms

Management

• Goals:
  • Relieve symptoms (dyspnea)
  • Improve exercise tolerance
  • Improve health status
  • Prevent disease progression
  • Prevent and treat exacerbations
  • Reduce mortality

Non-pharmacological management in stable COPD

• Smoking cessation
• Immunization
• Pulmonary rehabilitation
• Oxygen therapy
• Non-invasive positive pressure ventilation

Pharmaceutical interventions

• Stepwise drug therapy
• Single short-acting inhaled B2-agonist
• Combination therapies
• Inhaled corticosteroids (ICS): combined with LABA or LABA+LAMA+ICS
• Long-acting Beta agonists (LABA)
• Long-acting Muscarinic antagonists (LAMA)

COPD Exacerbations

• An event characterized by increasing dyspnea, cough, sputum that worsens over 14 days
• Often associated with increased local and systemic inflammation caused by airway infection, pollution, or other insult.
• Often require hospitalization

Management of exacerbations of stable COPD

• Consider different factors as needed: including mMRC scores and CAT and other diagnostic test results