COPD Flashcards
What is Chronic Obstructive Pulmonary Disease (COPD)?
Is this disease chronic or acute?
- persistent inflammation of the airways, parenchyma (alveoli) and vasculature
- it is chronic and worsens as it progresses
- individuals have acute, recurrent, chronic obstruction of the airways (acute episodes within their chronic condition)
Which diseases are included under COPD?
- chronic bronchitis
- emphysema
What most often causes COPD and why?
leading cause of COPD is smoking (80-90%) because the carcinogens and irritants:
- cause increased mucus
- damage cilia
- induce inflammation… which causes tissue damage (airway damage and blood vessels)
- induces coughing (which can further damage tissue)
What, other than smoking, can cause COPD?
- recurrent respiratory infections
- ageing (degenerative changes to tissues)
- genetic defect of alpha1 antitrypsin
What are the three causes of airflow obstruction in COPD?
1) hypertrophy of bronchial wall
2) inflammation and hypersecretion of mucus
3) damage to elastic tissue
What is chronic bronchitis?
chronic inflammation and obstruction of the airway
What causes chronic bronchitis?
- mostly smoking
- also recurrent infections
What are two characteristics of chronic bronchitis?
1) large airways are affected first
- hypertrophy of submucosal glands (reaction to increased demand since they produce mucus as a defense)
- hypersecretion of mucus (this is initially beneficial)
2) small airways are affected later
- there is an increase in the number of goblet cells and a consequent increase in mucus production
What is the pathology of chronic bronchitis?
- excess mucus from inflammation (from smoke or recurrent infections) impairs mucociliary defenses, leads to an infection (maintains cycle of inflammation and causes exacerbations)
- bronchial walls become inflamed and the lumen is obstructed (plugged with exudate)
- the obstruction can cause airway collapse, where air is trapped in parts of the lung
- this decreases alveolar ventilation, causing an imbalance in the ventilation to perfusion ratio
- this imbalance leads to hypoxemia
What is hypoxemia?
deficiency of oxygen in arterial blood
What is the ventilation to perfusion ratio?
volume of air that moves in and out of lungs in a minute
to
volume of blood moving through the lungs in a minute
What is the normal ventiltaion to perfusion ratio? (V/Q ratio)
0.8
How is chronic bronchitis diagnosed?
- chronic productive cough for at least 3 months in a year, for two consecutive years
What are the manifestations of chronic bronchitis?
- impaired respiratory function: hypoxemia and hypercapnia
- activity intolerance
- increased sputum
- dyspnea
- wheezing and crackles (wet)
- prolonged expiration
What is emphysema?
- destruction of alveolar tissue and capillary beds
What does emphysema cause?
- loss of compliance (ease with which you fill and empty the lungs)
- enlarged distal airspaces ( “merging” of adjacent alveoli creates enlarged spaces with less surface area)
What causes emphysema?
- smoking
- genetic defect of alpha1 antitrypsin (less than 1% of COPD)
What is alpha1 antitrypsin?
- an inhibitor of proteases, enzymes that breakdown protein
- protects the lungs
- it regulates proteases, without regulation the proteases will breakdown protein in the lungs and destroy tissue
What is the pathology of emphysema?
smoking:
1) inhibits alpha1 antitrypsin, the proteases can then cause tissue destruction in the lungs
2) components in smoke attract inflammatory cells and in this way cause tissue damage
- there is an increase in proteases = destruction of the alveolar walls = alveoli merge = decreasing surface area and permanent, distended air spaces
- air is trapped in between alveoli = increased deadspace
- ventilation is impaired = increased work of breathing
- capillaries associated with the alveoli are also destroyed = impaired perfusion
There are two types of emphysema. Name the two types and explain which area of the lungs are affected in each type. Which type is more common?
1) centriacinar
- destruction of the terminal and respiratory bronchioles
2) panacinar
- destruction of the alveoli as well as the terminal and respiratory bronchioles
What is a bullae?
when the trapped air pushes on the pleural membrane, making a pocket
What is a bleb?
small bullae
What are manifestations of emphysema?
- dyspnea
- increased ventilatory effort
- barrel chest (transverse diameter decreases)
- pursed lip breathing, nasal flaring
What are accessory muscles of inspiration?
- scalene muscles (elevates first two ribs)
- sternocleidomastoid muscles (raises the sternum)
- alae nasi (flares nostrils)
