COPD

Question 1

What is Chronic Obstructive Pulmonary Disease (COPD)?

Is this disease chronic or acute?

Answer 1

• 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)

Question 2

Which diseases are included under COPD?

Answer 2

• chronic bronchitis

- emphysema

Question 3

What most often causes COPD and why?

Answer 3

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)

Question 4

What, other than smoking, can cause COPD?

Answer 4

• recurrent respiratory infections
• ageing (degenerative changes to tissues)
• genetic defect of alpha1 antitrypsin

Question 5

What are the three causes of airflow obstruction in COPD?

Answer 5

1) hypertrophy of bronchial wall
2) inflammation and hypersecretion of mucus
3) damage to elastic tissue

Question 6

What is chronic bronchitis?

Answer 6

chronic inflammation and obstruction of the airway

Question 7

What causes chronic bronchitis?

Answer 7

• mostly smoking

- also recurrent infections

Question 8

What are two characteristics of chronic bronchitis?

Answer 8

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

Question 9

What is the pathology of chronic bronchitis?

Answer 9

• 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

Question 10

What is hypoxemia?

Answer 10

deficiency of oxygen in arterial blood

Question 11

What is the ventilation to perfusion ratio?

Answer 11

volume of air that moves in and out of lungs in a minute

to

volume of blood moving through the lungs in a minute

Question 12

What is the normal ventiltaion to perfusion ratio? (V/Q ratio)

Answer 12

0.8

Question 13

How is chronic bronchitis diagnosed?

Answer 13

• chronic productive cough for at least 3 months in a year, for two consecutive years

Question 14

What are the manifestations of chronic bronchitis?

Answer 14

• impaired respiratory function: hypoxemia and hypercapnia
• activity intolerance
• increased sputum
• dyspnea
• wheezing and crackles (wet)
• prolonged expiration

Question 15

What is emphysema?

Answer 15

• destruction of alveolar tissue and capillary beds

Question 16

What does emphysema cause?

Answer 16

• 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)

Question 17

What causes emphysema?

Answer 17

• smoking

- genetic defect of alpha1 antitrypsin (less than 1% of COPD)

Question 18

What is alpha1 antitrypsin?

Answer 18

• 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

Question 19

What is the pathology of emphysema?

Answer 19

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

Question 20

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?

Answer 20

1) centriacinar
- destruction of the terminal and respiratory bronchioles
2) panacinar
- destruction of the alveoli as well as the terminal and respiratory bronchioles

Question 21

What is a bullae?

Answer 21

when the trapped air pushes on the pleural membrane, making a pocket

Question 22

What is a bleb?

Answer 22

small bullae

Question 23

What are manifestations of emphysema?

Answer 23

• dyspnea
• increased ventilatory effort
• barrel chest (transverse diameter decreases)
• pursed lip breathing, nasal flaring

Question 24

What are accessory muscles of inspiration?

Answer 24

• scalene muscles (elevates first two ribs)
• sternocleidomastoid muscles (raises the sternum)
• alae nasi (flares nostrils)

Question 25

How is COPD diagnosed?

Answer 25

• history and presentation
• labs (CBC, ABGs)
• chest x-ray
• pulmonary function tests

Question 26

How is COPD treated?

Answer 26

• limit progression: quit smoking and avoid airway irritants
• flu and pneumococcal vaccines
• drugs

Question 27

What are the drugs used to treat COPD?

Answer 27

stage based:

1) short acting beta agonists and anticholinergics to cause bronchodilation
2) the above plus inhaled steroids
3) long acting beta agonists
4) theophylline