11 - Chronic Obstructive Pulmonary Disease

Question 1

COPD is mostly caused by ___ and ___.

Answer 1

Emphysema and chronic bronchitis

Question 2

Patients with asthma can be considered to have COPD if they have ___.

Answer 2

airway remodeling (leads to irreversible obstruction)

Question 3

What is the definition of emphysema?

Answer 3

• abnormal permanent distal airspace enlargement (in respiratory bronchioles)
• destructive changes of alveolar wall without obvious fibrosis
• can be distal acinar, pan acinar, paraseptal, or subpleural

Question 4

What is the definition of chronic bronchitis?

Answer 4

• Cough and sputum most days for a minimum of 3 months for 2 consecutive years
• airflow obstruction may not be present
• excess mucus secretion

Question 5

What are the risk factors for COPD?

Answer 5

Exposures

• tobacco smoke
• environmental tobacco smoke
• occupational dust and chemicals
• indoor/outdoor pollution
• infection

Host factors

• bronchial hyperreflexiveness (BHR)
• bronchopulmonary dysplasia (BPD)
• genetic
• maternal smoking
• childhood asthma
• HIV
• tuberculosis
• decreased socioeconomic status

Question 6

What are the three mechanisms of disease in COPD?

Answer 6

• chronic inflammation (lymphocytes, alveolar macrophages, neutrophils)
• elastase/anti-elastase imbalance
• oxidative stress

Question 7

What causes COPD to continue to progress after the precipitating factor is no longer present?

Answer 7

• immune dysregulation/autoimmunity

- alveolar epithelial cell senescence

Question 8

In which lung disease is hyperinflation most common? Why?

Answer 8

Emphysema

Not as likely in other lung diseases because they are usually not associated with decreased elastic recoil or decreased radial traction

Question 9

What are the pathophysiologic explanations for signs and symptoms of COPD?

Answer 9

• increased WOB, increased dead space, decreased respiratory muscle function, hypoxemia –> dyspnea and tachypnea
• airflow obstruction –> wheeze, increased expiratory time
• mucus gland and airway receptor stimulation –> cough and sputum
• decreased food intake and systemic inflammation –> weight loss and peripheral weakness
• hyperinflation and diaphragm dysfunction –> thoracoabdominal paradox, Hoover sign, accessorry muscle use
• increased pulmonary vascular resistance –> pulmonary hypertension, cor pulmonale

Question 10

What PFT pattern is consistent with COPD?

Answer 10

• decreased FEV1
• decreased or normal FVC
• decreased FEV1/FVC
• increased TLC
• decreased DLCO (if emphysema is present)
• decreased MIP (if significant hyperinflation)

Question 11

What causes hypoxemia in COPD?

Answer 11

V/Q mismatch

Question 12

What causes hypercapnia in COPD?

Answer 12

• increased dead space
• decreased diaphragmatic capacity
• abnormal control of breathing
• smaller tidal volumes (leading to increased dead space fraction)

Question 13

Why might COPD patients breathe rapidly and shallowly?

Answer 13

Hyperinflation and increased elastic work of breathing –> fast, shallow breathing minimizes work on each breath

Question 14

At what PaO2 do you give supplemental oxygen to someone with COPD?

Answer 14

PaO2 ≤ 55 mmHg OR PaO2 ≤ 60 mmHg if there is also pulmonary hypertension

Question 15

What are the treatments for COPD?

Answer 15

• smoking cessation
• supplemental oxygen (in some cases)
• short acting bronchodilators as needed
• long acting bronchodilators and inhaled corticosteroids
• pulmonary rehab

Question 16

What is the definition of COPD?

Answer 16

• persistent respiratory symptoms and airflow limitation due to airway and/or alveolar abnormalities
• mixture of small airway disease and parenchymal destruction

Question 17

What are the known alpha-1 antitrypsin mutations? Which is the most common? Most severe?

Answer 17

• PiZZ (most common and most severe)
• PiSZ
• PiMZ
• PiSS
• PiMM

Question 18

What does emphysema at an early age suggest?

Answer 18

Alpha-1 antitrypsin deficiency

Question 19

What part of the lungs does alpha-1 antitrypsin deficiency affect? What part of the lobe?

Answer 19

Lower lobes, panlobular/panacinar

Question 20

What is the proper treatment for someone with alpha-1 antitrypsin deficiency-induced emphysema

Answer 20

• stop smoking, if applicable
• replacement therapy
• treat infections

Question 21

What small airway changes are seen in COPD?

Answer 21

• thickening of airway wall
• goblet cells
• lymphoid follicles
• loss of elasticity and disrupted alveolar attachments (airway-parenchymal interdependence)
• lumen occlusion by mucus and inflammatory exudate
• fibrosis

Question 22

What mechanisms in emphysema cause expiratory flow limitation? What mechanisms in chronic bronchitis cause expiratory flow limitation?

Answer 22

Emphysema:

• loss of radial traction
• loss of elastic recoil

Chronic bronchitis
- increased airway resistance (from edema, smooth muscle, mucus, and inflammation)

Question 23

How does hyperinflation affect work of breathing?

Answer 23

It increases it because there is reduced compliance

Question 24

At what PaO2 and SpO2 levels do you give someone with COPD supplemental oxygen?

Answer 24

PaO2 ≥ 55 mmHg or SpO2 ≥ 88%