Obstructive Lung Diseases

Question 1

list the obstructive lung diseases

Answer 1

• emphysema
• chronic bronchitis
• asthma
• bronchiectasis

Question 2

list the restrictive lung diseases

Answer 2

• acute restrictive disease
  
  • ARDS
• chronic restrictive disease
  
  • interstitial fibrosis
  • pneumoconiosis
  • granulomatous
• chest wall deformities
• neuromuscular

Question 3

summarize the differences between obstructive vs. restrictive diseases

Answer 3

Question 4

____ is a reversible anatomic airway narrowing,

while

_____ are irreversible.

Answer 4

asthma is a reversible anatomic airway narrowing,

while

CB, emphysema, bronchiectasis are irreversible.

Question 5

describe the structural change in emphysema

Answer 5

• abnormal permanent airspace enlargement distal to the terminal bronchioles accompanied by destruction of airspace walls without fibrosis

Question 6

describe the pathogenesis of emphysema

Answer 6

Question 7

describe genetic factors involved in emphysema

Answer 7

• A1AT deficiency
  
  • 1% of all emphysema
  • Pi gene on chr. 14
    
    • PiMM = normal, PiZZ = abnormal
  • protein accumulates in the liver if abnormal
  • chronic liver disease
• polymorphisms in TGFB gene
• polymorphisms in matrix metalloproteinases (MPPs)

Question 8

describe the centrilobular vs. panlobular forms of emphysema

Answer 8

• centrilobular (centriacinar)
  
  • smoking
  • upper lung zones
  • respiratory bronchioles is affected
• panlobular (panacinar)
  
  • A1AT deficiency
  • lower lung zones
  • acinus distal to RB is involved

Question 9

describe septal (distal acinar) vs. irregular (paracicatrical) forms of emphysema

Answer 9

• septal (distal acinar) emphysema:
  
  • rare
  • next to atelectasis, along septa, margins of lobes, subpleural
  • more common in upper lobes
  • may form bullae
  • can lead to pneumothorax
• irregular (__paracicatrical__) emphysema
  
  • surrounding scar
  • asymptomatic

Question 10

describe the gross morphology of emphysema

Answer 10

• gross
  
  • hyperinflated lungs +/- bulla formation
  • parenchyma has a “moth-eaten” appearance
• histo:
  
  • destruction of alveolar septa without fibrosis
    
    • free floating alveolar septa in air spaces
  • destruction of elastin within small airways
    
    • aids in obstruction with exhalation due to airway collapse

Question 11

describe what is seen in the image

Answer 11

emphysema

Question 12

describe the clinical presentation of emphysema

Answer 12

• clinical: “pink puffers”
  
  • symptoms appear late (earlier if coexistent chronic bronchitis)
  • barrel chest, dyspnea, prolonged expiration
  • sitting in a forward hunched position trying to squeeze air out of the lungs
  • x-ray: flat domes of diaphragm
  • weak and skinny
    
    • skinny because of excess puffing and panting due to hyperventilation
  • blood gases normal until late with onset of hypoxia, hypercapnia and resp. acidosis

Question 13

chronic bronchitis is diagnosed when cough occurs ____ months in ____ years

Answer 13

chronic bronchitis is diagnosed when cough occurs in >3 consecutive months in >2 consecutive years

Question 14

describe the etiology of chronic bronchitis

Answer 14

• etiology:
  
  • common among smokers and urban dwellers
    
    • inhaled irritants: cigarette smoke, SO2, NO2
  • can occur in conjunction with emphysema

Question 15

in chronic bronchitis, irritants induce…

Answer 15

• inhaled irritants induce…
  
  • hypertrophy of seromucous glands
  • increased goblet cells (via metaplasia) in surface epithelium

Question 16

describe the pathogenesis of chronic bronchitis

Answer 16

• pathogenesis:
  
  • airflow obstruction in CB is peripheral (distal) and results from:
    
    • small airways disease: goblet cell metaplasia at the level of the bronchioles accompanied by inflammation, smooth muscle hyperplasia and peribronchiolar fibrosis
    • coexisting emphysema increases impairment
    • coexistent infxn can complicate and exacerbate symptoms
    • infiltrate of CD8+ T cells, macrophages and PMNs
      
      • no eosinophils in contrast to asthma
    • distinctive feature is hypersecretion of mucus​

Question 17

describe the Reid index and name a disease where it is increased

Answer 17

• Reid index = ratio of the thickness of the mucous gland layer to the thickness of the wall between the epithelium and cartilage
  
  • this is increased in chronic bronchitis because of the seromucous gland hyperplasia

Question 18

describe the clinical presentation of chronic bronchitis

Answer 18

• clinical = blue bloaters
  
  • hypoxia, hypercapnia, cyanosis
    
    • persistent hypercapnia → respiratory centers insensitive to pCO2
    • respiratory drive is driven by low pO2
  • complicated by secondary infxns
  • over time → pulm. hypertension → cor pulmonale
    
    • common in any disease where hypoxia occurs

Question 19

Answer 19

Question 20

summarize the differences between chronic bronchitis and emphysema

Answer 20

Question 21

describe the etiology of asthma

Answer 21

• etiology:
  
  • chronic inflammatory disease
  • hyperactive airways
  • recurrent wheezing, breathlessness, chest tightness and cough
  • episodic, reversible bronchoconstriction

Question 22

describe the pathogenesis of type 1 hypersensitivity seen in atopic asthma

Answer 22

• pathogenesis:
  
  • allergic sensitization; type I IgE mediated hypersensitivity rxn
    
    • patients often have allergic rhinitis or eczema
  • Th2 → cytokines
    
    • IL-4 stimulates IgE production
    • IL-5 activates eosinophils
    • IL-13 stimulates mucus production and promotes IgE production by B-cells
  • IgE coats mast cells which degranulate with antigen exposure

Question 23

describe the pathogenesis of mast cell degranulation in atopic asthma

Answer 23

Question 24

describe the pathogenesis of non-atopic asthma

Answer 24

• no evidence of sensitiation
  
  • serum IgE = normal
• virus induces mucosal damage → lower threshold of subepithelial vagal receptors to irritants
• drug induced asthma
  
  • triad: recurrent rhinitis, nasal polyps, urticaria and bronchospasm
  • aspirin inhibits COX without affecting lipo-oxygenase route → bronchoconstriction mediated by leukotrienes

Question 25

aspirin-induced asthma results in.... (4 symptoms)

Answer 25

* aspirin-induced asthma results in: * recurrent rhinitis * nasal polyps * urticaria * bronchospasm

Question 26

describe occupational asthma

Answer 26

* asthma stimulated by fumes, organic dusts, chemical dusts and gases * epoxy resins, plastics * wood, cotton, platinum * toluene * asthma attacks following repeated exposure

Question 27

describe what is seen in the image

Answer 27

* Curschmann spirals = strings of mucus with dead epithelial cells in it

Question 28

describe the clinical presentation of asthma

Answer 28

* recurrent sudden attacks of resp. distress, tightness of chest * expiratory dyspnea, wheezing/ronchi * thick sputum * progressive hyperinflation of lungs with air trapped distal to mucous packed bronchi * episodic = nights and early mornings * attacks last a couple hours and subside spontaneously or with therapy

Question 29

describe pulmonary function tests in asthmatics

Answer 29

* FEV1 \<30%, hyperventilation * hypoxia, hypercapnia, resp. acidosis * symptom-free intervals but residual resp. defects on spirometry

Question 30

describe the etiology of bronchiectasis

Answer 30

* bronchiectasis: permanent dilation of bronchi/bronchioles secondary to destruction of supporting tissue * etiology: * obstruction and chronic infxn * bronchial obstruction: tumor, foreign body * congenital/hereditary conditions * CF, immunodeficiency states, Kartagener syndrome * necrotizing/suppurative pneumonia * virulent organisms (S. aureus, Klebsiella spp.)

Question 31

describe the pathogenesis of bronchiectasis

Answer 31

Question 32

describe what is seen in the image

Answer 32

Question 33

describe microscopic findings in bronchiectasis

Answer 33

* intense acute and chronic inflammatory exudate in bronchial walls, necrotizing ulceration * squamous metaplasia of bronchial epithelium * lung abscesses may be present * fibrosis of bronchial walls leading to bronchiolitis obliterans * cultures are usually positive

Question 34

name a hereditary cause of bronchiectasis

Answer 34

* primary ciliary dyskinesia (Kartagener syndrome): * AR disorder of ciliary microtubules * structural abnormalities of cilia impair mucociliary escalator * persistent infxns → bronchiectasis * decreased motility of spermatozoa → sterility in males * 1/3 have situs inversus