B4.057 Obstructive Lung Disease Flashcards
what are obstructive airway diseases
increased resistance to airflow due to partial or complete obstruction at any level
decreased maximal airflow rates during forced expiration (FEV1)
restrictive lung diseases
not airway disease
reduced expansion of lung parenchyma
decreased total lung capacity/volume
decreased compliance
emphysema
abnormal permanent enlargement of the airspaces distal to the terminal bronchiole destruction of walls without obvious fibrosis small airway (bronchiole) fibrosis
epidemiology of emphysema
male predominance
smoking major cause
gradual development, symptoms seen at age 40+
when does emphysema manifest?
once 1/3 of the functioning lung parenchyma is impaired
2 primary emphysema types
centriacinar
panacinar
2 secondary emphysema types
distal acinar/paraseptal
irregular
centriacinar emphysema
central/proximal portions of acini (resp bronchioles) affected, but distal alveoli are spared
more common in upper lobes
most common type of emphysema
centriacinar
>95% of cases
panacinar emphysema
acini are uniformly enlarged from respiratory bronchiole to the alveoli
worst at bases of lungs
which type of emphysema is seen with alpha 1 antitrypsin deficiency
panacinar
distal acinar emphysema
distal acinus is predominantly involved
adjacent to pleura, along the septa
next to fibrosis, scarring, or atelectasis
worse in upper lungs
which type of emphysema predisposes to pneumothorax
distal acinar/ paraseptal
bullae near pleura is the issue
irregular emphysema
occurs in small foci
clinically insignificant
gross pathology of centriacinar vs panacinar emphysema
centriacinar has a mix of dilated and normal air spaces
panacinar is uniformly dilated
pathogenesis of emphysema
smoking/genetic predisposposition/ A1AT deficiency initiate cascade
lungs experience:
-oxidative stress, increased apoptosis and senescence
-inflammatory cells and release of inflammatory mediators
-protease/antiprotease imbalance
all result in alveolar wall destruction
what enzymes contribute to tissue damage in emphysema
proteases
neutrophil elastases
macrophage elastase
metalloproteinases
prevalence of A1AT def
1% of emphysema patients
100,000 americans
predisposed to liver disease
what finding might you see on histo of emphysema in addition to dilated air spaces
ruptured alveolar septae due to breakdown by proteases etc.
mechanism of emphysema
functional airflow obstruction
normally small airways are tethered open by the elastic recoil in the walls of surrounding alveoli
loss of elastic tissue in alveolar walls allows the resp bronchioles to collapse during expiration
chronic bronchitis definition
productive cough of unknown cause occurring for 3 or more months in at least 2 successive years
chronic irreversible obstruction of airflow
chronic bronchitis epidemiology
all people, all ages
longtime smokers, polluted urban areas
more common > 45
more common in men
pathogenesis of chronic bronchitis
initiating factor: exposure to noxious inhaled substances
mucus hypersecretion in airways (IL-13)
metaplasia/hypertrophy/remodeling of small airways
inflammation
infection (maintains disease process and causes acute exacerbations)
pathogenesis of chronic bronchitis in the context of smoking
- injures airway epithelium > chronic inflammation
2. impairs ciliary action of airway epithelium > mucus > infection
histo findings in chronic bronchitis
goblet cell metaplasia of bronchial epithelium
increased size of mucus glands (thickness > 40% of bronchial wall)
mucus plugs
lymphocytes in bronchiolar wall
anatomic compartment affected by chronic bronchitis
bronchus
characteristics of a patient w predominant bronchitis
40-45 mild dyspnea copious sputum rhonchi common infections repeated resp insufficiency cor pulmonale common increased airway resistance normal elastic recoil no weight loss
CXR findings in chronic bronchitis
prominent vessels
large heart
cor pulmonale
characteristics of a patient w predominant emphysema
50-75 severe dyspnea scant sputum prominent weight loss diminished breath sounds occasional infections terminal resp insufficiency/ cor pulmonale normal airway resistance low elastic recoil
CXR findings in emphysema
hyperinflation, small heart
complications of COPD
pulm hypertension leading to cor pulmonale (R heart failure)
pneumothorax with massive lung collapse (emph)
superimposed infections (bronch)
asthma definition
chronic disorder of the conducting airways, usually caused by an immunological reaction
episodic bronchoconstriction due to increased airway sensitivity to a variety of stimuli
inflammation of bronchial walls
increased mucus secretion
symptoms of asthma
recurrent episodes of wheezing, breathlessness, chest tightness, cough
particularly at night or in the early morning
usually reversible, either spontaneously or with treatment
epidemiology of asthma
5% of pop
any age
most common in kids, decreases at puberty, increases with age
increasing incidence
continuous asthma symptoms
status asthmaticus
can be fatal
atopic asthma
evidence of allergen sensitization and immune activation
often with allergic rhinitis or eczema
non atopic asthma
no evidence of allergen sensitization
triggers of asthma
seasonal exercise drugs occupational asthmatic bronchitis in smokers
characterize atopic asthma
most common type begins in childhood antigen is implicated positive fam history allergic rhinitis, urticarial, or eczema
atopic asthma testing findings
IgE mediated type 1 hypersens
high serum levels of IgE
RAST detects presence of IgE for specific allergens
skin test wheal and flare reactions
pathogenesis of atopic asthma
complex and multifactorial
TH2 and IgE response to environmental allergens in genetically predisposed individuals
fundamental abnormality is an exaggerated TH2 response to normally harmless environmental antigens
susceptibility locus for asthma
chromosome 5q
encodes interleukins; IL-13
environmental factors for asthma development
airborne pollutants
hygiene hypothesis
young children with aeroallergen sensitization and lower resp tract viral infections have a 10-30x risk of developing asthma
drug induced asthma
several drugs can provoke
aspirin induced asthma
+ recurrent rhinitis, nasal polyps
small doses of NSAIDs provoke asthmatic attacks and urticarial
inhibits COX pathway of AA metabolism > decrease PGE2
release inhibition of enzymes that generate pro inflamm mediators (LTB4,C4,D4,E4)
histo findings with asthma
mucus plugs
curschmann spiral - coiled fragment of inspissated mucus
eosinophils
Charcot Leyden crystals from eosinophil breakdown
airway remodeling seen in asthma
thickening of airway wall
sub BM fibrosis
increased vascularity and macrophages in lamina propria
increased size of submucosal glands and number of airway goblet cells
hypertrophy/hyperplasia of muscle
what is bronchiectasis
destruction of airway muscle and elastic tissue, resulting in permanent dilation of bronchi and bronchioles
often due to chronic necrotizing infections
clinical features of bronchiectasis
cough (copious, foul smelling, purulent sputum)
hemoptysis
recurrent acute infective exacerbations can lead to severe lung function impairment
dyspnea and wheezing
primary causes of bronchiectasis
idiopathic (30-53%) postinfectious (29-42%) congenital or hereditary bronchial obstruction other
pathogenesis of bronchiectasis
- bronchial obstruction > normal clearing mechanisms are impaired > pooling of secretions distal to obstruction > secondary infection and inflammation
- severe infections > inflammation, necrosis, fibrosis, airway dilation
both paths lead to destruction of bronchiole wall
how does bronchiectasis arise in CF
inherited defect in ion transport impairs mucociliary action and creates airway obstruction by thick viscous secretions
predisposes to chronic bacterial infections > extensive airway damage > destruction of SM and elastic tissue
result of bronchiectasis in CF
markedly dilated bronchi and fibrotic obliteration of smaller bronchioles
what is primary ciliary dyskinesia
autosomal recessive syndrome
defect in ciliary motor protein (dynein)
ciliary function is necessary for proper rotation of organs during development and for bacterial clearance in the sinus and airways
poorly functioning cilia lead to retention of secretions and recurrent infections
what is Kartagener’s Syndrome
50% of people w primary ciliary dyskinesia have it
situs inversus
bronchiectasis
sinusitis
complications of bronchiectasis
cor pulmonale
amyloidosis
metastatic brain abscesses
management of bronchiectasis
treatment of underlying cause
chest physical therapy to facilitate airway clearance
antibiotic therapy
histo findings with bronchiectasis
necrotizing inflammation of bronchi and bronchioles
fibrosis
atelectasis and intraluminal secretions
