Pulmonary airways disease Flashcards
what are the host defences
same infectious agents can produce markedly different effects in different people
cough reflex, cilia, mucus, antibody deficiency, immunosuppression (diseases, drug) macrophages dysfunction, pulmonary oedema
describe acute bronchitis
inflammation of bronchi, often viral, can be bacterial (H. influenzae), can involve larynx and trachea (laryngotracheobronchitis), acute exacerbations of chronic bronchitis are common
describe bronchiolitis
inflammation of bronchioles, a feature of chronic bronchitis
primary bronchiolitis - usually in children, respiratory syncytial virus (RSV), tachypnoea and dyspnoea
rare types are follicular bronchiolitis and bronchiolitis obliterans
describe localised airway obstruction
airway obstruction - lesion outside the wall (large lymph node), lesion in the wall (tumour), lesion in lumen (foreign body)
causes distal collapse or over-inflation
may be distal lipid or infective pneumonia
normal pulmonary function tests
describe diffuse obstructive airways disease
chronic bronchitis, emphysema, asthma, bronchiectasis
what is COPD
spectrum of co-existence of chronic bronchitis and emphysema
most patients exhibit a mixture of features
airway involvement also leads to a productive cough as a result of increased mucus production
describe chronic bronchitis
cough and sputum for 3 months in 2 consecutive years
aetiology - pollution, smoking
clinical - middle-aged heavy smokers, recurrent low-grade bronchial infections (exacerbations), H. influenzae or S. pneumoniae viruses, airway obstruction may be partially reversible
progression of chronic bronchitis
hypercapnia (high CO2 in blood)
hypoxia
pulmonary hypertension
right ventricular failure
coined ‘blue bloater’they appear overweight, fluid retained and blue as they are hypoxic
pathology of chronic bronchitis
respiratory bronchiolitis, this can lead to centrilobular emphysema
mucus hypersecretion this can lead to mucus gland hypertrophy which is irreversible
chronic bronchial inflammation which can lead to squamous metaplasia (change in growth from respiratory epithelium) causing an increased risk of malignancy
describe emphysema
irreversible dilation of acinar spaces with destruction of walls
usually confined to alveoli but often extended to include respiratory bronchioles
associated with loss of SA for gas exchange
describe centrilobular emphysema
strongly associated with smoking
seen in some with pneumoconiosis, particularly coal-workers
must commonly in upper lobes
respiratory bronchiolitis is often present
describe panlobular emphysema
usually lower lobes
lungs over distended
associated with alpha-1-antitrypsin deficiency
markedly accelerated in smokers with this disorder
describe the other forms of emphysema
paraseptal - distension to pleural surfaces, may be associated with scarring
irregular - associated with scarring, overlap with paraseptal emphysema
bollus - distended areas of more than 10mm
interstitial
clinical features of emphysema
hyperventilation
normal pO2 and pCO2
weight loss
right ventricular failure
often co-existing chronic bronchitis, clinical features are mixed
‘pink puffer’
how is COPD assessed
using pulmonary function tests
FEV1/FVC less than 0.7 for diagnosis
percent predicted FEV1 to assess severity
FEV1 >80 - mild
FEV1 50-79 - moderate
FEV1 30-49 - severe
FEV1 <30 very severe
correlation with COPD symptoms
destruction of alveolar walls leads to loss of SA for gas exchange
increased respiratory drive compensated for drop in O2
pCO2 may be low due to high resp rate
in some cases resp drive may fall, with tolerance of low pO2 and elevation of pCO2
pulmonary vasoconstriction (due to hypoxia) and destruction of pulmonary vasculature lead to pulmonary hypertension
what is the eventual consequence of pulmonary hypertension
right ventricular failure
ankle swelling
hepatic congestion, leading to pain, abnormal LFTs and ‘nutmeg’ liver
describe asthma
reversible wheezy dyspnoea
increased irritability of bronchial tree with attacks (paroxysmal) of airway narrowing
five aetiological categories - atopic, non-atopic, aspirin-induced, occupational and allergic bronchopulmonary aspergillosis (ABPA)
describe atopic asthma
associated with allergy
triggered by a variety of factors (dust, pollen, dust mite etc)
often associated with eczema and hay fever
bronchoconstriction mediated by a type 1 hypersensitivity reaction
what does a hypersensitivity reaction lead to
bronchial obstruction with distal overinflation or collapse
mucus plugging of bronchi
bronchial inflammation
mucus gland hypertrophy
bronchial wall smooth muscle hypertrophy
thickening of bronchial basement membranes
last 3 are all irreversible
describe non-atopic asthma
associated with recurrent infections
not immunologically mediated
skin testing negative
aspirin-induced asthma
associated with recurrent rhinitis, nasal polyps and urticaria (rashes)
mechanism is unclear
occupational asthma
hypersensitivity to an inhaled antigen may be non-specific in those woth hyper-reactive airways
may be a specific allergen response
ABPA
Specific allergic response to the spores of Aspergillus
fumigatus
Mixed type I and type III hypersensitivity reaction
Mucus plugs common
Associated with bronchiectasis
Not to be confused with an aspergilloma, which is a
fungal ball, usually colonising a pre-existing cavity in
the lung (often tuberculous)
