Respiratory Pathology Flashcards
What does a ‘barrel chest’ indicate?
Hyperinflation, as in COPD. In particular, it may be seen in emphysema
What do unilateral diminished breath sounds indicate?
Pneumothorax
What do acute bilateral diminished breath sounds indicate?
Asthma (attack)
What do chronic bilateral diminished breath sounds indicate?
Emphysema (due to reduced lung tissue)
What may chronic wheeze suggest?
Obstructive disease, e.g. asthma or COPD
What may acute wheeze suggest?
FB aspiration
What does stridor represent?
Tracheal or laryngeal obstruction
What does dullness to percussion indicate?
Lung consolidation, e.g. pneumonia
What does increased tactile remits indicate?
Lung consolidation, e.g. pneumonia
What are the 3 obstructive lung diseases?
- COPD (emphysema + bronchitis)
- Asthma
- Bronchiectasis
What is the hallmark finding of obstructive lung disease?
A reduced FEV1/FVC ratio
What 2 diseases does COPD include?
- Emphysema
2. Chronic bronchitis
What is the underlying pathogenesis of emphysema?
= underlying loss of elastic recoil + dilatation of terminal air spaces
How may smoking cause emphysema?
The enzyme elastase digests elastin. Cigarette smoke both inactivates alpha-1-antitrypsin (which prevents elastase becoming active) and attracts inflammatory cells (which produce elastase)
How may hereditary alpha-1-antitrypsin deficiency cause emphysema?
There is a lack of alpha-1-antitrypsin and it is alpha-1-antitrypsin that prevent elastase from being constitutively active
What proportion of emphysema does hereditary alpha-1-antitrypsin deficiency constitute?
1%
Where does emphysema shift the compliance curve of the lungs?
Up + left
How might a typical emphysema patient be described?
Pink puffer (not cyanotic, although both ventilation and perfusion are both reduced, the V/Q mismatch is not severe)
What are the signs of emphysema O/E?
- Cachexic
- Tri-poding
- Accessory muscle use
- Signs of hyperinflation
What are the 2 main pathological types of emphysema?
- Panacinar
2. Centriacinar
What is panacinar emphysema?
Primarily affects the lower lobes. Dilatation of the entire acinus. Associated with alpha-1-antitrypsin deficiency
What is centriacinar emphysema?
Pattern of involvement is irregular, or localised to the upper lobes. Dilatation of the just the proximal part of the acinus, i.e. the respiratory bronchioles. Associated with smoking
What is the clinical definition of chronic bronchitis?
A productive cough for at least 3/12 per year over 2 consecutive years
What is the underlying pathogenesis of chronic bronchitis?
- Smoking = proliferation and hypertrophy of bronchial mucous glands. = excessive mucus production, which is also more viscous than normal.
- The cilia lining of the bronchial lumen us also damaged, impeding mucus clearance.
- Inflammatory cell influx = airway inflammation.
How might a typical chronic bronchitis patient be described?
Blue bloater (cyanotic - there is significant V/Q mismatch due to the reduced ventilation as a result of damaged airways, but the preservation of perfusion)
What are the signs of chronic bronchitis O/E?
- Obese
- Peripheral oedema (due to associated right ventricular failure)
- Cyanosis of peripheries
- Clubbing - as a result of the hypoxaemia
What condition might arise as a result of chronic bronchitis?
Cor pulmonale, as a result of the pulmonary HTN secondary to hypoxaemia and pulmonary vasoconstriction
What lung condition may occur in CF patients? + why?
Bronchiectasis. Because the thick mucus secretions produced are difficult to clear + harbour bacteria, resulting in chronic infection
What bacteria, although rare, almost exclusively colonises the lungs of patients with CF?
Burkholderia cepacia
What bacteria more commonly colonise the lungs of CF patients?
- Pseudomonas aeruginosa
- S.aureus
- H.influenzae
What drug may be given to CF patients to break down the thick mucus secretions?
DNase
What is bronchiectasis?
Irreversible dilatation of the airways
What are the causes of bronchiectasis?
- CF (due to the thick mucus causing chronic infection)
- Infection
- Obstruction (often tumour)
- Airway clearance defect (e.g. Kartagener syndrome)
(all lead to the inflammatory destruction of airways)
What may be seen on a bronchiectasis XR?
Ring shadows
What is the preferred method of bronchiectasis diagnosis?
CT
What are the patterns of airway dilatation seen in bronchiectasis?
- Cylindrical
- Varicose
- Saccular
What is the difference between asthma and COPD?
Asthma = a REVERSIBLE obstructive disease (whereas COPD is IRREVERSIBLE)
What are the 2 sub-types of asthma?
- Extrinsic
2. Intrinsic
What type of hypersensitivity reaction is extrinsic asthma?
Type I
What are the features of extrinsic asthma?
Type I hypersensitivity, involving IgE and mast cells.
Begins in childhood/in those with a FHx of atopy.
Allergens = animal dander (esp. cats); pollen; mold; dust mites
What are the features of intrinsic asthma?
Allergens = cold; exercise; cigarette smoke; medication (esp. aspirin); stress
Which mediators are associated with inflammation in asthma?
Eosinophils; lymphocytes; histamine; leukotrines; IgE
Which growth factors cause fibrosis in asthma?
EGF; IGF-1; PDGF
With epithelial-derived mediator causes bronchoconstriction in asthma?
Endothelin-1
With epithelial-derived mediators cause vasodilation in asthma?
NO; PGE2; 15-HETE
With epithelial-derived mediators (all cytokines) cause inflammation in asthma?
GM-CSF; IL-8; RANTES; Eotaxin
What are the ‘relievers’ used in asthma?
- Short-acting beta-2-agonists
- Ipratropium
- IV steroids
- Magnesium sulfate
- Epinephrine
What are the ‘controllers’ used in asthma?
- PO steroids
- Inhaled steroids
- Long-acting beta-2-agonists
- Xanthines
- Mast cell stabilisers
- Leukotrine blockers
- Omalizumab
What is the name of a severe asthma attach refractory to therapy?
Status asthmaticus
What actions of steroids are useful in their relief of asthma?
Reduce inflammation by:
- Decrease cytokine formation
- Inactivation of a nuclear factor of activated B cells
- Inhibition of generation of vasodilators
- Decreasing microvascular permeability
- Reducing mediator release from eosinophils
What is the action of Xanthines?
Increase cAMP in smooth muscle cells though inhibition of phosphodiesterase isoenzymes, leading to airway dilatation
What is the action of mast cell stabilisers?
Inhibits the release of inflammatory mediators from mast cells
What is the action of leukotrine blockers?
Inhibit 5-lipoxygenase, reducing the conversion of arachidonic acid to leukotrienes
What is the action of Omalizumab?
= monoclonal Ab. Binds to circulating IgE
What are the 2 categories of restrictive lung diseases?
- Extrapulmonary disorders
2. Interstitial lung diseases
What characterises sarcoidosis?
Non-caseating granulomas, often involving multiple organ systems
How does hypersensitivity pneumonitis differ from asthma and allergy?
= not a type I hypersensitivity reaction.
It is an alveolar disease, whereas asthma is a disease of the bronchi.
How is hypersensitivity pneumonitis definitively diagnosed?
Biopsy - loosely organised granulomas - + consistent Hx
What is the usual cause of a spontaneous pneumothorax?
Rupture of an air-filled lung bleb
In what direction will the mediastinum/trachea deviate in a tension pneumothorax?
AWAY from the side of the pneumothorax