Pathology of respiratory tract infection Flashcards
3 types of microorganism pathogens
- Primary
- Facultative
- Opportunistic
Upper Respiratory Tract Infection examples
- Coryza, common cold
- Sore throat syndrome
- Acute Laryngotracheobronchitis (Croup)
- Laryngitis
- Sinusitis
- Acute Epiglottitis
Acute Epiglottitis
Bacterial infection of the epiglottis
- Group A beta-haemolytic Streptococci
- Haemophilus influenzae (type b- Hib)
Lower Respiratory Tract infections
- Bronchitis
- Bronchiolitis
- Pneumonia
What are the respiratory tract defence mechanisms?
- Macrophage-mucociliary escalator system!
- General immune system
- Respiratory tract secretions
- Upper respiratory tract as a ‘filter’
Composition of the macrophage-mucociliary escalator system
- Alveolar macrophages
- Mucociliary escalator
- Cough reflex
Action of the macrophage-mucociliary escalator system
They contact deposited particles either by chance or by oriented motion in response to chemical agents in particles
3 classifications of Pneumonia
- Anatomical
- Aetiological (circumstances)
- Microbiological
Aetiological classifications of Pneumonia
- Community acquired pneumonia
- Hospital acquired (nosocomial) pneumonia
- Pneumonia in the immunocompromised
- Atypical pneumonia
- Aspiration pneumonia
- Recurrent pneumonia
Patterns of Pneumonia
- Bronchopneumonia
- Segmental
- Lobar
What is bronchopneumonia?
inflammation of the lungs, arising in the bronchi or bronchioles
What is lobar pneumonia?
a form of pneumonia characterised by inflammatory exudate within the intra-alveolar space resulting in consolidation that affects a large and continuous area of the lobe of a lung.
- A whole lobe is affected.
Complications of Pneumonia
- Pleurisy, Pleural Effusion and Empyema
- Lung Abscess
- Bronchiectasis
What is Cryptogenic Organising Pneumonia (COP)?
COP is a swelling of the small airways in your lung. It has symptoms that can closely mimic a pneumonia infection.
-It is also known as bronchiolitis obliterans organising pneumonia (BOOP).
What is a lung abcess?
Abscesses occur most commonly when microbial infection causes necrosis of the lung parenchyma, forming 1 or more cavities.
- Forms necrotic lung
How does Bronchiectasis occur?
Pathological dilatation of Bronchi due to:
- Severe infective episode
- Recurrent infections, many causes
- Proximal bronchial obstruction
- Lung parenchymal destruction
complications of aspiration pneumonia
- Vomiting
- Oesophageal lesion
- Obstetric anaesthesia
- neuromuscular disorders
- Sedation
What are opportunistic infections?
- Infection by organism not normally capable of producing disease in patients with intact lung defences
- Increased chance of “ordinary “ infections
What PaO2 and PaCO2 is in Type I respiratory failure?
PaO2 < 8kPa
PaCO2 normal or low
What PaO2 and PaCO2 is in Type I respiratory failure?
PaCO2 > 6.5kPa
PaO2 usually low
What 4 abnormal states are associated with Hypoxaemia?
- Ventilation/Perfusion imbalance
- Diffusion impairment
- Alveolar hypoventilation
- Shunt
What occurs during physiological pulmonary arteriolar vasoconstriction?
- Alveolar oxygen tension falls
- Can be localised effect
- All vessels constrict if there is arterial hypoxaemia!!!
What is a protective mechanism for pulmonary vascular changes in Hypoxia?
Do not send blood to alveoli short of oxygen.
What does a shunt cause?
- Severe bronchopneumonia
- Lobar pattern with areas of consolidation
What does V/Q stand for?
Ventilation perfusion
-The V/Q ratio is the amount of air that reaches your alveoli divided by the amount of blood flow in the capillaries in your lungs.
What is the commonest cause of hypoxaemia encountered clinically?
Low V/Q
-Low V/Q in some alveoli arises due to local alveolar hypoventilation due to some, focal disease.
How does hypoxaemia due to low V/Q respond due to small increases in FlO2?
Hypoxaemia due to low V/Q responds well to even small increases in FIO2!
Is there ventilation of abnormal alveoli in shunt?
NO
Is there ventilation of abnormal alveoli in ventilation/perfusion abnormality (mismatch)?
Some ventilation of abnormal alveoli, just not enough.
Features of shunt
- Blood passing from Right to Left side of Heart WITHOUT contacting ventilated alveoli
- Normally 2-4% shunt
- Pathological shunt in AV malformations, congenital heart disease and PULMONARY DISEASE
- Large shunts respond poorly to increases in FI O2 Blood leaving normal lung is already 98% saturated
What is Chronic (hypoxic) cor pulmonale?
-Hypertrophy of the Right Ventricle resulting from disease affecting the function and/or the structure of the lung.
