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What is an infection of the lung called

pneumonia or pneumonitis


Describe how the size of the air micron affects where it is deposited in the airway

- particles that are more than 10 micron in size are held in the upper airways
- 3-10 microns are trapped in the tracheobronchial mucus
- 1-5 microns(bacteria) are deposited in terminal airways and alveoli
- less than 1 micron is suspended in alveolar air


What are the defence mechanisms of the lung

- Nasal clearance
- Tracheobronchial clearance: mucociliary action
- Alveolar clearance: Alveolar macrophages


How can lung mechanisms be disturbed

- Suppression of cough reflex = due to coma, anaesthesia, drugs, chest pain, neuromuscular disease
- Injury to mucociliary apparatus = due to smoking, inhalation of hot/corrosive gases, congenital
- disturbance of macrophage function = due to smoking, alcohol, anoxia, oxygen toxicity
- pulmonary congestion and oedema
- accumulation of secretions


What is pneumonia

- Alveolar inflammation


What are the types of pneumonia

- lobar pneumonia
- bronchopneumonia
- atypical pneumonia


what is lobar pneumonia also known as

- community acquired pneumonia


what part of the lobe does lobar pneumonia affect

- affects large part or the entire lobe


what causes lobar pneumonia

- 90% caused by streptococcus pneumonia


What are the clinical features of lobar pneumonia

- high grade fevers with riggers
- productive cough
- rusty sputum
- pleuritic chest pain
- signs of consolidation - when you look at the chest X ray, when you tap there chest, when you listen to the chest (bronchial breath sounds)


describe what the pathology of lobar pneumonia looks like

- the lobe that is affected looks more consolidated
- has 4 different stages


Describe the pathogenesis of lobar pneumonia

1. Congestion (24 Hours)
- vessel engorged
- oedema in alveoli
- heavy, red lung

2. Red hepatisation (2-4 days)
- outpouring of neutrophils and RBC's into alveoli, red, solid, airless, liver-like lung (resembles the liver)

3l. Grey hepatisation(4-8 days)
- fibrin and macrophage replace neutrophils and RBC's, grey, solid, airless lung

4. Resolution (8-10 days)
- gradual return to normal

- these stages are not seen with prompt treatment


What are the complications of lobar pneumonia

- rarely you can have suppurative complications such as lung abscess or emyema especially with Klebsiella or staphylococcus infections


What is the commonest type of pneumonia

- Bronchopneumonia


Where do you see bronchopneumonia

- chronic debilitating illness
- secondary to viral infections
- infancy
- old age


How does bronchopneumonia begin

- begins as bronchitis and bronchiolitis and then spreads to alveoli


What causes bronchopneumonia

- Low virulence bacteria such as staph, street viridian's, H influenzas, pseudomonas, coliform


describe the pathology of bronchopneumonia

- bilateral - affects both lung
- worse in the basal as there is more statsis and the air supply is worse
- patchy
- grey or grey-red spots of consolidation
- microscopically acute inflammatory infiltrate in bronchioles and alveoli


What are the complications of bronchopneumonia

- death - because usually complicating/terminal event in other debilitating illness or extremes of age
- resolution
- scarring
- abscess/empyema - rare


what are the x ray differences between lobar pneumonia and bronchopneumonia

- X ray and clinical signs: complete lobar opacity

- Focal opacities, clinical sign less pronounced


What is more important that the difference between the lobar and bronchopneumonia

- Correct identification of causative agent
- determination of extent of disease


What is interstitial (atypical) pneumonia

- caused by different organisms
- inflammation is restricted to alveolar septa and interstitial tissues: interstitial pneumonitis
- no or minimal alveolar exudate
- can be patchy or extensive
- congested subcrepitant lungs
- rarely intra-alveolar proteinancous material forming hyaline membrane


what can you get in interstitial (atypical) alveoli

rarely intra-alveolar proteinancous material forming hyaline membrane


Why is interstitial pneumonia atypical

- they don't have the normal symptoms of pneumonia
- don't have a normal X ray that you would see in pneumonia


What can cause interstitial pneumonia atypical

- mycoplasma pneumonia
- Viruses: influenza A and B, RSV, acino, rhino, rubeola, varicella
- chlamydia
- coxiella
- often undetermined


What are the predisposing conditions to interstitial atypical pneumonia

- malnutrition
- alcoholism
- debilitating illnesses


What is the clinical course of interstitial pneumonia

- variable
- clinically general rather than localised symptoms, out of proportion to signs
- usually sporadic form usually mild and self limiting
- epidemic forms associated with higher mortality
- secondary bacterial infections common


What is pulmonary tuberculosis

- infection of the lungs by mycobacterium tuberculosis or M Bovis


how does infection occur in endemic areas of pulmonary tuberculosis

- infection occurs early in childhood


How does spread of pulmonary tuberculosis occur

- infection is airborne from open cases (not under control)