1. PNEUMONIA & other patterns of acute lung injury
DIFFUSE ALVEOLAR DAMAGE

2. PNEUMONIA Nasal clearance Tracheobronchial clearance
Inflammatory consolidation of the lung parenchyma
NORMAL DEFENCES MECHANISMS
Nasal clearance
Tracheobronchial clearance
Alveolar clearance

3. PNEUMONIA – why? Local Factors Impaired Host Resistance
Loss / impairment of cough reflex
Impaired mucociliary elevator
Impaired function of alveolar macrophages
Accumulated / stagnant secretions
Impaired Host Resistance
Chronic Disease
Malignancy
Immune Defficiency
Iatrogenic – immunosuppressive Rx

4. PNEUMONIA Classification Anatomic Distribution Aetiology
Nature of host inflammatory reaction

5. PNEUMONIA - Anatomic Distribution
Lobar vs. Bronchopneumonia
Lobar (less frequent) - widespread fibrinosuppurative consolidation of a large portion of a lobe or an entire lobe
Bronchopneumonia - patchy consolidation, usually extension of pre-existing bronchitis / bronchiolitis

6. PNEUMONIA - Aetiology INFECTIOUS ASPIRATION
Acute Bacterial Pneumonia
NB Streptococcus pneumoniae = pneumococcus
The others: Staphyllococcus aureus
Streptococcus pyogenes
Haemophilius Influenza
Klebsiella pneumoniae
Legionella pneumoniae
Viral, Mycobacterial, Fungal, Parasitic
(NB in an immunocompromised population)
ASPIRATION
LIPID – endogenous vs. exogenous

7. PNEUMONIA - Nature of Host Response
Acute fibrinous
Granulomatous
Organizing
Interstitial
Eosinophilic

11. LOBAR PNEUMONIA Abrupt onset Pleuritic chest pain, rusty sputum
High fever, rapid & shallow resps,
Leucocytosis
Healing “by crisis”

12. LOBAR PNEUMONIA Structural Changes: uniform 4 Stages: Congestion
Red Hepatization
Grey Hepatization
Resolution

14. BRONCHOPNEUMONIA Successive infection of conductive airways
Infants, debilitated young children, elderly, post-operative
Insidious onset
Peripheral hypoxia
Slow healing, resolution “by lysis”

15. BRONCHOPNEUMONIA
Widespread patchy areas of inflammation spreading from bronchitis and bronchiolitis
Lower lobes – larger and more numerous foci
Pale areas raised above the surface of the surrounding lung parenchyma
Recovery – liquefaction – but also by fibrosis

22. Acute Pneumonia
Alveolar Spaces filled by acute inflammatory cells (neutrophils)

23. Acute Pneumonia
Acute Inflammatory cells within alveolar spaces

26. PNEUMONIA - Complications
Abscess Formation
Organization
Empyema – suppurative pericarditis
Bronchiectasis
Bacteraemic dissemination to other organs (metastatic abscesses) – endocarditis
meningitis
peritonitis
suppurative arthritis

27. LUNG ABSCESS
Localized focus of suppuration consisting of a collection of pus that is walled off by chronic inflammatory / granulation tissue and fibrous tissue
Formation of an abscess entails necrosis and destruction of lung tissue
Causes – preceding pneumonia, bronchial obstruction – tumour, foreign body, aspiration, septic embolism

29. BRONCHIECTASIS
Permanent dilatation of the bronchi accompanied by inflammatory changes in their walls and surrounding parenchyma
Recurrent inflammation of bronchial walls & fibrosis in the surrounding parenchyma – traction on bronchi – dilatation
Divided into post-inflammatory, post-obstructive, and congenital / hereditary conditions
Cough, fever, foul sputum

30. BRONCHIECTASIS Localized vs. widespread
Basal segments of LLs, RML & lingula
Gross: dilated bronchi exending to pleural surface, surrounding scarring
Microscopy: mucosal ulceration, submucosal CI & granulation tissue, adjacent OP
Complications: Cor pulmonale
Brain abscess
Amyloid

36. DIFFUSE ALVEOLAR DAMAGE (DAD)
Pathologic manifestation of Adult Respiratory Distress Syndrome (ARDS)
Sequence of events that follows acute lung injury caused by a variety of toxic insults
Diffuse = damage to all parts of the alveolus: epithelium, endothelium and interstitium

37. DAD - Clinical Syndrome
Acute onset of dyspnoea
Diffuse pulmonary infiltrates
Rapid development of respiratory failure
High mortality ~ 50%

38. DAD - Pathology Two Discrete but Overlapping Stages: Early and Late
Acute and Organizing
Exudative and proliferative

39. DAD Early / Acute / Exudative Phase:
Day 1: Interstitial / alveolar haemorrhage & fibrin
Day 3-7: Hyaline membranes
Type II pneumocyte hyperplasia
Week 1: Interstitial inflammation
Late / Organizing / Proliferative Phase:
1-2 weeks: Fibroblast proliferation
Organization & fibrosis

43. DAD has many Aetiolgies
Infection
Inhalants
Ingestants
Drugs
Shock
Sepsis
Radiation
Misc.
Idiopathic