Pathology of Respiratory Tract Infections

Question 1

Name some examples of URTIs

Answer 1

Laryngitis 
Coryza (common cold)
Sore throat symptoms 
Acute epiglottitis 
Sinusitis 
Acute larygotracheobronchitis (croup)

Question 2

What is the respiratory tract defence?

Answer 2

Macrophage-mucociliary escalator system

General immune system
Resp. tract secretions
Upper resp. tract as ‘filter’

Failure in any of these increases risk of infection

Question 3

What is the mechanism of the macrophage-mucociliary escalator system?

Answer 3

Clearance by:
Alveolar macrophage phagocytosis
Leave lung through ciliary escalator or cough reflex

Keeps lower tract sterile

Question 4

What happens if escalator is damaged?

Answer 4

If surface is damaged then it is unable to remove mucous. Epithelium is damaged by bacteria

Question 5

What are the possible outcomes of Pneumonia?

Answer 5

Pleurisy, pleural effusion or empyema - if spread to pleura
Organisation (fibrosis due to prolonged inflammation)
Lung abscess - due to necrosis
Bronchiectasis

Question 6

Name some examples of LRTIs

Answer 6

Bronchiolitis
Bronchitis
Pneumonia

Question 7

Pathology of bronchiectasis

Answer 7

Dilation of bronchi due to:
Severe infective episode 
Recurrent infections
Proximal bronchial obstruction 
Lung parenchyma destruction

Question 8

Symptoms of Bronchiectasis

Answer 8

Cough
Purulent foul sputum (contains pus)
Haemoptysis
Coarse crackles
Clubbing

Question 9

Normal PaO2 and PaCO2 levels

Answer 9

PaO2: 10.5-13.5 kPa

PaCO2: 4.8-6 kPa

Question 10

Abnormal PaO2 and PaCO2 levels in respiratory failure

Answer 10

Type I: PaO2 < 8 kPa

Type II: PaCO2 > 6.5 kPa

Question 11

What are 4 abnormal state associated with hypoxaemia?

Answer 11

V/Q mismatch
Diffusion impairment
Alveolar hypoventilation
Shunt

Question 12

Pathology of Cor Pulmonale

Answer 12

Abnormal enlargement of the right side of the heart

Question 13

Aetiology of Cor Pulmonale

Answer 13

Pulmonary vasoconstriction
Loss of capillary bed
Secondary polycythaemia

Question 14

Treatment of hypoxaemia

Answer 14

Responds well to small increase in FlO2 (fraction of inspired air which is oxygen)

Question 15

Explain shunt and treatment

Answer 15

Blood passing from R to L heart without contacting ventilated alveoli

Responds poorly to increase FlO2

Question 16

What 3 factors that determine a microorganisms ability to cause infection?

Answer 16

Microorganism pathogenicity
Capacity to resist infection
Population at risk

Question 17

What type of Microorganism pathogenicities are there?

Answer 17

Primary
Facultative (microorganism that requires some help to be able to grow)
Opportunistic

Question 18

What determines an individual’s capacity to resist infection?

Answer 18

State of host defence mechanism

Age of patient

Question 19

What are the two routes of exit in the lung?

Answer 19

Clearance via the much-ciliary escalator

Interstitial pathway via lymph to the lymph nodes

Question 20

What is a cytopathic effect?

Answer 20

Structural changes in host cells that are caused by viruses i.e. influenza destroys normal respiratory epithelium

Question 21

What are the etiological classifications of pneumonia?

Answer 21

Community Acquired 
Hospital Acquired (Nosocomial) 
In the Immunocompromised
Atypical 
Aspiration 
Recurrent

Question 22

What are 6 different anatomical patterns of pneumonia?

Answer 22

Bronchopneumonia
Segmental
Lobar
Hypostatic
Aspiration
Obstructive, Retention, Endogenous Lipid

Question 23

Describe the pattern go bronchopneumonia

Answer 23

Bilateral basal patchy opacification, relating to the focal nature of the consolidation

Question 24

What is Cryptogenic organizing pneumonia (COP)?

Answer 24

Rare condition affecting the bronchioles and alveoli causing inflammation and stiffening of connective tissue

Question 25

What 3 organisms can cause a lung abscess?

Answer 25

Staph aureus
Pneumococci
Klebsiella

Question 26

What is pyaemia?

Answer 26

Blood poisoning (septicaemia) caused by the spread in the bloodstream of pus-forming bacteria released from an abscess

Question 27

What investigations do you use for bronchiectasis?

Answer 27

Thin section CT

Question 28

What is the treatment for bronchiectasis?

Answer 28

Postural drainage
Antibiotics
Surgery

Question 29

What could a local bronchial obstruction be caused by?

Answer 29

Tumour

Foreign body

Question 30

What could local pulmonary damage be caused by?

Answer 30

Bronchiectasis

Question 31

What could general lung disease be caused by?

Answer 31

Cystic fibrosis

COPD

Question 32

What are some non-respiratory disease?

Answer 32

Immunocompromised (i.e. HIV)

Aspiration

Question 33

What are causes of aspiration pneumonia?

Answer 33

Vomiting 
Oesophageal lesion 
Obstetric anaesthesia 
Neuromuscular disorders
Sedation

Question 34

Describe the organisms that cause opportunistic infections

Answer 34

Organisms are not capable of producing disease in patients with intact lung defects - opportunistic pathogens

Question 35

What does air flow depend on?

Answer 35

Pressure difference

Question 36

What changes occur to pulmonary vasculature changes in hypoxia?

Answer 36

Pulmonary arteriolar constriction due to shunt

Question 37

What pathological conditions can cause V/Q mismatch?

Answer 37

Bronchitis
Bronchopneumonia

Both cause inflammation causes decrease in ventilation

Question 38

What pathological condition can cause shunt?

Answer 38

Severe bronchopneumonia - no ventilation

Lobar pattern with large areas of consolidation (less diffusion)