Respiratory Tract Infection Pathology

Question 1

Examples of URTIs

Answer 1

Coryza - common cold
'Sore throat syndrome'
Croup
Laryngitis
Sinusitis
Acute Epiglottitis
 (group A beta-haemolytic streptococci, H. flu, viral)

Question 2

Examples of LRTIs

Answer 2

Bronchitis
Bronchiolitis
Pneumonia

Question 3

Respiratory Tract Defense Mechanisms

Answer 3

Macrophage-mucociliary escalator system
(cough)

General immune system

Question 4

How can pneumonia be classified?

Answer 4

Anatomically
Aetiologically
Microbiologically

Question 5

Aetiological classification of pneumonia

Answer 5

Community acquired
Nosocomial (hospital)
Immunocompromised
Atypical
Aspiration
Recurrent

Question 6

Possible outcomes of pneumonia

Answer 6

Resolution
Pleursy, effusion, empyema
Organisation
Lung abscess
Bronchiectasis

Question 7

What is bronchiectasis?

Answer 7

Pathological dilatation of bronchi due to:

• severe infective episode
• recurrent infections
• proximal bronchial obstruction
• lung parenchymal destruction

75% start in childhood

Question 8

Symptoms/Signs of Bronchiectasis

Answer 8

Cough
Abundant, purulent, foul, sputum
Haemoptysis
Signs of chronic infection
Coarse crackles
Clubbing

Question 9

Types of Respiratory Failure

Answer 9

Type I - PaO2 <8kPa
(PaCO2 normal or low)

Type II - PaCO2 >6.5kPa
(PaO2 usually low)

Question 10

Pulmonary vascular changes in response to hypoxia?

Answer 10

Physiological pulmonary arteriolar vasoconstriction when alveolar O2 tension falls
Can be localised, done to prevent sending blood to alveoli that are short of O2.

All vessels constrict if there is arterial hypoxaemia

Question 11

What is a normal V/Q ratio?

Answer 11

0.8

4L of O2 per 5L of blood

Question 12

What is normal percentage of shunt in pulmonary circulation?

Answer 12

2-4%

Large shunts respond poorly to increases in FIO2