CPRS Case 8: Pulmonary infection

Question 1

Anatomy of lung, pleura and surface anatomy

Answer 1

See lecture

Question 2

Cardinal signs and symptoms of acute inflammation

Answer 2

See lecture

Red
Swelling
Pain
Heat

Question 3

Pathophysiological bases of fever

Answer 3

Fever:

Macrophage release IL1, TNF —> PGE2 —> increase thermal set-point

Question 4

Pathophysiological bases of cough

Answer 4

Cough: clean foreign material and excess secretion from central airway
Cough reflex: abdominal muscle contraction, closure of glottis

Causes:

• virus induced acute upper respiratory tract infection (dry cough)
• chronic respiratory disease (asthma)
• increased mucus production
• increased sensitivity of cough reflex

Receptors:
- Larynx
—> irritant receptor (myelinated)
—> C-fibre ending (non-myelinated)
- Lung
—> stretched receptor (myelinated)
—> Pulmonary + Bronchial C fibre endings (non-myelinated)

Question 5

Pathophysiological bases of haemoptysis

Answer 5

Causes:

• Bronchitis (most common cause)
• lung cancer
• pulmonary infection —> Pneumonia, Tuberculosis

Superficial mucosal acute inflammation and oedema —> rupture of superficial vessels —> haemorrhage

Haemorrhage + cough —> Haemoptysis

Question 6

Important pathogens in community-acquired pneumonia

Answer 6

Bacteria:

1. S. pneumoniae
2. S. aureus
3. Haemophilus influenzae

Virus: Respiratory syncytial virus, parainfluenza virus (children)

Question 7

Aetiology, pathogenic mechanism, pathology, treatment and prevention of disease caused by influenza virus and S. pneumoniae

Answer 7

See lecture + senior notes

Question 8

Influence of pneumonia on gas exchange function

Answer 8

1. Reduction in total available SA of respiratory membrane
2. VQ mismatch since ventilation is reduced while blood flow remains normal
   —> hypoxaemia + hypercapnia

Question 9

Common acute and long term complications to pneumonia

Answer 9

1. Fibrosis
2. Lung abscess

Spread of infection:
Adjacent organ: pleuritis, empyema thoracis, pericarditis
Distant organ: meningitis, arthritis

Question 10

Lung function data of obstructive and restrictive lung diseases

Answer 10

Obstructive:

• Difficulty in exhaling air from lungs (exhalation problem)
• FEV1 ↓↓ while FVC ↓ —> FEV1 / FVC ↓ —> FEV1/FVC < 80%

Restrictive:

• FEV1 ↓, FVC ↓ —> ↓FVC > ↓FEV1 —> FEV1/FVC > 80%
• Pneumonia is in restrictive category

Question 11

Signs and symptoms of pneumonia and sepsis

Answer 11

Pneumonia:
- Systemic:
—> fever and chills
- Respiratory symptoms:
—> stabbing chest pain
—> cough with sputum
—> SOB if severe

Signs:
- Palpation:
—> limited chest expansion
—> increased tactile fremitus
- Percussion:
—> dull / no resonance
- Auscultation:
—> bronchial breath sounds
—> coarse crepitation

Sepsis:

• Tachypnea
• Tachycardia
• Drowsiness

Question 12

Key investigations and precautions for community acquired pneumonia

Answer 12

Key investigations

• Blood count
• Sputum culture
• Radiological exam
• Viral investigation
• Urine antigen detection assay

Precaution: Droplet precaution

Question 13

Appropriate antibiotics for community acquired pneumonia

Answer 13

Beta-lactam +/- macrolide

Question 14

Role of vaccination in prevention of infectious diseases

Answer 14

1. Induction of ACQUIRED immunity against pathogen

2. Protection of HERD immunity

Question 15

Role of smoking in respiratory infection and respiratory disease

Answer 15

1. Irritation of trachea and larynx
2. Swelling and narrowing of airways + excess mucus —> reduced lung function + breathlessness
3. Impairment of lungs’ clearance system —> build up of poisonous substance —> lung irritation and damage —> risk of lung infection
4. Permanent damage to air sacs —> COPD