Pathology of Pulmonary Infection Flashcards

1
Q

What types of Microorganism Pathogenicity exist? How invasive it is, infectivity etc

A

Primary - very invasive and infectious to healthy people Facultative (most common)- A bit of illness needed for invasion to occur Opportunistic -cause infections in immuno compromised host

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2
Q

What does the capacity to resist infection depend on?

A

State of Host Defence Mechanisms Age of Patient

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3
Q

Give examples of upper respiratory tract infections. Pathology all involves inflammation.

A

Coryza - common cold Sore throat syndrome Acute Laryngotracheobronchitis (Croup) Laryngitis Sinusitis Acute Epiglottitis

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4
Q

What causes acute epiglottitis?

A

Group A beta-haemolytic Streptococci Haemophilus influenzae (type b - Hib) Rarely caused by Parainfluenza virus type 4 but other viruses may also be reponsible

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5
Q

Describe the effects of acute epiglottitis

A

Potentially life threatening, affects children. Swells up and obstructs airway. Causes extreme respiratory difficulty.

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6
Q

Give examples of Lower Respiratory Tract Infections

A

Bronchitis Bronchiolitis Pneumonia Consequences Possible Complications

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7
Q

How do lower respiratory tract infections compare to upper?

A

More morbidity and mortality rate with lower respiratory tract infections

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8
Q

What are the respiratory tract defence mechanisms?

A

Macrophage-mucociliary escalator system General immune system -Humoral and cellular immunity Respiratory tract secretions Upper respiratory tract as a ‘filter’ Cough reflex

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9
Q

Which part of the respiratory tract is sterile?

A

Lower

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10
Q

Which part of the upper respiratory tract acts as a filter?

A

Nose

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11
Q

What components of the the upper respiratory tract as a filter?

A

Hair, moist, mucous and cilia in epithelium.

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12
Q

What is the effect of alveolar macrophages?

A

Phagocytose, (if they cannot digest) travel towards the ciliary escalator for digestion

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13
Q

Why might the macrophage pass through the alveolar membrane?

A

To reach Interstitial pathway via lymph to the lymph nodes

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14
Q

Where does particle deposition occur?

A

Deposition on the conducting airways Deposition on the terminal bronchioles/ proximal alveoli

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15
Q

How can the ciliary escalator fail?

A

Viral infections (influenza) – damage to normal respiratory epithelium – no longer functional or cilia, severe when there is no mucociliary membrane. Common cause of bacterial chest infections.

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16
Q

What are the three ways you can classify pneumonia?

A

Anatomical, aetiological and microbiological.

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17
Q

What are the Aetiological Classifications of Pneumonia?

A

Community Acquired Pneumonia (usually treated by GP’s) Hospital Acquired (Nosocomial) Pneumonia (more likely to be severe, bacteria more likely to be resistant) Pneumonia in the Immunocompromised (AIDS patients) Atypical Pneumonia (unusual infectious agents) Aspiration Pneumonia (result in the inhalation of gastric content) Recurrent Pneumonia – signal that there is something particularly odd going on)

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18
Q

Which type of pneumonia is usually treated by GP’s?

A

Community acquired pneumonia

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19
Q

What are the different patterns of pneumonia?

A

Bronchopneumonia

Segmental

Lobar

Hypostatic

Aspiration

Obstructive, Retention, Endogenous Lipid

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20
Q

What does

  • A) Bronchopneumonia
  • B) Lobar pneumonia

Affect?

A

A) Both lungs and the bronchi

B) One or more sections or lobes of the lungs

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21
Q

What causes most cases of bacterial pneumonia?

A

Streptococcus pneumonia

Other culprits:

Staphylococcus aureus

Haemophilus influenzae

Klebsiella pneumoniae

22
Q

What is the classic type of pneumonia that is community acquired?

A

Shows lung consolidation of one lung segmental lobe

23
Q

What is hypostatic pneumonia?

A

Infection in the dependent portions of the lungs due to decreased ventilation of those areas

Failure to drain bronchial secretions

Occurs primarily in old people or those debilitated by disease who remain recumbent in the same position for long periods

24
Q

What is aspiration pneumonia?

A

Aspiration pneumonia is a lung infection that develops after you aspirate (inhale) food, liquid, or vomit into your lungs.

25
Q

What is the effect of acute inflammation in bronchopneumonia?

A

Lung filled with pus, neutrophils and inflammatory exudate

It is the most common hypostatic pneumonia story

26
Q

How does the action of bacteria differ in lobar pneumonia?

A

Organisms are more aggressive, greater tissue reaction, greater spread of organism. Infection stops at the pleura

27
Q

What are the outcomes of pneumonia?

A

Most Resolve

Pleurisy, Pleural Effusion and Empyema

•Organisation – formation of fibrous tissue, inflammatory area becomes scar tissue

–mass lesion

–COP(cryptogenic organising pneumonia (BOOP))

–Constrictive bronchiolitis

Lung Abscess - necrosis, hole in lung

Bronchiectasis

Pneumonia is still a potentially fatal disease

28
Q

What happens during the organisation in pneumonia?

A

Formation of fibrous tissue, inflammatory area becomes scar tissue

29
Q

What is a lung abscess?

A

Pus forms in the space where there was tissue destruction.

30
Q

What organisms are more likely to cause abscess?

A

Staph aureus, some pneumococci, Klebsiella

31
Q

When is lung abscess metastatic?

A

Pyaemia

32
Q

What is Bronchiectasis?

A

Abnormal dilation of the bronchi in the periphery of the lung.

Symptoms: SOB, coughing up blood, chest pain, clubbing.

The mechanism of disease is breakdown of the airways due to an excessive inflammatory response.

Involved airways (bronchi) become enlarged and thus less able to clear secretions. These secretions increase the amount of bacteria in the lungs, result in airway blockage and further breakdown of the airways.

It is classified as an obstructive lung disease, along with chronic obstructive pulmonary disease and asthma.

33
Q

What causes Bronchiectasis?

A

Severe Infective Episode

Recurrent Infections - many causes

Proximal Bronchial Obstruction (occurs in the trachea or main bronchi) (tumour)

Lung Parenchymal Destruction

34
Q

What are the symptoms of Bronchiectasis?

A

75% start in childhood

COUGH, ABUNDANT PURULENT FOUL SPUTUM

Haemoptysis, signs of chronic infection

Coarse crackles

Clubbing

Thin section CT, (previously bronchography)

Postural Drainage

Antibiotics

Surgery

35
Q

How might you get a recurrent lung infection?

A

Local Bronchial Obstruction - Tumour, Foreign body?

Local Pulmonary Damage - Bronchiectasis?

Generalised Lung Disease - Cystic Fibrosis?, COPD?

Non-Respiratory Disease - Immunocompromised (HIV, other)?, Aspiration?

36
Q

What causes aspiration pneumonia?

A

Vomiting

Oesophageal Lesion

Obstetric Anaesthesia (any anaesthetic used in childbirth)

Neuromuscular Disorders Sedation

37
Q

Where is the most common location for aspiration pneumonia?

A

Apical segment of right lower lobe

38
Q

What are oppurtunistic pathogens and can you give an example of one?

A

Infection by organisms not normally capable of producing disease in patients with intact lung defences

–Pneumocystis jirovecii

39
Q

What is the difference between laminar flow versus turbulent flow?

A

Laminar - Smooth, streamlined, highly ordered, much less resistance

Turbulent - Velocity fluctuations, highly disordered, increased pressure difference is needed to maintain flow, this response itself increases resistance

Larger airways are more prone to turbulent flow than smaller airways

In cases of upper airway obstruction the development of turbulent flow is a very important mechanism of increased airway resistance

40
Q

What are the definitions of respiratory failure?

A

Type I PaO2 <8 kPa (PaCO2 normal or low) Type II PaCO2 >6.5 kPa (PaO2 usually low)

41
Q

What are values for normal Pa O2 and Pa CO2?

A

Normal PaO2 10.5 – 13.5 kPa Normal PaCO2 4.8 – 6.0 kPa

42
Q

What are the Four abnormal states associated with HYPOXAEMIA?

A

Ventilation / Perfusion imbalance - V/Q

Diffusion impairment

Alveolar

Hypoventilation

Shunt

43
Q

What happens when alveolar oxygen tension falls?

A

All vessels constrict if there is arterial hypoxaemia (localised)

A protective mechanism

Do not send blood to alveoli short of oxygen!

44
Q

What is the effect of constriction of the heart?

A

Right ventricle has to pump harder

45
Q

What is the cause of Hypoxaemia?

A

Ventilation / Perfusion abnormality (•LOW V/Q is COMMONEST cause of hypoxaemia encountered clinically) (mismatch) Bronchitis / Bronchopneumonia

Shunt (Severe bronchopneumonia Lobar pattern with large areas of consolidation) - no ventilation of abnormal alveoli

46
Q

What causes Low V/Q?

A

In some alveoli arises due to local alveolar hypoventilation due to some, focal disease

•Hypoxaemia due to low V/Q responds well to even small increases in FIO2

47
Q

Why is normal V/Q 0.8?

A

Normally breathe about 4 litres per minute

Cardiac output is 5 litres per minute

48
Q

What is Shunt?

A

•Blood passing from Right to Left side of Heart WITHOUT contacting ventilated alveoli

49
Q

How can shunt arise from congenital heart disease and pulmonary disease?

A

Pathological shunt in arteriovenous malformations

50
Q

What makes the alveoli good for allowing the diffusion between air and blood?

A

Alveolar walls, rich with capillaries