Pathology of respiratory tract infection Flashcards

1
Q

what common viruses can cause URTI

A

rhinoviruses, adenoviruses,

parainfluenza, influenza and EB virus

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2
Q

what determines the capacity of a patient to resist infection

A

state of host defence mechanisms

age of the patient

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3
Q

name some common URTI’s (6)

A
Coryza - common cold
Sore throat syndrome
Acute Laryngotracheobronchitis (Croup)
Laryngitis
Sinusitis
Acute Epiglottitis
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4
Q

which 2 main organisms cause acute epiglottitis

A

caused by beta-haemolytic streptococci

or haemophilus influenzae

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5
Q

name some common LRTI’s

A

Bronchitis
Bronchiolitis
Pneumonia

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6
Q

4 main 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’

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7
Q

what 3 parts are involved in the macrophage mucociliary escalator system

A

alveolar macrophages
mucociliary escalator
cough reflex

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8
Q

process of particle clearance from the lungs

A

clearance by alveolar macrophage phagocytosis

interstitial pathway via lymph to the lymph nodes

then from the nodes to the trachea- clearance via the mucociliary escalator

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9
Q

what is the mucociliary escalator

A

whole process of cilia beating secreted mucus with foreign particles within it up the trachea towards the laryngopharynx. It is then either swallowed (it goes to stomach where acidity helps neutralise foreign particles) or it is coughed up

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10
Q

what different classes of pneumonia exist? (6)

A
Community Acquired Pneumonia
Hospital Acquired (Nosocomial) Pneumonia
Pneumonia in the Immunocompromised
Atypical Pneumonia
Aspiration Pneumonia
Recurrent Pneumonia
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11
Q

spatial patterns of pneumonia? (3)

A

bronchopneumonia
segmental
lobar

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12
Q

patterns in characteristics of pneuomonia? (3)

A

hypostatic
aspiration
obstructive, retention, endogenous lipidq

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13
Q

outcome/complications of pneumonia

A

most resolve

pleurisy, pleural effusion and empyema

organisation (mass lesion, constrictive bronchiolitis)

lung abscess

bronchiectasis

pneumonia is still a potentially fatal disease

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14
Q

lung abscess

A

often caused by aspiration

staph aureus, some pneumococci and klebsiella

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15
Q

bronchiectasis is dilatation of Bronchi which can be caused by what? (4)

A

Severe Infective Episode

Recurrent Infections

Proximal Bronchial Obstruction

Lung Parenchymal Destruction

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16
Q

Bronchiectasis disease profile

A

75% start in childhood
cough, abundant purulent (pus) sputum
coarse crackles, clubbing

17
Q

treatment/ investigations for Bronchiectasis

A

thin section CT
postural drainage antibiotics
surgery

18
Q

how do recurrent lung infections occur?

A

Local Bronchial Obstruction - Tumour, Foreign body

Local Pulmonary Damage - Bronchiectasis?

Generalised Lung Disease - Cystic Fibrosis? COPD?

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

19
Q

what is normal pulmonary gas exchange

A

air flow in airways - bulk flow and depends on pressure difference

beyond the terminal bronchiole - diffusion occurs

O2 gets pulled into blood by haemoglobin

CO2 is v soluble and rapidly equilibrates between blood and air

20
Q

what are the 4 abnormal states associated with hypoxaemia?

A

ventilation/perfusion imbalance
diffusion impairment
alveolar hypoventilation
shunt

21
Q

type 1 respiratory failure values

A

NORMAL
PaO2 10.5-13.5 kPa

FAILURE
PaO2 <8 kPa (PaCO2 normal or low)

22
Q

type 2 respiratory failure values

A

NORMAL
PaCO2 4.8 – 6.0 kPa

FAILURE
PaCO2 >6.5 kPa (PaO2 usually low)

23
Q

differentiation between type 1 and 2 respiratory failure?

A

type 1 and 2 are different based on whether there is a high carbon dioxide level or not

24
Q

what pulmonary vascular changes occur in hypoxia

A

pulmonary arteriolar vasoconstriction (when alveolar O2 tension falls)

25
Q

what do all vessels do if there is arterial hypoxaemia?

A

constrict

so that blood is not sent to alveoli that are short of oxygen

26
Q

what is the most common cause of hypoxaemia enzountered in clinic?

A

low V/Q which can arise due to local alveolar hypoventilation due to some focal disease

27
Q

what is V/Q

A

ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the alveoli per minute

28
Q

Hypoxaemia due to low V/Q responds well to

A

small increases in FIO2 (fraction of inhaled O2)

29
Q

shunt and pneumonia?

A

can be caused by severe bronchopneumonia

shunt means no ventilation of abnormal alveoli

30
Q

define shunt

A

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

31
Q

why do large shunts not responde well to increases in FIO2?

A

because the blood leaving a normal lung is already 98% saturated (haemoglobin) so can’t increase it much more)

32
Q

how is a fall in PaO2 due to hypoventilation corrected?

A

by raising FIO2

33
Q

where is there deposition?

A

on the conducting airways

on the terminal bronchioles/proximal alveoli

34
Q

what is bronchopneumonia?

A

inflammation of the lungs, arising in the bronchi or bronchioles

35
Q

what is hypoxic cor pulmonale

A

a maladaptive response to pulmonary hypertension

36
Q

croup/epiglottitis

definition
signs
symptoms
diagnosis/investigation
management
A

epiglottitis
inflammation of the upper portion of the larynx or the epiglottis

symptoms - sudden onset of sore throat, stridor, muffled voice, dry cough, pain swallowing, drooling, fever

diagnosis/investigation - do nnot examine with tongue depressor!! due to risk of laryngeal obstruction; rather, they should be urgently referred for laryngoscopy

management - augmentin/cephalosporin
may require intubation

croup
inflammation inside wind pipe

signs - barking cough, stridor, difficulty breathing, no drooling

diagnosis/investigation - clinical diagnosis by ruling out other conditions (diagnosis by exclusion)

management - oral steroids, O2 therapy

37
Q

what is ottitis media

A

a common complication of URTI

inflammatory disease of the middle ear

signs - erythema (redness of the skin or mucous membranes), bulging ear drum

symptoms- painful ear, history of URTIs, discharge from ear

diagnosis/investigation - examination of ear

management - painkillers or antibiotics if severe or bilateral

38
Q

What is coryza (common cold) caused by?

A

inflammation and irritation of the mucous membranes