Pathology of respiratory tract infection

Question 1

what common viruses can cause URTI

Answer 1

rhinoviruses, adenoviruses,

parainfluenza, influenza and EB virus

Question 2

what determines the capacity of a patient to resist infection

Answer 2

state of host defence mechanisms

age of the patient

Question 3

name some common URTI’s (6)

Answer 3

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

Question 4

which 2 main organisms cause acute epiglottitis

Answer 4

caused by beta-haemolytic streptococci

or haemophilus influenzae

Question 5

name some common LRTI’s

Answer 5

Bronchitis
Bronchiolitis
Pneumonia

Question 6

4 main respiratory tract defence mechanisms?

Answer 6

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

Question 7

what 3 parts are involved in the macrophage mucociliary escalator system

Answer 7

alveolar macrophages
mucociliary escalator
cough reflex

Question 8

process of particle clearance from the lungs

Answer 8

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

Question 9

what is the mucociliary escalator

Answer 9

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

Question 10

what different classes of pneumonia exist? (6)

Answer 10

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

Question 11

spatial patterns of pneumonia? (3)

Answer 11

bronchopneumonia
segmental
lobar

Question 12

patterns in characteristics of pneuomonia? (3)

Answer 12

hypostatic
aspiration
obstructive, retention, endogenous lipidq

Question 13

outcome/complications of pneumonia

Answer 13

most resolve

pleurisy, pleural effusion and empyema

organisation (mass lesion, constrictive bronchiolitis)

lung abscess

bronchiectasis

pneumonia is still a potentially fatal disease

Question 14

lung abscess

Answer 14

often caused by aspiration

staph aureus, some pneumococci and klebsiella

Question 15

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

Answer 15

Severe Infective Episode

Recurrent Infections

Proximal Bronchial Obstruction

Lung Parenchymal Destruction

Question 16

Bronchiectasis disease profile

Answer 16

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

Question 17

treatment/ investigations for Bronchiectasis

Answer 17

thin section CT
postural drainage antibiotics
surgery

Question 18

how do recurrent lung infections occur?

Answer 18

Local Bronchial Obstruction - Tumour, Foreign body

Local Pulmonary Damage - Bronchiectasis?

Generalised Lung Disease - Cystic Fibrosis? COPD?

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

Question 19

what is normal pulmonary gas exchange

Answer 19

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

Question 20

what are the 4 abnormal states associated with hypoxaemia?

Answer 20

ventilation/perfusion imbalance
diffusion impairment
alveolar hypoventilation
shunt

Question 21

type 1 respiratory failure values

Answer 21

NORMAL
PaO2 10.5-13.5 kPa

FAILURE
PaO2 <8 kPa (PaCO2 normal or low)

Question 22

type 2 respiratory failure values

Answer 22

NORMAL
PaCO2 4.8 – 6.0 kPa

FAILURE
PaCO2 >6.5 kPa (PaO2 usually low)

Question 23

differentiation between type 1 and 2 respiratory failure?

Answer 23

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

Question 24

what pulmonary vascular changes occur in hypoxia

Answer 24

pulmonary arteriolar vasoconstriction (when alveolar O2 tension falls)

Question 25

what do all vessels do if there is arterial hypoxaemia?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

what is V/Q

Answer 27

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

Question 28

Hypoxaemia due to low V/Q responds well to

Answer 28

small increases in FIO2 (fraction of inhaled O2)

Question 29

shunt and pneumonia?

Answer 29

can be caused by severe bronchopneumonia | shunt means no ventilation of abnormal alveoli

Question 30

define shunt

Answer 30

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

Question 31

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

Answer 31

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

Question 32

how is a fall in PaO2 due to hypoventilation corrected?

Answer 32

by raising FIO2

Question 33

where is there deposition?

Answer 33

on the conducting airways on the terminal bronchioles/proximal alveoli

Question 34

what is bronchopneumonia?

Answer 34

inflammation of the lungs, arising in the bronchi or bronchioles

Question 35

what is hypoxic cor pulmonale

Answer 35

a maladaptive response to pulmonary hypertension

Question 36

croup/epiglottitis ``` definition signs symptoms diagnosis/investigation management ```

Answer 36

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

Question 37

what is ottitis media

Answer 37

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

Question 38

What is coryza (common cold) caused by?

Answer 38

inflammation and irritation of the mucous membranes