Pathology of Respiratory Tract Infections Flashcards
What 3 factors determine a microorganisms ability to cause infection
Microorganism pathogenicity
Capacity to resist infection
Population at risk
What type of Microorganism pathogenicities are there
Primary, facultative or opportunistic
What is primary pathogenicity
A microorganism that is able to infect hosts at any given opportunity
What is faculative pathogenicity
A microorganism that requires some help to be able to grow
Where is a high amount of microorganisms with faculative pathogenicity seen
Clinical settings
What is opportunisitc pathogenicity
Microorganisims that will mainly affect immunocompromised individuals
Name 6 upper respiratory tract infections
Coryza (common cold) Sore throat syndrome Acute laryngotracheobronchitis (croup) Laryngitis Sinusitis Acute epiglottis
What can cause acute epiglottis
Haemophilus influenzae (type b - Hib) Group A beta-haemolytic Streptococci Parainfluenza virus type 4 (rarely)
Why is acute epiglottis dangerous in babies
It can rapidly kill a child due to the inflamed epiglottis increasing the risk of suffocation.
Name 3 lower respiratory tract infections
Bronchitis
Bronchiolitis
Pneumonia
Name the 4 main respiratory tract defence mechanisms
Macrophage-mucociliary escalator system
General immune system
Respiratory tract secretions
Upper respiratory tract as a ‘filter’ and humidifier
What are the two types of immunity we have
Humoral and cellular immunity
Give an example of something in the upper respiratory tract which acts as a filter
Nose hairs which can catch some microorganisms
In what type of conditions does the mucociliary escalator system work best
Warm damp environments
Will not work as well when cold air is being breathed in
What can the macrophage-mucociliary escalator system further be split into
Alveolar macrophages
Mucociliary escalator
Cough reflex
What are the two routes of exit in the lung
Mucociliary escalator
Interstitial pathway
What process does the muctociliary escalator have
Moves mucus up into the mouth to be swallowed or spat out
It is vital in keeping the LRT sterile
What process does the interstitial pathway have
Uses lymph to reach the lymph nodes
How does clearance occur using alveolar macrophages
Phagocytosis
What are the macrophages carries along
Mucociliary escalator
What happens to the mucociliary escalator if the airway becomes blocked or surface is damaged
It will not be able to clear the lungs
What are the three ways in which pneumonia can be classified
Anatomical
Aetiological (circumstances)
Microbiological
Which of the 3 methods which can be used to classify pneumonia is the most useful
Aetiological
Which of the 3 methods which can be used to classify pneumonia is appropriate for treatment
Microbiological
Name 6 ateiological pneumonia’s
Community Acquired Pneumonia Hospital Acquired (Nosocomial) Pneumonia Pneumonia in the Immunocompromised Atypical Pneumonia Aspiration Pneumonia Recurrent Pneumonia
Name 6 anatomical pneumonia’s
Bronchopneumonia Segmental Lobar Hypostatic Aspiration Obstructive, Retention, Endogenous Lipid
In what population group is hypostatic pneumonia seen and why
Elderly
Their cough reflex may not be as efficient
What is bronchopneumonia
An acute infection which causes acute inflammation
How does bronchopneumoina present
Bilateral basal patchy opacification which relates to the focal nature of the consolidation
What is a common co-morbidity with lobar pneumonia
Pleurisy
What is the outcome of most pneumonia’s
Most will resolve
What are some of the complications of pneumonia
Pleural Effusion Empyema Pleurisy Lung abscess Bronchiectasis
Name 3 things which will occur in the organisation of the lung
COP (cryptogenic organising pneumonia (BOOP))
Constrictive bronchiolitis
Mass lesions
Is pneumonia able to form scar tissue
Yes
What can become obstructed due to a lung abcess
Bronchus
What 3 organisms can cause lung abcesses
Staph aureus
Some pneumococci
Klebsiella
What can the metastasis of a lung abscess cause
Pyaemia
Secondary infection causing lung necrosis
What is bronchiectasis
The pathological dilatation of the bronchi
What can cause bronchietasis
Severe Infective Episode
Recurrent Infections - many causes
Proximal Bronchial Obstruction
Lung Parenchymal Destruction
How many cases of bronchiectasis start in childhood
75%
What are the main symptoms of bronchiectasis
Cough
Abundant purulent foul sputum
Haemoptysis
Signs of chronic infection
What are some other symptoms which can occur with bronchiectasis
Coarse crackles and clubbing
How can bronchiectasis be diagnosised
Through a thin section CT
Previously bronchography was used
How is bronchiectasis treated
Postural drainage
Antibiotics
Surgery
What could a local bronchial obstruction be caused by
Tumour
Foreign bodies
What could a local pulmonary damage be caused by
Bronchiectasis
What could generalised lung disease be caused by
Cystic fibrosis
COPD
What can aspiration pneumonia be caused by
Vomiting Oesophageal Lesion Obstetric Anaesthesia Neuromuscular Disorders Sedation
What are opportunistic infections
The increased chance of ordinary infections
What are opportunistic pathogens
Organisms which are not normally capable of producing disease in patients that have intact lung defences
What causes opportunistic infections
Opportunistic pathogens
Give 4 example of opportunistic pathogens
Low grade bacterial pathogens
Cytomegalovirus
Pneumocystis jirovecii
Other fungi and yeasts
What is FIO2
Fraction of Inspired air that is Oxygen
In what two forms can the bulk flow of the air in airways be
Laminar or Turbulent
What is the airflow of air in the airways dependant on
Pressure difference
What will occur beyond the terminal bronchiole
Diffusion through the blood-air barrier
What is the normal PaO2 and PaCO2 levels
PaO2 = 10.5 - 13.5 kPa PaCO2 = 4.8 - 6.0 kPa
When does type 1 respiratory failure occur
When PaO2 falls below 8 kPa
PaCO2 is usally normal or low
When does type 2 respiratory failure occur
When PaCO2 is above 6.5 kPa
PaO2 is usually low
What happens in type 2 respiratory failure
Retention of CO2
What are the 4 abnormal states associated with hypoxaemia
Ventilation / Perfusion imbalance - V/Q
Diffusion impairment
Alveolar Hypoventilation
Shunt
When does physiological pulmonary arteriolar vasoconstriction occur
When the alveolar oxygen tension falls
It can be a localised effect which can cause all vessels to constrict is there is arterial hypoxaemia
How is physiological pulmonary arteriolar vasoconstriction a protective mechanism
It prevents blood from being sent to alveoli which are short of oxygen
Where is ventilation/perfusion imbalance seen
Bronchitis/bronchopneumonia
There is some ventilation of the abnormal alveoli however it is not enough
What will occur is severe bronchopneumonia
Shunt
A lobar pattern with large areas of consolidation will be seen
How saturated is the blood which normally leaves the lung
98%
