pathology of resp tract infections Flashcards
What are lung infections the outcome of?
microorganism pathogenicity
-primary- invasive
-facultative
-opportunistic- in normal would not cause infection
capacity to resist infection
-state of host defence mechanisms
-age of patient
population at risk
Give characteristics of acute epiglottis? I love you btw - Gregor
specific infection of the epiglottis
big issue in children
causes swelling and inflammation in the epiglottis and can completely obstruct it
may be caused by bacteria or viruses
Which out of upper and low resp tract is sterile?
lower
What are the respiratory tract defence mechanisms?
-macrophage- mucociliary escalator system
-humoral and cellular immunity antibodies and lymphocytes, leukocytes
-respiratory tract secretions
-upper resp tract- acts as a filter
What are the components of the macrophage- mucocililary escalator system?
alveolar macrophages
mucociliary escalator
cough reflex
Describe particle clearance from the lungs? how it stays sterile
alveolar macrophages cruising around, mopping up debris that gets as far as the lung alveoli.
Macrophages then digest material and / or get out of lungs.
Main route of escape is through terminal and respiratory bronchioles, where they encounter the respiratory epithelium (comprises large numbers of ciliated cells).
Beating of cilia transports a very thin layer of liquid (result of resp secretion) that this fluid layer is always on move but always out wards and towards throat.
Either swallow or cough a little bit.
What is another escape route?
for the same macrophages containing material ingested to get out via the lymphatic system into the lymph nodes
What are the causes for the mucociliary escalator to fail?
-blockage in the airway so that the materials cannot get up
-respiratory epithelial cells can become damaged and non functional (viral damage)
- leading to secondary bacterial pneumonia
What is the main organism that causes pneumonia?
staphylococcus aureas
What can severe bronchiolitis cause?
severe airflow limitation
What is the pathology of bronchiolitis?
inflammations and secretions- which cause the small airways to become really narrowed-limiting ventillation
How is pneumonia classified?
anatomically
aetiological (circumstances)
microbiological
What is hypostatic pneumonia?
secretions accumulate in the dependent lower parts of the lung and then not being able to clear it. And bacteria can grow.
What does bronchopneumonia refer to?
refers to an infection, pathology being acute inflammation.
The accumulation of neutrophil polymorphs and fluid secretion.
Can spill into alveoli.
Patchy infection and pneumonia.
Facultative pathogens.
What does lobar pneumonia refer to?
consolidation of an entire lobe.
Often occurs in different circumstances.
Primary pathogens- invasive.
Stimulate a vigorous inflammatory response- involving an enormous exhumation of fluid and sometimes bleeding into the lungs, washing the organism further and throughout the lobe of the lung.
What are the outcomes/ complications of pneumonia?
- most resolve
-may be problems in pleura where it becomes infected (for e.g. lobar pneumonia not broncho)
-inflammatory process might organise into fibrous tissue
-may cause so much damage that tissue dies (lung abscess)
-bronchiectasis
-potentially fatal
Describe Bronchiolitis obliterans?
individual bronchioles that were infected and inflamed - then they get a fibrous plug in middle
Give characteristics of a lung abscess?
-if obstruction of bronchus caused by tumor- more likely to get an abscess
-if infection caused by aspiration of gastric contents into lung more likely for abscess
-certain organisms can more likely lead to abscess
-spread of infection to lungs via blood can more likely lead to abscess
-infection of pulmonary infarct more likely for abscess
What is Bronchiectasis?
pathological dilatation of bronchi due to infection or obstruction leading to accumulation of secretions- which causes airways to dilate.
How do the defences fail for recurrent lung infection?
infection in same place each time - anatomical problem with a particular bronchus or particular area of the lung. Tumour, bronchiectasis.
Immunocompromised
Generalised lung disease?
Questions to ask when someone has aspiration pneumonia?
problem with GI tract?
Lots of reflux?
Vomiting?
Something wrong with protective reflexes in upper respiratory tract?
Neurological problem leading to failure of protection of the opening into the trachea when theres stuff in oropharynx?
Commonest cause of aspiration pneumonia?
too much alcohol
puke goes into trachea and goes into apical segment of right lower lob
How efficient is carbon dioxide and oxygen at diffusing across blood barrier?
Hb affinity for oxygen means blood leaving capillary bed is 98% saturated despite only 21% of alveoli being oxygenated
carbon dioxide very soluble and rapidly equillibriates between blood and air
what is normal partial pressure of oxygen and carbon dioxide in arterial blood?
normal paO2: 10.5-13.5kPa
paCO2: 4.8-6.0 kPa
