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CR - Intro to Resp Path + Pneumonia (i) (Pneumonia (caused by infection (S…
CR - Intro to Resp Path + Pneumonia (i)
Intro
function of lungs = excrete CO2 from blood + replenish O2
pul defences
against dust, noxious gases, microbes, pollutants, allergens
cough reflex
lost in coma + anaesthesia
impaired in stroke, neuro disorder, alcohol/drug overdose
mucociliary apparatus
injured by smoking (accumulation of mucus)
alveolar macrophages
depleted by alcohol + smoking
IgA
microflora of upper resp tract
nasal hairs
can be broken down by pul congestion, oedema + obstruction (cancer)
Pneumonia
inflamm consolidation of lung parenchyma (alveoli filled with fluid)
intra-alveolar inflamm exudate (protein rich) hampers gas exchanges - dyspnoea
caused by infection
S pneumoniae (60% of CAP)
H influenzae
S aureus
atypical (Mycoplasma pneumoniae + Legionalla pneumoniae)
viruses (influenza, RSV)
PCP (fungus, rare, only in immunocompromised)
methods of infection: inoculation, aspiration, inhalation, haematogenous
opportunistic pathogens = PCP, CMV, mycobacteria, toxoplasma
risk factors
65+ y/o
smoker
malnourished
high virulence organism
immunocompromised
recurrent RTIs
winter
immune response
influx of WBCs, RBCs + exudate
CKs released -> pyrexia
vasodilators released -> increased vasc permeability -> congestion
increased mucus + bronchoconstriction -> cough reflex
pain Rs in alveoli cause chest pain
can be classified based on source of organism (HAP, HCAP, CAP, VAP, aspiration pneumonia, atypical pneumonia)
Dx
Hx
ask duration of symptoms (should be acute)
clinical exam
CXR
FBC, U+E, LFTs, glucose, CRP
BAL/sputum/blood for culture
Ddss: congestive heart failure, PE, pul vasculitis, malignancy
prognostic tools
CURB65
if score between 0-1 - oral Tx @ home
pneumonia severity index (PSI)
help determine management strategy
complications
parapneumonic effusion
delirium (acute confusional state)
septicaemia (shock, multiorgan failure, death)
adult resp distress syndrome (ARDS) or acute lung injury (ALI)
resp failure
spread to other sites
endocarditis
otitis
meningitis
arthritis
empyema
high mortality
collection of pus within pleural cavity (physiological cavity with fluid between visceral + parietal pleura) - aka pleural space/interstitium
Dx
CXR
aspirate pleural fluid for cytology + microbiology
Tx
antibiotics
if severe chest drain or surgical decortification (removal of surface layer - thick inelastic pleural peel)
abscess
collection of pus in a pathological cavity
localised area of suppurative necrosis in pul parenchyma
necrotising pneumonia
leads to formation of 1+ cavities
anaerobic bacteria almost always present
Tx = antibiotics +/- surgical drainage
aetiology
aspiration
complication of bacterial pneumonia
bronchial obstruction (e.g. neoplasm)
septic embolus
haematogenous bacterial spread
vary in site, often depends on aetiology (e.g. aspiration usually in right post upper lobe as right bronchus is more vertical)
cough + copious amounts of foul-smelling sputum
clubbing, weightloss, anaemia, secondary amyloidosis id chronic, 10% mortality
may embolism to brain -> meningitis, brain abscess
risk of rupture into pleural space -> bronchopleural fistula / empyema / pneumothorax
Aspiration pneumonia
risk factors
impaired/lost cough reflex
unconsciousness
oesophageal obstruction
pyloric stenosis
hiatus hernia (stomach pushes through diaphragm into chest cavity)
gastric contents (food, drinks, gastric acid) are non-sterile + hence are irritants in trachea
causes chemical pneumonitis
acute or chronic
not infectious but does weaken immune system