12/2 Acute Pneumonia - Nagella Flashcards
causes of lung injury
blood: ruptured vessels
water/swelling: pressure issue (ex. CHF exacerbation)
cells: cancer
PUS: response to infection → neutrophils, exudate, cytokines, etc
can have any combo of above
pneumonia overview
definition
role of defense mechanisms
- mech defense
- immune dysreg
- immunocompromise
“infection of lung parenchyma”
occurs when defense mechs are impaired and systemic resistance of host is lowered → URT germs geain access into LRT
- loss/suppression of cough reflex
- injury to mucociliary apparatus (cig smoke, acute inf, ciliary defects)
- accumulation of secretions
- alveolar macrophage dysfx
- pulmo vascular congestion → edema
cell-mediated immunity defects
- aging
- during/after some viral illnesses
- thymic dysplasia
- congenital conds assoc with defects in cell-mediated immunity
- 3rd trimester preg
- lymphatic malignancies of T cell origin
- immunosuppressive tx (esp corticosteroids and cyclosporine)
role of immune defects in pneumonia inf
compromised innate immunity
- neutrophil, complement, humoral definiciency → more inf by pyogenic bacteria
TLR mutations
- more pneumococcal bacterial inf
defects in cell-mediated immunity
- more intracellular microbes, herpes viruses, pneumocystic jiroveci
stages of acute bacterial pneumonia
four stages of infl respose:
- congestion
- red hepatization
- gray hepatization
- resolution (poss with residual fibrous thickening, adhesions, scarring)
- normal, healthy
- acute pneumonia
- congested septal capillaries
- all alveoli have neutrophils
- don’t have fibrous/thickening formation yet
- early organization of intraalveolar exudate (pores of Kohn)
- inflammatory pus, T cells, dead bacteria
- thickening of alveolar border
- advanced organizing pneumonia
- exudated material → fibromyxoid mass
bhronchopneumonia
usually bacterial
might start in airways as acute bronchitis → multifocal disease
identifying causative microbe is important
how do you get pneumonia?
typical and atypical sx
sick contacts
travel and work history
URT → moving lower
hematogenous seeding from another site
nosocomial infections
typical symptoms
- cough, sputum production, dyspnea, pleuritic chest pain
- fever and abnormal breath sounds
atypical symptoms
- confusion, failure to thrive, worsening of chornic illness, falling
- gradual onset of cough/extrapulm sx
- infiltrates not easy to identify in chronic lung disease patients
- elderly will show less of a cough, less WBC changes
usual duration of sx in community-acquired pneumonia
- tachycardia, hypotension
- fever, tachypnea, hypoxia
- cough
- fatigue
- infiltrate on chest radiograph
- tachycardia, hypotension → 2d
- fever, tachypnea, hypoxia → 3d
- cough → 14d
- fatigue → 14d
- infiltrate on chest radiograph → 30d
cormorbidities can delay recovery (COPD, alcoholism, neurologic disease, HF, chornic kidney disease, malignancy, HIV, DM)
why are atypical bugs called atypical?
Mycoplasma, Chlamydia, Legionella, Coxiella
dont grow in normal cultures → need to grow in special media
community acquired pneumonia
inf in otherwise healthy individs acquired from normal environment
- bacterial or viral
- see: alveolar filling with inflammatory exudate (“consolidation of pulmonary tissue”)
- decreased or absent splenic fx can impact which type of bug infects (higher rate of encapsulated bacterial inf in these pts)
Streptococcus pneumoniae
most common cause of comm acquired pneumonia
alveolar architecture preserved
yellow sputum (eh)
baseline comromised lung fx → can lead to decomp
Haemophilus influenzae
A-F serotypes, pleomorphic Gram negative bacteria
- vaccine targets b-type (most virulent form)
- capsulated and non-capsulated forms
- incidence of non-cap forms increasing : often see URI symptoms first (otitis media, sinusitis, bronchopneumonia)
- targets: neonates, cancer pt, immune compromised pts
Moraxella catarrhalis
Gram negative diplococcus
- more in elderly
- common cause of otitis media in children
Staphylococcus aureus
common cause of secondary bacterial pneumonia after virus/influenza
can lead o persistent anatomic complications → abscess or empyema
*seen in IV drug users → seeds R lung via bacteremia
Klebsiella pneumoniae
most common cause of Gram negative bacterial pneumonia
- often in debilitated, malnourished, alcoholic
- thick, mucoid, blood-tinged sputum (viscid capsular polysacch which makes it tough to expectorate)
- can form abscess
community acquired viral penumonia
ex. influenza A/B, RSV (resp syncytial virus), human metapneumovirus, rhinovirus, rubeola, varicella
- usually start with URI, proceed to LRT → become pneumonia
- viruses have tropisms for resp lining cells → viral replication and immune response cause inflammation
- predisposes to bacterial superinf
keys to recognize…
- bacterial or Legionella pneumonia
- atypical bacterial pneumonia (mycoplasma/chlamydia)
- viral pneumonia
- influenza pneumonia
ARDS
pathophys
symptoms
tx
acute respiratory distress syndrome
- endothelial activation
- adhesion and extravasation of neutrophils
- accumulation of intraalveolar fluid and formation of hyaline membranes
- resolution (sometimes)
- dyspnea and tachypnea
- cyanosis and hypoxemia
- hypoxemia even refractory to O2 tx
- resp failure
- diffuse bilateral infiltrates on CXR
- stiff lungs (due to loss of surfactant)
treatment
- lower ventilator set tidal volumes
- prone positioning
- extracorporeal membrane oxygenation (ECMO)
