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Pneumonia

Pathogens can cause pneumonia through aspiration, hematogenous spread, or contiguous extension. Alveolar macrophages initiate an inflammatory response when their capacity to fight microorganisms is exceeded. This leads to the release of inflammatory mediators and chemokines that cause fever, recruit neutrophils, and can result in hypoxemia, respiratory alkalosis, and dyspnea if severe enough. The inflammatory response and alveolar filling can worsen to cause death in severe cases.

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Ayen Fornolles
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547 views1 page

Pneumonia

Pathogens can cause pneumonia through aspiration, hematogenous spread, or contiguous extension. Alveolar macrophages initiate an inflammatory response when their capacity to fight microorganisms is exceeded. This leads to the release of inflammatory mediators and chemokines that cause fever, recruit neutrophils, and can result in hypoxemia, respiratory alkalosis, and dyspnea if severe enough. The inflammatory response and alveolar filling can worsen to cause death in severe cases.

Uploaded by

Ayen Fornolles
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Etiologic Agent

Aspiration from the oropharynx

Hematogenous spread, or by
contiguous extension from
an infected pleural or
mediastinal space

Pathogens inhaled as contaminated droplets

When barriers are overcome or when the microorganisms are small


enough to be inhaled to the alveolar level

When the capacity of the alveolar macrophages to


ingest or kill the microorganisms is exceeded
Alveolar macrophages initiate the inflammatory
response to bolster lower respiratory tract defenses

Release of inflammatory
mediators: interleukin (IL)-1
and tumor necrosis factor
(TNF)

Fever

Chemokines: IL-8, GCSF

Release of Neutrophils

If severe enough, the changes in lung


mechanics secondary to reductions in
lung volume and compliance and the
intrapulmonary shunting of blood may
cause the patient's death.

Peripheral
leukocytosis and
increased purulent
secretions
Hemoptysis

Inflammatory mediators released by macrophages + neutrophils

Alveolar
capillary leak
(initially
localized)

Rales
Radiographic infiltrate
Alveolar Filling

Increased respiratory drive


in SIRS

Respiratory Alkalosis

Dyspnea
Hypoxemia

+ Some bacterial pathogens


Severe Hypoxemia

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