pneumonia

1
Aspiration from the oropharynx Pathogens inhaled as contaminated droplets Hematogenous spread, or by contiguous extension from an infected pleural or mediastinal space Etiologic Agent 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 Peripheral leukocytosis and increased purulent secretions Inflammatory mediators released by macrophages + neutrophils Alveolar capillary leak (initially localized) Radiographic infiltrate Hemoptysis Hypoxemia Rales Alveolar Filling + Some bacterial pathogens Severe Hypoxemia Increased respiratory drive in SIRS Respiratory Alkalosis Dyspnea 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.

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Pneumonia pathophysiology

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Page 1: Pneumonia

Aspiration from the oropharynx Pathogens inhaled as contaminated droplets Hematogenous spread, or by

contiguous extension from

an infected pleural or

mediastinal space

Etiologic Agent

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

Peripheral

leukocytosis and

increased purulent

secretions

Inflammatory mediators released by macrophages + neutrophils Alveolar

capillary leak

(initially

localized) Radiographic infiltrate

Hemoptysis

Hypoxemia

Rales

Alveolar Filling

+ Some bacterial pathogens

Severe Hypoxemia

Increased respiratory drive

in SIRS Respiratory Alkalosis

Dyspnea

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.