2. Definition
Pneumoniais an inflammation of the lung parenchyma, associatedwith
alveolar edema and congestion that impair gas exchange. Pneumoniais
caused by a bacterial or viral infectionthat is spread by droplets or by
contact and is the sixth leading cause of death in the United States.The
prognosis is typically good for people who have normal lungs and
adequate host defenses before the onset of pneumonia.
3. Causes
Pneumonia is classified based on its microbiologic etiology – they
can be viral, bacterial, fungal, protozoan, mycobacterial,
mycoplasmal, or rickettsialin origin.
4. Types
Pneumonia may also be classified dependingon its location and radiologic
appearance.
Bronchopneumonia (bronchial pneumonia) involves the terminal bronchioles
and alveoli.
Interstitial (reticular) pneumonia involves inflammatory response within lung
tissue surroundingthe air spaces or vascular structures rather than the area
passages themselves.
Alveolar (or acinar) pneumoniainvolves fluid accumulation in the lung’s distal
air spaces. Necrotizingpneumonia causes the death of a portion of lung tissue
surrounded by a viable tissue.
Aspiration pneumonia, another type of pneumonia, results from vomiting and
aspiration of gastric or oropharyngeal contents into the trachea and lungs.
5. Pneumoniais a particular concern in high-risk patients: persons who are
very young or very old, people who smoke, bedridden, malnourished,
hospitalized, immunocompromised, or exposed to MRSA.
