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Pneumonia – Pathophysiology



Pneumonia is an infection that inflames the air sacs in one or both lungs. It can be bacterial, viral or even fungal. Bacterial pneumonia has a faster onset than viral.
Community Acquired Pneumonia (CAP) is generally found in persons WHO HAVE NOT recently been in the hospital or other health care facility. Hence, CAP has been acquired out in the community.
Hospital Acquired Pneumonia (HAP) or Nosocomial Pneumonia is often associated with patients who caught pneumonia while in a health care facility. Usually begins in the nonventilated patient within 48 hours of admission.

Nosocomial pneumonia’s are the second most common nosocomial infection and is the most prevalent in medical and surgical intensive care units. It is usually bacterial in origin. This adds significantly to the cost of hospital care and length of hospital stays. Nosocomial pneumonia is responsible for 25% of infections in ICU’s and can account for 50% of all antibiotics administered in the hospital.
Ventilator-associated Pneumonia (VAP) is also a form of nosocomial pneumonia that begins more than 48 hours after the patient is intubated.
The most common cause of pneumonia is Steptococcus pneumoniae (pneumococcus).
Atypical Pneumonia is also referred to as walking pneumonia and is caused by other bacteria.
A bacterium called Pneumocystis jiroveci can cause pneumonia in patients whose immune system is already compromised.
Viruses such as the flu virus are also a common cause of pneumonia.
Some ways to contract pneumonia:
Bacteria and viruses living in your nose, sinuses or mouth may spread to lungs.
You can breath some of these germs directly into your lungs.
You can breathe in (inhale) food, liquids, vomit or fluids from the mouth into the lungs (aspiration pneumonia).

Risk Factors:

Chronic lung disease
Brain disorders (dementia, CVA, brain injuries, and cerebral palsy)
Compromised immune system (i.e. cancer treatments HIV/AIDS, organ transplant, or any other disorders that compromises the bodies immune system)
Serious illnesses (heart disease, cirrhosis of the liver, diabetes)
Recent surgery or trauma
Signs and symptoms: They can vary between bacterial and viral. Symptoms can also vary from mild to severe:
Productive cough some pneumonia’s may have greenish, yellow or even bloody mucus).
Shaking chills
Possible shortness of breath
Possible sharp or stabbing pain in chest with inspiration
Loss of appetite
Hyperresonance and increased fremitis over the infected area.




Chest xray (may be normal if viral. CBC may show increased WBC’s.
other more intensive testing may be required:
ABG’s to see if enough oxygen is getting into your blood from the lungs
CT scan to see how lungs are functioning
Sputum Tests to look for organism
Pleural fluid culture (if there is fluid in the space surrounding the lungs)
Bronchoscopy a procedure used to look into the lungs which would be performed if you are hospitalized and the antibiotics are not working well.



Viral pneumonia, if otherwise normal, may be sent home for rest.
If diagnosis is bacterial pneumonia, antibiotics are initiated within 4 hours of admission. fluids and rest are also ordered.
In severe cases: the patient may be placed on BiPAP, CPAP or even intubated. Other treatments include:
fluids to loosen secretions
DO NOT take cough medicines unless directed by MD. Cough medicines make it harder for your body to cough up extra sputum
Control fever (consult with MD) Acetaminophen, NSAIDS such as ibuprofen. NEVER GIVE ASPIRIN TO CHILDREN
Prevention: The flu shot can help. The flu can often lead to pneumonia, frequent hand washing. If a person is at high risk for pneumonia, there is also a pneumococcal pneumonia vaccine.


Anna C. RN-BC, BSN, PHN, CMSRN Anna began writing extra materials to help her BSN and LVN students with their studies. She takes the topics that the students are learning and expands on them to try to help with their understanding of the nursing process. She is a clinical instructor for LVN and BSN students along with a critical care transport nurse.

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One comment

  1. kayinda

    Superb hope to learn more

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