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Lecture 12

PAT 20A/B Lecture Notes - Lecture 12: Salbutamol, Edema, Humidifier


Department
Pathotherapeutics
Course Code
PAT 20A/B
Professor
Audrey Kenmir
Lecture
12

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(2)PAT20 Fall Week 12 Notes (CAP, HAP & COPD)
By: Bina Nsimba
Pneumonia
-Pneumonia: acute inflammation of the lung parenchyma caused by a microbial agent.
Etiology
Factors Predisposing to Pneumonia
Pneumonia is more likely to result when defence mechanisms become
incompetent or are overwhelmed by the virulence or quantity of infectious agents.
Decreased consciousness depresses the cough and epiglottal reflexes, which may
allow aspiration of oropharyngeal contents into the lungs.
Tracheal intubation interferes with the normal cough reflex and the mucociliary
escalator mechanism.
The mucociliary escalator mechanism is impaired by air pollution, cigarette
smoking, viral upper respiratory infections (URIs), and normal changes of aging.
In the presence of malnutrition, the functions of lymphocytes and
polymorphonuclear leukocytes are altered.
Certain diseases such as leukemia, alcoholism, and diabetes mellitus are
associated with an increased frequency of Gram-negative bacilli in the
oropharynx. (Gram-negative bacilli are not normal flora in the respiratory tract.)
Altered oropharyngeal flora can also occur secondary to antibiotic therapy given
for an infection elsewhere in the body.
Table 30-1 Factors Redisposing to Pneumonia
Aging
Air pollution
Altered consciousness: alcoholism, head injury, seizures, anaesthesia, drug overdose,
stroke
Altered oropharyngeal flora
Bed rest and prolonged immobility
Chronic diseases: chronic lung disease, diabetes mellitus, heart disease, cancer, end-stage
renal disease
Debilitating illness
Human immunodeficiency virus infection
Immunosuppressive drugs (corticosteroids, cancer chemotherapy, immunosuppressive
therapy after organ transplant)
Inhalation or aspiration of noxious substances
Intestinal and gastric feedings
Malnutrition
Smoking
Tracheal intubation (endotracheal intubation, tracheostomy)
Upper respiratory tract infection

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Acquisition of Organism
oOrganisms that cause pneumonia reach the lung by three methods:
1. Aspiration from the nasopharynx or oropharynx; (ex. organisms of the
pharynx).
2. Inhalation of microbes present in the air; (ex: M. pneumoniae and fungal
pneumonias).
3. Hematogenous spread from a primary infection elsewhere in the body;
(ex. Staphylococcus aureus).
Types of Pneumonia
Pneumonia can be caused by bacteria, viruses, Mycoplasma, fungi, parasites, and
chemicals.
Community-Acquired Pneumonia
-Community-acquired pneumonia (CAP): a lower respiratory tract infection of the
lung parenchyma with onset in the community or during the first 2 days of
hospitalization.
-Smoking is an important risk factor.
-Organisms that are commonly implicated in CAP include S. pneumoniae and
atypical organisms (e.g., Legionella, Mycoplasma, Chlamydia, viral).
-Modifying risk factors include the presence of COPD, recent use of antibiotics,
and conditions incurring risk of aspiration.
Hospital-Acquired Pneumonia (HAP)
Hospital-acquired pneumonia (HAP): pneumonia occurring 48 hours or longer
after hospital admission and not incubating at the time of hospitalization.
Bacteria are responsible for the majority of HAP infections, including
Pseudomonas, Enterobacter, S. aureus, methicillin-resistant Staphylococcus
aureus (MRSA), and S. pneumoniae.
Immunosuppressive therapy, general debility, and endotracheal intubation may be
predisposing factors.
Contaminated respiratory therapy equipment is another source of infection.
Pathophysiology
Pneumococcal pneumonia is the most common cause of bacterial pneumonia.
However, regardless of causative factors, pneumonia is characterized by four stages of
the disease process:
i. Congestion-
After the pneumococcus organisms reach the alveoli via droplets or saliva,
there is an outpouring of fluid into the alveoli.
The organisms multiply in the serous fluid, and the infection is spread.
The pneumococci damage the host by their overwhelming growth and
interference with lung function.
ii. Red hepatisation-
There is massive dilation of the capillaries, and alveoli are filled with
organisms, neutrophils, red blood cells (RBCs), and fibrin.
The lung appears red and granular, similar to the liver, which is why the
process is called hepatization.
iii. Grey hepatisation-

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Blood flow decreases, and leukocytes and fibrin consolidate in the affected
part of the lung.
iv. Resolution-
Complete resolution and healing occur if there are no complications.
-The exudate becomes lysed and is processed by the macrophages.
-The normal lung tissue is restored, and the person's gas-exchange
ability returns to normal.
Clinical Manifestations
Sudden Onset
oPatients with pneumonia usually have a constellation of symptoms including sudden
onset of fever, chills, cough productive of purulent sputum, and pleuritic chest pain.
oIn the older adult or debilitated patient, confusion or stupor (possibly related to hypoxia)
may be the predominant finding.
oOn physical examination, signs of pulmonary consolidation, such as dullness to
percussion, increased fremitus, bronchial breath sounds, and crackles, may be found.
Gradual Onset
oPneumonia may also manifest atypically with a more gradual onset, a dry cough, and
extrapulmonary manifestations such as headache, myalgias, fatigue, sore throat, nausea,
vomiting, and diarrhea.
oOn physical examination, crackles are often heard.
oThis necrotizing infection causes destruction of lung tissue, and these patients are usually
very sick.
Complications
a) Pleurisy (inflammation of the pleura)
-Relatively common accompanying problem of pneumonia.
b) Pleural effusion (excess fluid that accumulates in the pleural cavity)
-Usually the effusion is sterile and is reabsorbed in 1 to 2 weeks.
c) Atelectasis (collapsed, airless alveoli) of one or part of one lobe may occur.
-These areas usually clear with effective coughing and deep breathing.
d) Delayed resolution (results from persistent infection)
-Usually, the physical findings return to normal within 2 to 4 weeks.
e) Lung abscess (liquefactive necrosis of the lung tissue and formation of cavities
containing necrotic debris or fluid caused by microbial infection)
-It is seen with pneumonia caused by S. aureus and Gram-negative
pneumonias.
f) Empyema (accumulation of purulent exudate in the pleural cavity)
-Relatively infrequent issue of pneumonia.
g) Pericarditis (spread of the infecting organism from an infected pleura or via a
hematogenous route to the pericardium (the fibroserous sac around the heart)).
h) Bacteremia (presence of bacteria in the blood)
-Occurs with pneumococcal pneumonia.
i) Meningitis (an acute inflammation of the protective membranes covering the
brain and spinal cord)
-Caused by S. pneumoniae.
j) Endocarditis (an inflammation of the inner layer of the heart, the endocardium)
Diagnosis Studies
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