Pathophysiology - Pneumonia

Pneumonia – inflammatory process of the lung parenchyma

Classification

1. Community Acquired – used to describe infections found in the community rather than the hospital/nursing home. Defined as an infection that begins outside the hospital or is diagnosed 48 hours after admission to the hospital in a person who has not resided in a long term facility for 14 days or more before admission
2. Hospital Acquired or Nosocomial – is defined as a lower respiratory tract infection that was not present or incubating on admission to the hospital. Increase risk for those with mechanical ventilation, compromised immune function, chronic lung disease and airway instrumentation such as e-tube, tracheostomy, etc.

Types According to Causative Agent

1. Gram Positive Bacteria

• Streptococcus pneumonia (pneumococcal pneumonia)
• most common cause of community acquired pneumonia.
• follows influenza I situations in which groups of people live in close contact
• rust colored sputum, blood tinged, purulent
• Staphylococcus aureus
• acquired thru blood or by aspiration
• creamy yellow sputum

2. Gram Negative Bacteria

• Haemophilus influenza
• common cause of infection in children
• high mortality rate
• greenish colored sputum
• Klebsiella pneumoniae (Friedlander’s bacillus)
• most common gram negative organism acquired outside hospitals
• occurs in people with malignancies
• necrosis, abscess foration, hemoptysis and fibrotic changes occur
• high mortality rate
• red gelatinous sputum
• Pseudomonas aeroginosa
• most common gram negative organism acquired in the hospital
• common in the respiratory tract of hospital employees and those with cystic fibrosis
• greenish colored sputum
• Legionella pneumophilia (Legionnaires’ disease)
• most common cause of community acquired pneumonia
• found in warm standing water

3. ANAEROIC BACTERIAL PNEUMONIAS

• Commonly caused by anaerobic streptococcus
• History of poor dental hygiene, periodontal disease, dysphagia and altered consciousness

4. OTHER INFECTIOUS AGENTS

• Mycoplasma pneumoniae
•  an organism with the characteristics of both bacteria and viruses
• it causes atypical/interstitial pneumonia
• Viral agents
• influenza virus, adenovirus and parainfluenza virus
• self-limiting
• may predispose to secondary bacterial infection
• Fungi
• candidiasis, histoplasmosis, blastomycosis, cryptococcosis, aspergillosis, actinomycosis and nocardiosis
• follows after extended antibiotic use, immunocompromised and seriously ill people
• Non-infectious causes
• inhalation of toxic gases, chemicals or smoke from fires and aspiration of water due to near drowning, gastric contents, vegetable/mineral oils, liquid petroleum
• Pneumocystis carinii pneumonia
• opportunistic, often fatal form of lung infection seen in debilitated, impaired immune function

RISK FACTORS

• Smoking
• Air pollution
• Upper Respiratory Tract Infection
• Altered consciousness: alcoholism, head injury, seizure disorder, drug overdose, general anesthesia
• Tracheal intubation
• Prolonged immobility
• Immunosuppressive therapy: corticosteroids, chemotherapy
• Non-functional immune system: AIDS
• Severe periodontal disorders
• Prolonged exposure to virulent organisms
• Malnutrition
• Dehydration
• Chronic disease: Diabetes Mellitus, Heart disease, chronic lung disease
• Prolonged debilitating disorders
• Inhalation of noxious substances
• Aspiration of oral/gastric material
• Aspiration of foreign material
• Chronically ill, elderly people who generally have poor immune systems, often residing in group living situations where there is an increase in probability of disease transmission especially through the respiratory system

SIGNS AND SYMPTOMS

• Fever
• Chills
• Sweats
• Dullness on percussion on affected area
• Sputum production
• Hemoptysis
• Pleuritic chest pain
• Dyspnea
• Headache
• Fatigue
• Unequal chest expansion
• Cough

Pathophysiology

Inhalation of droplet nuclei

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Establishes in the alveolus (usually lower lobe)

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Bacterial infection develops

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Vascular engorgement, presence of large number of bacteria

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Serous exudate pours into alveoli from dilated leaking vessels (engorgement first 4-12 hours)

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Decrease in RBC and Increase in Neutrophils and precipitation of fibrin that fills the alveoli

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Continuing accumulation of fibrin

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Consolidation of leukocytes and fibrin

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Exudate is lyzed and reabsorbed by macrophage

DIAGNOSTIC TESTS

• Chest x-ray
• Sputum smear
• Blood cultures
• Bronchoscopy
• Transtracheal aspirate

MEDICAL MANAGEMENT

1. medications – antimicrobial therapy, pain medication for pleuritic chest pain
2. oxygen therapy
3. bed rest
4. high-calorie diet
5. adequate fluid intake

NURSING MANAGEMENT

1. Secure airways and ensure adequate oxygenation.
2. Administer analgesics when needed.
3. Administer antibiotics as prescribed.
4. Maintain adequate nutrition.
5. Educate the patient how to cough properly and deep breathing exercises.
6. Position the client properly so as to help clear secretions.