Pneumonia is a serious lung infection that causes inflammation of the alveoli (air sacs), filling them with mucus, fluid, and debris. This impairs gas exchange — preventing oxygen from entering and carbon dioxide from exiting — leading to hypoxia and potentially life-threatening complications if untreated.
This guide will take you through pneumonia’s pathophysiology, symptoms, risk factors, complications, diagnosis, treatment, and prevention in detail.
Pathophysiology
When bacteria, viruses, or fungi infect the lungs, the immune response causes inflammation and fluid accumulation in the alveoli. This results in:
- Impaired oxygen diffusion
- CO₂ retention
- Reduced lung compliance
If untreated, this can progress to sepsis, ARDS, or respiratory failure.
Causes and Risk Factors
Common Causes
- Bacterial infections – Streptococcus pneumoniae, Haemophilus influenzae
- Viral infections – Influenza, RSV, COVID-19
- Fungal infections – Especially in immunocompromised patients
Major Risk Factors
- Age over 65 years
- Chronic diseases (COPD, diabetes, heart failure)
- Smoking
- Immunosuppression
- Prolonged immobility
- Ventilator use (Ventilator-Associated Pneumonia – VAP)
Signs and Symptoms
Respiratory Symptoms
- Productive cough with yellow or green sputum
- Shortness of breath (dyspnea)
- Fine or coarse crackles on auscultation
- Pleuritic chest pain
- Pleural friction rub (grating sound during breathing)
Systemic Symptoms
- Fever (>100.4°F / 38°C)
- Altered mental status (especially in elderly)
- Restlessness, agitation, confusion
- Fatigue
Critical Complications
1. Pleural Effusion
- Fluid accumulation between lung and chest wall
- Signs: chest pain, dyspnea, diminished breath sounds, dull percussion note
2. Acute Respiratory Distress Syndrome (ARDS)
- Severe inflammation → stiff, noncompliant lungs
- Refractory hypoxemia (low PaO₂ not improved with oxygen)
- Signs: agitation, restlessness, confusion
3. Septic Shock
- Infection spreads to bloodstream → severe hypotension, multiple organ failure
- Signs: systolic BP < 90 mmHg, MAP < 65 mmHg, cold extremities, low urine output
Diagnosis
- Sputum culture (before antibiotics) – identifies causative organism
- Chest X-ray – shows consolidation or infiltrates
- Blood tests – WBC > 10,000, elevated inflammatory markers
- Pulse oximetry / ABG – assess oxygenation
Treatment & Patient Care
1. Antibiotics
- Prescribed based on culture results
- Complete full course to prevent recurrence
2. Supportive Care
- Oxygen therapy for hypoxia
- Fluids (2–3 L/day) to thin mucus
- Antipyretics for fever
3. Mobilizing Secretions
- Chest physiotherapy
- TCDB – Turn, Cough, Deep Breathe
- Huff coughing technique
- Incentive spirometry
4. Avoid
- Cough suppressants (unless prescribed for comfort)
- Prolonged bed rest
Prevention
- Pneumonia vaccine (every 5 years for high-risk groups)
- Smoking cessation
- Handwashing
- Early mobilization after surgery
- Oral hygiene (especially in ventilated patients)
Quick Reference Table: Pneumonia Overview
| Feature | Details |
|---|---|
| Cause | Bacteria, viruses, fungi |
| Risk Groups | Elderly, chronic illness, smokers |
| Key Symptoms | Fever, cough, dyspnea, chest pain |
| Complications | Pleural effusion, ARDS, septic shock |
| Diagnosis | Sputum culture, chest X-ray, WBC count |
| Treatment | Antibiotics, oxygen, physiotherapy |
| Prevention | Vaccination, hygiene, mobility |
Frequently Asked Questions (FAQs)
1. How long does pneumonia recovery take?
Most healthy adults recover in 1–3 weeks, though fatigue may last longer.
2. Can pneumonia be treated at home?
Mild cases may be managed with oral antibiotics and rest, but severe cases need hospitalization.
3. Is pneumonia contagious?
Yes, bacterial and viral pneumonia can spread via respiratory droplets.
4. Can pneumonia cause permanent lung damage?
Severe or repeated infections may cause scarring, reducing lung capacity.
5. What is the difference between hospital-acquired and community-acquired pneumonia?
Hospital-acquired pneumonia occurs ≥48 hours after admission and often involves more resistant bacteria.
