Introduction
- The terms pneumonia and pneumonitis strictly represent any inflammatory condition involving the lungs, which include the visceral pleura, connective tissue, airways, alveoli, and vascular structures.
- Lower respiratory tract infection (LRTI) is frequently used interchangeably to include bronchitis, bronchiolitis, and pneumonia, or any combination of the three.
Aetiology
Age
- Early onset neonatal pneumonia
- Late onset neonatal pneumonia
- 1 month to 2 years old
- 2 to 5 years old
- 5 to 13 years old
Type of Penumonia
- Bacterial
- Atypical Bacterial
- Viral
Pathophysiology
- Pneumonia is an invasion of the lower respiratory tract, below the larynx by pathogens either by inhalation, aspiration, respiratory epithelium invasion, or hematogenous spread.
- There are barriers to infection that include anatomical structures (nasal hairs, turbinates, epiglottis, cilia), and humoral and cellular immunity.
- Once these barriers are breached, infection, either by fomite/droplet spread (mostly viruses) or nasopharyngeal colonization (mostly bacterial), results in inflammation and injury or death of surrounding epithelium and alveoli. This is ultimately accompanied by a migration of inflammatory cells to the site of infection, causing an exudative process, which in turn impairs oxygenation.
- Lobar pneumonia
- The first stage occurs within 24 hours and is characterized by alveolar edema and vascular congestion. Both bacteria and neutrophils are present.
- Red hepatization is the second stage, and it has the consistency of the liver. The stage is characterised by neutrophils, red blood cells, and desquamated epithelial cells. Fibrin deposits in the alveoli are common.
- The third of gray hepatization stage occurs 2-3 days later, and the lung appears dark brown. There is an accumulation of hemosiderin and hemolysis of red cells.
- The fourth stage is the resolution stage, where the cellula infiltrates is resorbed, and the pulmonary architecture is restored. If the healing is not ideal, then it may lead to parapneumonic effusions and pleural adhesions.
- In bronchopneumonia, there is often patchy consolidation of one or more lobes. The neutrophilic infiltrate is chiefly around the center of the bronchi.
Clinical Presentation
History
- Fever, cough and tachypnea is suggestive of pneumonia.
- Fever - infants with bacterial pneumonia are often febrile, viral or atypical may have low grade fever or afebrile.
- Signs of respiratory distress include
- tachypnea,
- hypoxemia (peripheral arterial oxygen saturation [SpO2] <90 percent on room air at sea level),
- increased work of breathing (intercostal, subcostal, or suprasternal retractions; nasal flaring; grunting; use of accessory muscles),
- apnea, and
- Constitutional symptoms, e.g headache, pleuritic chest pain, abdominal pain, vomiting, diarrhea, pharyngitis
- Cyanosis in very severe cases.
- Travel history
Examination
- Crackles
- Decreased breath sounds
- Bronchial breath sounds (louder than normal, with short inspiratory and long expiratory phases, and higher-pitched during expiration), egophony (E to A change)
- Bronchophony (the distinct transmission of sounds such as the syllables of "ninety-nine")
- Whispered pectoriloquy (transmission of whispered syllables)