Introduction à la Pneumonie Sévère

Study Notes

Severe pneumonia is a serious lung infection requiring urgent medical attention.
It's characterized by acute inflammation of the lung's alveoli, caused by infection, leading to significant breathing difficulties.

Pathogens: Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, viruses (influenza, COVID-19), atypical bacteria.
Risk factors: Advanced age, comorbidities (chronic diseases), immunocompromised status, smoking, alcoholism.
At-risk populations: Elderly individuals, infants, immunocompromised patients, those hospitalized for prolonged periods.
Epidemiology has evolved due to antibiotic-resistant bacterial strains and vaccination campaigns.

Massive inflammatory infiltration: Lungs are filled with numerous inflammatory cells (neutrophils, macrophages, lymphocytes), releasing inflammatory mediators (cytokines), damaging lung tissue and causing edema.
Alveolo-capillary barrier disruption: Inflammatory infiltration and damage to alveolar epithelial cells worsen gas exchange by thickening the alveolar-capillary membrane.
Fibrin production: Fibrin accumulation in the alveoli contributes to lung consolidation and respiratory mechanics impairment.
Reduced lung compliance: The above factors diminish the lung's ability to expand, making breathing increasingly difficult.
Systemic inflammatory response: Severe pneumonia can trigger a systemic inflammatory response syndrome (SIRS) characterized by fever, tachycardia, tachypnea, and altered mental status.

Signs: Cough (productive or non-productive), fever, dyspnea, chest pain exacerbated by breathing, fatigue, anorexia, loss of appetite.
Other alarming signs: Cyanosis, confusion, tachycardia, hypotension.
Clinical examination: Tachypnea, cyanosis, use of accessory respiratory muscles, chest pain, dullness on percussion, abnormal breath sounds, rales, crackles.

Imaging: Chest X-ray, CT scan to confirm pneumonia diagnosis and assess extent.
Blood tests: complete blood count, inflammatory markers (e.g., CRP), blood gases, liver and kidney function tests, to detect infections and potential organ damage.
Other tests: bronchoscopy (if needed), pleural fluid aspiration.

Other infections (tuberculosis, aspergillosis, mycoplasma or chlamydia pneumonia).
Exacerbation of chronic obstructive pulmonary disease (COPD).
Pulmonary embolism potentially mimicking pneumonia.
Left heart failure edema.
Lung cancer.
Autoimmune diseases (lupus).
Foreign body aspiration.

Respiratory complications: acute respiratory distress syndrome (ARDS), abscess, empyema, pleurisy, pulmonary fibrosis; extra-pulmonary complications: sepsis, organ dysfunction.

Antibiotics (tailored to suspected pathogen, initial empiric, followed by targeted therapy based on culture & sensitivity).
Supportive therapy: oxygen therapy, mechanical ventilation (for respiratory failure), symptom management, treatment of complications.