ARDS

Acute Respiratory Distress Syndrome (ARDS) is a severe lung injury that can occur due to various causes, such as:
- Trauma (e.g., car accident, blast injury)
- Infections
- Toxins
- Systemic shock
- Irritant gases
- Near-drowning
- Aspiration of stomach contents
ARDS leads to:
1. *Diffuse alveolar damage*: Widespread injury to the lung epithelium (the thin layer of cells lining the air sacs).
2. *Respiratory failure*: Victim experiences severe breathing difficulties, becoming hypoxaemic (low oxygen levels in the blood).
3. *Lung changes*:
- Stiff, heavy lungs that retain their shape after removal (like a "dry sponge").
- Histological changes:
- Initial phase (days 1-3): Shedding of type I pneumocytes, intra-alveolar exudates, hyaline membrane formation, and patchy alveolar hemorrhage.
- Proliferative phase (after a few days): Type II pneumocytes fill the alveoli, and a mononuclear response infiltrates the interstitial areas.
- Eventual pulmonary fibrosis (scarring) may occur in survivors, leading to long-term lung damage.
Respirator lung is a similar condition that develops in patients who have been on mechanical ventilation for an extended period. It's characterized by:
- Stiff, rigid lungs
- Microscopic changes: Proteinaceous fluid and proliferative cells in the alveoli