Overview
This lecture covers Acute Respiratory Distress Syndrome (ARDS), including its causes, pathophysiology, clinical presentation, and key nursing interventions.
ARDS Basics
- ARDS is a type of rapid-onset respiratory failure due to fluid leakage from capillaries into alveolar sacs.
- This leakage impairs gas exchange and can cause alveolar collapse, leading to hypoxemia (low blood oxygen).
- ARDS is a life-threatening condition with a high mortality rate, often requiring intensive care.
Causes of ARDS
- Indirect causes: systemic inflammation from conditions like sepsis (most common), severe burns, multiple blood transfusions, pancreatitis, or drug overdose.
- Direct causes: lung injuries like pneumonia, aspiration, inhalation of toxins, near drowning, or embolism.
Pathophysiology & Phases
- Exudative phase (~24 hours): capillary membrane damage leads to protein-rich fluid entering alveoli, reduced surfactant, alveolar collapse, and formation of hyaline membrane.
- Proliferative phase (~14 days): body attempts repair with dense, fibrous tissue, worsening lung compliance and hypoxemia.
- Fibrotic phase (~3 weeks): lung fibrosis results in nonfunctional "dead space," causing permanent lung damage.
Signs & Symptoms
- Early: subtle, possible normal or slight crackles in lung sounds.
- Progressive: severe dyspnea, increased respiratory rate, refractory hypoxemia (doesn't improve with oxygen), cyanosis, confusion, chest retractions, widespread crackles.
- Hallmark: refractory hypoxemia and "white-out" or bilateral infiltrates on chest X-ray.
Nursing Interventions & Management
- Goal: maintain airway/oxygenation (PaO2 ≥ 60 mmHg, O2 sat ≥ 90%).
- Most patients require mechanical ventilation with high positive end-expiratory pressure (PEEP).
- Monitor for complications: hypotension, decreased cardiac output, pneumothorax, subcutaneous emphysema.
- Use prone positioning to improve oxygenation and ventilation/perfusion matching.
- Pulmonary artery wedge pressure helps distinguish ARDS (<18 mmHg) from cardiac causes.
- Monitor renal output, mental status, vital signs, and prevent pressure injuries.
- Administer corticosteroids for inflammation, antibiotics for infection, GI drugs for ulcer prevention, and ensure nutritional support.
- Watch for ventilator-acquired infections and nutrition problems.
Key Terms & Definitions
- ARDS (Acute Respiratory Distress Syndrome) — Rapid-onset respiratory failure from fluid leakage into alveoli.
- Alveoli — Tiny lung sacs where gas exchange occurs.
- Hypoxemia — Low blood oxygen level.
- Surfactant — Substance reducing alveolar surface tension, preventing collapse.
- PEEP (Positive End-Expiratory Pressure) — Ventilator setting to keep alveoli open.
- Refractory Hypoxemia — Hypoxemia unresponsive to high oxygen.
- Hyaline Membrane — Dead cell/protein layer reducing lung elasticity.
- Pulmonary Edema — Fluid accumulation in lungs.
- Prone Positioning — Laying patient on their stomach to improve lung function.
Action Items / Next Steps
- Take the free quiz on ARDS.
- Review pathophysiology and phases of ARDS.
- Remember hallmark features: refractory hypoxemia and white-out on chest X-ray.
- Study nursing interventions and monitoring priorities.